AU2020344119B2

AU2020344119B2 - Improved fiber cement products and methods for the production thereof

Info

Publication number: AU2020344119B2
Application number: AU2020344119A
Authority: AU
Inventors: Ruben Bordin; Julien SOULHAT
Original assignee: Etex Services NV; Etex Building Performance International SAS
Current assignee: Etex Services NV; Etex Building Performance International SAS
Priority date: 2019-09-09
Filing date: 2020-09-04
Publication date: 2026-03-05
Anticipated expiration: 2040-09-04
Also published as: EP4028376A1; AU2020344119A1; WO2021048020A1; BR112022003334A2

Description

PCT/EP2020/074802

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IMPROVED FIBER CEMENT PRODUCTS AND METHODS FOR THE PRODUCTION THEREOF

Field of the invention

The present invention relates to fiber cement products comprising at least two layers, wherein the

two layers each have a different density. The present invention further relates to methods for the

manufacturing of these fiber cement products as well as to uses of these fiber cement products in

the building industry and a building system comprising the fiber cement products.

Background of the invention

Fiber cement products, essentially consisting of water, cement and fibers, have been used for

buildings since the nineteenth century and have a typical density of between about 1.1-1.9 g/cm³.

The variation in density is achievable by compression and dewatering of the fiber cement slurries

used in manufacture and by varying the amount of fibers used. At these densities, the cement-

based matrix has few voids, resulting in lower water absorption which has usually been considered

necessary for good durability performance of cement matrices.

In comparison, the density of natural timber sheets typically ranges from about 0.7-0.9 g/cm3 for

dry hardwoods and from about 0.38-0.6 g/cm³ for dry softwoods. Hence, typical fiber cement

products are harder, heavier and have a reduced workability compared to timer-based products.

Workability encompasses the ease with which the products are handled, installed and finished.

Typically, timber-based products as well as fiber cement products are fixed by using nails or

threaded fasteners, such as screws. While nails are usually easier and faster to install, screws have

stronger holding abilities, deliver a higher tensile strength than nails and can draw pieces together.

However, due to the high density and hardness of fiber cement products, even screws with sharp

tips are hard to start. Furthermore, when installing fiber cement products using screws, excess fiber

cement material collects around the screw head which makes a smooth finishing of the fiber

cement boards difficult or even impossible.

In the prior art this problem is solved by pre-drilling clearance holes or by removing the excess fiber

cement material by sanding the fiber cement products before the finishing step. However, this

makes the installation and finishing of fiber cement products, in particular by using screws, a very

labor-intensive job.

Therefore, there is a need for improved fiber cement products which have a better workability, are easier to install and easier to finish, in particular when screws are used during installation, while retaining excellent mechanical performance, durability, fire resistance, rot proof and water resistant properties. 5 A reference herein to a patent document or any other matter identified as prior art, is not to be 2020344119

taken as an admission that the document or other matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Summary of the invention 10 The inventors have now surprisingly found that it is possible to provide fiber cement products fulfilling the above-mentioned needs. Thus, an aspect of the present invention is to provide fiber cement products having an improved workability while retaining a good mechanical performance and good water-resistant properties. In this respect, the present inventors have achieved to develop fiber cement products containing 15 at least two different fiber cement materials. In particular, the fiber cement products of the present invention at least comprise a first layer or top layer, which is made of a low-density fiber cement composition comprising at least one lightweight filler, and a second layer or bottom layer, which is made of a fiber cement composition having a medium to high density.

20 In a first aspect, the present invention provides fiber cement products comprising a first layer and a second layer characterized in that: - the first layer is the top layer and the first layer material at least comprises cement and a lightweight filler and has a density in the range from about 0.4 to about 0.9 g/cm³, and - the second layer is the bottom layer and covers only one of the main surfaces of the first 25 layer wherein the second layer material at least comprises fibers and cement and has a density in the range from about 0.9 to about 1.4 g/cm³. The inventors have found that the weight of the fiber cement products of the present invention is reduced whereas the mechanical, fire-resistant and water-resistant properties are the same or even improved when compared to fiber cement products known in the art. The inventors have further 30 surprisingly found that the fiber cement products of the present invention are much easier to install, when using screws, and are less labor intensive to finish. Although there is some excess fiber cement material that collects around the screw head, the excess material can easily be removed by brushing or rubbing over the screw head without the need of more aggressive and labor-intensive

methods such as sanding. The inventors have further surprisingly found that during installation of fiber cement products of the present invention, screws are able to penetrate the product more easily and are easier to start.

5 In a second aspect, the present invention provides methods for the production of fiber cement 2020344119

products as defined herein, at least comprising the steps of:

i) Providing a first cementitious material at least comprising cement and a lightweight filler and having a density in the range from about 0.4 to about 0.9 g/cm³, 10 ii) Providing a second fiber cement material at least comprising fibers and cement and having a density in the range from about 0.9 to about 1.4 g/cm³, and iii) Assembling the first cementitious material and the second fiber cement material to obtain a fiber cement product comprising a first layer of the first cementitious material and a second layer of the second fiber cement material. 15 In a third aspect, the present invention provides uses of a fiber cement product as defined herein as a building product.

In one set of embodiments, the present invention provides use of a bi-layered fiber cement product 20 as a building product, wherein the bi-layered fiber cement product comprises a first layer of a first layer material, which first layer is covered by at least one second layer of a second layer material, wherein: - the first layer material has a density of between about 0.4 and about 0.9 g/cm3 inclusive, and comprises cement and between 1 wt% and 70 wt% (relative to the total dry weight of said first 25 layer material) of a lightweight filler, wherein the first layer material further comprises fibers in an amount of between 1 wt% and 5 wt% relative to the total dry weight of said first layer material, wherein said fibers in said first layer material comprise cellulose fibers, - said at least one second layer covers only one of the main surfaces of the first layer, thereby forming a bi-layered fiber cement product, 30 - the second layer material has a density of between about 1.0 and about 1.4 g/cm 3 inclusive, and at least comprises fibers and cement, wherein the second layer material comprises fibers in an amount of between 6 wt% and 10 wt% relative to the total dry weight of the second layer material, wherein said fibers in the second layer material comprise cellulose fibers, and

3a 16 Feb 2026

- the bi-layered fiber cement product is fixed to a substrate, with the second layer acting as a bottom layer facing the substrate and the first layer acting as a top layer.

In a fourth aspect, the present invention provides a building system comprising at least two fiber 5 cement products as defined herein jointed to each other, thereby forming a building system. 2020344119

The inventors have surprisingly found that a building system comprising the fiber cement products according to the present invention, such as fiber cement boards, is much less prone to cracking, in particular to cracking in the joint area where the fiber cement products are jointed together, thereby exhibiting a more durable, crack free joint. 10 In one set of embodiments, the present invention provides a building system comprising a wall to which a fiber cement product is fixed, wherein the fiber cement product is a bi-layered fiber cement product comprising a first layer of a first layer material, which first layer is covered by at least one second layer of a second layer material, wherein: 15 - the first layer material has a density of between about 0.4 and about 0.9 g/cm3 inclusive, and comprises cement and between 1 wt% and 70 wt% (relative to the total dry weight of said first layer material) of a lightweight filler, wherein the first layer material further comprises fibers in an amount of between 1 wt% and 5 wt% relative to the total dry weight of said first layer material, wherein said fibers in said first layer material comprise cellulose fibers, 20 - said at least one second layer covers only one of the main surfaces of the first layer, thereby forming a bi-layered fiber cement product, - the second layer material has a density of between about 1.0 and about 1.4 g/cm 3 inclusive, and at least comprises fibers and cement, wherein the second layer material comprises fibers in an amount of between 6 wt% and 10 wt% relative to the total dry weight of the second layer 25 material, wherein said fibers in the second layer material comprise cellulose fibers, and - the fiber cement product is fixed with the second layer acting as a bottom layer facing the wall and the first layer acting as a top layer.

The independent and dependent claims set out particular and preferred features of the invention. 30 Features from the dependent claims may be combined with features of the independent or other dependent claims, and/or with features set out in the description above and/or hereinafter as appropriate.

3b 16 Feb 2026

The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The reference figures quoted below refer to the attached drawings. 5 2020344119

Detailed description

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It is to be noted that the term "comprising", used in the claims, should not be interpreted as being

restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to

be interpreted as specifying the presence of the stated features, steps or components as referred

to, but does not preclude the presence or addition of one or more other features, steps or

components, or groups thereof. Thus, the scope of the expression "a device comprising means A

and B" should not be limited to devices consisting only of components A and B.

Throughout this specification, reference is made to "one embodiment" or "an embodiment". Such

references indicate that a particular feature, described in relation to the embodiment is included in

at least one embodiment of the present invention. Thus, appearances of the phrases "in one

embodiment" or "in an embodiment" in various places throughout this specification are not

necessarily all referring to the same embodiment, though they could. Furthermore, the particular

features or characteristics may be combined in any suitable manner in one or more embodiments,

as would be apparent to one of ordinary skill in the art.

The following terms are provided solely to aid in the understanding of the invention.

As used herein, the singular forms "a", "an", and "the" include both singular and plural referents

unless the context clearly dictates otherwise.

The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with

"including", "includes", "having", "has" or "containing", "contains", and are inclusive or open-

ended and do not exclude additional, non-recited members, elements or method steps.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed

within the respective ranges, as well as the recited endpoints.

The term "about" as used herein when referring to a measurable value such as a parameter, an

amount, a temporal duration, and the like, is meant to encompass variations of +/-10% or less,

preferably +/-5% or less, more preferably +/-1% or less, and still more preferably +/-0.1% or less of

and from the specified value, insofar such variations are appropriate to perform in the disclosed

invention. It is to be understood that the value to which the modifier "about" refers is itself also

specifically, and preferably, disclosed.

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The terms "predetermined" and "predefined" as used herein when referring to one or more

parameters or properties generally mean that the desired value(s) of these parameters or

properties have been determined or defined beforehand, i.e. prior to the start of the process for

producing the products that are characterized by one or more of these parameters or properties.

"At least one" as used herein when referring to parts, entities, constituents, components, elements,

objects etc. is intended to be construed as one or more parts, entities, constituents, components,

elements, objects etc., such as one, two, three, four, five, six, seven, eight, nine, ten, or more parts,

entities, elements, objects etc.

"A part" as used herein refers to an entity, constituent, component, element and/or object of a

larger whole comprising two or more entities, constituents, components, elements and/or objects.

"At least one part of material" as used herein, such as for example in the expressions "at least one

part of lightweight material" or "at least one part of fiber cement material", means that one or

more parts of are made from or are consisting of this material. In this respect, "at least one part of

lightweight material" means that one or more parts of a larger multi-part whole are made from or

are consisting of lightweight material. In the same way, "at least one part of fiber cement material"

means that one or more parts of a larger multi-part whole are made from or are consisting of fiber

cement material.

The terms "(fiber) cementitious slurry" or "(fiber) cement slurry" as referred to herein generally

refer to slurries at least comprising water, fibers and cement. The fiber cement slurry as used in the

context of the present invention may also further comprise other components, such as but not

limited to, limestone, chalk, quick lime, slaked or hydrated lime, ground sand, silica sand flour,

quartz flour, amorphous silica, condensed silica fume, microsilica, metakaolin, wollastonite, mica,

perlite, vermiculite, aluminum hydroxide, pigments, anti-foaming agents, flocculants, lightweight

fillers and other additives. In the context of the processes of the present invention, the fiber cement

slurry can thus be provided by one or more sources of at least cement, water and fibers. Optionally,

these one or more sources of at least cement, water and fibers may operatively be connected to a

continuous mixing device constructed to form a cementitious fiber cement slurry.

"Fiber(s)" present in the fiber cement products or fiber cement slurry as described herein may be

for example process fibers and/or reinforcing fibers which may be organic fibers such as but not

limited to cellulose fibers and/or synthetic fibers such as but not limited to polyvinylalcohol,

PCT/EP2020/074802

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polyacrilonitrile, polypropylene, polyamide, polyester, polycarbonate or mixtures of two or more

thereof.

In particular embodiments, when using cellulose fibers or the equivalent of waste paper fibers, a

minimum of about 2wt%, such as at least about 3wt%, such as at least about 4wt% of these cellulose

fibers (compared to the total initial dry weight of the slurry) may be used. In further particular

embodiments, when exclusively cellulose fibers are used, between about 4wt% to about 12wt%,

such as more particularly, between about 7wt% and about 10wt% of these cellulose fibers

(compared to the total initial dry weight of the slurry) may be used. If cellulose fibers are replaced

by short mineral fibers such as rock wool, it is most advantageous to replace them in a proportion

of 1.5 to 3 times the weight, in order to maintain approximately the same content per volume. In

long and cut fibers, such as glass fiber rovings or synthetic high-modulus fibers, such as

polypropylene, polyvinyl acetate, polycarbonate or acrylonitrile fibers the proportion can be lower

than the proportion of the replaced cellulose fibers. The fineness of the fibers (measured in

Shopper-Riegler degrees, DEG SR herein after) is in principle not critical to the processes of the

invention. Yet in particular embodiments, where autoclave-cured fiber cement products are

envisaged, it has been found that a range between about 15 DEG SR and about 45 DEG SR can be

particularly advantageous for the processes of the invention.

"Cement" present in the fiber cement products or fiber cement slurry as described herein may be

for example but is not limited to Portland cement, cement with high alumina content, Portland

cement of iron, trass-cement, slag cement, plaster, calcium silicates formed by autoclave treatment

and combinations of particular binders. In more particular embodiments, cement in the products

of the invention is Portland cement.

"Binder" or "mineral binder" or "hydraulic binder" as used herein may refer, without limitation, to

cement, mixtures of cement and quartz sand, mixtures of cement and slaked lime (Ca(OH)2 and

optionally quartz or mixtures of slaked lime and quartz flour.

"Fiber cement product" as used herein generally refers to any object or product comprising fiber

cement material.

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"Fiber cement material" refers to a material essentially consisting of a fiber cement composition,

which composition at least comprises fibers and cement.

The terms "first layer", "top layer", "low density layer" or "low density first layer" as used

interchangeably herein refer to the low density layer of the fiber cement products of the present

invention, which layer comprises a first cementitious material or first layer material and has an

average density in the range from about 0.4 to 0.9 g/cm³ and is covered on at least 60% of only one

of its main surfaces by a high-density second layer (also referred to herein as "the bottom layer").

The terms "second layer", "bottom layer", "bottom fiber cement layer", "high density layer" or

"high density second layer" as used interchangeably herein refer to the high density layer of the

fiber cement products of the present invention, which layer comprises a second fiber cement

material or second layer material and has an average density in the range from about 0.9 to 1.4

g/cm³ and covers at least 60% of only one main surface of the first layer.

When generally referring to a "fiber cement layer" herein, it is intended to refer to any substantially

flat, optionally substantially rectangular, layer or cake essentially consisting of a fiber cement

composition and having a thickness of at least about 0.2 mm, in particular between about 0.5 mm

and 200 mm, more particularly between about 1 mm and about 150 mm, most particularly between

about 2 mm and about 100 mm.

A "Hatschek fiber cement layer" or a "Hatschek layer" as interchangeably used herein refers to a

fiber cement layer (as defined herein), which is produced according to a Hatschek process, which

at least comprises the steps of:

(i) building a fiber cement film on a sieve, which rotates in contact with a fiber cement slurry in a

vat;

(ii) transferring the fiber cement film from the sieve to a felt transport belt, and

(iii) accumulating the fiber cement film on an accumulator roll via the felt transport belt.

A "non-Hatschek fiber cement layer" or a "non-Hatschek layer" as interchangeably used herein

refers to a fiber cement layer (as defined herein), which is formed according to a fiber cement layer

production process other than a conventional Hatschek process.

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In the context of the present invention, the use of the term "fiber cement film" refers to such a thin

layer of fiber cement being applied onto the felt transport belt by one or more sieves rotating in a

fiber cement slurry that is present in one or more vats of the Hatschek process. As may be

understood from the aforementioned, series of thin fiber cement layers are produced on the one

or more sieves from the Hatschek machine and subsequently superimposed and transferred from

the one or more sieves to the transport belt, resulting in one or more uncured Hatschek fiber

cement layers after accumulation on an accumulation roll. Thus, it will be clear that, when referring

to "a fiber cement film" in the context of the present invention, it is to be understood that this term

encompasses, where applicable, both the meaning of one single fiber cement film having a

thickness of between about 0.01 mm and about 0.9 mm, such as in particular between about 0.05

mm and about 0.5 mm, such as between about 0.1 mm and about 0.4 mm, such as about 0.3 mm.

(i.e. one thin layer of fiber cement also called a mono-layer, a single layer or a primary layer, that is

applied onto the felt transport belt by a sieve from a vat of the Hatschek process) as well as the

meaning of a layer comprising two or more superimposed fiber cement layers, each having a

mm and about 0.5 mm, such as between about 0.1 mm and about 0.4 mm, such as about 0.3 mm

(i.e. two or more superimposed thin layers of fiber cement applied onto the felt transport belt by

two or more sieves from a vat of the Hatschek process). The skilled person will understand,

depending on the particular configuration of the Hatschek section, that when referring to processes

of the invention in general both meanings of the term "fiber cement film" as described above will

be applicable, while in more particular embodiments only one of both meanings are applicable. For

instance, in a particular case where only one sieve is used in the Hatschek section for performing

the processes of the invention, "a fiber cement film" as used herein means only one single layer

having a thickness of between about 0.01 mm and about 0.9 mm that is applied onto the felt

transport belt by the sieve from a vat of the Hatschek process. On the other hand, where two or

more sieves are used in the Hatschek section for performing the processes of the invention, "a fiber

cement film" as used herein means a superposition of two or more single layers, each having a

thickness of between about 0.01 mm and about 0.9 mm, which are applied onto the felt transport

belt by the sieve from a vat of the Hatschek process.

A "(fiber cement) sheet" as used herein, also referred to as a panel or a plate, is to be understood

as a substantially flat, usually rectangular element, a fiber cement panel or fiber cement sheet being

provided out of fiber cement material. The panel or sheet has two main faces or surfaces, being the

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surfaces with the largest surface area. The sheet can be used to provide an outer surface to walls,

both internal as well as external a building or construction, e.g. as façade plate, siding, ceiling board,

flooring panel etc.

The term "lightweight material" as used herein refers to any material that, when used as an

ingredient, component or constituent in a (building) product (formulation), adds a significant

amount of volume without adding a significant amount of weight. Lightweight materials as referred

to herein have a density of between about 0.01 to about 0.90 g/cm³.

The term "filler(s)" as used herein refers to any material(s) interacting with binders in composites,

such as cement, which improve particle packing and give the composite other properties. The use

of fillers also allows to reduce the amount of cement to be used in cementitious products without

resulting in loss of mechanical strength. "Lightweight filler(s)" as used herein refers to filler(s) made

from or consisting of lightweight material.

The term "aggregate" as used herein refers to a broad category of coarse particulate material used

in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic

aggregates. A category of aggregate materials can be used as specialty lightweight aggregates, such

as but not limited to clay, pumice, (expanded) perlite, (expanded) vermiculite, expanded

polystyrene, extruded polystyrene, foam, concrete foam, pumice, calcium silicate hydrate gel (CSH

gel), microspheres, cenospheres (ceramic microspheres) and/or alkali resistant expanded glass

spheres / beads, xonotlite, expanded shale and mixtures of two or more thereof.

"Density" as used in the context of the present invention refers to the average density of a fiber

cementitious material or to the average density of a fiber cement product and represents the mass

per unit volume (expressed in g/cm³ herein) of the fiber cement material or fiber cement product.

The density as referred to herein can be measured by any suitable standard test known in the art.

For example, a sample of the fiber cement material or fiber cement product can be taken and the

volume of the specimen can be determined by any method capable of giving a result accurate to

within 2% of the results obtained by the water displacement method.

Water displacement test can be performed per Standard Test Methods C20, in which the volume

(V) of the test specimen is obtained in cubic centimeters by subtracting the suspended weight (W)

from the saturated weight (S), both in grams as follows:

V=W-S where:

V = volume, cm³,

W = saturated weight, g, and

S = suspended weight, g.

This assumes that 1 cm³ of water weighs 1 g. This is true within about three parts in 1000 for water

at room temperature. Suspended weight (S) is obtained for each test specimen by suspending the

specimen in a loop or halter of AWG gage No. 22 (0.644 mm) copper wire hung from one arm of

the balance. The balance shall be previously counter balanced with the wire in place and immersed

in water to the same depth as is determining the suspended weight, blot each specimen lightly with

a moistened smooth linen or cotton cloth to remove all drops of water from the surface, and

determine the saturated weight (W) in grams by weighing in air to the nearest 0.1 g.

The density of the fiber cement specimen can then be calculated in g/cm³ using the equation:

Density= W/V in grams per cubic centimeter (g/cm³)

where: where: W = dry mass of specimen, g, and

V = volume, cm³.

The term "water-permeable" as used herein when referring to a water-permeable (region of a)

transport belt generally means that the material of which the water-permeable (region of the) belt

is made allows water to flow through its structure to a certain extent.

The "water-permeability" as used herein when referring to the water-permeability of a (region of

a) transport belt generally refers to the extent or degree to which the material of which the water-

permeable (region of the) belt is made, allows water to flow through its structure. Suitable

materials for water-permeable transport belts are known to the person skilled in the art, such as

but not limited to felts.

The invention will now be further explained in detail with reference to various embodiments. It will

be understood that each embodiment is provided by way of example and is in no way limiting to

the scope of the invention. In this respect, it will be clear to those skilled in the art that various

modifications and variations can be made to the present invention without departing from the

scope or spirit of the invention. For instance, features illustrated or described as part of one

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embodiment, can be used in another embodiment to yield a still further embodiment. Thus, it is

intended that the present invention covers such modifications and variations as encompassed

within the scope of the appended claims and equivalents thereof.

[First layer]

Thus, the fiber cement products according to the present invention comprise a first layer of low-

density cementitious material, which at least comprises cement and a lightweight filler and has a

density in the range from about 0.4 to about 0.9 g/cm³.

The inventors have found that the low density first layer provides the fiber cement product with an

improved workability in terms of weight but also in terms of easier installation and finishing.

Without being bound to this theory, the inventors believe that the low density and thus softer,

more flexible first layer or top layer allows fastening means, in particular threaded fastening means,

such as screws, to penetrate the fiber cement product more easily. Hence, the driving of screws

into the fiber cement product during installation will be easier to start and it will be easier to make

the screws flush with the surface of the fiber cement product. When the screws are flush with the

surface of the fiber cement product after installation, it is much easier to finish the top surface and

the screws will be nearly invisible in the finished surface.

Furthermore, although some excess fiber cement material collects around the screw head while

the screw is driven into the fiber cement product, it is easily removed by gently brushing or rubbing

over the screw head and there is no need for more aggressive and more labor-intensive removal

methods such as sanding. The inventors believe that this advantageous effect is caused by the soft

and fluffy nature of the low density first layer.

When traditional fiber cement products are used it is more difficult to make the screws flush with

the surface and the excess fiber cement material which collects around the screw head is impossible

to remove by brushing or rubbing.

In one embodiment, the first layer of the fiber cement products according to the present invention

has a density in the range from about 0.5 g/cm³ to about 0.8 g/cm³. In particular embodiments, the

first layer of the fiber cement products according to the present invention has a density in the range

from about 0.55 g/cm³ to about 0.75 g/cm³, such as of about 0.6 g/cm³ or of about 0.7 g/cm³.

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In particular embodiments, the fiber cement products according to the present invention are

characterized in that the first layer material comprises a lightweight filler in an amount in the range

from 5 wt% to 75 wt%, relative to the total dry weight of the first layer material. In further particular

embodiments, the fiber cement products according to the present invention are characterized in

that the first layer material comprises a lightweight filler in an amount in the range from 5 wt% to

70 wt%, relative to the total dry weight of the first layer material, such as particularly from 10 wt%

to 60 wt%, more particularly from 15 wt% to 50 wt%, most particularly from 20 wt% to 40 wt% of

lightweight filler, relative to the total dry weight of the first layer material.

The choice of the lightweight filler in the first layer of the fiber cement product according to the

present invention is not particularly limited. This lightweight filler may be a lightweight aggregate

(as defined herein), such as but not limited to a masonry-lightweight aggregate and/or a structural

lightweight aggregate.

In further particular embodiments, the fiber cement products according to the present invention

are characterized in that the first layer material comprises a lightweight filler which is chosen from

the group consisting of expanded perlite, expanded vermiculite, expanded polystyrene, extruded

polystyrene, foam, concrete foam, calcium silicate hydrate gel (CSH gel), microspheres,

cenospheres (ceramic microspheres) and (alkali resistant) expanded glass spheres / beads,

xonotlite, expanded shale or any suitable combination thereof.

characterized in that the first layer material comprises a lightweight filler which is expanded perlite.

are characterized in that the first layer material comprises expanded perlite as a lightweight filler

in an amount in the range from about 5 wt% to 40 wt%, such as from about 20 wt% to 40 wt%,

relative to the total dry weight of the first layer material.

In other particular embodiments, the fiber cement products according to the present invention are

characterized in that the first layer material comprises a lightweight filler which is expanded

polystyrene. In further particular embodiments, the fiber cement products according to the present

invention are characterized in that the first layer material comprises expanded polystyrene as a

lightweight filler in an amount in the range from about 5 wt% to 30 wt%, relative to the total dry

weight of the first layer material.

In certain other embodiments, the fiber cement products according to the present invention are

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lightweight filler in an amount in the range from about 1 wt% to 30 wt%, such as in the range from

about 1 wt% to 20 wt%, relative to the total dry weight of the first layer material.

characterized in that the first layer material comprises a lightweight filler which is extruded

invention are characterized in that the first layer material comprises extruded polystyrene as a

characterized in that the first layer material further comprises fibers.

are characterized in that the first layer material comprises fibers in an amount in the range from 0

wt% to 5 wt% relative to the total dry weight of the first layer material. In yet further particular

that the first layer material comprises fibers in an amount in the range from 1 wt% to 4 wt%, relative

to the total dry weight of the first layer material, such as about 2 wt%, about 3 wt% or about 4 wt%

of fibers relative to the total dry weight of the first layer material.

characterized in that the first layer material comprises cellulose fibers. In particular embodiments,

the fiber cement products according to the present invention are characterized in that the first layer

material comprises cellulose fibers in an amount in the range from 0 wt% to 5 wt%, relative to the

total dry weight of the first layer material. In yet further particular embodiments, the fiber cement

products according to the present invention are characterized in that the first layer material

comprises cellulose fibers in an amount in the range from 1 wt% to 4 wt%, relative to the total dry

weight of the first layer material, such as about 2 wt%, about 3 wt% or about 4 wt% of cellulose

fibers, relative to the total dry weight of the first layer material.

In certain particularly preferred embodiments, the fiber cement products according to the present

invention are characterized in that the first layer material comprises 0 wt% cellulose fibers and

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comprises at least 1 wt% of synthetic fibers having a length of between 2 and 12 mm and a thickness

in the range from 0.1 dtex to 15 dtex, preferably in the range from 0.5 dtex to 5 dtex, most

preferably of about 2 dtex.

are characterized in that the first layer material comprises chemical pulps, such as, but not limited

to, pulps originating from a Kraft process.

are characterized in that the first layer material comprises mechanical pulps, such as, but not

limited to, SGW pulp - Stone Groundwood pulp, PGW pulp - Pressure Groundwood pulp, RMP -

Refiner Mechanical Pulp, TMP - Thermo Mechanical Pulp, CTMP - Chemi Thermo Mechanical Pulp,

as it can be found in a recycled furnish.

are characterized in that the first layer material comprises recycled fiber cement waste, such as

recycled autoclaved fiber cement waste, recycled air-cured fiber cement waste and/or milled or

ground fiber cement waste.

The first layer material of the fiber cement products according to the present invention further

comprises cement, which can be any suitable cement type (as defined herein). In particular

embodiments, the first layer material of the fiber cement products according to the present

invention comprises cement in an amount of 5 wt% to 85 wt%, relative to the total dry weight of

the first layer material, such as 5 wt% to 80 wt%. In further particular embodiments, the first layer

material of the fiber cement products according to the present invention comprises cement in an

amount of 10 wt% to 75 wt%, relative to the total dry weight of the first layer material. In yet

further particular embodiments, the first layer material of the fiber cement products according to

the present invention comprises cement in an amount of 20 wt% to 70 wt%, such as more

particularly 30wt% to 65wt%, such as most particularly 40wt% to 60 wt%, relative to the total dry

weight of the first layer material.such as 20 wt% to 75 wt%.

[Second layer]

It is understood that the first layer, as detailed above, is covered (on at least 60% of one of its main

surfaces) by a second layer, which at least comprises fibers and cement. The first layer material has

a lower density than the second layer fiber cement material. It is further understood that all

definitions and preferences, as described above, equally apply for all further embodiments, as

described below.

The inventors have found that the high-density second layer ensures that the fiber cement end

product retains the same or similar mechanical strength and the same or similar water resistance

properties compared to a fiber cement product, which would completely and exclusively consist of

such high-density fiber cement material(s). Furthermore, the second layer ensures that the screws

are firmly anchored into the fiber cement product and that the screws do not easily wear out the

fiber cement material surrounding them when the fiber cement products are subjected to stress

after installation.

In one embodiment, the second layer of the fiber cement products according to the present

invention has a density in the range from about 0.95 g/cm³ to about 1.3 g/cm³, such as of about

1.0, 1.05, 1.1, 1.15, 1.20 or 1.25 g/cm³.

In particular embodiments, the present invention provides fiber cement products comprising a first

layer material, which first layer material is covered by a second layer, characterized in that:

- the first layer material at least comprises cement and a lightweight filler and has a density

in the range from about 0.4 to about 0.9 g/cm³, and

- the second layer material at least comprises fibers and cement and has a density in the

range from about 1.0 to about 1.4 g/cm³.

characterized in that the second layer material comprises cellulose fibers in an amount in the range

from 6 wt% to 10 wt%, relative to the total dry weight the second layer material. In further

particular embodiments, the fiber cement products according to the present invention are

characterized in that the second layer material comprises cellulose fibers. In yet further particular

that the second layer material comprises cellulose fibers in an amount in the range from 7 wt% to

9 wt%, relative to the total dry weight the second layer material, such as about 7 wt%, about 8 wt%

or about 9 wt% of cellulose fibers relative to the total dry weight of the second layer material.

The second layer material further at least comprises cement, which can be any suitable type of

cement (as defined herein). In particular embodiments, the second layer material of the fiber

cement products according to the present invention comprises cement in an amount of 5 wt% to

95 wt%, relative to the total dry weight of the second layer material, such as 5 wt% to 90 wt%. In

further particular embodiments, the second layer material of the fiber cement products according

to the present invention comprises cement in an amount of 10 wt% to 90 wt%, relative to the total

dry weight of the second layer material. In yet further particular embodiments, the second layer

amount of 20 wt% to 85 wt%, such as more particularly 30wt% to 85wt%, such as most particularly

40wt% to 80 wt%, relative to the total dry weight of the second layer material. In even further

particular embodiments, the second layer material of the fiber cement products according to the

present invention comprises cement in an amount of 50 wt% to 85 wt%, such as more particularly

55wt% to 85wt%, such as most particularly 60wt% to 70 wt%, relative to the total dry weight of the

second layer material.

According to particular embodiments, the first layer material and/or the second layer material of

the fiber cement products according to the invention optionally comprise further components. Said

further components are known to those skilled in the art and may include, but are not limited to,

water, sand, silica sand flour, condensed silica fume, microsilica, fly-ashes, amorphous silica, ground

quartz, the ground rock, clays, pigments, kaolin, metakaolin, blast furnace slag, carbonates,

pozzolans, aluminium hydroxide, wollastonite, mica, perlite, calcium carbonate, and other additives

(e.g. colouring additives) and any suitable combinations thereof. It will be understood that each of

these components is present in suitable amounts, which depends on the type of the specific fiber

cement product and can be determined by the person skilled in the art without any undue burden.

In particular embodiments, the total quantity of such further components is preferably lower than

70 wt%, relative to the total initial dry weight of the first layer material and/or the second layer

material.

the fiber cement products according to the invention optionally comprise further additives to

enhance the appearance, easiness of production, storage, transport, handling and/or performance

of the product. Said further additives are known to those skilled in the art and may include, but are

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not limited to, dispersants, plasticizers, antifoam agents and flocculants. In particular

embodiments, the total quantity of further additives is preferably from about 0.1 wt% to about 1

wt% relative to the total initial dry weight of the first layer material and/or the second layer

material.

In particular embodiments, the present invention provides fiber cement products, where the first

layer is completely (i.e. all over one of its main surfaces) covered by a second layer of fiber cement

material, thereby forming a bi-layered fiber cement material.

The skilled person will understand that, in all embodiments, the second layer partially or completely

covers only one of the main surfaces of the first layer and can never cover both main surfaces since

then one could not refer to the first layer as the top layer and to the second layer as the bottom

layer. The skilled person will further understand that the terms top and bottom layer are not

important in relation to the manufacturing of the fiber cement products, however, they are

important when the fiber cement products are in use. In practice, the fiber cement products

according to the present invention are generally installed onto a substrate such as a wall. Here it is

important that the bottom layer, or second layer, faces the substrate while the first layer remains

on top and is also the layer that may be further finished, and which usually remains the visible side

of the fiber cement product.

In certain other embodiments, the invention provides fiber cement products, where the first layer

is partially covered by the second layer. In such embodiments, about 60% to about 100%, such as

about 95%, of one of the main surfaces of the first layer is covered by the second layer. In further

embodiments, the invention provides fiber cement products, where one of the main surfaces of

the first layer is essentially completely covered by the second layer, i.e. in these embodiments,

about 80% to about 100%, such as about 95%.

In particular embodiments, the fiber cement products according to the present invention are flat

(or at least substantially flat) multi-layered fiber cement products, such as flat multi-layered boards,

sheets, panels, sidings, planks, or plates. In such embodiments, the multi-layered fiber cement

products of the present invention comprise a first layer, which is covered on one of its largest

opposite surfaces by at least one second layer, characterized in that:

in the range from about 0.4 g/cm³ to 0.9 g/cm³, and

range from about 0.9 g/cm³ to about 1.4 g/cm³.

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are flat (or at least substantially flat) multi-layered fiber cement products, such as flat multi-layered

boards, sheets, panels, sidings, planks, or plates. In such embodiments, the multi-layered fiber

cement products of the present invention comprise a first layer, which is covered on one of its

largest opposite surfaces by at least one second layer, characterized in that:

in the range from about 0.4 g/cm³ to 0.9 g/cm³, and

range from about 1.0 g/cm³ to about 1.4 g/cm³.

are flat bi-layered fiber cement products, such as flat bi-layered boards, sheets, panels, sidings,

planks, or plates. In these particular embodiments, the present invention provides flat bi-layered

fiber cement products, characterized by the presence of a first layer having a density in the range

from about 0.4 g/cm³ to about 0.9 g/cm³ inclusive, which first layer is covered on one of its two

largest opposite surfaces (i.e. its largest lower surface or its largest upper surface) by one second

layer having a density in the range from about 0.9 g/cm³ to about 1.4 g/cm³ inclusive.

In yet further particular embodiments, the present invention provides flat multi-layered fiber

cement products, characterized by the presence of a first layer having a density in the range from

about 0.4 g/cm³ to about 0.9 g/cm³, which first layer is covered on one of its largest opposite

surfaces by a second layer having a density in the range from about 0.9 g/cm³ to about 1.4 g/cm³

which second layer is covered by at least one consecutive (i.e. overlapping) layer, each consecutive

layer having a density in the range from about 0.9 g/cm³ to about 1.4 g/cm³.

In particular embodiments, each consecutive layer present in the flat multi-layered fiber cement

products of the invention may have a different composition or may have the same composition as

the second layer, as long as these fiber cement layers comprise at least fibers and cement and have

a density in the range from 0.9 g/cm³ to 1.4 g/cm³. It is understood that all definitions and

preferences for the second layer, as described above, equally apply for each of the consecutive

layers covering the second layer.

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In particular embodiments, the first layer present in the flat multi-layered or bi-layered fiber cement

products of the invention has a thickness in the range from 1 mm to 100 mm, such as from 2 mm

to 80mm, such as from 3 mm to 60 mm, more particularly from 3 mm to 50 mm, most particularly

a thickness of about 8 mm, of about 12 mm, of about 16 mm, of about 18 mm, or of about 40 mm.

In particular embodiments, the second and consecutive layers present in the flat multi-layered or

bi-layered fiber cement products of the invention have a thickness in the range from 0.2 mm to 10

mm, such as from 0.5 mm to 5 mm, such as from 0.7 mm to 3 mm, more particularly from 0.8 mm

to 2 mm, most particularly a thickness of about 1 mm. In particular embodiments, the second and

consecutive layers present in the flat multi-layered or bi-layered fiber cement products of the

invention may each have thicknesses which are the same or which are different.

sheets, panels, sidings, planks, or plates, having a thickness in the range from 1.4 mm to 60 mm,

such as from 2 mm to 50 mm, such as from 5 mm to 40 mm, such as from 7 mm to 20 mm, more

particularly from 9 mm to 13 mm, most particularly a thickness of about 10 mm or about 11 mm.

The lengths and widths of the fiber cement products of the present invention are not critical to the

invention and may in principle be any suitable lengths and widths, which are appropriate for a given

application or use of these particular fiber cement products in the building industry.

The fiber cement products or sheets as referred to herein include roof, wall, ceiling or floor covering

products made out of fiber cement, such as fiber cement sidings, fiber cement boards, flat fiber

cement sheets, corrugated fiber cement sheets and the like. According to particular embodiments,

the fiber cement products according to the invention can be roofing or façade elements, flat sheets

or corrugated sheets.

According to further particular embodiments, the fiber cement products of the present invention

are fiber cement sheets.

[METHOD]

It is understood that all definitions and preferences, as described above, equally apply for all further

embodiments, as described below.

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In a second aspect, the present invention provides methods for manufacturing fiber cement

products as defined herein, at least comprising the steps of:

i) Providing a first cementitious material at least comprising cement and a lightweight

filler and having a density in the range from about 0.4 g/cm³ to about 0.9 g/cm³,

ii) Providing a second fiber cement material at least comprising fibers and cement and

having a density of in the range from about 0,9 g/cm³ to about 1.4 g/cm³, and

iii) Assembling the first cementitious material and the second fiber cement material

to obtain a fiber cement product comprising a first layer made of the first

cementitious material, which first layer covers a second layer made of the second

fiber cement material.

In particular embodiments, the present invention provides methods for the production of bi-

layered or multi-layered fiber cement products as described herein, the methods at least comprise

the steps of:

i) Providing a cementitious layer made of a first cementitious material, which at least

comprises cement and a lightweight filler and has a density in the range from about

0.4 g/cm³ to about 0.9 g/cm³,

ii) Providing one or more fiber cement layers made of a second fiber cement material,

which at least comprises fibers, cement and has a density in the range from about

0.9 g/cm³ to about 1.4 g/cm³, and

iii) Assembling the cementitious layer of step (i) made of the first material and the one

or more fiber cement layer of step (ii) made of the second material, so as to obtain

a bi-layered or multi-layered fiber cement sheet comprising a first layer made of

the first cementitious material, wherein the first layer covers one of the largest

opposite surfaces of a second layer made of the second fiber cement material and

which second layer is optionally covered by one or more consecutive layers made

of the second fiber cement material.

Steps (i) and (ii) of the methods of the invention can be performed, either simultaneously or

consecutively in any desired order. In these steps (i) and (ii), preparing a first cementitious material comprising at least cement and a lightweight filler and preparing a second fiber cement material comprising at least cement and fibers, can be done by any standard method known in the art.

For instance, first, a (fiber) cement slurry can be prepared by one or more sources of at least

cement, water and optionally fibers. In certain specific embodiments, these one or more sources

of at least cement, water and optionally fibers are operatively connected to a continuous mixing

device constructed to form a cementitious fiber cement slurry.

In step (i), when using fibers, such as cellulose fibers or the equivalent of waste paper fibers,

between about 0.1% and about 5% of the total slurry mass of these cellulose fibers is used. In

addition, in step (i) between about 1% and 70%, more particularly between 1% and 40%, of a

lightweight filler (as defined and described herein) is added to the fiber cement slurry to obtain a

cementitious material having a density of between about 0.4 g/cm³ and 0.9 g/cm³.

In step (ii), between about 5% and about 10% of the total slurry mass of these cellulose fibers is

used, such as more particularly, between about 6% and about 10%.

The fineness of the fibers (measured in Shopper-Riegler degrees) is in principle not critical to the

methods of the invention.

Once the at least two types of fiber cement slurries are obtained, the preparation of the first

cementitious material of step (i) and the second fiber cement material of step (ii) can be executed

according to any known procedure.

The process most widely used for manufacturing fiber cement materials is the Hatschek process,

which is performed using a modified sieve cylinder paper making machine. Other manufacturing

processes include the Magnani process, injection, extrusion, filter press, flow-on and others.

In particular embodiments, the fiber cement materials of the present invention are provided by

using a combination of any of the known fiber cement product manufacturing processes, without

limitation chosen from the group consisting of a Hatschek process, a Magnani process, an injection

technology, an extrusion process, a filter press process and a flow-on process.

In further particular embodiments, the fiber cement materials of the present invention are provided

by using a combination of Hatschek process(es) and/or one or more flow-on process(es). In these

particular embodiments, steps (i) and/or (ii) of the methods according to the present invention each

at least comprise the preparation of a (fiber) cement slurry followed by the formation of one or

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more uncured (fiber) cement layers (as defined herein) according to a Hatschek process and/or the

formation of one or more uncured (fiber) cement layers (as defined herein) according to a flow-on

process.

In yet further particular embodiments, steps (i) and (ii) of the methods of the present invention

comprise forming one or more uncured fiber cement layers of a first cementitious material and

forming one or more uncured fiber cement layers of a second fiber cement material, wherein the

first cement material comprises at least cement and a lightweight filler and has a density in the

range from 0.4 g/cm³ to 0.9 g/cm³ the second fiber cement materials comprises at least fibers and

cement and has a density in the range from 1.0 g/cm³ to 4 g/cm³.

In this respect, forming one or more uncured fiber cement layers according to a Hatschek process

at least comprises the steps of one complete cycle of a conventional Hatschek process as known in

the art, i.e. (i) initial formation of a filter layer on the surface of a sieve; (ii) building of a very watery

layer of fiber cement over the filter layer as the sieve rotates in contact with fiber cement slurry in

a vat; (iii) low intensity dewatering of the wet film as it is transferred to a felt and (iv) high intensity

dewatering of the film as it is passed through the nip of an accumulator roll.

The step of forming one or more uncured Hatschek fiber cement layers according to the invention

is performed by means of a Hatschek machinery section, which is part of the apparatus according

to the present invention (as further described herein).

Hatschek processes are generally known in the art and performed using a Hatschek machinery. As

is known by the person skilled in the art, the fundamental part of a Hatschek machinery consists of

one or more vats, in each of which vats a cylindrical sieve rotates in contact with a dilute water

based fiber cement slurry. On the surface of each of the sieves, a filtering film and mineral materials

including cement is formed. The sieve cylinder is mounted on an axle and driven by a an endless

felt belt wrapped around the top of the sieve by a couch roller. The felt is threaded around a drive

or anvil roller and a tail roller. The drive or anvil roller is pushed into hard contact with an

accumulation roller. The actual Hatschek layers are formed as follows. As the clean sieve is pulled

under the slurry in the vat, water from the slurry runs through the sieve depositing a soft porous

film of fibers and cement on the surface of the sieve. The sieve carrying the film exiting the vat is

brought into contact with the felt belt, which is stretched tightly across the sieve. This removes

much of the water from the film by forcing it back through the film. The solid film floats on this

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layer of water and is transferred to the transport belt partly in response to the effect of removal of

water and partly because the felt has a greater affinity for the film than the sieve. The film is carried

on the transport belt to an accumulator roll to which it is transferred by further removal of water

at high pressure. A sufficient number of films are wrapped on the accumulator roll to form a layer

of the desired thickness. The stack of films is then removed from the roller and laid out flat to form

the Hatschek layer. The action of dewatering successive films in contact with each other under

pressure is sufficient to bind the films together to form a contiguous solid layer.

In particular embodiments, the one or more uncured fiber cement layers according to a Hatschek

process can be formed directly on the felt transport belt and further on the accumulator roll of a

Hatschek machine. In alternative embodiments, the one or more uncured fiber cement layers

according to a Hatschek process can be formed on the surface of one or more preformed but

uncured fiber cement layers, which were produced by a flow-on process using the felt transport

belt or the accumulator roll of a Hatschek machine as a forming surface.

Furthermore, forming one or more uncured (fiber) cement layers according to a flow-on process at

least comprises the step of discharging a (fiber) cement slurry composition, either directly or

indirectly (as further specified herein), on a forming surface.

The forming surface can in principle be any surface that is substantially flat, corrugated or otherwise

shaped but should at least be suitable to retain a liquid layer of (fiber) cement slurry in place. The

material of the forming surface should be alkali-resistant (i.e. resistant to a pH up to about 13). In

particular embodiments, the forming surface is water-permeable. In further particular

embodiments, the forming surface is a felt transport belt, such as a felt transport belt of a Hatschek

machine. In yet further particular embodiments, the forming surface is an accumulator roll, such as

an accumulator roll of a Hatschek machine.

In certain particular embodiments, the one or more uncured (fiber) cement layers, which are

produced according to a flow-on process, are made by discharging a (fiber) cement slurry

composition either directly onto a felt transport belt of a Hatschek machine or onto one or more

previously formed Hatschek layers formed onto a felt transport belt of a Hatschek machine.

composition either directly onto an accumulator roll of a Hatschek machine or onto one or more

previously formed Hatschek layers formed onto an accumulator roll of a Hatschek machine.

In certain particular non-limiting embodiments, forming one or more uncured (fiber) cement layers

by a flow-on process comprises discharging a flow of (fiber) cement slurry onto a forming surface

using one or more flow-on distribution devices. In these particular embodiments, the (fiber) cement

slurry distribution process at least comprises one or more flow-on distribution steps. Suitable flow-

on distribution devices for the present invention at least comprise one or more flow-on dispensing

systems with at least one outlet, thereby allowing the slurry to flow continuously onto the transport

belt. In particular embodiments, the one or more outlets of the device are circularly or rectangularly

shaped. In certain particular embodiments, the flow-on distribution devices further comprise one

or more inlets, which are directly or indirectly operatively connected with a source of (fiber) cement

slurry. Sources of (fiber) cement slurry can for example be but are not limited to one or more

continuous (fiber) cement feeding systems or one or more continuous mixing devices constructed

so as to form a cementitious (fiber) cement slurry and means for indirectly or directly feeding the

slurry to one or more distribution devices.

In yet further particular embodiments, the length of the one or more flow-on dispensing systems

for the continuous discharge of the cementitious slurry is at least 2.5 times the total width of the

one or more inlets, such as at least 3.0 times, more particularly at least 3.5 times, such as at least

4.0 times, for instance at least 4.5 times or even at least 5.0 times the total width of the one or

more inlets.

In certain particular embodiments, the step of continuously discharging the (fiber) cement slurry

on the belt can be performed through at least one device which continuously and randomly spatters

or sprays (droplets of) (fiber) cement slurry onto the transport belt. In these particular

embodiments, the (fiber) cement slurry distribution process at least comprises one or more

spattering and/or spraying distribution steps, such as at least one spattering and at least one

spraying distribution step.

In these particular embodiments, the step of continuously discharging the (fiber) cement slurry on

the belt can be performed through one or more spattering devices, such as for instance but not

limited to one or more agitated brush systems, which continuously and randomly spatter (droplets

of) (fiber) cement slurry onto the forming surface.

According to these particular embodiments, the one or more agitated brush-like devices, such as

bristle-brush-like devices, are partly or entirely in contact with the (fiber) cement slurry, which is

provided by one or more sources of (fiber) cement slurry. In this way, droplets of (fiber) cement

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slurry stick to and are picked up by the bristles of the one or more brush-like devices. Through

agitation of the one or more brush-like devices, the droplets of (fiber) cement slurry are discharged

from the different bristles of the one or more brush-like devices onto the forming surface. Thus,

according to these particular embodiments, a plurality of bristles are used in a brush-like

configuration, which is agitated (e.g. rotated, vibrated, etc.) so as to flick small droplets of the

(fiber) cement slurry from the supply source onto the forming surface. Such dispensing devices may

be in a brush form (such as a bristle-brush form) in roll or cylindrical configuration, or in a brush

form (such as a bristle-brush form) in an upstanding array which, when agitated, flicks the pellets

or droplets of (fiber) cement slurry from the edge of the bristles onto the forming surface.

In still further particular embodiments, the step of continuously discharging the (fiber) cement

slurry onto the forming surface can be performed through one or more spraying systems, which

continuously and randomly spray (droplets of) (fiber) cement slurry, provided by one or more

sources of (fiber) cement slurry onto the forming surface. In these particular embodiments, the

(fiber) cement slurry distribution process at least comprises one or more spraying distribution steps.

Characteristics of spraying devices suitable for use in the present invention are not critical to the

present invention as long as such devices are configured to discharge (fiber) cement slurry droplets

from an atomizer or other device (part) onto the forming surface. The spraying devices for use in

the present invention are known to the person skilled in the art and can be developed using routine

techniques.

In yet further particular embodiments, the step of continuously discharging the (fiber) cement

slurry onto the forming surface can be performed through any suitable combination of the one or

more dispensing systems as described herein.

Thus, in particular embodiments, the step of continuously discharging the (fiber) cement slurry onto

the belt can be performed consecutively by one or more flow-on distribution devices, continuously

producing a (fiber) cement slurry flow, and/or one or more spattering distribution devices, which

continuously and randomly spatter (droplets of) (fiber) cement slurry and/or one or more spraying

distribution devices, which continuously and randomly spray (droplets of) (fiber) cement slurry onto

the forming surface.

As a non-limiting example of these embodiments, the step of continuously discharging the (fiber)

cement slurry on the belt can be performed consecutively by one or more flow-on distribution

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devices, which continuously and randomly produce a flow of cement slurry onto the forming

surface, and/or one or more brush-like distribution systems and/or one or more spraying systems,

which continuously and randomly spatter and/or spray, respectively, (droplets of) (fiber) cement

slurry onto the forming surface.

on the belt can be performed consecutively by producing a flow of cement slurry onto the forming

surface by means of one or more flow-on distribution devices, followed continuously and randomly

spattering (droplets of) (fiber) cement slurry onto the forming surface by means of one or more

brush-like dispensing systems. It will be understood that in these specific embodiments, the step of

discharging (fiber) cement slurry can also be performed by first continuously and randomly

spattering (droplets of) (fiber) cement slurry onto the forming surface using one or more brush-like

dispensing systems, and then continuously and randomly producing a flow of cement slurry onto

the forming surface by using one or more flow-on distribution devices.

In certain other particular embodiments, the step of continuously discharging the (fiber) cement

slurry on the belt can be performed consecutively by continuously and randomly producing a flow

of cement slurry onto the forming surface by means of one or more flow-on distribution devices,

followed continuously and randomly spraying (droplets of) (fiber) cement slurry onto the forming

surface by means of one or more spraying distribution systems. It will be understood that in these

specific embodiments, the step of discharging (fiber) cement slurry can also be performed by first

continuously and randomly spraying (droplets of) (fiber) cement slurry onto the forming surface

using one or more spraying distribution systems, and then continuously and randomly producing a

flow of cement slurry onto the forming surface by using one or more flow-on distribution devices.

In further particular embodiments, the step of continuously discharging the (fiber) cement slurry

onto the forming surface can be performed consecutively by continuously and randomly producing

a flow of cement slurry onto the transport belt by means of one or more flow-on distribution

devices, followed by continuously and randomly spattering (droplets of) (fiber) cement slurry onto

the forming surface by means of one or more brush-like distribution systems, further followed by

continuously and randomly spraying (droplets of) (fiber) cement slurry onto the forming surface by

means of one or more spraying distribution systems.

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It will be understood that in these specific embodiments, the step of discharging (fiber) cement

slurry can also be performed by consecutively producing a flow of cement slurry onto the forming

surface by means of one or more flow-on distribution devices, followed by continuously and

randomly spraying (droplets of) (fiber) cement slurry onto the forming surface by means of one or

more spraying systems, further followed by continuously and randomly spattering (droplets of)

(fiber) cement slurry onto the forming surface by means of one or more brush-like distribution

systems.

Alternatively, in these specific embodiments, the step of discharging (fiber) cement slurry can also

be performed by first continuously and randomly spraying (droplets of) (fiber) cement slurry onto

the forming surface using one or more spraying systems, and then continuously and randomly

either (i) first producing a flow of cement slurry onto the forming surface by using one or more

flow-on distribution devices and then continuously and randomly spattering (droplets of) (fiber)

cement slurry onto the forming surface using one or more brush-like distribution systems or (ii) first

continuously and randomly spattering (droplets of) (fiber) cement slurry onto the forming surface

using one or more brush-like distribution systems and then producing a flow of (fiber) cement slurry

onto the forming surface by using one or more flow-on distribution devices.

Yet in an alternative scenario according to these specific embodiments, the step of discharging

(fiber) cement slurry can also be performed by first continuously and randomly spattering (droplets

of) (fiber) cement slurry onto the forming surface using one or more brush-like dispensing systems,

and then continuously and randomly either (i) first producing a flow of cement slurry onto the

forming surface by using one or more flow-on distribution devices and then continuously and

randomly spraying (droplets of) (fiber) cement slurry onto the forming surface using one or more

spraying systems or (ii) first continuously and randomly spraying (droplets of) (fiber) cement slurry

onto the forming surface using one or more spraying systems and then producing a flow of (fiber)

cement slurry onto the forming surface by using one or more flow-on distribution devices.

In the processes of the present invention, in order to obtain a (fiber) cement sheet with

predetermined dimensions (i.e. thickness, length) and densities, the amount of cementitious slurry

that is discharged onto the forming surface per time unit is controlled but will depend on different

parameters, such as the type and predetermined dimensions of the final product to be made and

the specific composition of the (fiber) cement slurry. It will be clear that the amount of cementitious slurry that is to be discharged onto the forming surface per time unit in order to obtain a certain

(fiber) cement product can be determined by the skilled person using routine techniques.

In particular embodiments, the obtained one or more uncured (fiber) cement layers can optionally

be treated in various ways. For instance, the (fiber) cement layers can be pressed by mechanical

means, such as by a (cylindrical) belt press.

Alternatively, or additionally the obtained one or more uncured (fiber) cement layers can be treated

with various agents to improve or alter their structure or properties. For example, the layers can be

treated with a hydrophobic agent.

The processes according to the present invention further comprise the step (iii) of producing a fiber

cement product by assembling the one or more uncured (fiber) cement layers (being Hatschek

layers, non-Hatschek layers or a combination thereof), to obtain a fiber cement product comprising

a first layer made of at least one layer of a first cementitious material, which first layer covers one

of the largest opposite surfaces of a second layer made of a second fiber cement material, wherein:

i) the first layer material at least comprises cement and a lightweight filler and having

a density in the range from about 0.4 g/cm³ to about 0.9 g/cm³, and

ii) the second layer material at least comprises fibers and cement and having a density

in the range from about 0.9 g/cm³ to about 1.4 g/cm³.

In particular embodiments, the present invention provides methods for the production of fiber

cement products as defined herein, at least comprising the steps of:

filler and having a density in the range from about 0.4 to about 0.9 g/cm³,

having a density in the range from about 1.0 to about g/cm³, and

to obtain a fiber cement product comprising a first layer made of the first

fiber cement material.

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Accordingly, step (iii) of the methods of the present invention comprises combining or assembling

the first layer and the second layer as obtained in steps (i) and (ii), respectively, in such a way so as

to produce a fiber cement product comprising a first layer made of the first cementitious material,

which first layer covers (on at least 60% of the surface) a second layer made of the second fiber

cement material.

Step (iii) of the processes of the present invention can be performed according to any manner

known in the art.

In particular embodiments, the uncured (fiber) cement layers, as obtained in steps (i) and (ii) of the

methods of the invention, may be superimposed either simultaneously with their formation step

or alternatively after their formation step.

In particular embodiments, an uncured Hatschek (fiber) cement layer may be superimposed onto

another layer during (i.e. simultaneously with) the Hatschek formation step in the processes of the

present invention. Typically, a Hatschek layer is formed by producing a series of fiber cement films

(primary layers or monolayers) and subsequently juxtaposing these on an accumulator roll. Thus,

in these particular embodiments, superimposing the Hatschek layer onto another layer may be

done during the accumulation step of the Hatschek formation process, whereby the Hatschek layer

being formed is wrapped around one or more previously formed uncured Hatschek or uncured non-

Hatschek layers already wound onto the accumulator roll. Accordingly, in these particular

embodiments of the processes of the present invention, step iii) of superimposing in a

predetermined order the one or more Hatschek (fiber) cement layers and the one or more non-

Hatschek (fiber) cement layers, is performed on the accumulator roll.

In alternative embodiments, an uncured Hatschek layer may be superimposed onto another layer

after the Hatschek formation step in the processes of the present invention. Typically, a Hatschek

layer, after being formed on the accumulator roll, may be cut to a predetermined length. Thus, in

these particular embodiments, superimposing the Hatschek layer onto another layer may be done

after cutting the Hatschek layer and by subsequently transferring the Hatschek layer onto a

previously formed (and optionally cut) uncured Hatschek or non-Hatschek layer or onto a stack of

one or more previously formed (and optionally cut) uncured Hatschek and/or non-Hatschek layers.

In particular embodiments, an uncured non-Hatschek layer may be superimposed onto another

layer during (i.e. simultaneously with) the (fiber) cement distribution step in the processes of the

present invention. In the processes according to the invention, a non-Hatschek layer is formed by

discharging a (fiber) cement slurry composition onto an endless transport belt by means of a flow-

on, a spattering or a spraying mechanism as described herein. Thus, in these particular

embodiments, superimposing the Hatschek layer may be done during this flow-on, spattering or

spraying fiber cement distribution step, whereby the non-Hatschek layer being formed is directly

discharged onto one or more previously formed uncured Hatschek or uncured non-Hatschek layers

present on the transport belt.

In alternative and/or additional embodiments, an uncured non-Hatschek layer may be

superimposed onto another layer during (i.e. simultaneously with) the (fiber) cement distribution

step in the processes of the present invention. In the processes of the present invention, after

forming a non-Hatschek layer, this layer may be wrapped or accumulated onto an accumulator roll

(also referred to as a forming cylinder). Thus, in these particular embodiments, superimposing the

non-Hatschek layer may be done by wrapping the already formed non-Hatschek layer around one

or more previously formed uncured Hatschek or uncured non-Hatschek layers already wound onto

the accumulator roll.

superimposed onto another layer after the (fiber) cement distribution step in the processes of the

present invention. In the processes of the present invention, a non-Hatschek layer, after being

formed, may be cut to a predetermined length. Thus, in these particular embodiments,

superimposing the non-Hatschek layer may be done after cutting the layer and by subsequently

transferring the non-Hatschek layer onto a previously formed (and optionally cut) uncured

Hatschek or non-Hatschek layer or onto a stack of one or more previously formed and (and

optionally cut) uncured Hatschek and/or non-Hatschek layers.

In particular embodiments of the processes of the present invention, after formation, each of the

one or more Hatschek layers and each of the one or more non-Hatschek layers can be superimposed

by winding each of the formed but uncured layers onto a forming cylinder in a predetermined order.

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Thus, in principle, using the processes of the invention, a fiber cement product comprising any

combination of uncured Hatschek and non-Hatschek layers can be produced by superimposing (as

described herein) the produced uncured Hatschek and non-Hatschek layers in an arbitrary,

although predefined, sequence.

It should be understood that the fiber cement products produced according to the processes of the

invention are not limited as to the number of Hatschek or non-Hatschek layers comprised therein.

Accordingly, the total number of Hatschek layers and non-Hatschek layers comprised in the fiber

cement products of the present invention is at least two. In particular embodiments, the fiber

cement products of the present invention may comprise at least three, at least four, at least five,

at least six, at least seven, at least eight, at least nine, such as at least ten superimposed layers,

which may be made of the same or of a different material, and each of which may be a Hatschek

layer or a non-Hatschek layer. In further particular embodiments, the fiber cement products of the

present invention may comprise at least two superimposed layers, of which each layer is made of

a different material, and each layer may be a Hatschek layer or a non-Hatschek layer. In yet further

particular embodiments, the fiber cement products of the present invention may comprise at least

three superimposed layers, of which at least two layers are made of a different material, and each

of which layer may be a Hatschek layer or a non-Hatschek layer.

The one or more Hatschek layers and the one or more non-Hatschek layers produced according to

the processes of the invention are superimposed as soon as possible, i.e. during or immediately

after formation, thereby avoiding any setting to occur between the layers as well as preventing any

additional transport steps to be undertaken. The process is therefore easy to implement, highly

flexible, cost-effective and efficient.

In certain particular embodiments, the processes according to the invention are continuous

processes, meaning that the formation of Hatschek layers, non-Hatschek layers and fiber cement

products is performed in a continuous way, i.e. without any interruption in between any of the

different steps of the process and/or in between one cycle of a fiber cement product formation and

a following cycle of a (i.e. another) fiber cement product formation.

In certain other particular embodiments, the processes according to the invention are

discontinuous processes, meaning that the formation of Hatschek layers, non-Hatschek layers and

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fiber cement products is performed in a discontinuous way, i.e. being characterized by one or more

interruptions occurring in between any of the different steps of the process and/or in between one

cycle of a fiber cement product formation and a following cycle of a (i.e. another) fiber cement

product formation.

While any combination of Hatschek layers and non-Hatschek layers can be made in order to obtain

a fiber cement product according to the present invention, in certain particular embodiments, the

fiber cement products according to the present invention are made by an alternate superimposition

of a Hatschek layer onto a non-Hatschek layer or vice versa until the desired number of layers is

reached. In these embodiments, each Hatschek formation step starts when a fiber cement

distribution step ends and vice versa.

For instance, the fiber cement distribution step may be started by discharging a fiber cement slurry

on a dewatering conveyor belt either through one or more mechanisms of flow-on, spattering

and/or spraying. In addition, the fiber cement distribution step may be stopped by interrupting the

flow-on, spattering and/or spraying of fiber cement slurry onto the conveyor belt.

The Hatschek formation step may for example be started by initiating the Hatschek machinery and

bringing the Hatschek sieves into contact with fiber cement slurry. On the other hand, by way of

example, the Hatschek step may be stopped by rinsing the rotating sieves of the Hatschek machine

with water (instead of being in contact with a source fiber cement slurry), thereby avoiding the

formation of a fiber cement film on each the sieves.

According to the invention, when the Hatschek formation step is stopped, i.e., for example when

the water spray nozzles have started to rinse the sieves, the Hatschek build-up step is not

immediately stopped since it is needed to wound the just formed series of fiber cement layers on

the forming cylinder. The same applies for the fiber cement distribution step and build-up step. It

is also clear from the aforementioned that the Hatschek formation step and the Hatschek build up

step are separated steps operating concomitantly. The same applies for the fiber cement

distribution formation and build-up steps.

The fiber cement products manufactured according to the processes of the present invention

combine high strength (due to the presence of the medium- to high-density surface layers) and light

weight, good thermal and acoustic insulating properties and enhanced workability (due to the

presence of the low density first layer layer(s)).

As previously set out, the process according to the invention allows any desired design of a fiber

cement product, which design is represented by a specific combination of Hatschek and non-

Hatschek layers of the same or of a different composition

According to particular embodiments, the thickness of each Hatschek or non-Hatschek layer can be

monitored by tuning the duration of each Hatschek formation step or fiber cement distribution step

(i.e. working through flow-on, spattering or spraying).

It will be clear to the skilled person that, in particular embodiments, one or more of the same

compositions of (fiber) cement slurry or one or more different compositions of (fiber) cement

slurry, and optionally one or more compositions other than (fiber) cement slurry compositions, can

be used in each of the one or more Hatschek formation steps as well as in each of the one or more

non-Hatschek formation steps (i.e. the latter being interchangeably used with the terminology

"fiber cement distribution step(s)").

In this manner, by making use of one or more consecutively installed Hatschek formation systems

and one or more fiber cement slurry distribution systems as described herein, fiber cement

products comprising at least three or multiple layers having a specific and predetermined

composition, can be manufactured by the processes of the invention.

According to certain particular embodiments of the invention, the resulting fiber cement products,

obtainable by the processes described herein, comprise two layers, i.e. a lower and upper layer. In

these particular embodiments, it may be envisaged that the at least one non-Hatschek layer formed

according to the fiber cement distribution step comprises lightweight fillers to form a lightweight

first layer. In addition, in these embodiments, the second layer having a higher density than the

light weight first layer may be manufactured according to a Hatschek formation step and

subsequently superimposed on one side of the first layer. In these particular embodiments, the

Hatschek layer manufactured according to a Hatschek formation step, which layer represents the

lower layer of the resulting product, preferably comprise substantially no lightweight fillers. On the

other hand, the at least one non-Hatschek layer manufactured according to a fiber cement

distribution step, which layer represents the first layer of the resulting product, preferably

comprises a certain amount of lightweight fillers as described herein. These lightweight fillers are

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used to reduce the density of the at least one layer manufactured according to the fiber cement

distribution step, and can, without limitation, be chosen from the group consisting of: expanded

minerals such as perlite, vermiculite, microspheres, such as cenospheres (ceramic microspheres),

alkali resistant expanded glass spheres / beads, polymeric microspheres or beads, expanded clay,

xonotlite, expanded polystyrene hollow spheres etc. Preferred density modifiers are those with a

closed porosity, such as microspheres, as they avoid water absorption of the cement sheet during

manufacturing and consequently intensive drying. The amount of lightweight fillers is preferably in

the range from from 1 to 70 wt %, such as between 1 and 40%, relative to the total dry weight of

the composition used for the manufacture of the first layer. The use of lightweight fillers reduces

the density (and hence the weight) of the layer manufactured according to the fiber cement

distribution step, which results in easier handling and improved insulating properties. Preferably,

the diameter of the lightweight fillers is in the range from between about 2 um and about 2000 um.

Preferably, and in the present specific embodiments, the fiber cement product comprises a non-

Hatschek first layer comprising no fibers, or at least less fibers than the one or more Hatschek

second layers. The total amount of fibers in the first layer is preferably equal to or less than 15% by

weight (wt % relative to the initial total weight in the dry state of the hydraulic-setting composition,

and more preferably this content is equal to or less than 10% by weight (wt %) relative to the initial

total dry weight of the hydraulic-setting composition. The content of fibers in the first layer is most

preferably between about 0 and 5% by weight (wt %) relative to the initial total dry weight of the

hydraulic-setting composition.

In particular embodiments, the non-Hatschek layers and the Hatschek layers according to the

present invention can, independently of each other, be composed of:

- a hydraulic binder, preferably present in a concentration of about 10 to about 80 wt % (relative to

the initial total weight in the dry state of the composition), more preferably about 20 to about 50

wt %, and most preferably about 25 wt % to about 40 wt %;

- auxiliary materials including but not limited to inert fillers, additives improving or achieving

specific product performance, pozzolans, processing aids,... optionally present in a concentration

of about 0 to about 80 wt %, more particularly less than about 50 wt %; and optionally

- fibers, optionally present in a concentration of about 1 wt % to about 30 wt %.

The orientation of the fibers in layers manufactured according to the Hatschek process of the

Hatschek formation step is primarily parallel to the planar series of fiber cement monolayers of the

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sheet, and especially in the machine loading direction. This planar orientation imparts the strength

of the fiber reinforced cement building material.

In particular embodiments, the processes of the invention at least use one or more endless

transport belts or conveyor belts, onto which the different Hatschek and optionally the different

non-Hatschek layers of fiber cement are produced.

In particular embodiments, only the one or more Hatschek layers are formed on a dewatering

conveyor belt, while the one or more non-Hatschek layers are formed on a forming surface other

than a conveyor belt, such as for instance but not limited to a plate, a corrugated plate, a water-

permeable flat material, a membrane, a fleece, an accumulator roll etc.

In particular embodiments, the one or more Hatschek layers and the one or more non-Hatschek

layers are formed on the same type but on different, i.e. separately installed, dewatering conveyor

belts.

In other particular embodiments, the one or more Hatschek layers and the one or more non-

Hatschek layers are formed on the same dewatering conveyor belt, thereby increasing compactness

of the process machinery and reducing transport costs during production.

In the processes of the present invention, the (fiber) cement slurry is continuously discharged by

one or more distribution systems (as described herein), either directly or indirectly, onto the water-

permeable transport belt.

Thus, in particular embodiments of the present invention, the (fiber) cement slurry is discharged by

one or more distribution systems directly onto the surface of a water-permeable transport belt.

In other particular embodiments, the (fiber) cement slurry is discharged by one or more distribution

systems onto a water-permeable transport belt in an indirect manner.

In these specific embodiments, the (fiber) cement slurry may first be discharged by one or more

distribution systems onto a surface other than a water-permeable transport belt, such as for

example but not limited to a transport belt which is not water-permeable, and only then further

transported, deposited, or placed onto a water-permeable transport belt.

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In other specific embodiments, the (fiber) cement slurry may be discharged indirectly onto the

transport belt, by discharging it directly onto the surface of an already formed uncured Hatschek

layer or onto the surface of an already formed uncured non-Hatschek layer, which uncured layers

in their turn were either formed directly onto the (water-permeable) transport belt or indirectly

onto the transport belt, such as for instance onto another preformed Hatschek or non-Hatschek-

layer, which were again in their turn formed directly or indirectly onto the belt, etc. In this way, it

will be understood that the superimposition of these different Hatschek and/or non-Hatschek

layers results in an (fiber) cement product, which is composed of these different uncured Hatschek

and/or non-Hatschek layers.

The processes according to the present invention may further comprise the step of cutting the fiber

cement product obtained in step (c) to a predetermined length. Cutting the fiber cement sheet to

a predetermined length can be done by any technique known in the art, such as but not limited to

water jet cutting, air jet cutting or the like. The fiber cement sheets can be cut to any desirable

length, such as but not limited to a length of between about 1 m and about 15 m, such as between

about 1 m and about 10 m, more particularly between about 1 m and about 5 m, most particularly

between about 1 m and about 3 m.

It will be understood by the skilled person that the processes of the present invention may further

comprise additional steps of processing the produced fiber cement products.

For instance, in certain particular embodiments, during the processes of the present invention, the

fiber cement slurry and/or the fiber cement sheets can undergo various intermediate treatments,

such as but not limited to treatment with one or more hydrophobic agents, treatment with one or

more flocculants, additional or intermediate pressing steps, etc.

It will be clear to the person skilled in the art that such intermediate processing steps can be

introduced in the processes of the invention at any stage, i.e. before, during and/or after any of the

different steps of the processes of the invention.

As soon as the fiber cement sheet is formed, it may optionally be trimmed at the lateral edges. The

border strips can optionally be recycled through immediate mixing with the recycled water and

directing the mixture to the mixing system again.

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In particular embodiments of the present invention, the processes of the present invention may

further comprise the step of producing a corrugated fiber cement sheet from the obtained fiber

cement sheet. In these embodiments, the step of producing the corrugated fiber cement sheet may

comprise for example at least the step of transferring the obtained fiber cement sheet to a

corrugated sheet mold to form a corrugated fiber cement sheet. However, other techniques to

produce corrugated sheets from flat sheets are known to the skilled person and may as well be

used in combination with the processes of the present invention in order to obtain corrugated fiber

cement sheets.

In particular embodiments, the processes of the invention may further comprise the step of curing

the obtained fiber cement sheets. Indeed, after production, fiber cement products can be allowed

to cure over a time in the environment in which they are formed, or alternatively can be subjected

to a thermal cure (e.g. by autoclaving or the like).

In further particular embodiments, the "green" fiber cement sheet is cured, typically by curing to

the air (air cured fiber cement products) or under pressure in presence of steam and increased

temperature (autoclave cured). For autoclave cured products, typically sand is added to the original

fiber cement slurry. The autoclave curing in principle results in the presence of 11.3 À (angstrom)

Tobermorite in the fiber cement product.

In yet further particular embodiments, the "green" fiber cement sheet may be first pre-cured to

the air, after which the pre-cured product is further air-cured until it has its final strength, or

autoclave-cured using pressure and steam, to give the product its final properties.

According to the process of the present invention, the resulting fiber cement sheet leaves the

forming cylinder in an uncured and green state. Thus, the Hatschek and non-Hatschek layers are

subsequently co-cured, thereby producing a strong interfacial layer bonding, which avoids

delaminations during handling, cutting, installation and service; the assembly of the layers

manufactured in the process according to the invention does not require any adhesive.

Advantageously, the resulting fiber cement sheet is autoclaved.

In particular embodiments of the present invention, the processes may further comprise the step

of thermally drying the obtained fiber cement sheets. After curing, the fiber cement product being

a panel, sheet or plate, may still comprise a significant weight of water, present as humidity. This

may be up to about 10 weight % even 15 weight % (wt %), expressed per weight of the dry product.

The weight of dry product is defined as the weight of the product when the product is subjected to

drying at 105°C in a ventilated furnace, until a constant weight is obtained.

In certain embodiments, the fiber cement product is dried. Such drying is done preferably by air

drying and is terminated when the weight percentage of humidity of the fiber cement product is

less than or equal to 8 weight %, even less than or equal to 6 weight %, expressed per weight of dry

product, and most preferably between 4 weight % and 6 weight %, inclusive.

According to a third aspect, the present invention provides uses of the fiber cement products and

fiber cement sheets according to the present invention in the building industry. In particular

embodiments, the fiber cement sheets of the present invention can be used to provide an outer

surface to walls, both internal as well as external a building or construction, e.g. as façade plate,

siding, etc.

In further particular embodiments, the fiber cement sheets of the present invention are used as a

building material and fixed to a substrate, such as a wall, with the second layer acting as a bottom

layer facing the substrate and the first layer as the top layer which may be further finished.

The invention will now be further illustrated in detail with reference to the following Examples.

It is to be understood that although preferred embodiments and/or materials have been discussed

for providing embodiments according to the present invention, various modifications or changes

may be made without departing from the scope and spirit of this invention.

EXAMPLES

It will be appreciated that the following examples, given for purposes of illustration, are not to be

construed as limiting the scope of this invention. Although only a few exemplary embodiments of

this invention have been described in detail above, those skilled in the art will readily appreciate

that many modifications are possible in the exemplary embodiments without materially departing

from the novel teachings and advantages of this invention. Accordingly, all such modifications are

intended to be included within the scope of this invention that is defined in the following claims

and all equivalents thereto. Further, it is recognized that many embodiments may be conceived

that do not achieve all of the advantages of some embodiments, yet the absence of a particular

advantage shall not be construed to necessarily mean that such an embodiment is outside the

scope of the present invention.

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Example 1: Production of fiber cement sheets according to a specific embodiment of the

invention

A fiber cement sheet consisting of one Hatschek high density layer (also referred to herein as

"second layer") having a thickness of about 9 mm and one non-Hatschek low density layer (also

referred to herein as "first layer") with a thickness of about 3.5 mm was manufactured according

to the process of the invention.

The formulation of the low density first layer comprised about 30 wt % relative to the total dry

weight of the composition of perlite, while the high density layers are exempt of light weight fillers.

Table 1 shows the composition of the low density first layer material and the composition of the

high density second layer material.

TABLE 1

Low density (first layer) High density (second layer)

Absolute Relative weight Absolute Relative

weight of compared to weight of each weight

each of the total weight of of the dry compared to

dry matter dry matter matter total weight

components components components of dry matter

(kg) (weight %) (kg) components

(weight %)

Cellulose 4,00 4,00 8,00 8,00

25°SR

(Tasman)

Expanded 30,00 30,00 -- --

perlite

Cement 26,40 26,40 36,80 36,80

Quartz 39,60 39,60 55,20 55,20

TOTAL 100,00 100,00 100,00 100,00

Table 2 shows the densities of each of the layers (one low density first layer and one high density

second layer).

TABLE 2

Low density first layer High density second layer

Density [g/cm³] 0.66 1.20

Thickness [mm] 3.5 9.0

E mod MPa 1688 8056

Example 2: Workability tests of the fiber cement sheets produced according to the specific

embodiment of Example 1

The bi-layered sample according to the present invention, further on called sample A, as produced

in accordance with the description of Example 1, was further tested for its workability.

Comparative Example 1

A fiber reinforced cement Hatschek sheet with a thickness of about 15 mm having the same

formulation as the Hatschek high density layers in Example 1, further on called comparative sample

B, was tested on workability in the same way.

2.1 Screwing test

In the Screwing test, typical fiber cement screws as shown in Table 3, were screwed into the sample

A and the comparative sample B.

TABLE 3

Screw number Brand Type of screw

1 Eternit Cedral screw: 4.2 * 45 mm for fixing on timber, square drive

head

2 LaFarge gypsum Universal LaDura screws: 3.9*45 mm; grey phosphated, flat

cutting head, reverse fine thread, PH2 drive head

3 WEE FER bvba GKP-screw 45 mm

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Automatic screwing

In a first screwing method, tests 1 to 5, a weight of 5 kg or 10 kg was applied on a column drill (BDS

Maschinen, MAB 485, speed 2).

Manual screwing

In a second screwing method, tests 6 to 11, a battery powered manual screw driver was used

(Makita, DDF484 18V). The manual screw driver can be regulated in applied torque by selecting a

screw intensity between 1 to 21 - arbitrary units on the selecting wheel. Three levels were selected:

13, 17 and 21.

The screwing test protocols 1 to 11 were performed on the bi-layered sample A, consisting of one

high density second layer and one low density first layer, with compositions as indicated in Table 1.

Also, a mono-layer comparative sample B, completely consisting of the high density second layer

composition as indicated in Table 1, was incorporated in the test as a reference. The different test

protocols and the remaining heights of the screws which did not enter into the sample, are

summarized in Table 4 below.

TABLE 4

Test protocol Screwing method Screw Screw intensity

1 Automatic 1 5 kg

2 Automatic 1 10 kg

3 Automatic 3 10 kg

4 Automatic 2 5 kg

5 Automatic 2 10 kg

6 Manual 2 13 7 Manual 2 17 8 Manual 2 21 9 9 Manual 1 13 10 Manual 1 17 11 Manual 1 21

In case the screws did not penetrate the samples completely, it is clear that the screws penetrate

further into sample A compared to the comparative sample B (i.e. the remaining height of the screw

is shorter for samples A than for the comparative samples B). The remaining heights of the screws

which did not penetrate in the sample completely, were measured and reported in Table 5 below.

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TABLE 5

Remaining height screw (in mm) Sample A (bilayer) Comparative sample B / /

/ /

1.0 2.1

3.9 13.4

/ 5.4

/ 1.2

/ 1.5

/ 1.8

/ 1.1 / 1.0

It can be concluded that the bi-layered products as produced according to the methods of the

present invention have an improved workability.

2.2 Removability of fiber cement residue

When screws enter a fiber cement product, excess fiber cement material heaps up around the

screw head which is clearly visible in the figures in column C1 and C3 of figure 1. To test the

removability of this residue material, a household hand brush with polyester bristles was used to

brush over the surface of the samples two times (two times a forward and a backward motion).

The figures in column C1 of figure 1 show the sample A, the sample according to the present

invention, directly after performing the screwing test protocols 1 to 11.

The figures in column C3 of figure 1 show the comparative sample B directly after performing the

screwing test protocols 1 to 11.

In these test protocols, the applied force on the screw remains constant. From comparing the

figures in column C1 to the figures in column C3 of figure 1, it is clear that the screws penetrate

further into sample A compared to the comparative sample B.

The figures in column C2 of figure 1 show the sample A, according to the present invention, after

performing the screwing test protocols 1 to 11 and directly after performing the brushing

treatment.

The figures in column C4 of figure 1 show the comparative sample B, the reference fiber cement

sample, after performing the screwing test protocols 1 to 11 and directly after performing the

brushing treatment.

From the figures in column C2 of figure 1, it is clear that in the sample A, according to the present

invention, regardless the screwing test protocol and hence the type of screw used, the excess fiber

cement residue is nearly always completely removed by simple brushing.

On the other hand, in the comparative sample B in the figures in column C4 of figure 1, the excess

fiber cement residue is not removed completely. Such a surface requires further refining before a

finishing treatment can be applied.

Claims

The claims defining the invention are as follows:

1. Use of a bi-layered fiber cement product as a building product, wherein the bi-layered fiber cement product comprises a first layer of a first layer material, which first layer is covered by at least one 5 second layer of a second layer material, wherein: - the first layer material has a density of between about 0.4 and about 0.9 g/cm 3 inclusive, and 2020344119

comprises cement and between 1 wt% and 70 wt% (relative to the total dry weight of said first layer material) of a lightweight filler, wherein the first layer material further comprises fibers in an amount of between 1 wt% and 5 wt% relative to the total dry weight of said first layer material, 10 wherein said fibers in said first layer material comprise cellulose fibers, - said at least one second layer covers only one of the main surfaces of the first layer, thereby forming a bi-layered fiber cement product, - the second layer material has a density of between about 1.0 and about 1.4 g/cm3 inclusive, and at least comprises fibers and cement, wherein the second layer material comprises fibers in an 15 amount of between 6 wt% and 10 wt% relative to the total dry weight of the second layer material, wherein said fibers in the second layer material comprise cellulose fibers, and - the bi-layered fiber cement product is fixed to a substrate, with the second layer acting as a bottom layer facing the substrate and the first layer acting as a top layer.

20

2. Use according to claim 1, wherein said lightweight filler is chosen from the group consisting of expanded perlite, expanded vermiculite, expanded polystyrene, extruded polystyrene, foam, concrete foam, calcium silicate hydrate gel (CSH gel), microspheres, cenospheres (ceramic microspheres), alkali resistant expanded glass spheres / beads, expanded shale, and xonotlite.

25

3. Use according to claim 1 or claim 2, wherein said lightweight filler is expanded perlite.

4. Use according to claim 3, wherein said expanded perlite is present in the first layer material in an amount of between 15 wt% and 70 wt% (relative to the total dry weight of said first layer material).

30 5. Use according to claim 4, wherein said expanded perlite is present in the first layer material in an amount of between 20 wt% and 40 wt% (relative to the total dry weight of said first layer material).

6. Use according to any one of claims 1 to 5, wherein the bi-layered fiber cement product is fixed to the substrate by means of threaded fastening means.

7. Use according to claim 6, wherein the threaded fastening means are screws.

8. Use according to claim 7, wherein the screws are flush with a surface of the top layer of the fiber cement product after installation. 5 9. Use according to claim 7 or claim 8, wherein excess fiber cement material collecting around a screw 2020344119

head during installation is removed by brushing or rubbing over the screw head.

10. Use according to any one of claim 1 to 9, further comprising a finishing step after fixation to the 10 substrate.

11. Use according to any one of claims 1 to 10, wherein the cellulose fibers have a fineness measured in Shopper-Riegler (SR) degrees between 15 and 45 degrees SR, and wherein the bi-layered fiber cement product is an autoclave-cured fiber cement product. 15

12. Use according to any one of claims 1 to 11, wherein the substrate is a wall.

13. Building system comprising a wall to which a fiber cement product is fixed, wherein the fiber cement product is a bi-layered fiber cement product comprising a first layer of a first layer material, 20 which first layer is covered by at least one second layer of a second layer material, wherein: - the first layer material has a density of between about 0.4 and about 0.9 g/cm 3 inclusive, and comprises cement and between 1 wt% and 70 wt% (relative to the total dry weight of said first layer material) of a lightweight filler, wherein the first layer material further comprises fibers in an amount of between 1 wt% and 5 wt% relative to the total dry weight of said first layer material, 25 wherein said fibers in said first layer material comprise cellulose fibers, - said at least one second layer covers only one of the main surfaces of the first layer, thereby forming a bi-layered fiber cement product, - the second layer material has a density of between about 1.0 and about 1.4 g/cm 3 inclusive, and at least comprises fibers and cement, wherein the second layer material comprises fibers in an 30 amount of between 6 wt% and 10 wt% relative to the total dry weight of the second layer material, wherein said fibers in the second layer material comprise cellulose fibers, and - the fiber cement product is fixed with the second layer acting as a bottom layer facing the wall and the first layer acting as a top layer.

14. Building system according to claim 13, wherein the bi-layered fiber cement product is fixed to the wall by means of threaded fastening means, such as screws.

15. Building system according to claim 14, wherein the screws are flush with a surface of the top layer 5 of the fiber cement product after installation. 2020344119

16. Building system according to any one of claims 13 to 15, wherein said lightweight filler is chosen from the group consisting of expanded perlite, expanded vermiculite, expanded polystyrene, extruded polystyrene, foam, concrete foam, calcium silicate hydrate gel (CSH gel), microspheres, 10 cenospheres (ceramic microspheres), alkali resistant expanded glass spheres / beads, expanded shale, and xonotlite.

17. Building system according to claim 16, wherein said lightweight filler is expanded perlite.

15

18. Building system according to claim 17, wherein said expanded perlite is present in the first layer material in an amount of between 15 wt% and 70 wt% (relative to the total dry weight of said first layer material).

19. Building system according to claim 18, wherein said expanded perlite is present in the first layer 20 material in an amount of between 20 wt% and 40 wt% (relative to the total dry weight of said first layer material).

20. Building system according to any one of claims 13 to 19, wherein the cellulose fibers have a fineness measured in Shopper-Riegler (SR) degrees between 15 and 45 degrees SR, and wherein the 25 bilayered fiber cement product is an autoclave-cured fiber cement product.

FIGURES

Figure 1

Test According to the According to the Reference after protocol invention after Reference invention swiping swiping C3 C1 C4 C2

1

2

3

According to the Test According to the Reference after protocol invention after Reference invention swiping swiping C3 C1 C4 C2

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7 7