ES2561730B2 - Composition of thermally insulating plaster - Google Patents

Abstract

Composition of thermally insulating plaster # The present invention relates to a composition of thermally insulating plaster, the method of protection thereof and the plates obtained with the composition.

Description

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DESCRIPTION

Composition of thermally insulating plaster

The present invention relates to a thermally insulating plaster composition. The invention is framed in the sectors of construction materials, mineral wool and insulating materials, prefabrication of plasterboard, interior divisions of buildings and suspended ceilings.

Background of the invention

The need to look for forms of passive conditioning, in which the energy saving has an important component is fundamental, since it not only allows to reduce expenses, but also limit the use of traditional fuels.

Therefore, the use of thermal insulating materials has a primary role in edification since it represents a saving in the use of energy and the improvement of thermal comfort, reducing energy losses and thus favoring the passive conditioning of the enclosure. Thermal insulating materials are natural or synthetic products, which have a high resistance to heat. In addition, most of the insulators also produce an improvement in the acoustic insulation of the building and, in some cases, such as mineral wool, in fire protection. There is a great variety of insulating materials on the market with differences between them, being the main thermal insulating materials used in construction; polyurethane foams, expanded polystyrene, extruded polystyrene and mineral wool.

Mineral wool has a great acceptance in the market thanks to the fact that they have a very competitive price and are applicable in multiple situations, both in new construction and in building rehabilitation. Due to its amorphous structure it has excellent thermal and acoustic insulation properties, therefore, it is used in the construction industry for thermal insulation, fire protection and as acoustic insulation.

Wall, floor and ceiling are commonly insulated parts with sheets of mineral wool both in the construction of new construction buildings and in rehabilitation. Mineral wool is also used in borra format (loose wool), blown is used for the insulation of wooden decks, joists or beams. They can also be found in the form of a preformed tube for pipe insulation or in the formation of conduits for

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air conditioning. Another of its benefits lies in its high understandability, since more than 400% increase in storage capacity can be achieved, so that a truck can transport four to five times more merchandise to the site, saving costs.

For example, the Spanish patent with publication number ES2282516 describes a separating wall element made of two coatings, especially drywall and between them a layer of mineral wool. Mineral wool is not mixed with plaster but they are differentiated layers.

On the other hand the plaster has been used usually in the manufacture of ceilings, walls, gripping pastes, continuous coatings (trim, plasters, stucco, fireproof coatings), mechanical projection plasters, panels for partitions, anhydrite-based leveling pastes, plaster and fiber plates, plasterboard, plates for removable suspended ceilings, etc. During the last years the plaster industry has been looking for new applications in the construction process, improving the existing limitations in some of its properties and optimizing its use through specific additions.

One of the current research lines on gypsum and its properties focuses on the improvement of its thermal behavior. Studies on this behavior differ in two currents of great importance; the first one consists of the application of additives in the plaster for the improvement of its thermal properties and the second of them in the application of additions or loads in the plaster improving, once hardened, the thermal properties of the compound.

Within the first research stream, the additives studied are, among others, sulfuric acid, silicone resins and, above all, the so-called phase change materials. With the phase change materials, the specific heat capacity of the plaster has been improved by up to 5 times.

As a second research stream, it is worth highlighting the additions or charges of silica, perlite, vermiculite or expanded silica granules. With the additions of silica smoke, the thermal conductivity is reduced by up to 14%, while with additions of fly ash, a reduction of 18% is achieved in cement-based compounds. In the Spanish patent with publication number ES2170612 a plasterboard is described as a fire protection, whose faces are coated with a

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reinforcement material based on mineral fibers, silica and talc.

With the present invention it is intended to develop a composition that improves the thermal insulation capacity of the plaster while maintaining its mechanical properties.

Description of the invention

In the present invention a plaster-based composition has been developed for its availability, profuse utilization in the field of building and low cost.

In the present invention mineral wool is used, which is added to the plaster, so that a composition is obtained that is used to obtain prefabricated materials applied to the construction of buildings as thermal insulators.

Therefore, a first aspect of the invention relates to a thermally insulating plaster composition comprising gypsum in a proportion comprised between 84.5% - 74.5% by weight, mineral wool in a proportion comprised between 15% and 25% by weight and plasticizers in a proportion between 0.2% to 0.5% by weight; with a water / plaster weight ratio between 0.6 to 1.2.

The percentages of the composition of the invention are adequate so that the composition has the best thermal insulation capacity, maintaining the mechanical strength once the composition is set. Said composition with respect to a gypsum without mineral wool has a greater specific heat capacity, thermal resistance and lower thermal conductivity and thermal diffusivity.

In the present invention the term "gypsum" generally refers to products containing calcined powder and water (CaSO4.2H2O) with or without other substances, such as retarders, hardening or accelerating agents, fiber, fillers.

In the present invention the term "mineral wool" is a general term that encompasses a variety of inorganic insulation materials such as: rock wool, glass wool and slag wool, all manufactured from different raw materials. Raw materials. Most commonly used for the production of mineral wool are diabasa, amphibolite, granite and basalt, and additives such as dolomite or limestone.

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In the present invention the term "plasticizer" refers to a water reducing additive, which increases the consistency and workability of the plaster without adding water, they are also used to reduce the water content of the plaster thus increasing its resistance without loss of consistency The result is a more moldable plaster, or an increase in performance in applications that require greater strength.

The thermal properties of the gypsum-mineral wool composite are enhanced by the low density and the low thermal conductivity of mineral wool. The mechanical properties of the composite material are the result of the complementarity of functions between the fibers and the matrix, as well as the relationships established between them, allowing joint work. In this way a mechanical union is provided, without chemical reaction, but of great stability. The fibers absorb the tensile stresses that are generated inside the material, and the matrix absorbs the compression stresses that are generated inside the material. The resulting compound is a material of lower density, lower thermal conductivity and greater porosity, maintaining up to 20% of addition its mechanical properties.

A second aspect of the invention relates to a method of obtaining the composition of the invention comprising the steps of:

a) Crush mineral wool

b) Mix mineral wool with water

c) Add the plaster and plasticizer;

d) Mix the set until the composition is homogenized.

A third aspect of the invention relates to the plates comprising the composition of the invention. These plates are especially used in transdos and interior partitions. Because the plate comprises the composition of the invention, it increases the specific calorific capacity thereof while reducing its conductivity, and its density is decreased. These improvements mean a saving in the utilization of energy as well as the improvement of thermal comfort, which favors the passive conditioning of the enclosure while improving the manageability of the plate. All this is achieved without reducing the mechanical properties.

Detailed description of the invention

As said the first aspect of the invention is a plaster composition

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thermally insulating comprising:

plaster in a proportion between 84.5% -74.5% by weight, mineral wool in a proportion between 15% and 25% by weight and plasticizers in a proportion between 0.2% to 0, 5% by weight; with a water / plaster weight ratio between 0.6 to 1.2.

Preferably the composition comprises: plaster in a proportion between 84.5% -74.5% by weight, mineral wool in a proportion between 15% and 20% by weight and plasticizers in a proportion between a 0.2% to 0.5% by weight; with a water / plaster weight ratio between 0.6 to 1.2.

In a preferred materialization the plaster is selected from E-35 or E-35-L. Plaster E-35 is a special plaster consisting of calcium sulfate semihydrate SHp (SO4Ca ^ 1 / 2H2O), with the possible incorporation of setting regulating additives, with greater purity than E-30, with a minimum flexural strength of 3 , 5 N / mm2 and a thermal conductivity of 0.34 W / m ^ K. The E-35-L plaster is a slow setting product.

In a particular embodiment of the invention, mineral wool is a recycled mineral wool.

Preferably the wool has a length in a range between 10mm and 30mm and a thickness in a range between 6 ^ m and 21 ^ m.

The use of recycled mineral wool is very advantageous since in 2011, in Europe, the estimated amount of mineral wool waste was 2.4 million tons, representing 0.2% of all construction and waste Demolition generated in Europe. The current solutions for the recycling of mineral wool waste are scarce, we have worked with mineral wool residues in cement-based composite materials or as a filler in polypropylene compounds. Therefore the use of recycled mineral wool in gypsum compositions would improve the problem of recycling them, in addition to reducing the cost, by replacing part of the main gypsum compound with a mineral wool residue.

As stated above, the second aspect of the invention is a method of obtaining the composition of the invention comprising the steps of:

a) Crush mineral wool

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b) Mix mineral wool with water

c) Add the plaster and plasticizer;

d) Mix the set until the composition is homogenized.

In a particular materialization the wool is crushed until it has a length in a range between 10mm and 30mm and a thickness in a range between 6 ^ m and 21 ^ m.

Examples of the invention

Example 1

Fabrication of plates of 2.50 m x 1.20 m x 25mm.

Preparation of quantities for each component:

-Escayola E-35 ............................................. .................................. 30 Kg

-Water relation water / plaster ............................................ ................. 24 liters

-Recycled mineral wool .............................................. ........... 4,5 to 7,5 Kg

-Plastifier ................................................ .............................. 60 to 150 g

The recycled mineral wool before being added to the plaster was crushed in a machine of 1500 W of power and a frequency of 50/80 Hz for two minutes.

Once the quantities of each material were arranged, they were mixed. To make the mixture, the mineral wool residue was first beaten together with the water. Subsequently the plaster was added as the paste was mixed.

Once the mixture was homogenized, it was poured onto the molds placed horizontally, of the specified dimensions, which were impregnated with a release agent to facilitate its demolding.

The mixture was spread on the mold, once extended, the upper face was smoothed so that the constant thickness of the plate was guaranteed. Once the compound was set, it was demolished. Once unmold the plates were stacked vertically for drying.

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The combined effect of the new gypsum-mineral wool material, observed in the test specimens, produced significant improvements in the thermal behavior of the material, while maintaining its mechanical properties while reducing its density considerably.

Thermal behavior: the effect of the combination of materials produced significant improvements in thermal behavior, increasing the specific heat capacity or specific heat by 21% and decreasing the thermal conductivity by 46%, for the plates tested, with respect to the values of thermal conductivity obtained with the plaster or plaster, without additive. Accordingly, the thermal resistance of the new gypsum-mineral wool material increases by 86%, its thermal diffusivity decreases by 45%. It should be noted that the thermal conductivity values reach 0.194 W / mK, while the thermal resistance of the new material reaches 5,158 mK / W.

Mechanical efforts: the mechanical behavior of the prismatic specimens of the gypsum-mineral wool compound decreases with reference to those of plaster or plaster without additive, this decrease being between 2% and 30% for its compressive strength. However, both its flexural strength and surface hardness are maintained up to 20% of addition decreasing by 18% and 7%, respectively, for 25% of addition. It should be noted that all the results comply with the minimum values established in the UNE EN 13279-1 Standard both for use as a construction plaster and for special construction plaster.

Porosity and bulk density: The porosity of the new compound based on recycled mineral wool and gypsum or plaster is reduced between 10% and 18%, in prismatic specimens, with respect to the values obtained with the plaster or plaster, without additive . Likewise, its apparent density is reduced between 14% and 22%, in prismatic specimens, with respect to the values obtained with the plaster or plaster, without adding.

It is observed that the fragile ruptures of the matrix do not give rise to the separation into two parts of the material, mineral wool residues, with their short fiber shape, keep the two breaking surfaces sewn.

The texture of the material is pleasant for architectural purposes indoors, being also porous, and the degree of porosity can be controlled by varying the gypsum / plaster water ratio, which makes it suitable for applications where absorption is necessary

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acoustics.

Claims (5)

5 10 fifteen twenty 25 ES 2 561 730 A1 1. Composition of thermally insulating plaster comprising: plaster in a proportion between 84.5% -74.5% by weight, mineral wool in a proportion comprised between 15% and 25% by weight and plasticizers in a proportion comprised between 0.2% to 0.5% by weight; with a water / plaster weight ratio between 0.6 to 1.2. 2. Thermally insulating plaster composition according to claim 1 comprising mineral wool in a proportion comprised between 15% and 20% by weight. 3. Plaster composition according to claims 1-2 wherein the mineral wool has a length in a range between 10mm and 30mm and a thickness in a range between 6 ^ m and 21 ^ m. 4. Method of obtaining the composition of claim 1 to 3 comprising the steps of: a) Crush mineral wool b) Mix mineral wool with water c) Add the plaster and plasticizer; d) Mix the set until the composition is homogenized. 5. Thermally insulating construction plates comprising the composition of claim 1, 2 or 3.