JPS5838377B2 - Method for producing hardened gypsum flooring material - Google Patents

Description

[Detailed description of the invention] The present invention relates to a manufacturing method for hardened gypsum flooring.

Specifically, the present invention includes a force method for constructing a floor base using a gypsum composite with a specific composition, and a method for producing a hardened gypsum body suitable for use as a floor base.

Traditionally, when constructing floors for buildings made of reinforced concrete or steel structures, cement mortar was applied to adjust the unevenness of the concrete slab, and then PVC tiles were applied with adhesive as a surface finishing material. is a common construction method.

When implementing this construction method, cement mortar is applied to the concrete slab using a plastering trowel.
The surface is troweled about three times to create a smooth floor, but this work requires skill and the labor of many dogs.

In addition, in order to apply surface finishing materials such as PVC tiles on top of the mortar finish, it is necessary to dry the cement mortar sufficiently in advance. The moisture in the adhesive reduces its adhesive strength, causing problems such as tiles that have been pasted peeling off.

In order to apply a surface finishing material such as PVC tiles with a commonly used adhesive such as vinyl acetate emulsion, it is necessary to dry the cement mortar to a moisture content usually below 8%.

The period required for this will of course vary depending on conditions such as temperature and humidity, but even in summer it will be necessary to wait at least two weeks, so it is inevitable that the construction period will be longer.

For this reason, there has been a strong demand for a subfloor construction method that does not require plastering skills, has good work efficiency, and has a short construction period.

However, on the other hand, the cement mortar construction method mentioned above is widely used and can be constructed relatively inexpensively in terms of materials.
The construction costs of the new method must be competitive with the costs of the conventional method.

The present invention was created as a result of various studies to meet the above requirements using gypsum.

The purpose of the present invention is to provide a gypsum slurry that has self-smoothing ability when poured onto a concrete slab, etc., has excellent workability, has a high initial hardness of the cured product, and dries quickly in the initial stage. It is an object of the present invention to provide a method for constructing a floor base that allows finishing materials to be applied and is economical, or a method for producing a hardened gypsum body suitable for use as such a floor base.

The above object is achieved according to the present invention by 20-80% by weight of ■-type anhydrite, α-type hemihydrate and (
or) 100 parts by weight of a gypsum mixture consisting of 80 to 20% by weight of β-type hemihydrate gypsum, 10 parts by weight or less of one or more powders of alkaline substances such as slaked lime, dolomite plaster, Bortland cement, limestone, and Prepare a gypsum slurry by kneading 25 to 50 parts by weight of water, pour this onto a concrete slab or any other surface to cure by hydration, mold it into a desired shape and use it as it is as a floor base, or This is achieved by transferring it to another location and applying it as a flooring material.

The circumstances that led to the adoption of the above-mentioned constituent elements and the reasons why the effects of the present invention appear are as follows.

In general, to improve the fluidity of gypsum slurry and give it self-smoothing ability, it is sufficient to increase the amount of mixed hydrophobicity, but if the amount of water is excessive, excess water after curing will increase, causing a breathing phenomenon and decreasing strength. This leads to deterioration and delayed dryness.

Therefore, it is desirable to keep the amount of mixed hydrophobicity as low as possible.

However, the cheap β-type hemihydrate gypsum, which is most commonly used in the production of ordinary hardened gypsum, contains 7 parts by weight per 100 parts by weight.
Unless 0 to 80 parts by weight of water is added, fluidity sufficient to effect self-smoothing cannot be obtained, and this amount of water is excessive from the above point of view.

On the other hand, the ■-type anhydrite has the disadvantage that it hardens very slowly compared to the α-type hemihydrate gypsum and the β-type hemihydrate gypsum, but on the other hand, the initial drying of the hardened product is fast.

This is considered to be because a large amount of crystallization water is required, and therefore, when the amount of kneading water is the same, there is less surplus water.

Although α-type hemihydrate gypsum requires less water for mixing, its hardened product has poorer initial drying properties than ■-type anhydrite, and is more expensive, making it economically disadvantageous.

The present inventor attempted to utilize type ■ anhydrite, which is cheaper than α type hemihydrate gypsum, and researched using this as the main ingredient and combining either or both of α type hemihydrate gypsum and β type hemihydrate gypsum. did.

■When type anhydrite is combined with α-type and (or) β-type hemihydrate, the anhydrite gradually fills the voids in the hardened material created by hydration of these hemihydrates. It is thought that hydrated crystals grow from the hydrated product, and this, together with the above-mentioned small amount of surplus water, is understood to improve the initial drying properties of the cured product according to the present invention and further enhance the long-term strength. .

The present invention investigates the relationship between the appropriate blending ratio of the above-mentioned components, the amount of mixed water, the pH of the gypsum slurry, the realization of fluidity that provides self-smoothing ability, and the initial strength and drying properties of the cured product, and claims It was completed by determining the structural requirements as stipulated in .

The composition of the gypsum mixture used in the present invention is
~80% by weight of α-type hemihydrate gypsum and/or
β-type hemihydrate gypsum should be 80 to 20% by weight.

(2) If the amount of type anhydrite exceeds 80% by weight, the initial hardness of the hardened product will be insufficient, and the purpose of making it possible to apply a surface finishing material within a short period of time after the foundation work will not be achieved.

On the other hand, if the amount of type (■) anhydrite does not reach 20% by weight, the effect of using anhydrite will not be obtained, and the initial drying properties of the cured product will be low, making it impossible to apply the surface finishing material at an early stage.

Preferably, the former is 40 to 70% by weight, and the latter 60 to 30% by weight, but since it varies somewhat depending on the combination of materials used, it should be determined experimentally in practice.

The gypsum hemihydrate to be added to type ① anhydrite may be either α-type or β-type, or both may be used in combination.

The ■-type anhydrite used in the present invention is anhydrite obtained by calcining natural gypsum, by-product phosphate gypsum, wet flue gas desulfurization gypsum, etc., usually at a temperature of 500°C or higher, anhydrite produced as a by-product during the production of hydrofluoric acid, etc. It is optional, such as dry and crushed natural anhydrite.

α-type hemihydrate gypsum can be obtained from a variety of sources, including those manufactured by the autoclape method, those produced as a by-product in the dihydro-hemihydrate method of wet phosphoric acid production, and those produced as a by-product in wet flue gas desulfurization. can.

In addition, as β-type hemihydrate gypsum, calcined gypsum, which is used as a raw material for ordinary gypsum plaster and gypsum board, may be used.
It is not limited to anything specific.

Slaked lime, dolomite plaster, added to gypsum mixture
Powders of alkaline substances such as Bortland cement and limestone act as setting regulators and setting stabilizers for gypsum.

The amount added is 10 parts by weight or less per 100 parts by weight of the gypsum mixture.

Even if more than 10 parts by weight is added, no further effect can be obtained, leading to an increase in the amount of mixed hydrophobicity and a decrease in strong change.

In order to reliably obtain the effect of addition, the amount should be 0.5 part by weight or more.

However, some raw materials used may contain an effective amount of alkali.

For example, natural gypsum calcined to form ■-type anhydrite contains a considerable amount of quicklime.

In such a case, there is no need to particularly add an alkaline substance.

For 100 parts by weight of the above-mentioned powder material, that is, the gypsum mixture and 10 parts by weight or less of the alkaline substance, the amount of kneading water is 25 to 25 parts by weight.
The amount is 50 parts by weight.

If the amount is less than 25 parts by weight, the fluidity of the gypsum slurry will be low, self-smoothing ability will not be obtained, and water required for gypsum hydration will be insufficient and hardening will not occur.

Normally, 40 parts by weight or more of water is required, but if it exceeds 50 parts by weight, the initial stiffness of the cured product is low and the initial drying properties are also poor.

In manufacturing the gypsum hardened body of the present invention, if necessary,
Gypsum curing retarders to control curing time, various admixtures to prevent breathing, expansion reducers, water reducers to reduce the amount of mixing water, antifoaming agents to prevent inclusion of air bubbles, or It goes without saying that any additives, such as aggregates for increasing the volume, may be used as long as they do not interfere with achieving the purpose of the invention.

As the hardening retardant, known gelatin, casein, peptone, etc. can be used.

Anti-breathing agents usually include methylcellulose,
'Polyvinyl alcohol, carboxymethyl cellulose, vinyl acetate, etc. are used.

As the swelling reducing agent, known potassium malate, borax, potassium sulfate, etc. can be used.

Examples of water reducing agents include lignin sulfonate, Melment (a sulfonated melamine resin manufactured and sold by Showa Denko K.K.), and the like.

As the antifoaming agent, polyoxyethylene alkylphenol ether, polyoxyalkylene siloxane, etc. can be used, and as the extender, for example, limestone powder, silica powder, slag powder, etc. can be used without any problem.

According to the present invention, by using a gypsum slurry with high fluidity and self-smoothing ability and good workability, it is possible to construct or manufacture a subfloor without requiring skill or manpower, and the resulting hardened product is This method has excellent initial drying properties, shortens the construction period up to the application of the surface finishing material, and is fully competitive with the conventional cement mortar method in terms of cost.

It is expected that the production of gypsum will continue to increase due to factors such as the spread of flue gas desulfurization, so the present invention, which is useful for expanding its use, is a great industrial miracle.

Example 1 ■ Type anhydrite alone or a gypsum mixture containing α type anhydrite mixed with type ■ anhydrite in various proportions shown in Table IA,
Peptone and methyl cellulose were added, and to some of them, an alkaline substance was added and kneaded with water, and the amount of water at which the slurry had appropriate fluidity was recorded as the "kneading water amount".

The amount of kneading water was calculated by flowing 100g of gypsum slurry made by adding water to the gypsum mixture onto a horizontal glass plate from a distance of 10CrfL, and the diameter of the slurry was 120~
If the range is 150 mm, it is determined as the number of parts by weight of water relative to 100 parts by weight of the gypsum mixture.

The gypsum slurry containing the kneading water determined as above was poured into a mold, and after hardening, the mold was removed and kept indoors for 1 to 3 days.
After being left for 5 days, 10 days, and 15 days, the compaction strength and deformation of each specimen was measured using a compaction testing machine specified in JIS* *R5201 "Physical Test Methods for Cement."

The results are shown in Table IB.

Separately, the gypsum slurry containing the kneading water determined as described above was poured into a glass mold with a thickness of 2 crfl and a diameter of 10 cril, and after hardening, the mold was removed and placed in a room at a temperature of 20°C and a relative humidity of 60%. on the 1st, 3rd, 5th, 10th and 1st
The samples were left for 5 days and the initial degree of dryness was determined.

Each specimen was dried in a dryer at a temperature of 40° C. until it reached a constant weight.

From the difference in weight before and after drying, the excess moisture content was determined using the following formula.

Example 2 Slaked lime, peptone, and methyl cellulose were added to a gypsum mixture containing β-type anhydrite and β-type hemihydrate in various proportions, and in some cases Melment was added. Example 1
The amount of mixed hydrophobicity was determined in the same manner as above.

The blending ratio and amount of mixed hydrophobicity are shown in Table 2. Prepare a test piece by molding and hardening the slurry mixed with the above mixing water amount,
The crimp strength was measured in the same manner as in Example 1.

The results are shown in Table 2B.

Separately, a specimen for measuring excess moisture was prepared from the slurry with the above-mentioned amount of kneading water, and the degree of initial drying was measured in the same manner as in Example 1.

It is as follows.

The results are shown in Table 2C Example 3 Peptone and methylcellulose were added to a mixture of α-type anhydrite and β-type hemihydrate in various proportions to type anhydrite, and some of the mixtures were also treated with alkaline substances. In addition, the amount of kneading water was determined in the same manner as in Example 1.

The blending ratio and kneading water amount are listed in Table 3A.

The slurry kneaded with the above amount of kneading water was cured in a certain manner to prepare a test piece, and the degree of shrinkage strength was measured in the same manner as in Example 1.

The results are listed in Table 3B.

Separately, a specimen was made from the above kneading water amount, and Example 1
In the same manner as above, excess moisture was measured to find out whether there was early drying.

It is.

The results are shown in Table 3C. The following can be seen from the experimental results of Example 1.

That is, Experiment No. 1 is a case of using type 1 anhydrite alone, and even when an alkali is added and the amount of kneading water is 50 parts by weight, no initial strong deterioration occurs and the initial dryness is low.

Experiments Nos. 2 to 5 are cases in which α-type hemihydrate is added to ■-type anhydrite in various proportions, but because no alkali is added, compaction strength is insufficient and initial drying is slow. ,5
It is not suitable for attaching surface finishing materials because the excess moisture does not fall below 8% after a day.

In addition, in the case of experiment number 10, in which the amount of α-type hemihydrate gypsum blended is small, the strength of the concubine is not so high.

On the other hand, in experiment numbers 6 to 9, which is the case of the present invention,
After 1 day, the deformation was significantly increased, exceeding iooy,,'=, and when looking at the initial dryness, the surplus moisture after 5 days was less than 8%.

This means that in the present invention, the cured gypsum body is quickly stabilized, its strength, particularly its initial strength, is significantly improved, and its initial drying properties are also good.

From the results of Example 2, as seen in experiment numbers 11 to 13,
Even if slaked lime is added, if the kneading moisture is 50 parts by weight or more,
It can be seen that the initial strong change is low and the early drying property is poor.

Even if the amount of kneading water is 50 parts by weight or less and slaked lime is added,
In Experiment No. 17, in which the blended amount of β-type hemihydrate gypsum is small relative to the type ① anhydrite, the initial compaction strength is not developed much and there is a large amount of initial surplus moisture.

On the other hand, in experiments Nos. 14 to 16 according to the present invention, the initial compaction strength exceeded iookg,/i, and the excess moisture after 5 days was 8% or less, making it difficult to apply the surface finishing material. It is clear that this can be done quickly.

The results of Example 3 also demonstrate the same trend as above.

Claims (1)

[Claims] 1. 100 parts by weight of a gypsum mixture consisting of 20-80% by weight of type anhydrite and 80-20% by weight of α-type hemihydrate and/or β-type hemihydrate, slaked lime, dolomite plaster A gypsum slurry is prepared by kneading one or two to 10 parts by weight of powder of an alkaline substance such as Bortland cement, limestone, etc., and 25 to 50 parts by weight of water. A method for producing a hardened gypsum flooring material, characterized by forming it into a shape.