JPS5941939B2 - Fluid gypsum plaster composition - Google Patents

Description

Detailed Description of the Invention The present invention forms a free surface by natural flow by simply pouring a slurry containing a small amount of water as a dispersion medium, and further hardens within a suitable time to ensure excellent surface precision. The present invention relates to a fluid plaster composition that has excellent performance in terms of workability, dimensional accuracy, and strength of molded products after hardening.

In particular, the present invention uses α-type hemihydrate gypsum, which is produced as a by-product during wet phosphoric acid production, to α-type hemihydrate gypsum used as the main raw material, and adjusts the pH of the α-type hemihydrate gypsum to improve hardened product strength, fluidity, workability, etc. The aim is to improve dramatically.

In recent years, research has been carried out to apply α-type hemihydrate gypsum, which is produced as a by-product during wet phosphoric acid production, to building materials.
is very low at 2.0 to 3.5.

For this reason, the strength of the hardened slurry obtained by kneading it with water is extremely low, and the effect of the setting modifier is also extremely poor, so at present it is mixed with water and used in cement preparations.

From the above perspective, the present inventors conducted various studies on the fluidity of the slurry obtained by kneading α-type hemihydrate gypsum, which is a by-product during wet phosphoric acid production, with water, the strength of the hardened product of the slurry, etc. The present invention was completed based on the knowledge that these fluidities and strengths are closely related to the pH of the plaster composition and the particle size of the α-type hemihydrate gypsum that serves as the base material.

That is, the present invention has a particle size distribution of α-type hemihydrate gypsum produced as a by-product during wet phosphoric acid production, with a weight ratio of 50% or more of 0 to 60μ, 0
~10μ is 50% or less as a base material, and p
Contains an H regulator, a dispersant, and a coagulation regulator, and further contains a dispersion aid, a viscosity regulator, an expansion inhibitor, a water retention agent, an antifoaming agent,
In a composition obtained by containing one or more of antifreeze agents, aggregates, etc., the pH of a suspension of 10 parts by weight of the composition in 90 parts by weight of water is adjusted to 6 to 12. A fluid gypsum plaster composition comprising:

The composition according to the present invention has a low slurry viscosity and excellent initial fluidity, and forms a horizontal surface simply by being spread on the floor surface.

Furthermore, since the time until the start of hardening can be freely adjusted within the range of 15 to 600 minutes, it is possible to walk on the product within about 24 hours after pouring, the start of hardening can be further delayed if necessary, and it has good fluidity. Therefore, the workability and construction properties are excellent, the surface accuracy of the formed floor surface etc. is extremely excellent, and the molded product after curing has a compressive strength of 100 after drying.
The pipe has a sufficient strength of 50 kg/i or more and a bending strength of 50 kg/i or more.It has various advantages.

α-type hemihydrate gypsum, which is the base material of the composition of the present invention, is a by-product during wet phosphoric acid production. This by-product α-type hemihydrate gypsum contains a phosphoric acid component, and the pH is 2.0～
Since the pH is extremely low at 3.5, the pH is adjusted to 6 to 12 by adding a pH adjuster, aggregate, etc.

If the pH is lower than this, the setting regulator will not be effective, making it difficult to adjust the curing time, and the strength of the resulting cured product will be very weak, and the adhesive strength with cement will be significantly weakened.

If the pH is higher than this range, the effect of the setting modifier will be poor, the strength of the resulting cured product will be weak, and the fluidity of the slurry will be significantly reduced when kneaded with water.

The particle size distribution of α-type hemihydrate gypsum has a great effect on fluidity and water retention, and the distribution is such that, in terms of weight ratio, 0-60μ is 50% or more, O-10μ is 50% or less, preferably O-60μ is 65%. % or more, O~10μ is preferably 5~35%.

If the particle size distribution of α-type hemihydrate gypsum is larger than this range, a cured product with extremely low strength will be obtained, and warping will easily occur.

Furthermore, if the particle size is smaller than this range, the fluidity will be significantly reduced.

Calcium hydroxide, potassium carbonate,
Examples include one or more of calcium carbonate, potassium hydroxide, and type 2 type anhydrite which is produced as a by-product during the production of hydrofluoric acid.

■-type anhydrite, which is produced as a by-product during the production of hydrofluoric acid, has an excess of calcium-based alkali added to it to neutralize the sulfuric acid that remains after the production of hydrofluoric acid, making it usable as a pH adjuster, and also increases the hydration of anhydrite itself. Hardening also contributes to strength.

Even when these pH adjusters are added to adjust the pH, they do not cause problems such as efflorescence on the hardened gypsum, which is the case with sodium-based alkalis.

As aggregates, sand, silica sand, fly ash, slag, and other industrial wastes are used.As aggregates that also act as pH adjusters, there are calcium carbonate and type anhydrite, which is a by-product during the production of hydrofluoric acid. , ■-type anhydrite itself hydrates and hardens and becomes a reinforcing aggregate.

The amount of aggregate mixed varies depending on the type of aggregate, but is preferably 0 to 250 parts by weight per 100 parts by weight of α-type hemihydrate gypsum. have

The dispersant used as an additive is effective for loosening the primary particles of α-type hemihydrate gypsum and the like and improving the initial fluidity.

As the dispersant used in the present invention, common dispersants for cement mortar are used, including sodium ligninsulfonate, calcium ligninsulfonate, β-naphthalenesulfonic acid formaldehyde condensate soda salt, β-naphthalenesulfonic acid formaldehyde condensate sodium salt,
Typical examples include creosote sulfonic acid, cresol sulfonic acid condensates, melamine formaldehyde condensate sulfonates and sulfites, polyacrylic dispersants, and phosphate ester surfactants.

These dispersants can be used alone or in combination of two or more, if necessary.

The amount of dispersant added varies depending on the type of dispersant used, but is usually 0.1 to 100 parts by weight of α-type hemihydrate gypsum.
10 parts by weight are used, preferably 0.15 to 5 parts by weight.

If used in a large amount exceeding this range, the fluidity may decrease or the setting and hardening properties may be adversely affected.

There are various expansion inhibitors, but alkali metal sulfates are effectively used from the viewpoint of further enhancing the effect of the dispersant, improving the setting and hardening properties, and further increasing the sulfuricity of the slurry. Ru.

Among the alkali metal sulfates, potassium sulfate, sulfuric acid)
IJum is selected based on its economic efficiency.

The amount of alkali metal sulfate added is approximately 0.2 to 3.0 parts by weight per 100 parts by weight of α-type hemihydrate gypsum, etc.

If it is less than this range, the expansion suppressing effect will be insufficient, and if it is more than this range, the setting effect will be very rapid and the workability will be significantly reduced.

Setting regulators are used to adjust the setting start time, and for α-type hemihydrate gypsum, etc., there are various slowing agents such as various phosphates, various carboxylic acids, and various proteins, but the amount added The gelation time can be adjusted as desired.

The water retaining agent is used to prevent solid-liquid separation before the slurry begins to gel.

Particularly in the case of a poured bed, floating ice occurs due to solid-liquid separation, and after solidification and hardening, the strength of the upper surface is significantly reduced.

Therefore, when a finishing material, such as a plastic tile, is attached to the surface, the adhesive strength decreases, causing problems such as peeling.

Although the amount of water-retaining agent added is not necessarily uniform depending on the type of water-retaining agent, generally, adding a water-retaining agent increases the viscosity of the slurry.

Since this also functions as a so-called viscosity modifier, care must be taken in the amount added so as not to reduce the initial fluidity of the slurry.

Water retention agents include cellulose, vinyl, and acrylic agents, and cellulose agents are widely used, with hydroxyethyl cellulose being particularly preferred.

The amount added is 2.0 parts by weight or less, preferably 0.5 parts by weight or less, per 100 parts by weight of α-type hemihydrate gypsum.

If it is outside this range, the viscosity of the slurry will increase, resulting in poor workability and poor surface accuracy of the finished floor surface.

In addition, examples of the dispersion aid include potassium sulfate, sodium phosphate, and the like.

Water retaining agents play a role as viscosity modifiers, but there are also water glass substances.

Examples of antifreeze agents include calcium chloride, ethylene glycol, propylene glycol, and the like.

Antifoaming agents include silicone-based and sugar-based ones.
Silicon-based materials are preferred, and the appropriate amount of addition is 0.01 to 2% by weight based on α-type hemihydrate gypsum and the like.

As described above, the fluid gypsum plaster composition of the present invention is produced by adjusting the pH of α-type hemihydrate gypsum, which is produced as a by-product during wet phosphoric acid production as a base material, and adding a relatively small amount of water and various additives to the composition. By mixing , aggregate, etc., excellent fluidity and hardened body strength can be obtained.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited by these Examples.

The α-type hemihydrate gypsum used in the actual cases was all gypsum produced as a by-product during wet phosphoric acid production.

In addition, all percentages in the examples are by weight unless otherwise specified.

Furthermore, the flow value indicates a value measured by the following method.

That is, a pipe with an inner diameter of 5.4 CIn and a height of 9.5 cfrL was placed vertically on a flat surface (a glass plate), and slurry was poured into it, and after 40 seconds, the pipe was pulled upward to spread the slurry contents in a circular shape on the flat surface. This is the value measured by the radius when the fluid is blown, and the larger the value, the better the fluidity.

Example 1 The above materials were thoroughly mixed to prepare a slurry.

The flow value of this slurry was 13.5 CrfL.

Apply this slurry to a construction area of 1 m2 (Slab unland area: 7 m/m
) at an average pouring thickness of 15 m/m, it hardened in 10 hours and could be easily walked on the next day.

At this time, the horizontal plane accuracy was excellent at ±1.6 m/m.

The strength of the cured product is compressive strength 158 kg/crti after drying.
No abnormalities such as cracks were observed.

In addition, by mixing the remaining materials after removing the medium dispersion medium, a suspension of 10 parts by weight of the mixture in 90 parts by weight of water is obtained.
H was 9.0.

Example 2 A slurry was prepared by sufficiently mixing the materials used in Example 1 with various amounts of pH % adjuster (calcium hydroxide).

This slurry was applied to an area of 1 m2 (slab surface area 7 m).
/ m ) at an average pouring thickness of 15 m / m and hardened.

The table below shows the relationship between pH, flow value, curing time, curing time, and cured body probeability in that case.

The effect of the curing retarder becomes very poor when the pH is below 6, and also tends to become poor when the pH is above 12.

The flow value deteriorates when the pH is below 6 because the curing time is very fast, when the pH is above 6 it decreases as the pH increases, and when the pH is above 12 it decreases rapidly.

The strength of the cured product improves as the pH increases, but at pH 12
Above that, the value decreases rapidly.

The strength of the cured product increases as the pH increases, but it actually decreases when the pH increases to 12 or higher.

The above materials were thoroughly mixed to prepare a slurry.

The flow value of this slurry was 14.0 to 772.

Apply this slurry to a construction area of 1m' (slab uneven surface 7m/m
) with an average pouring thickness of 15 m/crrt.
It cured in 4 hours and was able to walk easily the next day.

At this time, the horizontal plane accuracy was excellent at ±1.8 m/m.

The strength of the cured product was a compressive strength of 154 kg/cyyt after drying, and no abnormalities such as warping or cracking were observed.

Mix the rest of the above materials except for the dispersion medium and mix with 90% water.
The pH of the suspension of 10 parts by weight of the mixture was 11.0.

The above materials were thoroughly mixed to prepare a slurry.

The flow value of this slurry was 12.8 CrrL.

This slurry has an average pouring thickness of 20 m on a construction area of 10 m2.
When poured at a depth of 7 cm, it hardened in 2 hours, and the horizontal accuracy was ±1.8 m/m.

The strength of the cured product was 130 kg/cri* after drying, and the surface condition was also good.

Incidentally, the pH of a suspension of 10 parts by weight of the mixture obtained by mixing the remaining materials after removing the dispersion medium in 90 parts by weight of water was 10.5.

Claims (1)

[Claims] 1. The particle size distribution of α-type hemihydrate gypsum produced as a by-product during wet phosphoric acid production is 50% or more in weight ratio of 0 to 60 μ and 5 of 0 to 10 μ.
0% or less as a base material, which contains a pH adjuster, a dispersant, and a coagulation adjuster, and further contains a dispersion aid, a viscosity adjuster, an expansion inhibitor, a water retention agent, an antifoaming agent, and an antifreeze agent. ,
A composition obtained by containing one or more types of aggregates, etc., characterized in that the pH of a suspension of 10 parts by weight of the composition in 90 parts by weight of water is adjusted to 6 to 12. Flowable gypsum plaster composition. 2. Fluidity according to claim 1, wherein the pH adjuster is one or more of potassium carbonate, calcium carbonate, potassium hydroxide, calcium hydroxide, and U-type anhydrite, a by-product during hydrofluoric acid production. Gypsum plaster composition. 3 The amount of aggregate is 0 to 100 parts by weight of α-type hemihydrate gypsum.
250 parts by weight of a fluid gypsum plaster composition according to claim 1.