JPH05213655A - Self-leveling gypsum composition excellent in dimensional accuracy - Google Patents

Abstract

PURPOSE:To provide a self-leveling gypsum compsn. excellent in fluidity and dimensional accuracy and well exhibiting strength. CONSTITUTION:This self-leveling gypsum compsn. excellent in dimensional accuracy contains gypsum consisting of 90-10 pts.wt. hydrofluoric acid II type anhydrous gypsum and 10-90 pts.wt. natural II type anhydrous gypsum.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a self-leveling gypsum composition having excellent dimensional accuracy.

[0002]

2. Description of the Related Art Conventionally, as a self-leveling gypsum composition, one type or a mixture of two or more types of type II anhydrous gypsum (hydrofluoric acid type II anhydrous gypsum), α hemihydrate gypsum, and β hemihydrate gypsum is used. It is used, but in order to prevent deterioration of smoothness due to expansion during setting and hardening of gypsum slurry, alkali metal or alkaline earth metal sulfate, borate, alkaline substance (caustic potash, caustic soda, slaked lime, quick lime) And the like are used. However, alkali metal or alkaline earth metal sulphate has a significantly different expansion suppressing effect depending on the amount added, and if it is added in a small amount, the effect is small and if added in a large amount, the fluidity retention time of the gypsum slurry will be shortened due to the effect of setting and the self-leveling. Sex is impaired.
Further, the addition of borate has the drawback that it delays the setting and causes curing failure and strength reduction, and that shrinkage due to drying after curing increases. Further, the addition of an alkaline substance or the like has a drawback that the self-leveling property is deteriorated due to the coagulation promoting action.

[0003]

[Problems to be Solved by the Invention] The performance required for a self-leveling gypsum composition is that it has appropriate viscosity and fluidity and is excellent in self-leveling ability; fluidity retention time and setting time are appropriate; It can be mentioned that the gypsum slurry has very little expansion and contraction during and after setting and hardening, and has excellent dimensional accuracy. All of the above-mentioned conventional techniques for improving the performance of (1) are accompanied by the acceleration or delay of the setting time, and thus the performance of (1) is likely to be impaired, and further, the expansion suppressing effect is likely to change depending on the curing temperature.

Therefore, the object of the present invention is to provide excellent fluidity,
An object of the present invention is to provide a self-leveling gypsum composition exhibiting good strength and excellent dimensional accuracy.

[0005]

[Means for Solving the Problems] In the process of examining an expansion suppressing technique which is an alternative to the conventional technique, two types of type II anhydrous gypsum are used.
As a result of investigating the hydration characteristics that are considered to be related to expansion of (hydrofluoric acid type II anhydrous gypsum and natural type II anhydrous gypsum), the expansion amount does not depend only on the hydration rate of gypsum (or the heat of reaction during setting). , It was found that it is closely related to the crystal shape and hydrated tissue structure of the produced gypsum dihydrate, and the hydrofluoric acid type II anhydrous gypsum, which has a large expansion at the time of setting, forms spherical crystals and has a low porosity. It was confirmed that natural type II anhydrous gypsum, which has a small swelling upon setting, forms columnar crystals and forms a hydrated structure with a relatively high porosity, while a hydrated structure is formed.

[0006] Here, the present inventors produce a gypsum composition that forms a hydrated structure having a small expansion upon setting like natural type II anhydrous gypsum and has a large strength development like hydrofluoric acid type II anhydrous gypsum. When the experiment was continued, the two kinds of type II anhydrous gypsum were mixed and used as a base material, so that the expansion at the time of setting was extremely small, the strength was excellent, and other performance required as a self-leveling gypsum composition was obtained. It was found that a sufficient self-leveling gypsum composition was obtained, and the present invention was completed.

That is, the self-leveling gypsum composition having excellent dimensional accuracy according to the present invention has 90 to 10 parts by weight of hydrofluoric acid type II anhydrous gypsum and 10 to 10 parts of natural type II anhydrous gypsum as gypsum.
It is characterized in that it is used together at a ratio of 90 parts by weight.

In the self-leveling gypsum composition of the present invention, the greater the proportion of hydrofluoric acid type II anhydrous gypsum, the better the strength development, and the greater the proportion of natural type II anhydrous gypsum, the smaller the expansion. Proportion is hydrofluoric acid type II anhydrous gypsum 90-
10 parts by weight and 10 to 90 parts by weight of natural type II anhydrous gypsum, preferably 70 to 30 parts by weight of hydrofluoric acid type II anhydrous gypsum and 30 to 70 parts by weight of natural type II anhydrous gypsum. A self-leveling gypsum composition can be used by adding a dispersant, a setting modifier, a viscosity modifier, a water retention agent, a defoaming agent, Portland cement, an aggregate and the like to both gypsums.

Although it is generally considered that the expansion coefficient of the plaster composition for floors is 0.15% or less, preferably 0.1% or less, in the self-leveling gypsum composition of the present invention, When the ratio is 70 to 30 parts by weight of hydrofluoric acid type II anhydrous gypsum and 30 to 70 parts by weight of natural type II anhydrous gypsum, the rate of length change is 0 to + 0.05% in 28 days and the dimensional accuracy is very high. Are better.

Furthermore, the self-leveling gypsum composition of the present invention has a large level of unevenness on the floor surface, and even when the height difference of the casting thickness is large, no separation of materials, sinking, generation of floating water, etc. are observed, and smoothness is obtained. It has extremely excellent performance of being excellent.

Fluoric acid type II anhydrous gypsum used in the self-leveling gypsum composition of the present invention (in the following examples, Central Glass Co., Ltd. hydrofluoric acid type II anhydrous gypsum was used) and natural type II anhydrous gypsum (below In the examples, natural Thailand I
Blaine value is 3000-900.
0cm ² / g, preferably 5000~7000cm ² / g
I like the one.

The self-leveling gypsum composition of the present invention contains potassium sulfate as a setting accelerator for anhydrous gypsum, the content of which is 100% by weight of the base material (hydrofluoric acid type II anhydrous gypsum + natural type II anhydrous gypsum). It is in the range of 0.3 to 3 parts by weight with respect to parts. If the content of the setting accelerator is less than 0.3 parts by weight, the setting time will be delayed and floating water will be generated, which is unsuitable. If it exceeds 3 parts by weight, the setting time will be too fast and workability will be deteriorated. It is not preferable to do. The preferred content is in the range of 0.5 to 1.5 parts by weight. Portland cement or slaked lime may be used in combination with potassium sulfate as the setting accelerator. In particular, the addition of Portland cement is effective in improving water resistance. In this case, it is desirable that the content of Portland cement is 10 parts by weight or less, the content of slaked lime is 4 parts by weight or less, and the content of potassium sulfate is 1.5 parts by weight or less in order to secure workability.

It is desirable to use a dispersant in the self-leveling gypsum composition of the present invention in order to improve the fluidity of the slurry, and the dispersant is a melamine formalin condensate sulfonate, lignin sulfonate, β Known substances such as naphthalene formalin condensate sulfonate can be used. Also, a plurality of these dispersants can be used in combination. Particularly, melamine formalin condensate sulfonate is preferable because it does not cause a significant delay in setting or a decrease in strength development. The content of the dispersant is within the range of 0.1 to 1.5 parts by weight, preferably within the range of 0.3 to 0.8 parts by weight, based on 100 parts by weight of the base material.

The self-leveling gypsum composition of the present invention preferably contains a water retention agent so as not to cause volume contraction, cracking, flexure and the like due to drying during setting of the slurry. Further, these water retention agents are viscosity modifiers. It also has the effect of preventing aggregate separation and floating water generation. As the water retention agent, known ones such as cellulose type, vinyl type and acrylic type can be used. Also, a plurality of these water retention agents can be used in combination. The content of the water retention agent is in the range of 0.005 to 1 part by weight, preferably 0.01 to 0.2 part by weight, relative to 100 parts by weight of the base material.

The self-leveling gypsum composition of the present invention preferably contains an ethylene vinyl acetate copolymer resin as a reinforcing agent for improving flexural strength. The content is in the range of 0.2 to 3 parts by weight, preferably in the range of 0.5 to 1.5 parts by weight. If it is less than 0.2 parts by weight, the effect of improving bending strength is not seen, and if it exceeds 3 parts by weight, further improvement in strength is not seen and it is uneconomical.

The self-leveling gypsum composition of the present invention may contain silicone oil to prevent cracking. As the silicone oil, dimethylpolysiloxane oil, methylphenylpolysiloxane oil, methylalkylpolysiloxane oil, methylaralkylpolysiloxane oil, methylvinylpolysiloxane oil, and other methyl-based silicone oils, as well as propyl-based silicone oils can be used. .. The silicone oil used here is a suitable inorganic fine powder.
It is desirable to use one in which silicone oil has been adsorbed as a carrier (calcium carbonate, slaked lime, Portland cement, gypsum, etc.), or one made into a water-soluble emulsion by using an appropriate solvent, because it can be easily mixed with the base material. The content of silicone oil is in the range of 0.001 to 2 parts by weight, preferably 0.005 to 1 part by weight. If it is less than 0.001 part by weight, the effect of preventing cracking is not obtained, and if it exceeds 2 parts by weight, the strength is lowered.

In the self-leveling gypsum composition of the present invention, in order to prevent air bubbles from being mixed during slurry kneading,
A known antifoaming agent can be contained.

When the self-leveling gypsum composition of the present invention is used, various sands such as river sand and crushed sand, as well as fly ash, blast furnace slag, calcium carbonate and the like can be used as an aggregate to be contained. The content is in the range of 10 to 150 parts by weight, preferably 30 to 100 parts by weight, based on 100 parts by weight of the substrate.
A suitable amount is within the range of 100 parts by weight.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following examples. Examples The materials used in the examples are as shown in Table 1 below.

[0020]

[Table 1]

Table 2 shows the material composition in the examples. The self-leveling gypsum composition of the present invention was tested in No.
It shows in 1-10. Also, as a comparative product, the one using only hydrofluoric acid type II anhydrous gypsum or natural type II anhydrous gypsum was tested N
It is shown in o.11 and 12.

[0022]

[Table 2]

The characteristics of the product of the present invention and the comparative product are shown in Table 3 to
5 shows.

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

In the above experiment, a mortar mixer was used for kneading, and kneading was performed for 3 minutes. The flow test is the Housing and Urban Development Corporation method (a pipe with an inner diameter of 5 cm and a height of 5 cm is placed on a glass plate, filled with slurry, and the pipe is pulled up to spread the slurry in a circular shape on the glass plate.
The diameter is measured). The length change is based on the length change test method of mortar and concrete (JIS A 1
129). The compressive strength test was measured based on the physical test method for cement (JIS R 5201). The generation of floating water was observed up to 1 day of age. For the aggregate separation, the cured product was cut at 28 days of age and the cross section was observed.

[0027]

As is clear from the experimental results shown in Tables 3 to 5, the strength development is large in the composition using only hydrofluoric acid type II anhydrous gypsum, but the change in length at 5 ° C and 20 ° C is large. It has the drawback of being large in the direction of expansion. In addition, in the case of blending using only natural type II anhydrous gypsum, strength development (compressive strength) is small at each temperature, and the change in length becomes large in the shrinking direction as the age advances (especially 30 ° C). .. Floating water was generated and aggregates were separated probably due to the slow setting time. On the other hand, in the product of the present invention, the change in length at each temperature is very small, and excellent dimensional accuracy can be secured. Furthermore, the product of the present invention showed good fluidity (flow value) and strength development (compressive strength), and neither floating water nor aggregate separation occurred.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location C04B 24:38 A 2102-4G 24:26 C 2102-4G 24:24 B 2102-4G 14:06 ) Z 2102-4G

Claims (1)

[Claims] 1. A self-leveling gypsum composition, characterized in that as gypsum, 90 to 10 parts by weight of hydrofluoric acid type II anhydrous gypsum and 10 to 90 parts by weight of natural type II anhydrous gypsum are used together. A highly leveling gypsum composition with self-leveling properties.