JPS6016381B2 - Heat-curing cement composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to a heat-curable cement composition.

The heat-curable cement composition in the present invention has a property of slow curing speed even in the presence of moisture at room temperature, but rapidly hardens in the presence of moisture when heated above a certain temperature, A composition whose main component is cement.
Compositions consisting of Bortland cement, alumina cement, gypsum, and lime have been conventionally provided as heat-curing cement compositions, and the curing speed is slow at room temperature even in the presence of moisture, with hardening speeds of 60% or higher. It has the property of rapidly curing in the presence of moisture when heated.

However, in conventional heat-curing cement compositions, the amount of boltland cement in the composition was small and the composition was made with a large amount of alumina cement. When the resulting molded product was again subjected to drying conditions of 6,000 or more, the mechanical strength decreased significantly, and the dimensional change due to drying shrinkage became significantly large, causing cracks to occur. Another disadvantage is that when molded products obtained from the heat-curable cement compositions are used for the interior and exterior walls of buildings, the explosion resistance required for fire protection performance is extremely low.

The present inventor has developed 80 to 9 parts by weight of Boltland Cement.
13 to 2.5 parts by weight of alumina cement, anhydrite or (
and) 7 to 1.5 parts by weight of gypsum hemihydrate to form a mixed cement to improve the mechanical strength of the molded product during high temperature drying, dimensional change due to drying shrinkage, and explosion resistance, and the weight of this mixed cement 10. It was discovered that by mixing 0.2 to 2 parts by weight of an alkali metal salt of an organic carboxylic acid per part, the mechanical strength of the molded product immediately after heating and curing can be improved.

The present invention eliminates the drawbacks of the conventional heat-curing cement compositions, prevents a decrease in mechanical strength when a molded product obtained by heat-curing is dried by maintaining it at a high temperature, and prevents dimensional changes due to drying shrinkage. It is an object of the present invention to provide a heat-curable cement composition that can improve explosion resistance, improve the mechanical strength of a heat-cured molded product, and prevent the molded product from deforming when removed from the mold. purpose.

Next, the heat-curable cement composition of the present invention will be explained in more detail.

The mixed cement in the present invention consists of 80 to 9 parts by weight of Bortland cement, 13 to 2.5 parts by weight of alumina cement, and 7 to 1.5 parts by weight of anhydrite or (and) hemihydrate.

Examples of boltland cement include ordinary boltland cement, early-strength boltland cement, ultra-early strength boltland cement, medium-heat boltland cement, low-heat boltland cement, white boltland cement, and highly oxidized boltland cement. . In the present invention, 80 to 9 parts by weight of Bortland cement is used in 100 parts by weight of mixed cement.

The reason why the amount of Bortland cement is set to 80 to 9 parts by weight is that the heat-curable cement composition of the present invention is heat-cured in the presence of moisture, and the molded product obtained is heat-cured and then cured for a long period of time. In order to maintain mechanical strength after
This is to prevent mechanical strength from decreasing when reheated to a temperature higher than C and dried, to prevent dimensional changes from occurring due to drying shrinkage, and to further improve explosion resistance. However, if the amount of Boltland cement is less than 8 parts by weight, the mechanical strength of the molded product will decrease when drying, the dimensional change due to drying shrinkage will be significant, and it will be difficult to obtain explosion resistance.
Furthermore, if the amount exceeds 9 parts by weight, the proportions of each component of alumina cement and gypsum will be too small, and the molded product will not have sufficient mechanical strength when heated and cured in the presence of moisture. Become. Alumina cement is a cement whose main component is calcium aluminate, and calcium contributes to the development of mechanical strength of molded products obtained by heat-curing the heat-curing cement composition of the present invention in the presence of moisture. It has the role of producing sulfoaluminate hydrate. The alumina cement is used in an amount of 13 to 2.5 parts by weight per 10 parts by weight of the mixed cement. If the amount of alumina cement is less than 2.5 parts by weight, the amount of calcium sulfoaluminate hydrate produced during heat curing will decrease, and the mechanical strength of the molded product will decrease when the molded product is heat cured. It becomes difficult to develop, and alumina cement becomes 1
If the amount is larger than the box weight part, the amount of Bortland cement used in the mixed cement must be reduced, resulting in a decrease in mechanical strength after a long period of time after heat curing, and mechanical strength during drying. This results in a decrease in physical strength, dimensional changes due to shrinkage, and a decrease in explosion resistance. Anhydrous gypsum and hemihydrate gypsum can be used alone or in combination to form a mixed cement 1
It is used in an amount of 7 to 1.5 parts by weight in 0 parts by weight.

In addition, these anhydrite and hemihydrate serve as sulfur sources and calcium sources for calcium sulfoaluminate hydrate, which is produced when the heat-curing cement composition of the present invention is heated and cured in the presence of moisture. . The above-mentioned mixed cement has disadvantages in conventional heat-curing cement.

The mechanical strength of the molded product during high temperature drying, dimensional change due to drying shrinkage, and explosion resistance can be significantly improved. However, in Namiai cement, the improvements in the various properties described above are not sufficiently realized in the region where the mechanical strength of the molded product is significantly improved immediately after heat curing (in the present invention, within 1 hour after the start of heat curing). On the other hand, in areas where the improvements in the above-mentioned properties are remarkable, the degree of improvement in the mechanical strength of the molded product immediately after heat curing is not necessarily sufficient. In particular, when the amount of Bortland cement exceeds 8 parts by weight in 100 parts by weight of mixed cement as in the present invention, the amount of calcium sulfoaluminate produced during heat curing decreases, and the amount of calcium sulfoaluminate produced immediately after heat curing decreases. The mechanical strength of the molded product decreases. Therefore, when the molded product is removed from the mold for curing and high-temperature drying, the molded product is likely to lose its shape. Therefore, in the present invention, per part by weight of the Namiai cement 10, 0.2
~2.0 parts by weight of an alkali metal salt of an organic carboxylic acid is mixed and the mechanical strength of the molded product is good even immediately after heating and curing, and the molded product does not lose its shape when demolded. This was done to prevent this from happening.

Examples of alkali metal salts of organic carboxylic acids include sodium or potassium salts of citric acid, malic acid, gluconic acid, glutaric acid, glycolic acid, and the like.

Alkali metal salts of organic carboxylic acids have the function of accelerating the hardening of mixed cement by heating.
Due to the hardening accelerating effect, the mechanical strength of the molded article immediately after being heated and hardened can be improved.

The alkali metal salt of the organic carboxylic acid does not impede mechanical strength during high temperature drying after demolding, dimensional change due to drying shrinkage, and improvement in explosion resistance. However, if the amount of organic carboxylic acid used is less than 0.2 parts by weight per part by weight of the mixed cement 10, the effect of accelerating the hardening of the mixed cement when heated will not be sufficient.
Further, if the amount is more than 2 parts by weight, demolding failure of the heat-cured molded product is likely to occur. In the present invention, the alkali metal salt of an organic carboxylic acid may be mixed with a mixed cement prepared in advance and mixed with this mixed cement, but it may be mixed with any one or more components of the mixed cement, By further adding and mixing the remaining components of the mixed cement, the alkali metal salt of the organic carboxylic acid may be finally mixed into the mixed cement. In the heat-curing cement composition of the present invention, various aggregates such as sand and gravel, reinforcing materials such as natural fibers, synthetic fibers, metal fibers, and mineral fibers, various polymeric substances, such as rubber to improve waterproofness are used. Latex etc. may be contained as necessary.

The temperature when heat-curing the heat-curing cement composition of the present invention is preferably from 6,000 to 10,000;
At a temperature lower than 0, the curing speed is slow, and at a temperature higher than 100 q○, the molded product obtained by heating and curing tends to have low mechanical strength.

According to the heat-curing cement composition of the present invention, the disadvantages of conventional heat-curing cement compositions can be overcome.

Mechanical strength when a molded product is once heat-cured and then heated again to 60q○ or more and dried, dimensional changes due to drying shrinkage that causes cracks, and heating required for building fire prevention performance. It is possible to improve the explosion resistance of the molded product, and also to impart mechanical strength to the molded product immediately after thermosetting and to prevent the molded product from losing its shape when removed from the mold, making the molded product suitable for mass production. I can do it. Examples of the present invention are described below.

Example 1 Hina Early Strength Voltland Cement 81. Weight parts of alumina cement 12. Sodium citrate per part by weight of 10 parts of mixed cement consisting of 6.4 parts by weight of calcined stone tube, 0.0 parts by weight of sodium citrate. Mix part by weight of Akebono and further water/cement ratio is 0.65.
Water and sand were mixed so that the sand/cement ratio was 2.0, and the mixture was placed in a mold to form a prismatic body with dimensions of 40 x 40 x 16 valent/m.

The molded product thus obtained was heated to 80°C to undergo rapid heat curing and then demolded, but the molded product did not lose its shape during demolding. Furthermore, the molded product is heated and hardened.
After continuing for a period of time, it was cured at room temperature for one week. The compressive strength of the molded product was measured one week after the start of curing. After curing, the molded product was kept in a temperature bath at 100° C. and dried.

The measurement results of compressive strength after 1 day, 3 days, 1 week, and 4 weeks from the start of drying are shown in the column of Example 1 in Table 1. After curing, the molded product was kept in a thermostat for 10,000 hours, and dimensional changes were measured after 1 day, 1 week, and 4 weeks. These measurement results were as shown in the column of Example 1 in Table 2.

Example 2 Parts by weight of ultra early strength boltland cement matrix 8, 8.4 parts by weight alumina cement, 3 parts by weight of burnt stone bone. Sodium citrate 0.6 per part by weight of 10 parts by weight of mixed cement consisting of part by weight
Parts by weight were mixed, water and sand were mixed in the same manner as in Example 1, molded and heated to harden, demolded, and then cured at room temperature.

The compressive strength of the molded product was measured one week after the start of curing. After curing, the molded product was kept in a 100° C. temperature bath and dried. The measurement results of the compressive strength one week after the start of drying, and the compressive strength after one day, three days, one week, and four weeks are shown in the column of Example 2 in Table 1. 100o after curing
The molded product was kept in a temperature bath of 100 mL, and dimensional changes were measured after 1 day, 1 week, and 4 weeks. These measurement results are shown in the Example 2 column of Table 2. Table 1 Table 2 Example 3 Ultra-early strength boltland cement woven fabric. 8.4 parts by weight of alumina cement, 3 parts by weight of burnt stone bone. 1.2 parts by weight of sodium malate per 10 parts by weight of mixed cement consisting of 1.2 parts by weight of
Mix parts by weight so that the sand (passed through a 2r/m mesh node)/cement ratio is 2.5 and the water/cement ratio is 0.5.
Add sand and water, mix, and place in a mold 40 x 40 x 1
A prismatic body with dimensions of 60 h/m was molded.

The molded product thus obtained was heated to 8,000 ℃ and held for 3 minutes to rapidly heat cure, then removed from the mold and cured at room temperature. The bending strength of the molded product after 30 minutes from the start of curing was 25.5k9/ground, and the compressive strength was 82.5.
It was k9/th. Comparative Example 1 In Example 3, the amount of sodium malate used was 0.1
A molded product was molded, heated and cured in the same manner as in Example 3 except that the amount was 5 parts by weight.

The song of the molded product after 3 nights from the start of curing. The strength was 1.2 kg/water, and the compressive strength was 5.0 k9/m. Example 4 Ultra early strength bolt land cement 82. Weight parts of alumina cement 12. Tortoise weight part, baked stone pipe 2.
0 parts by weight, anhydrite 2. 0.6 parts by weight of sodium citrate was mixed with 10 parts by weight of mixed cement consisting of parts by weight of sword, and the sand (passed through a mesh line of 2 h/m)/cement ratio was 2.
．． 5. Add and mix sand, water, and water reducer so that the water/cement ratio is 0.35 and the water reducer/cement ratio is 0.02, and place in a mold 40 x 40 x 16 h/ A prismatic body with dimensions of m was molded.

The temperature of the thus obtained molded product was raised to 7°C and held for 30 minutes to rapidly harden the molded product, and then the mold was demolded and cured at room temperature.

When 30 minutes had passed from the start of curing, the molded product had a bending strength of 52.9 k9/kg and a compressive strength of 179.2 kg/kg. Further, a flat sample was cut out from this molded product, and after being left at room temperature for 4 weeks, a heating test was conducted using a small fireproof performance testing device according to a two-stage heating curve according to JISAI 301.

As a result, no explosion occurred in the molded product.

Examples 5 and 6 A composition consisting of the components shown in the column of each example in Table 3 was prepared, and a composition with a water/cement ratio of 0.6 and a sand/cement ratio of 2 was prepared.
．． Mix water and sand so that it is 0, put it in a mold and
A prismatic body with dimensions of 40 x 160 h/m was molded.

The temperature of the thus obtained molded product was raised to 8,000 °C and held for 3 minutes to rapidly harden the molded product, and then the mold was demolded. The molded product did not lose its shape during demolding.

Then, it was cured at room temperature. The measurement results of bending strength and compressive strength after 3 minutes from the start of curing are shown in the column of each example in Table 3. Comparative Examples 2 to 5 A composition consisting of the components shown in the column of each comparative example in Table 3 was prepared, and a water/cement ratio of 0.65 and a sand/cement ratio of 2 were prepared.
．． Mix water and sand so that it is 0, put it in a mold and
A prismatic body with dimensions of 40×16 h/m was molded.

The temperature of the thus obtained molded product was raised to 8,000 ℃ to rapidly heat cure it. In Comparative Examples 2 and 3, demolding of the molded product after 3 minutes was poor, so demolding was performed after 50 minutes. Then, it was cured at room temperature. The measurement results of bending strength and compressive strength at the time point when 3 powders have passed since the start of curing are shown in the columns of Comparative Examples 2 and 3 in Table 3. In addition, comparative example 4
, 5, the molded product lost its shape and could not be removed from the mold.
Therefore, in Comparative Examples 4 and 5, it was impossible to measure bending strength and compressive strength. Table 3

Claims (1)

[Scope of Claims] 1. Per 100 parts by weight of a mixed cement consisting of 80 to 96 parts by weight of Portland cement, 13 to 2.5 parts by weight of alumina cement, and 7 to 1.5 parts by weight of anhydrite or (and) gypsum hemihydrate, Alkali metal salt of organic carboxylic acid from 0.2 to
A heat-curing cement composition characterized in that it contains 2 parts by weight. 2. The heat-curable cement composition according to claim 1, wherein the organic carboxylic acid is citric acid. 3. The heat-curable cement composition according to claim 1, wherein the organic carboxylic acid is malic acid. 4. The heat-curable cement composition according to claim 1, wherein the organic carboxylic acid is gluconic acid. 5. The heat-curable cement composition according to claim 1, wherein the organic carboxylic acid is glutaric acid. 6. The heat-curable cement composition according to claim 1, wherein the organic carboxylic acid is glycolic acid. 7. The heat-curable cement composition according to any one of claims 1 to 6, wherein the alkali metal salt is a sodium salt. 8. The heat-curing cement composition according to any one of claims 1 to 6, wherein the alkali metal salt is a potassium salt.