JPH0416537A - Method for curing acceleration of ii type anhydrous gypsum - Google Patents

Abstract

PURPOSE:To accelerate the curing of the II type anhydrous gypsum and to improve the strength of cured matter by adding the curing accelerator selected from dispotassium hydrogen phosphate, etc,. and the curing assistant selected from calcium hydroxide, etc., to the II type anhydrous gypsum powder. CONSTITUTION:The curing of the II type anhydrous gypsum is accelerated by adding (B) >=1 kinds among the dipotassium hydrogen phosphate, potassium dihydrogenphosphate and calcium dihydrogen phosphate as the curing accelerator and (C) >=1 kinds among the calcium hydroxide and potassium hydroxide as the curing assistant are added to (A) the II type anhydrous gypsum powder. The curing accelerating effect is higher with the curing assistant of the calcium system in the case of use of the curing accelerator of the potassium system. On the other hand, the higher effect is obtainable with the curing assistant of the potassium system in the case of use of the curing accelerator of the calcium system. Further, proper ratios of a setting retarder, water-reducing agent, etc., may be added to the above-mentioned mixture at need.

Description

[Detailed description of the invention] Industrial application fields> ■! J1 Anhydrite In industries that utilize the hydration hardening phenomenon of RI-type anhydrite π, such as in the production of hardened gypsum bodies such as building materials using anhydrite materials, or in self-leveling materials based on n-type anhydrite, compared to methods using conventional technology. too.

To provide a method for accelerating the hardening of n-type anhydrite, in which the [N rate during hydration of the RI-type anhydrite is fast, the rate of strength increase after setting is fast, and the final strength of the hardened gypsum is high. .

<Prior art> In the production of hardened gypsum products such as building materials using n-type anhydrite as raw material, or in industries that utilize the hydration hardening phenomenon of n-type anhydrite, such as self-leveling materials based on NG1 anhydrite, n-type The use of sulfates such as potassium sulfate, sodium sulfate, aluminum sulfate and potassium sulfate as hardening accelerators to promote the hydration of anhydrite has been practiced. (For example, Japanese Patent Publication No. 58-2188, Japanese Patent Publication No. 1988) It is also known that hydration is promoted when calcium hydroxide is used in combination as a hardening aid.

<Problem to be solved by the invention> Potassium sulfate, sodium sulfate, which is the above-mentioned prior art,
Sulfate-based hardening accelerators such as aluminum sulfate and potassium Meishun are effective to some extent. However, it has traditionally been used in the production of hardened gypsum products such as building materials using n-type anhydrite as a raw material, or in industries that utilize the hydration hardening phenomenon of n-type anhydrite, such as self-leveling materials based on n-type anhydrite. The setting speed of n-type anhydrite during hydration is faster than that of the hardening accelerator, and the rate of strength increase after setting is also faster, and the final strength of the hardened gypsum is higher. Development of a method is strongly desired. If such a new method for accelerating the hardening of n-type anhydrite is developed, several conventional problems as described below can be solved.

First, there is a problem in that natural n-type anhydrite has a slower hydration rate than n-type hydrofluoric anhydrite (industrial by-product), which has been widely used in the past.

Therefore, in the prior art, natural n! ! The only way to cope with this problem was to make the powder of anhydrite 2 finer, but this method has the disadvantage of increasing the cost of pulverization.

If a method for accelerating the hardening of n-type anhydrite, which has a faster hydration rate than conventionally used hardening accelerators, could be developed, it would be possible to process natural n-type anhydrite without making it finer. It has a large economic effect.

Furthermore, due to fluorocarbon regulations, the amount of n-type hydrofluoric anhydride, an industrial byproduct, is expected to decrease in the future.
Since natural n-type anhydrite, which has a slow hydration rate, has to be used extensively, it is desirable to develop a method for accelerating the hardening of n-type anhydrite, which has a faster hydration rate than the hardening accelerators conventionally used. The current situation is that

Second, since the hydration rate of n-type anhydrite increases as the curing temperature is lower, low temperature curing is generally employed. However, this poses a problem in that manufacturing costs such as the cost of equipment such as a refrigerator and a curing tank and the operating cost of the refrigerator increase. If a method for accelerating the curing of n-type anhydrite, which has a faster hydration rate than conventionally used curing accelerators, is developed, it would be possible to eliminate the need for low-temperature curing or shorten the low-temperature curing period. This makes it possible and has great economic effects.

Thirdly, since the hydration rate of n-type anhydrite is slow, the air-drying period is also long, resulting in low productivity. If a method for accelerating the hardening of TI type anhydrite that has a faster hydration rate than conventionally used hardening accelerators is developed,
It becomes possible to shorten the air-drying period and improve productivity, making it possible to produce economically.

Fourthly, there is a problem that the final strength of hardened gypsum products such as building materials made from n-type anhydrite gypsum is low.

If a method for accelerating the curing of n-type anhydrite with higher final strength than conventionally used curing accelerators is developed, ■
It is possible to improve the quality of hardened gypsum products such as building materials that use molded anhydrite as raw material.

Means for Solving the Problems When curing natural n-type anhydrite powder, as described above, the curing speed is slow with conventional techniques, making economical production impossible. Therefore, in order to develop a new method for accelerating the curing of Type 1 water in order to solve this problem, we focused on phosphates as a curing accelerator and conducted extensive research, resulting in the completion of the present invention.

For n-type anhydrite powder, IFi or higher of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, and calcium dihydrogen phosphate as a hardening accelerator, and one of calcium hydroxide and potassium hydroxide as a hardening aid. The above-mentioned problem can be solved by adding more than one type.

In addition, for n-type anhydrite powder, one or more of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, and calcium dihydrogen phosphate as a hardening accelerator, and one or more of potassium sulfate, aluminum sulfate, and potassium Meishun are added as hardening accelerators. The above-mentioned problem can also be solved by adding one or more types of calcium hydroxide and potassium hydroxide as hardening aids.

Furthermore, they discovered that it is possible to control setting time and improve fluidity by adding appropriate amounts of admixtures such as setting retarders and water reducers as necessary, and have completed the present invention. Ta.

In the past, sulfates such as potassium sulfate, sodium sulfate, aluminum sulfate, and potassium sulfate were generally used as hardening accelerators to promote and promote water utilization of n-type anhydrite. Calcium hydroxide is known as a hardening aid, but the present invention has faster setting speed during hydration of n-type anhydrite and faster strength increase speed after setting than the conventional technology. The present invention provides a method for accelerating the hardening of n-type anhydrous gypsum, which increases the final strength of the hardened gypsum body.

A specific effect of the present invention is that a water-soluble phosphate containing hydrogen ions, which is a curing accelerator, is used in the optimum pH range in the coexistence of an alkali metal or alkaline earth metal hydroxide, which is a curing aid. It is thought that by increasing the solubility of n-type anhydrite in this region, the rate of water utilization of n-type anhydrite is increased. In this case, hydrogen ions are thought to play an important role.

In addition, as shown in the examples, compatibility is observed between metal ions, and when using a potassium-based hardening accelerator,
Calcium-based curing aids are more effective; on the other hand,
It has also been found that when using a calcium-based hardening accelerator, a potassium-based hardening aid is more effective.

As shown in the examples, if the amount of curing accelerator and curing aid added to n-type anhydrite is too small, the effect will be small, and if the amount exceeds a certain limit, it will cause damage to n-type anhydrite. This is undesirable because the hydration rate becomes too fast and causes rapid setting, so there is an optimum amount to add.

If the setting time is too short, the setting time can be extended by adding an appropriate amount of an admixture such as a setting retarder, if necessary. In addition, if appropriate fluidity cannot be obtained when reducing the amount of crosstalk water and increasing the strength,
The fluidity can be improved by adding an appropriate amount of an admixture such as a water reducing agent or a fluidizing agent as required. These admixtures can be used for plaster or cement. A well-known admixture is fine.

In addition to those shown in the claims of the present invention as curing accelerators, disodium hydrogen phosphate and sodium dihydrogen phosphate have similar effects. However, although these sodium salts have a good curing accelerating effect, they cause efflorescence! Undesirable as it rubs.

In addition, phosphates such as potassium phosphate, sodium phosphate, potassium pyrophosphate, sodium pyrophosphate, and sodium tripolyphosphate, which do not contain hydrogen ions, do not have a hardening accelerating effect, and calcium phosphate-hydrogen does not contain hydrogen ions. Despite this, no curing accelerating effect was observed due to the lack of water solubility.

Any hydroxide of alkali metal or alkaline earth metal is effective as the curing aid. However, although sodium hydroxide is a good hardening aid, it is not preferred because it causes efflorescence, and calcium hydroxide and potassium hydroxide are preferred.

Incidentally, there is a method for accelerating the curing of type 1 anhydrite similar to the present invention by adding another agent that is compatible with the curing accelerator and curing auxiliary agent shown in the claims of the present invention. The method can be easily deduced from the present invention. Specifically, phosphoric acid () 1. By adding Po, ) and an alkali metal or alkaline earth metal hydroxide to control the pH, a reaction system similar to that of the present invention can be set up. That is, this is because the same agent as the curing accelerator of the present invention is simply synthesized in the reaction system.

Furthermore, a combined effect can be expected by using two or more of the curing accelerators or curing auxiliaries of the present invention. That is, there is a type with high initial strength and a type with high strength after drying, and by using these together, any desired strength development pattern can be designed.

In addition, as shown in Example 7, potassium sulfate and sodium sulfate are conventional hardening accelerators.

One or more types of sulfates such as aluminum sulfate and potassium Meishun, and dipotassium hydrogen phosphate, which is the curing accelerator of the present invention,
It is also possible to use one or more of potassium dihydrogen phosphate and calcium dihydrogen phosphate in combination, and compared to the conventional technology,
(2) It is possible to produce a hardened gypsum body in which type anhydrite has a fast setting speed during hydration, a fast strength increase rate after setting, and a high final strength.

<Example-1> Example-1 is a comparative example in which potassium sulfate is used as a hardening accelerator and calcium hydroxide is used as a hardening aid, which is a typical example of the conventional technology, and a hardening accelerator of the present invention. This is a comparison with an example in which dipotassium hydrogen phosphate was used as the hardening agent and calcium hydroxide was used as the hardening aid.

To 100 parts by weight of natural ■-type anhydrite powder with Blaine fineness of approximately 6000-/H, hardening accelerators and hardening aids in amounts shown in Table 1 (weight percentages relative to natural ■-type anhydrite powder) are added and dissolved. 43 parts by weight of water was added, mixed for 3 minutes, and tested in accordance with JIS R5201r Cement Physical Test Method J.

Table 1 shows the strength test results of the specimens that were air-dry aged for 1 and 7 days and dried at 40°C for 12 hours after air-dry curing until the 7th day. Table 2 shows the pH of the specimens dried at 40°C for 12 hours after air-drying.
It was shown to.

Table 1 Comparison of the strength enhancement effect of type anhydrite .

Table 2 Comparison of the hydration promoting effect of D-type anhydrite It can be seen that there is an optimum range of the amount of the agent added in which the setting rate of the example according to the present invention is accelerated compared to the comparative example which is the conventional technology. .

Example 2 Example 2 is a comparative example in which potassium sulfate is used as a curing accelerator and calcium hydroxide is used as a curing auxiliary agent, which is a typical example of the conventional technology, and a comparative example in which a curing accelerator of the present invention is used. This is a comparison with an example in which dipotassium hydrogen phosphate was used as the hardening agent and potassium hydroxide was used as the hardening aid.

To 100 parts by weight of natural ■ type aqueous gypsum powder with a Blaine fineness of approximately 6000 cm/2, add and dissolve hardening accelerators and hardening aids in amounts shown in Table 3 (weight percentages relative to natural ■ type anhydrite powder). 1 part of water 43i was added thereto, kneaded for 3 minutes, and tested in accordance with JIS R5201F Cement Physical Test Method J.

Table 3 shows the strength test results of the specimens that were air-dry aged for 1 and 7 days and dried at 40℃ for 12 hours after air-dry curing until the age of 7 days. Table 4 shows the pH of the specimens dried at 40°C for 12 hours after air-drying.
It was shown to.

Table-3 Comparison of the strength-enhancing effect of type 0 aqueous gypsum Table-4 Comparison of the hydration-promoting effect of type 0 anhydrite The strength enhancement of the example according to the present invention is extremely superior to that of the comparative example, which is the conventional technology. It can be seen that there is an optimal range of drug addition amount.

It can be seen that there is an optimum range of drug addition amount in which the setting rate of the example according to the present invention is significantly accelerated compared to the comparative example of the prior art.

Example 3 Example 3 is a comparative example in which potassium sulfate is used as a curing accelerator and calcium hydroxide is used as a curing aid, which is a typical example of the conventional technology, and a curing accelerator of the present invention. This is a comparison with an example in which potassium dihydrogen phosphate was used as the hardening agent and calcium hydroxide was used as the hardening aid.

To 100 parts by weight of natural ■ type aqueous gypsum powder with a Blaine fineness of about 6000 cm/g, the amount i shown in Table 5 was added. Add 43 parts by weight of water in which k (weight percentage based on natural ■ type anhydrite powder) of curing accelerator and curing auxiliary agent were added and dissolved.
The test was conducted in accordance with JIS R5201+cement physical test method.

Table 5 shows the strength test results of the specimens that were air-dry aged for 1 and 7 days and dried at 40℃ for 12 hours after air-dry curing until the age of 7 days. Table 6 shows the pH of the specimen that was air-cured @40℃ for 12 hours.
It was shown to.

Table 5: Comparison of the strength enhancement effect of type (1) anhydrite It can be seen that there is an optimum range of the amount of added chemicals in which the strength enhancement of the example according to the present invention is extremely superior to that of the comparative example of the prior art.

Table 6: Comparison of the hydration promoting effect of U-type anhydrite Compared to the comparative example, which is the conventional technology, there is an optimum range of the amount of the agent added in which the setting rate of the example according to the present invention is accelerated. I understand.

Example 4 Example 4 is a comparative example in which potassium sulfate is used as a curing accelerator and calcium hydroxide is used as a curing auxiliary agent, which is a typical example of the conventional technology, and a curing accelerator of the present invention. This is a comparison with an example in which potassium dihydrogen phosphate was used as the hardening agent and potassium hydroxide was used as the hardening aid.

Add and dissolve hardening accelerators and hardening aids in amounts shown in Table 7 (weight percentages relative to natural n-type anhydrite powder) to 100 parts by weight of natural ■-type aqueous gypsum powder with Blaine fineness of approximately 6000 d/. 43 parts by weight of water was added thereto, kneaded for 3 minutes, and tested in accordance with JIS R52011 Cement Physical Test Method.

Table 7 shows the strength test results of specimens that were air-dried for 1 and 7 days and dried at 40°C for 12 hours after air-dry curing until 7 days. Table 8 shows the PH of the specimens dried at f&40°C for 12 hours.

Table-7 Comparison of the strength-enhancing effect of ■-type anhydrite Table-8 Comparison of the hydration-promoting effect of ■-type anhydrite Compared to the comparative example of the prior art, the strength enhancement of the example according to the present invention is extremely superior. It can be seen that there is an optimal range of drug addition amount.

It can be seen that there is an optimum range of the amount of the agent added in which the coagulation rate of the examples according to the present invention is accelerated compared to the comparative example of the prior art.

Example 5 Example 5 is a comparative example in which potassium sulfate is used as a curing accelerator and calcium hydroxide is used as a curing auxiliary agent, which is a typical example of the conventional technology, and a curing accelerator according to the present invention. This is a comparison with an example in which calcium dihydrogen phosphate was used as a hardening agent and calcium hydroxide was used as a hardening aid.

To 100 parts by weight of natural ■ type aquatic gypsum powder with a Blaine fineness of about 6000-, add and dissolve hardening accelerators and hardening aids in the amounts shown in Table 9 (weight percentages relative to natural ■ type anhydrite powder). 43 parts by weight of water was added thereto, kneaded for 3 minutes, and tested in accordance with JIS R5201r cement physical test method j.

Table 9 shows the strength test results of the specimens that were air-dried on the 1st and 7th day of age, and on the specimens that were air-dried and dried at 40℃ for 12 hours until the 7th day of age. Table 1 shows the PH of the specimens dried at 40℃ for 12 hours after air-drying.
0.

Table 9: Comparison of the strength enhancement effect of ■-type anhydrite Compared to the comparative example which is the conventional technology, the strength enhancement of the example according to the present invention is
It can be seen that there is a range of optimal drug addition amounts that are superior.

Table 10 Comparison of hydration promoting effects of n-type anhydrite In the case of this drug combination, it is likely that both are calcium-based.
As shown in Table 9, compared to the comparative example of the prior art, the strength of the example according to the present invention was relatively good, but the setting time was rather long.

<Example-6> Example-6 is a comparative example in which potassium sulfate is used as a curing accelerator and calcium hydroxide is used as a curing auxiliary agent, which is a typical example of the conventional technology, and a curing accelerator of the present invention. This is a comparison with an example in which calcium dihydrogen phosphate was used as a hardening agent and potassium hydroxide was used as a hardening aid.

A hardening accelerator and a hardening aid in the amounts shown in Table 11 (weight percentages relative to natural n-type anhydrite powder) are added to 100 parts by weight of natural ■ type aqueous gypsum powder with a Blaine fineness of about 6000-/g. 43 parts by weight of added and dissolved water was added, kneaded for 3 minutes, and tested in accordance with JIS R52011 Cement Physical Test Method.

Table 11 shows the strength test results of specimens air-dry aged 1 and 7 days and dried at 40°C for 12 hours after air-dry curing until the 7th day. The pH of the specimen dried at 40℃ for 12 hours after air-drying is shown below.
12.

Table 11 Comparison of the strength-enhancing effect of n-type anhydrite -12 Comparison of the hydration-promoting effect of n-type anhydrite Compared to the comparative example of the prior art, the strength enhancement of the example according to the present invention is extremely superior. It can be seen that there is an optimal range of drug addition amount.

It can be seen that there is an optimum range of drug addition amount in which the setting rate of the example according to the present invention is significantly accelerated compared to the comparative example of the prior art.

Example 7 Example 7 is a comparative example in which potassium sulfate is used as a curing accelerator and calcium hydroxide is used as a curing aid, which is a typical example of the conventional technology, and a curing accelerator of the present invention. This is a comparison with an example in which dipotassium hydrogen phosphate and potassium sulfate were used in combination, and calcium hydroxide was used as a hardening aid.

To 100 parts by weight of natural n-type anhydrite powder having a Blaine fineness of approximately 6000-, hardening accelerators and hardening aids in amounts shown in Table 13 (weight percentages relative to natural n-type anhydrite powder) were added and dissolved. Add 43 parts by weight of water and mix for 3 minutes, JIS R52011 Cement Physical Test Method.
Tested according to.

Table 13 shows the strength test results of the specimens that were air-dry aged for 1 and 7 days and dried at 40℃ for 12 hours after air-dry curing until the age of 7 days. Table 1 shows the pH of the specimens that were air-dried and dried at 40°C for 12 hours.
14.

Table 13 Comparison of strength enhancement effect of n-type anhydrite By using dipotassium hydrogen phosphate and potassium sulfate in combination, strength enhancement is extremely superior compared to the comparative example, which is the conventional technology, and as shown in Example 1. It can be seen that the strength-enhancing effect is even greater than when dipotassium hydrogen phosphate is used alone at 2%.

Table 14: Comparison of the hydration promoting effect of n-type anhydrite By using dipotassium hydrogen phosphate and potassium sulfate in combination, the setting rate was considerably accelerated compared to the comparative example, which is the conventional technology, and in Example-1. Dipotassium hydrogen phosphate shown alone 2
It can be seen that the effect of promoting coagulation is even greater than when using %.

<Effects of the invention> Due to regulations on fluorocarbons, it will be difficult to use hydrofluoric acid n, an industrial byproduct.
The amount of type anhydrite generated is decreasing, and natural
Although there is no choice but to use type anhydrite frequently, according to the present invention, it is possible to quickly harden natural n-type anhydrite, which has a slow hydration rate, and the effects of the present invention are extremely large. I can say it.

Furthermore, even when manufacturing hardened gypsum for building materials etc. using hydrofluoric acid n-type anhydride as a raw material, the method of the present invention allows for faster hydration than conventional methods, so low-temperature curing is not required. It is possible to alleviate the curing conditions such as the need for curing or a long curing period, and economic effects can be expected.

Furthermore, according to the method of the present invention, it is possible to produce a cured gypsum body with a high final strength, so it is possible to improve the quality of building materials etc. using n-type anhydrite as a raw material.

Furthermore, the effects of the present invention are not limited to the field of building materials that use n-type anhydrite as a raw material, but also apply to all industries that utilize the hydration hardening phenomenon of n-type anhydrite, such as anhydrite-based self-leveling materials. Spread.

teenager Reason Man flat well Department

Claims (3)

[Claims] (1) For type II anhydrite powder, one or more of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, and calcium dihydrogen phosphate are added as hardening accelerators, and calcium hydroxide and potassium hydroxide are added as hardening aids. A method for accelerating hardening of type II anhydrite, characterized by adding one or more of the following. (2) For Type II anhydrite powder, one or more of dipotassium hydrogen phosphate, potassium dihydrogen phosphate, and calcium dihydrogen phosphate as hardening accelerators, and one or more of potassium sulfate, aluminum sulfate, and potassium phosphate. 1. A method for accelerating the hardening of type II anhydrite, the method comprising adding at least one of calcium hydroxide and potassium hydroxide as a hardening aid. (3) A method for accelerating the hardening of type II anhydrite according to claims 1 and 2, characterized in that an appropriate amount of an admixture such as a set retarder and a water reducer is added as necessary.