JPS5874553A - Manufacture of steam-cured lightweight foamed concrete - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to lightweight aerated concrete (hereinafter referred to as A) that is steam-cured.
(abbreviated as L, C).

More specifically, the present invention relates to an improvement in the A, L, , and CH manufacturing method in which a partial substitute for the main raw materials is used in combination with finely powdered calcium carbonate and a small amount of calcium sulfate.

Water is mixed in an appropriate ratio with crushed calcareous raw materials such as lime and cement and silicic raw materials such as silica sand and silica stone, and then metals such as aluminum are mixed with water in an appropriate ratio. It is manufactured by adding powder, stirring it, or adding air bubbles to it, semi-curing it, transferring it to an autoclave, and curing it in high-temperature, high-pressure steam.

Although the process for producing A, L, and O in this way is simple, it is difficult to control the raw materials, etc., so they are somewhat expensive, but they are also easily available and relatively stable. It is used.

In addition to the main raw materials, granulated blast furnace slag, fly ash, and crushed concrete containing tobermite are added because they are relatively inexpensive. However, these additives also have various drawbacks in practice. For example, in the case of granulated blast furnace slag, slight differences in the conditions during granulation can cause the product to become irregular and affect its reactivity. In addition, there are many problems such as the sulfide it contains generates hydrogen sulfide in the process of steam generation.

Due to the amount of fly ash added, it is difficult to ensure the correct amount of fly ash in the product. For example, even if the coal is generated from a well-managed boiler, the particle size varies greatly depending on the type of coal, which increases the quality of the product. Crushed concrete containing tobermolite is similar to fly ash. However, it does not work very efficiently because it requires equipment for crushing, and the limit on the amount added is small.

The present invention does not have the above-mentioned drawbacks, and A.

The purpose is to provide additives that significantly improve physical properties such as shrinkage rate of L and C products, and to obtain superior A, L and C products.

Conventional A is used as a material to be added in the method of the present invention.

Calcium carbonate, which has been little studied due to its low solubility in aqueous solutions under the production conditions of L and O, was used as a partial substitute for the main raw materials, especially calcareous raw materials, and it simply resulted in a significant cost reduction. In addition to experimentally confirming that it has an effective effect on the physical properties of the product, we conducted further intensive research.In the meantime, we discovered that, instead of using only calcium carbonate, we were able to develop a suitable amount of calcium sulfate with a small amount of sulfuric acid. We have arrived at the present invention by discovering that the physical properties can be further improved when used in combination. , .

The most important thing in producing A, L, and O is to uniformly produce a large amount of highly crystalline tobermolite in the product. Therefore, if the raw materials used are
The additive must not inhibit the formation of tobermolite. Naturally, the production of tobermolite with a high degree of crystallinity ensures the physical properties necessary for concrete IJ.8 According to the results of this study, calcium carbonate powder is used as a raw material. When used as one, the amount added is limited to 20% by weight based on the raw material solid ticket. When the amount of calcium carbonate added is 20% by weight or more, A and L are produced.
.

Among the physical properties of C, the drying shrinkage rate is further reduced, but this is not preferable because the compressive strength is extremely reduced. Addition of calcium carbonate with low solubility in aqueous solution is A,
It contributes to improving the drying shrinkage rate of L and C, and also maintains compressive strength up to 20 weights when divided into raw materials.

The weight ratio of total lime content to total silicic acid content, abbreviated as 9/s, which is the main raw material for A, L, and C, usually requires at least o. It produces a lot of water, and when soaked in water, it appears dark black.)
However, when calcium carbonate is used, O/s is a low value of a3, and this unreacted product is not generated and A, L,
C! The drying shrinkage rate of is improved.

In addition to this calcium carbonate, if 3 to 10% by weight of calcium sulfate is used in combination with the A, L, and C raw materials, the drying shrinkage rate of the product can be further improved and a high level of compression strength can be ensured. The reason for this is not clear, but at low temperatures around 1OO0C, calcium carbonate has a buffering action, and siliceous substances 1
The preferred addition amounts of calcium carbonate and calcium sulfate, which have been explained beyond imagination as suppressing or delaying the gelation of the fine powder of quartz (quartz), are 3 to 20% by weight, respectively, based on the solid content of the raw material. ~io% by weight.

The former has almost no effect if it is less than 3% by weight, and the latter has no effect even if it is added more than io weight%.
In addition, when the weight is less than 3, no significant effect is observed even when used in combination with calcium carbonate.As explained above, according to the method of the present invention, as seen in Examples, , the shrinkage rate of C products is significantly reduced,
Since stable products can be obtained even with low Q/H values, costs can be significantly reduced.

′　Examples will be described below.

Example Powdered silica stone, quicklime, and main raw materials for cement were each
A mixture of s, t-o, ss is used as base apricot, and 2 to 3% by weight of finely powdered calcium carbonate is added to this. In addition, finely powdered calcium carbonate 5-7ts and calcium sulfate (dihydrate) were added and mixed to a concentration of t to 10% by weight, and then the mixture was heated under high temperature and pressure according to normal operations. (/l00C,1
0,! (Atmospheric Pressure) Steam-cured lightweight cellular concrete IJ-crete was produced, and its compressive strength, shrinkage rate, etc. were measured. The results were compared with the case where the above items were not added.
Shown in Table and Table 2.

As is clear from the table, when the content of calcium carbonate is replaced with the three main raw materials in equal proportions, there is no significant decrease in compressive strength compared to that without additives up to 20% by weight. When the calcium content reaches 25% by weight, the compressive strength of the product decreases (A'I). For A5-7, no large change in compressive strength was observed when lime was replaced with calcium carbonate up to a calcium carbonate content of 6% by weight, and for A5-10, the same result was obtained when cement was replaced. Samples A// to 1 used lime sulfate dihydrate in combination with a calcium carbonate content of 0 to 23% by weight, and showed sufficiently low shrinkage when the calcium carbonate content was 20% by weight or less. The overall trend is that as the calcium carbonate content increases to 9% by weight when used in combination with calcium sulfate, the shrinkage rate of the product decreases.

As in A9 and 10, the value C/S of the silicic acid content to the lime content based on the weight ratio of the three main raw materials is 0.3I1. ．． Topelmolite with a high crystallinity of calcium silicate hydrate was produced even if the crystallinity was as small as 0.29. C76 is O, IS
In the following, when calcium carbonate was not used at all, a large amount of low-crystalline topelmolite was observed regardless of the presence or absence of calcium sulfate, and the formation of highly crystalline tobermolite was extremely small.0 Applicant: Sumitomo Metal Mining Co., Ltd. Agent Patent Attorney Katsunari Nakamura 4'・5. −

Claims (1)

[Claims] (1) In a method for manufacturing steam-cured lightweight cellular concrete using powdered silicic acid raw materials and calcareous raw materials as main raw materials, fine powder of not more than J weight % based on the total solid partial pressure in a slurry mixture of the raw materials is used. A steam-cured light violet characterized by adding calcium carbonate and calcium sulfate in an amount of 3 to 10% by weight.