JPS5919900B2 - GRC material with excellent long-term strength - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass fiber reinforced cementitious (GRC) material with low loss of long-term strength, and in particular to a GRC material suitable for rapid molding.

Various fiber-reinforced cementitious materials have been known, and among them, asbestos slate has been produced in large numbers, taking advantage of its thinness and high strength.

However, in recent years, asbestos has become a problem due to pollution and lack of resources, and there has been a desire to use other fibers as a substitute.

In contrast, glass fibers with excellent alkali resistance have recently been developed, making it possible to obtain cementitious materials with higher strength than asbestos-cementitious materials without impairing the nonflammability of the cementitious materials.

This glass fiber reinforced cementum (GRC)
Although the material has high strength, the glass fibers are gradually eroded by the alkali in the cement, and the long-term strength often decreases, that is, by 10 to 30% after 2 to 3 years, and improvements are desired. was.

For the purpose of improving these or preventing efflorescence, etc.
Additions such as activated alumina, pozzolan, and slag have been added.

The present invention is concerned with these improvements, and is a method that hardly causes a decrease in long-term strength.
To 100 parts by weight of a mixture consisting of ~30 parts by weight and 15 to 70 parts by weight of slag, add 0.1 to 5 parts by weight of a water-soluble salt of an alkaline earth metal, 0 to 40 parts by weight of gypsum, and 1 to 10 parts by weight of glass fiber. It is a GRC material with excellent long-term strength, which is made by adding 40 parts by weight of cementitious material and, if necessary, up to 6 times the weight of aggregate and additives.

The feature of the present invention is that the initial strength is relatively high and the long-term strength is also high. By using slag and a water-soluble salt of an alkaline earth metal in combination, the long-term strength is significantly improved compared to using slag alone. It is to be done.

Furthermore, the addition of slag does not easily reduce the initial strength of GRC even when added in a relatively large amount.

The cement of the present invention includes cements such as Portland cement, alumina cement, and mixed cements thereof.
It is most effective when blended with cements containing moderate heat Portland cement, white cement, etc., and is especially effective when blending specific amounts of slag and water-soluble salts of alkaline earth metals with cements containing Portland cement as the main component. This is preferable because the effect of improving long-term strength is large.

The slag of the present invention is one in which 15 to 70 parts by weight of slag is mixed with 85 to 30 parts by weight of the cement,
If the slag is less than 15 parts by weight, the improvement in long-term strength tends to be insufficient, and if the slag exceeds 70 parts by weight, the initial strength tends to be low and the absolute long-term strength is also low.

This slag is usually blast furnace slag, and its effect is great when it is made of glass.

Furthermore, the alkaline earth metal water-soluble salt of the present invention is added in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the mixture of cement and slag, and if it is less than 0.1 part by weight, long-term strength improvement is If the amount exceeds 5 parts by weight, it may adversely affect the hardening of cement, which is not preferable.

Among these water-soluble salts of alkaline earth metals, it is preferable to use Mg salts because they have a great effect of improving long-term strength, and particularly Mg C1322Mg (NO3)2.

Preferably, one or more salts selected from the group MgSO4 are used.

In addition, gypsum improves the long-term strength slightly by adding 40 parts by weight or less to 100 parts by weight of the mixture of cement and slag, but if it exceeds 40 parts by weight, it becomes like a filler. This is not preferable because the initial strength will be low and the long-term strength will also be low.

As the glass fiber of the present invention, an alkali-resistant glass fiber can be used, and filaments, strands, rovings, or cut products, aggregates, and woven products thereof can be used.

Glass fibers may be added in an amount of 1 to 40 parts by weight per 100 parts by weight of the mixture of cement and slag; if it is less than 1 part by weight, the strength will be low and insufficient; if it exceeds 40 parts by weight, it will form on the surface of the GRC molded body. The fibers tend to become fluffy, there is no increase in strength, and on the contrary, peeling may occur.

In addition, glass fiber has a ratio of 2 to the solid content of cementitious material.
From the viewpoint of strength and economy, it is preferable that the content be 10 wt%.

Furthermore, the present invention includes various types of cementitious materials that can be added to ordinary cementitious materials that do not impair the effects of the present invention, in addition to cementitious materials that are mixtures of cement, slag, water-soluble salts of alkaline earth metals, gypsum, and glass fibers. Additives and aggregates such as waterproofing agents, thickeners, dispersants, pigments, sand, lightweight aggregates, steel fibers, asbestos, polymers, perlite, expanded styro beads, etc. can be added, and are mixed in at around 6 times the weight of cementitious materials. It's okay to be.

The cementitious material of the present invention can be manufactured by mixing all the cement mixtures, adding water, kneading, pouring into a mold or making paper, or kneading after removing glass fibers, and supplying the mixture to a mortar spraying device. It can be used in various manufacturing methods such as spraying and mixing glass fiber at the supply port.
If necessary, suction dehydration, vibration, heating, etc. may be used in combination.

Further, a molding method such as introducing a kneaded cementitious material or an uncured cementitious plate-like material formed into a plate shape as described above into a press mold, and performing press molding or extrusion molding can also be used.

Furthermore, when the composition of the present invention is used for rapid molding, particularly for pressure and heat molding, it is preferable to use a mixed cement of Portland cement and alumina cement, specifically, alumina cement l-1 to 30 wt%. It is preferable to use a mixed cement containing both 99 to 70 wt% of alumina cement and 99 to 70 wt% of portland cement, or a mixed cement of 60 to 99 wt% of alumina cement and 40 to 1 wt% of portland cement. In molding, the initial strength can be made sufficiently high.

Among them, high early strength can be obtained by setting the mixing amount to 5 wt% or more.

In particular, this feature is that while heating to 60-120℃,
When this cementitious material is applied to rapid molding by heating and pressing at a pressure of 00 kg/CrIt, it produces a remarkable effect and can be demolded in a molding time of only a few minutes.

In each of the Examples and Comparative Examples, early strength Portland cement (manufactured by Mitsubishi Mining Cement Co., Ltd.) and alumina cement (trade name "Asahi Fuonsh" manufactured by Asahi Glass Co., Ltd.) were used, the plaster was trihydrate, and the slag had a plain value of 4800. The glassy blast furnace slag and glass fiber of cI11/ &
"IL Roving" cut into 37 mm length), water-soluble salts of alkaline earth metals are the compounds shown in the table, and if necessary, water reducing agents (product name: Mighty 150RJ, manufactured by Kao Soap Co., Ltd.), setting retarders. 5m by direct spray method with ethyl alcohol or citric acid added as
It was molded into a plate with a thickness of m, and after being leveled, it was cured in a humid atmosphere at room temperature for 28 days.

After this, the bending strength was measured, and the product was left to naturally cure indoors.
The bending strength after a year was measured.

The results are shown in the table. A6.1 to A4 are examples of the present invention, and waste 1 contains 60 parts by weight of Portland cement, 40 parts by weight of slag, 2 parts by weight of gypsum, 2 parts by weight of MgCl, 9 parts by weight of glass fiber, 1 part by weight of water reducing agent, and sand. It is a GRC material consisting of 50 parts by weight and 42 parts by weight of water, with a bending strength of 340 kg/crtt after 28 days and a bending strength of 355 after 1 year.
/crit, and the intensity is one year after 28 days.

This was an increase of 4.4%.

In addition, /i62 is an example using CaCl2 and a setting retarder, and due to the early strength effect of CaC112, the strength is 28 days,
After 1 year, both intensities were slightly lower, and the change in intensity was -3.6% and 7.
V), which was slightly lower than 1.

Both A63 and /164 are cements for rapid molding, and are mixed cements of Portland cement and alumina cement, and have a 28-day strength of 240klcyrt.

Although the results were low at 230 kg/ffl, it was possible to significantly shorten the time required for demolding after molding, and the change in strength was 3.3% and 3.5%, which was 1.
It was an excellent result, with a slight increase after a year.

A5 to A8 are comparative examples, and No. 5 is a blending example in which slag and water-soluble alkaline earth metals are not used at all, and the strength is reduced by about 14.3%.

Also, /I6.6 is an example of adding only slag, /167 is an example of Mg
This is an example of adding only Cl2, about 7% and 4%, respectively.
Only a slight improvement was observed, which was much lower than the degree of improvement in Example 1 of the present invention, which was about 19%.

In addition, when Ca C12 was used instead of MgCl in A67, the result was the same as when hardly any addition was made.

A6.8 is an example of 100% alumina cement, with no addition of slag or water-soluble salts of alkaline earth metals, and the strength change is -5.7%, which is an example of Portland cement. There was a much smaller decrease in strength compared to No. 5.

/V;9 is an example in which the present invention was applied to alumina cement, and the strength change was 1.4%, which was effective, but the effect was smaller than in the case of Portland cement. .

This seems to be because alumina cement alone does not seriously deteriorate the glass fibers.

/1610 to /V)12 are also examples of the present invention, and are examples in which the cement composition, slag, and water-soluble salt of alkaline earth metal are changed, and each has excellent 28-day strength and 1-year strength. However, samples /%10 and /1611 were capable of rapid demolding.

As is clear from the above, the present invention makes it possible to easily obtain GRC with excellent initial strength and long-term strength by using a cementitious material with a specific composition.
This can be applied to various GRCs in the future.

Claims (1)

[Claims] 1. 100 parts by weight of a mixture consisting of 85 to 30 parts by weight of cement and 15 to 70 parts by weight of slag, 0.1 to 5 parts by weight of a water-soluble salt of an alkaline earth metal, and 0 parts by weight of gypsum. A GRC material with excellent long-term strength, which is made by adding up to 6 times the weight of aggregate and additives as necessary to a cementitious material containing ~40 parts by weight and 1 to 40 parts by weight of glass fiber. 2. The GRC material according to claim 1, wherein the cement includes Portland cement. 3. The GRC material according to claim 2, wherein the cement is a cement whose main component is Portland cement. 4. The GRC material according to any one of claims 1 to 3, wherein the slag is glassy. 5. The GRC material according to any one of claims 1 to 3, wherein the water-soluble salt of an alkaline earth metal contains an Mg salt. 6 Mg salt is MgC122Mg(NO3)21Mg
The GRC material according to claim 5, which is S04.