JPS6256342A - Manufacture of glass fiber reinforced 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 (Field of Industrial Application) The present invention relates to a method for producing glass fiber reinforced concrete useful as a building material and a civil engineering material.

(Prior art) Concrete using glass fiber as a reinforcing material is known as glass fiber reinforced concrete (hereinafter referred to as GRC), which has traditionally been made of portland cement, mixed cement, alumina cement, etc., and alkali-resistant glass. It is manufactured by making a molded product from a mixture of fibers, sand, and water, which is then completely cured.

However, these hardened bodies are formed when Portland cement or mixed cement undergoes water reversal.
Rounding to produce 2 Its alkaline concentration is high and the - value is about 1
3 fcm In this case, the glass fiber used as a reinforcing material is chemically attacked by alkaline components during service life, and as a result, the strength of the fiber decreases significantly over time9.

For this reason, cheap E-glass fibers suffer from significant deterioration in strength (they cannot be used as reinforcing raw materials for GRC, and even alkali-resistant glass fibers developed specifically as raw materials for GRC are susceptible to alkali components). It was severely eroded by the earth, and its strength was halved during its several years of use.
The use of GRC as a structural material is extremely limited.

When alumina cement is used, the μ value of the hardened product is lower than that of Portland cement, about 12, because Ca (0■)2 is not generated in the process of water use reaction. Since minerals are converted into other minerals during service life, the strength of the hardened product is reduced by half during service life.

For these reasons, it is currently hoped that a long-term durable GRC using alkali-resistant glass fibers will emerge. In order to remove OH)2t', easily reactive silica has been added, but the situation is not always satisfactory.

(Problems to be Solved by the Invention) The present invention aims to produce a GRC with improved long-term durability. Furthermore, we are trying to obtain a method of manufacturing nine GRCffi that improves long-term durability not only when using alkali-resistant glass fiber, but also when using inexpensive ordinary E-glass fiber as a reinforcing material. It is something.

(Means for Solving the Problems) This invention uses γ Saint Kumaji lime powder as a binder,
This is a method for producing glass fiber reinforced concrete, which is characterized by forming a mixture containing glass fiber as a reinforcing material and water, and then carbonating and curing the mixture. To illustrate an embodiment of the present invention, the water content in the molded article is 0.25 to 0.95 in terms of water saturation defined as less than or equal to iit.
That is to say.

This invention will be further explained below.

The present invention uses r-type dicalcium silicate powder (hereinafter referred to as γ-C2S) as a binder to obtain a molded body, which is then cured with carbon dioxide gas, and the strength is increased by the carbonation reaction of the r-C2S powder. GRCf is produced by expressing it.

The present inventors used not a hydraulic substance as a binder, but
By using r -C2S f, which hardens by carbonation, it is possible to reduce the alkali concentration in the hardened material, thereby preventing the glass fiber used as a reinforcing material from degrading during long-term use, and as a result, the strength of GRC increases. This invention was completed based on the knowledge that there is no deterioration. The γ-C2S used in the present invention is so thin that it does not hydrate even when mixed with water, does not produce 2 ft of water, and can significantly reduce the alkali concentration in the cured product.

It is ideal for these uses. When r-C2S is kneaded with water and cured in a carbon dioxide atmosphere, the following reaction proceeds and strength is rapidly developed.

r −2CaO・8 i 02 + 2CO2+ 2H
20→2CaO-8102+2H2Co.

→2CaCO+ 5iOz + H20 The alkali concentration in such a cured product is -10.5 or less.

In the present invention, Maz γ-02S powder, glass fiber and water, or r-C28 powder and sand.

A molding is made from a mixture of glass fibers and water.

For mixing and molding these raw materials, any of the known premix methods, spray mixing methods, direct spray methods, or dry mix methods can be employed. The water content in the molded product is 0 at the water saturation level expressed by the formula shown below.
．． It is preferable to adjust the temperature to 25 to 0.95 and then cure with carbon dioxide gas.

When the water saturation is less than 0.25, the effect of carbon dioxide curing on strength development is small.
If it exceeds 5'i, carbon dioxide gas will not penetrate into the inside of the molded body during curing, and the carbonation reaction will occur only in the surface layer, which is not preferable. As shown in the experimental example below,
The moisture saturation is most preferably in the range of 0.25 to 0.95.

The water content of the molded product may be adjusted by preparing the added water R when making the molded product, or by obtaining a molded product with an excess water content in advance and then drying it to prepare its water content 1. The drying may be either heat drying or reduced pressure drying. The present invention will be further explained below with reference to experimental examples.

Experimental example-1 γ-028 powder 1 shown in Table 1! 1 part by weight, 2 parts by weight of Toyoura standard sand, and 0.15 parts by weight of E glass fiber (20vm?w Tsubuto strand) was mixed with 123 wt% of water, and then 45 pieces of 13-2 thickness and 90 m length were added and kneaded. A rectangular plate was compression-molded at a molding pressure of 100 and 9/1ype'', and some of the mixed water oozed out of the system during molding.
The water was removed.

The molded products were then dried under reduced pressure to prepare molded products with different moisture contents. The molded product was then heated at 20°C under a Co2W atmosphere for 2
I spent time curing it. Thereafter, this was subjected to a three-point bending test (Spannier α). In addition, the moisture content, apparent porosity, and apparent specific gravity of each of the prepared molded articles dried under reduced pressure were measured, and the moisture saturation degree was calculated from these, and the results shown in the attached figure were obtained.

As is clear from the figure, high-strength glass fiber-reinforced concrete can be produced by mixing γ-C2S powder, glass fiber, sand, and water metal, molding, and then curing with carbon dioxide gas. Also,
The molded product cured with carbonic acid has a water content of 0.0 in terms of water saturation.
It is clear that high strength can be obtained by curing with carbon dioxide gas after adjusting the strength to a range of 25 to 0.95.

The molded body shown in the figure with a moisture saturation of 1.0 develops strength when cured for a long period of time (7 days or more) while flowing carbon dioxide gas. This is considered to be due to the fact that the molded product is gradually dried and the water saturation level of the molded product is reduced.

Experimental Example-2 Experimental Example-1 was added to the γ-C2S powder used in Experimental Example-1 and the commercially available early-strength Portland cement at the ratio shown in Table 2.
The Toyoura standard sand used in E was mixed with lath fibers, and then water and gold were added and kneaded and molded in the same manner as in Experimental Example-1. Prepared and cured with carbon dioxide gas. Afterwards, we conducted a three-point bending test on this. Regarding early strength cement, a conventional molded body that does not dry is 1 fc at 20°C.

After curing for 7 days in a humid atmosphere with a relative humidity of 80 degrees or higher, a three-point bending test was conducted. Each sample f subjected to bending test
0.0, 5vm, and 50.9% of this was mixed with distilled water.
〇-The mixture was stirred and the μ value of the resulting liquid was measured after 24 hours, and the results shown in Table 2 were obtained.

Table 2 shows that according to the present invention, high strength can be obtained with short curing, and that the alkali concentration in the cured product is significantly lower than that of the comparative example and the prior art.

Calculated from μ value, the alkali content in the cured product of the present invention is about 1/300 or less of the comparative example and about 1/600 of the conventional technology.
It is as follows. The present inventors carefully investigated the cause of the high alkali concentration in the cured product of the comparative example and observed the microstructure of the cured product. As a result, a large amount of unreacted neelite and belite that were not carbonated were present in the cured product of the comparative example, and when the unreacted neelite and belite came into contact with water, they caused problems with water use, resulting in Ca ( It was confirmed that plZ was produced and the μ value increased.Unreacted neelite or belite remained as unreacted particles even if the carbon dioxide gas curing time was extended to 7 days.

On the other hand, unreacted γ-C that is not carbonated in the cured product of the present invention
2S is observed, but this is only in small mice, and it does not produce C&(0■)2 even when it comes into contact with water.
The value is significantly lower than that of the comparative example.

Experimental Example-3 The γ-C2S powder, early strength cement, Toyoura standard sand, E glass fiber, and alkali-resistant glass fiber (Cam-FIL 20 chopped chopped strand) used in Experimental Example-2 are shown in Table 3. After mixing at the mixing ratio shown, water was added in the same manner as in Experimental Example 1, and a molded article was obtained in the same manner as in Experimental Example 1. This molded body was then placed in an iron container placed in a dryer and cured at 80° C. for 5 hours while carbon dioxide gas was allowed to flow into the container. Regarding the curing molded body, 1) 10% in water
Immerse it for a minute, then take it out of the water, remove all surface water, and then measure the bending strength (t) and compare.

2) Soaked in hot water at 60°C for 30 days, then taken out from the hot water, removed all surface water, and measured bending strength.

Table 3 shows the measurement results. As a comparative example, a molded product of early strength cement was cured for 7 days in a humid atmosphere with an Ic relative humidity of 8° or more, and the same bending strength was determined.

As is clear from the results in Table 3, it can be seen that the glass fiber reinforced concrete according to the present invention shows very little deterioration in strength during service life.

Therefore, according to the present invention, E-glass fibers which could not be used in the prior art can also be used.

Experimental Example-4 The γ-C2S powder shown in Table 4 was used in Experimental Example-3.
'cE glass fiber and alkali-resistant glass fiber'18v
t% was mixed, and then 124vt% of water was added and mixed, and then molded at a molding pressure of 50 kll/cm to form a rectangular plate similar to Experimental Example-1. After curing with carbon dioxide gas at 60°C for 12 hours, the bending strength was tested and the μ value was measured, and the following results were obtained.

E Glass fiber cured body; bending strength...207 to 9/cm
”.

-...10.3, alkali-resistant glass fiber cured body; bending strength...211 to 9/m'', pH...10.
3 From this it can be seen that good glass fiber reinforced concrete can be produced even from a mixture of only γ-C2S and glass fiber.

Experimental Example-5 2 parts by weight of γ-C2S powder used in Experimental Example-4 and 2
A mortar was prepared by mixing 1 part by weight of the following river sand, and then adding and mixing 0.02 parts by weight of a polyalkylaryl sulfonic acid water reducing agent (Kao Soap Co., trade name: Mighty 150) and 1 part by weight of water. Alkali-resistant glass fiber (Cam
-FIL) was cut into chopped strands of 25mm thick, and mortar and glass fibers were sprayed onto the mold by a direct spray method to form a 15mm thick strand. Thereafter, the molded product was dried under reduced pressure until the water saturation level in the molded product reached 0.75, and then cured in carbon dioxide gas for 4 hours. After that, the surface sagging strength was measured, and the following results were obtained. Note that the amount of glass fiber mixed was 5 wt%.

Bending strength, 325kg/Tan Zhen (Effect of the invention) The effects of the present invention described above are as follows.

1) Glass fiber-reinforced concrete with significantly less deterioration in strength during service life can be manufactured at low cost.

■ As a reinforcing material for glass fiber reinforced concrete,
Cheap E glass can be used.

3) Curing time can be shortened.

That's nine times.

[Brief explanation of drawings]

The figure is a diagram showing the relationship between the degree of water saturation (%) in a molded product and the bending strength of the molded product, which is applied to the present invention. Applicant's agent Takehiko Suzue Continued on page 1 Inventor Junsuke Haruna 5-3 Tokai-cho, Tokai City Inventor Akira Suzuki 1618 Ida, Nakahara-ku, Kawasaki City

Claims (2)

[Claims] (1) A method for producing glass fiber-reinforced concrete, which comprises forming a mixture containing γ-type dicalcium silicate powder as a binder, glass fiber as a reinforcing material, and water, and then carbonating and curing the mixture. (2) The method for producing glass fiber reinforced concrete according to claim 1, wherein the water content 1 in the molded product is 0.25 to 0.95 in terms of water saturation as defined below. Moisture saturation = [Moisture content of molded product (%) / (100 - Moisture content of molded product (%))] x [100 - Apparent porosity of molded product (%) /
Apparent porosity (%) of molded product x apparent specific gravity of molded product