JPH0566347B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a cured fiber-reinforced cement, and in particular, a fiber-reinforced cement that is lightweight, has excellent strength, durability, and dimensional stability, has good productivity, and does not have unpleasant odors during production. The present invention relates to a method for producing a cured product. [Conventional technology] Hardened cement is mainly used for concrete structures and concrete products, but in recent years there has been an increasing demand for lightweight, high-strength materials for construction and civil engineering. It has been proposed to increase the strength by mixing alkali-resistant glass fibers (hereinafter referred to as ARG), etc., to reduce weight. For example, in the Japanese Patent Publication No. 60-20351, cement,
A method using a protein foaming agent to which water, ARG, and a cationic surfactant are added is disclosed. [Problems to be Solved by the Invention] However, in the conventional method typified by Japanese Patent Publication No. 60-20351, the curing resistance obtained is inferior to the durability. High shrinkage rate and poor dimensional stability. Curing speed is slow and productivity is poor. There is an unpleasant odor. The strength of the resulting cured product is insufficient. There is a problem. That is, conventionally, Portland cement such as ordinary Portland cement (hereinafter referred to as ordinary cement) has been used as a cement raw material for the hardened product, but tricalcium silicate (3CaO.
Calcium silicate hydrate, which is the main product, is produced in the process in which Portland cement, which is mainly composed of calcium silicates such as SiO 2 ) and dicalcium silicate (2CaO・SiO ₂ ) _, is mixed with water and then solidified and hardened. and produces calcium hydroxide. For example, in a cement containing 50% by weight of tricalcium silicate (3CaO・SiO ₂ ) and 25% by weight of dicalcium silicate (2CaO・SiO ₂ ), the stoichiometric amount of calcium hydroxide is calculated based on 100 parts by weight of the original cement. The top 30 parts by weight will be produced. Therefore, the pH of hardened cement is approximately 12.8 to 13.2, and the hardened cement becomes strongly alkaline. For this reason, ARG mixed in hardened cement is kept in a highly alkaline atmosphere of calcium hydroxide generated from cement for a long time, and even though it is alkali resistant, it erodes over time and the hardened cement Tensile strength, bending strength, impact resistance, etc. will decrease. In addition, because ordinary cement generally has a large curing shrinkage rate, conventional cement hardened products have poor dimensional stability due to shrinkage. Moreover, ordinary cement is slow to harden and usually takes two days to harden at a processing temperature of 30°C. , it is not possible to carry out efficient production. Furthermore, when a protein-based foaming agent is used as a foaming agent, an unpleasant odor is generated, and when mixed with a high performance water reducing agent such as polyalkylaryl sulfonic acid in cement paste, an antifoaming effect occurs. Unable to stably produce lightweight cement paste.
Therefore, in order to ensure the fluidity of the cement paste, it is necessary to increase the W/C (water-cement mixing ratio), and as a result, the strength of the hardened cement obtained is not sufficient and the shrinkage rate is high. , resulting in poor dimensional stability. [Means for Solving the Problems] The present invention solves the above-mentioned conventional problems, and provides a fiber-reinforced cement that is lightweight, has excellent strength, durability, and dimensional stability, has good productivity, and does not have unpleasant odors during manufacturing operations. The present invention provides a method for producing a hardened product, which comprises air milk obtained by mixing a polymeric surfactant-based foaming agent and water, a calcium silicate-auin-slag-based low-alkaline cement, water and A method for producing a fiber-reinforced hardened cement product, which comprises mixing a cement paste obtained by mixing a water reducing agent, adding reinforcing fibers to the resulting mixture, kneading it, shaping it, and then curing it. That is. The present invention will be explained in detail below. In the present invention, a polymeric surfactant-based foaming agent is used as a foaming agent, and the foaming agent and water are mixed to prepare air milk. As the polymeric surfactant-based foaming agent, alkenyl succinic acid is preferable, and when using it, it is preferable to add lime when preparing air milk and saponify the alkenyl succinic acid with an alkali. When preparing air milk, the mixing ratio of foaming agent and water is 0.01 to 2 parts by weight of foaming agent to 20 parts by weight of water.
~30 parts by weight, preferably 22 to 26 parts by weight of water to 1 part by weight of foaming agent. When lime is mixed and used, the proportion thereof is preferably 0.1 to 2 parts by weight, preferably 0.3 to 1.0 parts by weight, based on the amounts of the foaming agent and water. Note that lime is added to supply Ca ²⁺ ions for alkali saponification, so if it is a Ca ²⁺ ion supplying substance,
For example, it can be replaced with cement. In order to obtain air milk by mixing and foaming a foaming agent, water, and if necessary, lime, it is possible to mix and foam the mixture well by a batch method using a high-speed mixer. In addition, more stable foam can be obtained by using a connected foaming machine using high-pressure air. In the present invention, air milk is compared to ρ=0.02
~0.10, particularly preferably ρ = 0.04 to 0.06. Separately, a cement paste is prepared by mixing calcium silicate-auin-slag-based low-alkali cement, water, and a water reducing agent. The calcium silicate-auin-slag-based low-alkaline cement used as a cement raw material in the present invention is Portland cement whose main component is calcium silicate such as tricalcium silicate (3CaO・SiO ₂ ) and dicalcium silicate (2CaO・SiO ₂ ). Clinker 20-70% by weight, clinker mainly composed of calcium sulfoaluminate 3CaO, _3Al2O3 , _{CaSO4 ,} 10-40% by weight, anhydrite or dihydrite 10
~40% by weight, granulated blast furnace slag or fly ash
with a composition of 20 to 60% by weight, and (3Al ₂ O ₃ +
The molar ratio of 1.5SiO ₂ )/(CaO-SO ₃ ) is preferably 1.0 to 1.5. As such cement, Chichibu Cement Co., Ltd.
Chichibu GRC Cement manufactured by Chichibu is commercially available.
Chichibu GRC cement contains 3CaO・SiO ₂ , 2CaO・
It is a high-alumina, low-lime type cement whose main components are SiO ₂ , 3CaO・3Al ₂ O ₃・CaSO ₄ and granulated blast furnace slag, and its chemical composition is compared with that of ordinary cement as shown in Table 1. It is.

【table】

[Table] Furthermore, as the water reducing agent, a polyalkylarylsulfonic acid type water reducing agent is preferable, and a naphthalene sulfonic acid polymarin condensate type water reducing agent is particularly optimal. When preparing cement paste, the mixing ratio of low alkali cement, water and water reducing agent is 100% cement.
25 to 40 parts by weight of water, preferably 30 parts by weight
~33 parts by weight, 0.2 to 5 parts by weight of water reducing agent, preferably
The amount is preferably 0.5 to 2 parts by weight. In the present invention, the cement paste has a specific gravity ρ=
A value of about 2 is preferable. Next, the air milk and cement paste are mixed to prepare a lightweight cement paste.
At this time, by adjusting the mixing ratio of air milk and cement paste, the specific gravity of the lightweight cement paste obtained is ρ = 0.5 to 2.0, preferably ρ
It is preferable that the ratio be 1.0 to 1.5. Next, reinforcing fibers are added to this lightweight cement paste and thoroughly kneaded using a mixer or the like. As reinforcing fibers, glass fibers such as ARG, asbestos,
Carbon fibers and other organic fibers can be used. When using glass fiber as the reinforcing fiber, the fiber length is 3 to 50 mm, preferably 12 to 24 mm.
mm, and the amount added is preferably 2 to 10% by weight, preferably 3 to 5% by weight, based on the lightweight cement paste. If the fiber length of the glass fiber used is less than 3 mm, the reinforcing effect will be low;
If it exceeds 50 mm, poor mixing is likely to occur. Further, if the proportion of glass fiber added is less than 2% by weight, the reinforcing effect is low, and if it exceeds 10% by weight, poor mixing tends to occur. In the present invention, when glass fiber is used as the reinforcing fiber, the effect of improving the durability of the resulting cured product is particularly remarkable. After adding reinforcing fibers to lightweight cement paste and thoroughly kneading it, it is molded according to conventional methods.
Take care of yourself. Molding is performed by pouring uncured lightweight cement paste containing glass fiber into the desired formwork, and curing at a temperature of 10 to 60℃, preferably 30 to 50℃.
It is preferable to carry out the treatment at ℃ and humidity of 60% or more for 5 hours or more. The cement molded body hardened by curing is further cured after being demolded. In this case, the curing temperature is 15℃.
It is preferable to carry out the above process for 7 days or more at a humidity of 60% or more. This makes it possible to obtain fiber-reinforced cement products that are lightweight, have excellent strength, durability, and dimensional stability, have good productivity, and are free from unpleasant odors during manufacturing. In addition, in the present invention, in order to further reduce the alkalinity of the cement raw material,
The cement raw material can be replaced with silica fume within a range of % by weight or less. If the amount of silica fume substituted exceeds 20% by weight, the strength of the resulting hardened cement product decreases, which is not preferable. [Function] The calcium silicate-auin-slag-based low-alkaline cement used as a cement raw material in the present invention has low alkalinity and has a small shrinkage rate upon drying.
Moreover, the curing speed is fast. Therefore, when glass fibers are used as reinforcing fibers for cement, the cement does not erode the glass fibers, and the reinforcing effect of the glass fibers continues.
Changes in mechanical properties such as strength of the hardened cement body over time are significantly reduced. The effect is particularly great when alkali-resistant glass fibers are used. It also has excellent dimensional stability and extremely high productivity. Furthermore, since the polymeric surfactant-based foaming agent used in the present invention does not cause a defoaming effect even when mixed with a water-reducing agent, in the present invention, a water-reducing agent is used to reduce the water content in the cement paste. This makes it possible to obtain a hardened cement product with stable specific gravity and high strength. Although the details of the reason why polymeric surfactant-based foaming agents are stable and do not show antifoaming effects even when mixed with water-reducing agents are not clear, the constituent molecules of polymeric surfactant-based foaming agents are Certain alkenyl succinic acids have a large number of hydrophilic groups in their molecules and exhibit strong surface activity, while at the same time producing insoluble calcium salts through interaction with Ca ²⁺ ions in cement paste or added lime. This is thought to be because the bubbles become stable. [Examples] The present invention will be described in more detail with reference to Examples and Comparative Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. Example 1 Alkenyl succinic acid foaming agent (Fineform N), water and lime were mixed and foamed in a mixer,
18.4g (36.8cc) of air milk adjusted to a specific gravity of 0.05
and Chichibu GRC cement (manufactured by Chichibu Cement Co., Ltd.),
Mix water and water reducing agent (Kao Mighty 150),
A lightweight cement paste was obtained by mixing 1 kg (500 c.c.) of cement paste adjusted to W/C=0.30 and specific gravity 2.0. This is molded and cured using conventional methods,
When the specific gravity of the cured product was measured immediately after demolding, the specific gravity was 1.33. Comparative Example 1 After molding and curing in the same manner as in Example 1 except that a protein-based foaming agent was used as the foaming agent, the specific gravity of the obtained cured product was measured, and the specific gravity was 1.46. From this result, it is clear that when a protein-based foaming agent is used, the specific gravity of the resulting cured product increases due to the defoaming effect. Example 2 W/C was 0.25 to 0.25 by varying the amount of water reducing agent mixed.
0.40 was prepared, and using this, a lightweight cement paste was obtained in the same manner as in Example 1. Each lightweight cement paste has a fiber length of 24mm
4% by weight of ARG was added and thoroughly kneaded. This was poured into a mold, cured at 40°C and 100% humidity for 15 hours, then removed from the mold, and further cured at 20°C and 80% humidity for 28 days to obtain a hardened glass fiber reinforced cement product with a specific gravity of 1.3. The bending strength of each cured body was measured, and the relationship between the W/C ratio and the bending strength was determined. The results are shown in FIG. From FIG. 1, it is recognized that the smaller the W/C of the cement paste, the greater the bending strength. Furthermore, the results of a strength change test using 70°C hot water on a hardened cement body obtained from a cement paste with W/C = 0.30 are shown in Figure 2. Comparative Example 2 A glass fiber reinforced cement hardened body was produced from a cement paste with W/C=0.30 in the same manner as in Example 2 except that ordinary cement was used as the cement raw material. The results of the strength change test of the obtained hardened cement body are shown in Figure 2. Comparative Example 3 In Comparative Example 2, by changing the mixing ratio of air milk and cement paste (W/C = 0.30),
A lightweight cement paste was adjusted so that the air-dried specific gravity of the resulting cured product was 0.5 to 2.0, and each was molded and cured in the same manner as in Example 2. Figure 3 shows the relationship between air-dry specific gravity and shrinkage rate. Comparative Example 4 Molding and curing were performed in the same manner as in Example 3 except that ordinary cement was used as the cement raw material, and the relationship between air-dried specific gravity and shrinkage rate was determined. The results are shown in Figure 3. From FIGS. 2 and 3, the fiber-reinforced cement hardened body obtained by the present invention has high bending strength, its deterioration over time is extremely small compared to conventional ones, and the shrinkage rate due to drying is also compared to conventional ones. It is clear that there are fewer [Effects of the Invention] As detailed above, the method for producing a fiber-reinforced hardened cement of the present invention uses calcium silicate-auin-slag-based low-alkaline cement as a cement raw material, and foams it using a polymer surfactant-based foaming method. The cement is foamed with a foaming agent and reinforced with reinforcing fibers, and the resulting hardened cement product is lightweight and has high strength, and the glass fibers are hardly degraded by cement, so when glass fibers are used as the reinforcing fibers, The reinforcing effect lasts even in the middle of the day, and it has excellent durability. Low shrinkage due to drying and good dimensional stability. Fast curing speed and good production efficiency. No unpleasant odor. Since the W/C of the cement paste can be lowered by using a water reducing agent, the resulting cured product has extremely high strength and excellent dimensional stability and specific gravity stability. It has the following advantages and is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between W/C and bending strength in Example 2. FIG. 2 is a graph showing test results of changes in bending strength over time in Example 2 and Comparative Example 2. FIG. 3 is a graph showing the relationship between air-dried specific gravity and shrinkage rate in Example 3 and Comparative Example 3.

Claims (1)

[Claims] 1 Air milk obtained by mixing a polymeric surfactant-based foaming agent and water, and a calcium silicate-auin-slag-based low alkaline cement, water, and a water reducing agent. 1. A method for producing a fiber-reinforced hardened cement body, which comprises mixing the resulting mixture with a cement paste, adding reinforcing fibers to the resulting mixture, kneading it, shaping it, and then curing it. 2. Calcium silicate-auin-slag based low alkaline cement contains tricalcium silicate (3CaO・SiO ₂ ),
20-70% by weight of Portland cement clinker whose main component is calcium silicate such as dicalcium silicate (2CaO・SiO ₂ ), 10-40% by weight of clinker whose main component is calcium sulfoaluminate 3CaO・3Al ₂ O ₃・CaSO ₄ %, anhydrite or dihydrite 10-40% by weight, granulated blast furnace slag or blast furnace ash 20-60% by weight, and (3Al ₂ O ₃ +
_1.5SiO2 )/(CaO- _SO3 ) is a molar ratio of 1.0 to 1.5, the manufacturing method according to claim 1. 3. The manufacturing method according to claim 1 or 2, wherein the polymeric surfactant-based foaming agent is an alkenylsuccinic acid-based foaming agent. 4. Claim 1, wherein the water reducing agent is a polyalkylaryl sulfonic acid water reducing agent.
The manufacturing method according to any one of Items 1 to 3. 5. The manufacturing method according to any one of claims 1 to 4, wherein the reinforcing fiber is glass fiber.