JPH0518788B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing an aerated slag-gypsum composite material, which is used as an exterior wall material and an interior wall material for buildings, by a dry construction method and has excellent fire resistance performance. Conventional technology Conventional methods of using plaster or slag include:
Hemihydrate gypsum, which is typified by plasterboard, and molded anhydrite gypsum are used. This hardened gypsum body has the disadvantage of not being water resistant at all. Other methods include molding hemihydrate gypsum and glass fiber using the spray suction method. In addition, the combination of hemihydrate gypsum and portland cement has been studied as a method to improve the water resistance of gypsum, but when combining hemihydrate gypsum and portland cement, it shows rapid setting and is difficult to work with. There were problems such as the need to add a retarder due to the lack of Regarding the use of dihydrate gypsum and slag, a method has been proposed in which the water resistance of gypsum is improved by forming ettringite, but this method has problems such as the curing time required. Problems to be Solved by the Invention Conventional gypsum-based wall covering materials have problems with water resistance because they are mainly made of gypsum. In addition, some gypsum/slag-based or gypsum/slag/cement-based composite materials with improved water resistance have been commercialized, but gypsum (CaSO ₄ 2H ₂ O) It reacts with calcium aluminate (3CaO・Al ₂ O ₃ ) in cement, producing ettringite (3CaO・Al ₂ O ₃・3CaSO ₄・32H ₂ O),
It is not a perfect material as it lacks dimensional stability underwater and develops expansion cracks. Means for Solving the Problems Taking these circumstances into account, the present inventors utilized the short-time setting and hardening properties of gypsum hemihydrate,
In order to improve water resistance, a composite material with good underwater dimensional stability and excellent water resistance is continuously manufactured using a matrix of hydraulic material combining blast furnace water frame slag powder and Portland cement. The present invention was completed after conducting extensive tests, and the first invention is based on hemihydrate gypsum 40
~75% by weight, blast furnace water frame slag powder 20~50% by weight,
Then, when adding an appropriate amount of water to a hydraulic material consisting of 5 to 20% by weight of Portland cement and kneading it, an appropriate amount of air bubbles and fibers are mixed in and formed into a slurry, which is then heated at a temperature of 50 to 150 degrees Celsius. The second invention relates to a method for producing an aerated slag gypsum composite material characterized by curing and drying. Continuously poured and molded on a conveyor belt, solidified in 10 to 40 minutes, placed in a hot air drying oven at a temperature of 50 to 150°C, and cured and dried for 12 to 48 hours until the air-dried specific gravity
It is characterized by continuously producing a cured product with a particle size of 1.0 to 0.6. Effect A hardened body obtained as a slurry by adding water using a hydraulic material within the scope of the present invention consisting of gypsum hemihydrate, blast furnace slag powder, and Portland cement will not be cured when left in an air-dry state. There is no problem, but
When placed in water for a long period of time, gypsum ( _CaSO4.2H2O ) reacts with calcium aluminate ( _{3CaO.Al2O3 )} in _{slag and} cement, forming _ettringite ( _{3CaO.Al2O3.3CaSO4.32H} ). ₂ O) is formed, but the growth pressure caused by the continued formation of this ettringite may cause expansion cracks in the hardened material. However, by mixing air bubbles into this hardened material, the air bubbles will act as a buffer material and can be expected to have the effect of alleviating the growth pressure caused by the formation of ettringite, and acicular crystals of ettringite will form between the air bubbles. However, scanning electron microscopy revealed that the air bubbles were covered with a dense layer of hydrated structure, and the entire structure of the cured product was strengthened. Furthermore, it was observed that some ettringite was formed in the bubbles, which is inferred to support that the bubbles play a role in buffering the growth pressure of ettringite. Due to this effect, the composite material according to the present invention shows no dimensional change even when placed in water for a long period of time, and almost no deterioration in strength occurs. Here, it is important that the amount of air bubbles mixed is the amount necessary to make the air-dried specific gravity of the cured product after heat curing and drying to 1.0 to 0.6. That is, when the air-dried specific gravity is 1.0 or more, the stability in water is poor, and when the air-dried specific gravity is 0.6 or less, the cured product has low strength and a large amount of water absorption. The method of mixing air bubbles is generally called the air entrainment method, which is a preforming method in which air bubbles are created in advance.
Alternatively, any mix forming method may be used, in which a foaming agent is added at the same time as the slurry is prepared to cause foaming. Further, the foaming agent is not particularly limited, and any commercially available foaming agent can be used. However, aluminum powder-based inorganic foaming agents are not preferred because they react with gypsum. Moreover, a bubble stabilizer such as polyvinyl alcohol (PVA) can also be used if necessary. The reason for limiting the blending amounts of gypsum hemihydrate, blast furnace water frame slag powder, and portland cement in the present invention is that if the amount of gypsum hemihydrate is less than 40% by weight,
This is because it is difficult to set the gypsum within 40 minutes, resulting in poor productivity, and if the amount of gypsum hemihydrate exceeds 75% by weight, a problem will arise in water resistance. In addition, Portland cement acts as a setting accelerator for gypsum hemihydrate and as an alkaline stimulant for blast furnace water frame slag, and if it is less than 5% by weight, the above two effects are small; % or more, stability in water deteriorates even if the air-dried specific gravity is controlled to 1.0 to 0.6. Therefore, the hydraulic material used in the present invention is gypsum hemihydrate 40 to 75
%, blast furnace water frame slag powder 20-50% by weight, and Portland cement 5-20% by weight. Furthermore, there are two types of gypsum hemihydrate, the α type and the β type of general calcined gypsum, and either of these can be applied. Blast furnace water frame slag powder has a plain specific gravity area.
Anything over 2750cm ² /g can be used, but
Preferably, highly reactive blast furnace water frame slag powder of 4000 cm ² /g or more is suitable. Next, as the reinforcing fibers used in the present invention, synthetic fibers such as vinylon fibers, carbon fibers, alkali-resistant glass fibers, rock wool, etc. can be used. In producing the aerated slag gypsum composite according to the present invention, a continuous molding method can be employed since the slurry sets in 10 to 30 minutes. As a result, the low-strength hardened material that is continuously poured out onto the belt conveyor is placed in a drying oven at 50 to 150 degrees Celsius and cured and dried for 12 to 48 hours while controlling the internal humidity. By promoting the formation of calcium silicate hydrate and calcium silicate hydrate, it is possible to produce a wall material with excellent water resistance and the desired strength. Examples Example 1 β-hemihydrate gypsum 45-84% by weight, blast furnace water frame slag 13
~44% by weight and 3 to 11% by weight of ordinary Portland cement, reinforcing fiber (vinylon fiber), foaming agent, foaming stabilizer, and kneading water were used to prepare the 7 types of sample No. shown in Table 1. .1 to No. 7 were prepared, and after drying at 100℃ for 15 hours, these samples No. 1 to No. 7 were prepared.
The physical property values of No. 7 were determined and are shown in Table 2. As shown in Tables 1 and 2, Samples No. 1 and No. 2, which are outside the scope of the present invention, have a longer slurry coagulation time than Samples No. 3 to 7, which are products of the present invention.
It can also be seen that both the bending and compressive strengths of the cured product are low.

【table】

[Table] Example 2 A hydraulic material consisting of 55% by weight of β-hemihydrate gypsum, 36% by weight of blast furnace water frame slag, and 9% by weight of ordinary Portland cement, reinforcing fiber (vinylon fiber), and a bubble stabilizer. In order to prepare specimens with various specific gravity, the amount of foaming agent used was changed to make five types of samples No. 8 to No. 12 shown in Table 3. After drying at 100°C for 15 hours, these samples were The physical property values were determined and shown in Table 4, and the rate of change in length of these samples when immersed in water is shown in FIG.

【table】

[Table] As shown in Figure 1, the effect of air bubbles on the dimensional stability is very large, and sample No. 10 (air-dried specific gravity
0.82), the length change rate can be approximately 30×10 ^-4 regardless of the above composition. For sample No. 9 (air-dried specific gravity 1.11), the rate of change is 100
Expansion cracks due to the growth pressure of ettringite were observed when the temperature exceeded ×10 ^-4 . Based on this experimental result, in the present invention, the air dry specific gravity of the cured product is 1.0 to 1.0.
It was limited to a range of 0.6. Effects of the invention The aerated slag gypsum composite material made with this composition maintains continuous productivity, which is the most distinctive feature of gypsum-based materials, and is extremely water resistant due to its mineral composition of ettringite. It is an epoch-making material that exhibits excellent properties. In addition, expansion cracks that occur during the formation of ettringite can be prevented by appropriately incorporating air bubbles, and an inexpensive wall covering material with excellent water resistance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the rate of change in length of a sample when immersed in water.

Claims (1)

[Claims] 1. 40-75% by weight of gypsum hemihydrate, blast furnace water frame slag powder
20-50% by weight and Portland cement 5
A hydraulic material consisting of ~20% by weight is mixed with an appropriate amount of water, mixed with an appropriate amount of air bubbles and fibers, formed into a slurry, and then heated and cured at a temperature of 50 to 150°C to dry. A method for producing an aerated slag gypsum composite material. 2. Hemihydrate gypsum 40-75% by weight, blast furnace water frame slag powder
20-50% by weight and Portland cement 5
When adding an appropriate amount of water to a hydraulic material consisting of ~20% by weight and kneading it, an appropriate amount of air bubbles and fibers are mixed in to form a slurry, and the slurry is continuously conveyed on a belt conveyor moving at a constant speed. This is then heated and cured at a temperature of 50 to 150℃ and dried.
A method for producing an aerated slag-gypsum composite material, characterized by continuously producing a hardened material having an air-dry specific gravity of 1.0 to 0.6.