JP2007099546A - Method of producing autoclaved light-weight concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of producing an ALC (Autoclaved Light-weight Concrete) having excellent physical properties such as strength only by adjusting the grain size of silica stone used as a siliceous raw material. <P>SOLUTION: In the method of producing the ALC, the pulverized silica stone used as a silica stone raw material contains all of fine grains, medium grains and coarse grains when the fine grain is defined to have <10 μm particle diameter, the medium grain is defined to have ≥10 μm and <100 μm particle diameter and the coarse grain is defined to have ≥100 μm particle diameter, wherein the content of the coarse grain is adjusted 9-15% by weight, the ratio (fine grain)/(medium grain) is adjusted to 0.9-1.2 and the content of the fine grain is preferably 40-50% by weight. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing lightweight cellular concrete (ALC) used for building walls, roofs, floors and the like.

  In the production of ALC, raw materials obtained by mixing and stirring each main raw material consisting of quick lime, cement and silica and auxiliary raw materials such as gypsum and repetitive raw materials (cut scraps and ALC waste before autoclave) with water. A foaming agent such as aluminum powder is added to the slurry, and the slurry is poured into a mold having reinforcing reinforcing bars to foam. Furthermore, after it becomes a cake-like semi-cured body after a predetermined time, it is cut into a predetermined dimension with a piano wire, and steam curing at high temperature and high pressure is performed by an autoclave.

  The ALC produced in this way contains bubbles and pores inside, and is extremely lightweight with an absolute dryness specific gravity of about 0.5, while having high fire resistance and heat insulation properties and relatively high strength. Has excellent properties. For this reason, ALC is widely used as a building material. For example, it is cut into various dimensions according to specifications, and by performing various processing and finishing depending on the case, such as panels according to applications such as walls, roofs, floors, etc. ALC building material product.

  It is tobermorite produced by high temperature and high pressure steam curing with an autoclave that expresses the strength properties of ALC. Tobermorite is a low crystallinity calcium silicate hydrate (CSH) produced by hydration of cement and quicklime during the process of high temperature and high pressure steam curing, and reacts with the silicic acid component supplied from silica during steam curing. It has become. In general, in high-temperature and high-pressure steam curing in an autoclave, which is a production process of tobermorite, it is widely known that dissolution of silica stones controls the reaction. Accordingly, the particle size, single crystal size, purity, type and content of impurities, etc. of the silica used as the siliceous raw material have a great influence on the physical properties of ALC.

  Thus, many studies have been made on the particle size of silica, particularly silica, as a siliceous raw material. For example, as a method for producing ALC in which the particle size of silica is defined, JP-A-59-128254 discloses that the weight average diameter is 15 μm or less, JP-A-4-197605 discloses 2000-2500 and 6000-2000. The use of silica sand having a particle size distribution having a peak at 12,000 branes is described. Japanese Patent Application Laid-Open No. 2001-019571 discloses a method in which silica having an average quartz crystal grain size of less than 10 μm and 10-500 μm silica are mixed, the average quartz crystal grain size of the mixed silica is 15 to 300 μm, and 10 μm. The use of mixed silica with a mixing ratio of less than 60% by weight or less is described.

JP 59-128254 A Japanese Patent Laid-Open No. 04-197605 JP 2001-019571 A

  In view of such conventional circumstances, an object of the present invention is to provide a method capable of producing ALC excellent in various physical properties such as strength by adjusting the particle size of silica used as a siliceous raw material.

  In order to achieve the above object, the lightweight aerated concrete (ALC) production method provided by the present invention is a crushed silica used as a raw material of silica, fine particles having a particle size of less than 10 μm, medium particles of 10 μm or more and less than 100 μm, 100 μm or more. Is defined as coarse particles, all of fine particles, medium particles and coarse particles are included, the weight percentage of coarse particles is 9 to 15%, and the weight ratio of fine particles / medium particles is 0.9 to 1.2. It is characterized by.

  According to the present invention, ALC excellent in various physical properties such as strength can be produced only by adjusting the particle size of silica used as a siliceous raw material. Therefore, by using the ALC of the present invention as a building panel or the like, it is possible to cope with a recent special construction method, for example, holding the ALC panel with a strong force and lifting it with a crane or using a small mounting bracket. And can be enforced on buildings.

  Since ALC contains bubbles and pores inside, ALC has an excellent property of having a relatively high strength while having an extremely dry specific gravity of about 0.5. This strength is manifested in calcium silicate hydrate tobermorite produced during the high temperature and high pressure steam curing process using an autoclave. In this tobermorite production process, it is widely known that the dissolution of silica stones controls the reaction.

  The present inventors examined the particle size of silica stone, manufactured ALC using silica stone pulverized by various methods to change the particle size, and examined the physical property values of the obtained ALC. As a result, the fine grains contribute to the formation of crystal nuclei, the medium grains contribute to crystal growth, and the remaining coarse grains affect the physical property values due to the aggregate effect, etc., and these fine grains, medium grains, and coarse grains Has been found that ALC exhibits excellent strength when a certain condition is satisfied, and has led to the present invention.

  That is, for the silica after pulverization, when the particle size of less than 10 μm is defined as fine particles, 10 μm or more and less than 100 μm as medium particles, and 100 μm or more as coarse particles, all the fine particles, medium particles, and coarse particles are included, and the weight percentage of the coarse particles It was found that high strength ALC can be obtained when quartzite having a fine / medium grain weight ratio of 0.9 to 1.2 is used as the quartzite raw material. Furthermore, if the weight percentage of fine particles in the crushed silica is 40 to 50%, it is more preferable because high-strength ALC can be stably obtained.

  The reason why the ALC strength becomes high when the particle size is adjusted within the above range is not clear for the silica including all of the fine particles, medium particles, and coarse particles, but the weight ratio of the fine particles to the medium particles is 0. By adjusting to 9-1.2, the generation of crystal nuclei and crystal growth of tobermorite are promoted in a well-balanced manner, and sufficient tobermorite is generated, and at the same time, the weight percentage of coarse particles is 9-15%, The remaining coarse particles play an aggregate effect, and these are considered to be synergistic to improve the strength of ALC.

  ALC was produced using siliceous material produced from the same mine in Tokushima Prefecture as a siliceous raw material. At that time, the silica is previously pulverized by a ball mill to adjust the ratio of fine particles (particle size of less than 10 μm), medium particles (particle size of 10 μm or more and less than 100 μm), and coarse particles (particle size of 100 μm or more). The silica stones of Samples 1 to 7 having the particle size distribution shown in Table 1 were prepared and used as siliceous raw materials.

  As a calcareous raw material, 5 parts by weight of quick lime, 30 parts by weight of cement, and 20 parts by weight of repetitive raw materials are mixed with 45 parts by weight of the above silica, 60 parts by weight of water and a small amount of aluminum for a total of 100 parts by weight of these solid raw materials. Powder and surfactant were added and kneaded to prepare a slurry. The slurry was poured into a mold and foamed, cured by hydration to obtain a cake-like semi-cured product, and then subjected to high-temperature high-pressure steam curing for 6 hours in an autoclave at 180 ° C. and 10 atm.

The obtained ALC block was molded into a 100 mm square cube, and the compressive strength was measured according to JIS A5416. The results are shown in Table 2 below together with the weight percentage of fine particles, medium particles and coarse particles and the weight ratio of fine particles / medium particles. The standard value of compressive strength in JIS A5416 is 3.0 N / mm ² or more. However, in order to cope with a special construction method using a crane or a small mounting bracket, which is actually developed in recent years, 4 0.5 N / mm ² or more is required. Therefore, in the evaluation in Table 2, it applies the compressive strength 4.5 N / mm ² or more (○), 3.0N / mm ² or more 4.5 N / mm ² under improper (△), 3.0N / mm ² Less than was judged as impossible (x).

  In the samples 1 and 2 according to the present invention, all the determinations of the compressive strength were possible. In these samples, the coarse particles were relatively large in the range of 9 to 15%, and the weight ratio of fine particles / medium particles was substantially equal to 0.9 to 1.2. On the other hand, in the samples 3 to 7 as comparative examples, all the compressive strengths were unsuitable. In Samples 3 to 5, the coarse particles are 10% or more and relatively large, but the weight ratio of fine particles / medium particles is less than 0.9 and the fine particles are too few. In Samples 6 to 7, the coarse particles were less than 9% and the weight ratio of fine particles / medium particles was less than 0.9.

From the above results, in order to produce ALC having sufficient strength, when silica stone used as a siliceous raw material is defined as fine particles having a particle size of less than 10 μm, medium particles having a particle size of 10 μm or more but less than 100 μm, and coarse particles having a particle size of 100 μm or more. It is clear that it is necessary to include all of fine particles, medium particles, and coarse particles, the coarse particle weight percentage to be 9 to 15%, and the fine particle / medium particle weight ratio to be 0.9 to 1.2. became.

Claims (2)

  When the crushed silica used as a raw material for silica is defined as fine particles having a particle size of less than 10 μm, medium particles of 10 μm or more and less than 100 μm, and coarse particles of 100 μm or more, all of fine particles, medium particles, and coarse particles are included. A method for producing a lightweight aerated concrete having a weight percentage of 9 to 15% and a weight ratio of fine particles / medium particles of 0.9 to 1.2. The lightweight cellular concrete manufacturing method according to claim 1, wherein a weight percentage of the fine particles is 40 to 50%.