Such well-known in the construction material for a very long time could not find the application. The fact is that in the wild lime hardens very slowly, obtained from lime products have a low strength (1 – 2 MPa) and easily destroyed by water. Since under natural conditions in the lime sand – sand mixtures is inert and can not interact chemically with the lime. As a result of this acquisition of strength of plaster in vivo is achieved and only in 1880 it was discovered that autoclaving lime-sand mixtures under steam pressure of 0.8 MPa and temperatures above 170 C derived products have high strength, water resistance and durability. This discovery dramatically affect the ratio of lime sand mixtures in particular, to the silicate industry in general. At the moment given the silicate industry – one of the most developed industries of construction materials.
sand-lime brick, stone walls and other products designed for precast construction is made of lime-sand mixtures. Common lime and silica sand are the main materials for the manufacture of silica brick. Lime can be applied as a rock and a burnt copy, and partially dampened as zagashennoy or hydrant. In his all lime should be characterized by rapid quenching, and should not contain more than 5% MgO. It should be noted that for the production of autoclave silicate products should not contain lime burnout because burnout slows the rate of hydrated lime and can cause various defects in the products (cracks, swelling). As for the silica sand, the production of silicate products are usually used not ground, sometimes use a mixture of finely and not ground. The presence of impurities in the sand adversely affected the quality of products; For example mica reduces the strength and content of the sand is recommended not to exceed 0.5% swelling products can cause organic contaminants. Inclusion of clay in the sand should be uniform, because the large inclusion and reduce the quality of products. The ideal composition of lime-sand mixture for the manufacture of sand-lime brick is as follows: 92-95% pure quartz sand, 5-8% of air lime and about 7% water. silicate brick