Limesand Mixture
Such well-known in the construction material for a very long time could not find the application. The fact that lime in vivo hardens very slowly, derived from lime products have low strength (1 – 2 MPa) and easily destroyed by water. Since under natural conditions in the sand – lime sand mixtures is inert and can not chemically interact with the lime. As a result of this acquisition of strength lime-sand mortar in vivo was only achieved in 1880, it was discovered that during autoclaving lime-sand mixtures under steam pressure 0.8 MPa and temperatures above 170 C derived products possess high strength, water resistance and durability. This discovery radically changed the way to the lime sand mix in particular, to the silicate industry in general. At the given moment of silicate industry – one of the most developed industries of construction materials. calcium silicate bricks, stones for walls and other products designed for modular construction made from lime-sand mixtures.
Common lime and sand are the main materials for the manufacture of calcium silicate bricks. Lime can be applied in both the hammer and burnt as well as partially or zagashennoy dampened hydrant. In turn, the 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 lime silicate products should not contain burnout because burnout slows lime and can cause the appearance of products of various defects (cracks, swelling). As for quartz sand, the production of silicate products used usually not ground, sometimes a mixture and not ground finely. The presence of impurities in the sand adversely affect the quality of products; For example mica reduces the strength and content of the sand is not recommended exceed 0.5% of products can cause swelling of organic impurities. Inclusion of clay in the sand should be uniform, as large as the inclusion of lower quality products. Ideal composition of lime-sand mixture for the manufacture of silica brick is as follows: 92-95% pure quartz sand, 5-8% of air lime and about 7% water. silicate brick