Silica Concrete

Silica Concrete 

a concrete obtained by the steam treatment in autoclaves of mixtures consisting of a lime-and-silica binder, an inorganic aggregate, and water. Products made of silica concrete are steam-treated at a pressure of 0.9-1.5 meganewtons/m² and a temperature of 174.5°-197.4°C. During this treatment, the mixture hardens as a result of the formation of hydrosilicates and other calcium compounds and acquires a compressive strength of up to 60 meganewtons/m² and sometimes more.

Materials used as binders in manufacturing silica concrete are fine mixtures of air-hardening or hydraulic lime with materials that contain silica. Examples of such materials are quartz sands, volcanic rocks, metallurgical and fuel slags and slags from electric smelters, cinders, nepheline sludge, and waste products from concentration plants. Natural and man-made sands are used as aggregates, including quartz, feldspar, volcanic, carbonate, and slag sands; coarser aggregates may also be used.

The properties of silica concrete are similar to those of concrete made from Portland cement. The density of silica concrete is 1,800-2,200 kg/m³, and frost resistance is 75-200 cycles.

A. V. VOLZHENSKII [23–1071–]