Evolution of heat during the synthesis of hydrosilicates in aerated concrete

摘要

Concretes based on xonolite are more weather-resistant than those based on tobermorite [4, 5] but the production of aerated concretes based on xonolite gives rise to higher energy costs. There is also no guarantee of the stability of its phase composition under normal temperature conditions. For aerated concrete production it is therefore recommended that immediately after removal from the autoclave the product should be dried to a residual moisture content of not more than 20%, which also contributes to stabilization of the beneficial phase composition. Because of the above-mentioned results from the autoclaving of aerated concretes with densities D 400 and 500 the steam pressure should be reduced by 0.025-0.03 MPa for the first 3-4 hours after the correct operating point has been reached. The evolution of heat during the synthesis of silicon and aluminate hydrates also lowers the energy costs by a few percent.