Mouldings bonded by lime or cement, esp. sand lime bricks - where fly:ash, gypsum and water:glass are added to reduce shrinkage of bricks after hydrothermal hardening

摘要

The mouldings are made from a material which is mixed with small amts. of lime and/or cement and water, then hydrothermally treated and hardened. In the invention, the amt. of lime and/or cement is reduced, and small amts. are added of sodium water-glass, calcium sulphate, and fly-ash. The fly-ash is obtd. e.g. by removing dust from waste gas leaving power stations. The pref. material is silica sand, where up to 1/3 of the sand may be replaced by fly-ash and/or diatomite. The pref. moulding mixt. contains by wt. 55-90% silica sand, 0.01-1% milled sodium water-glass, 0.1-5% gypsum, 3-35% fly-ash, and 1-9% CaO. The shrinkage of the mouldings during setting is reduced.