Bricks made of coal fly-ash and slag, cured in the open air

Volume mass, compressive strength, water uptake and water absorption of pressed test samples made of a mixture of coal fly-ash, slag and sodium silicate solution (water-glass) were determined. It was found that such mixtures can solidify in the open air and form water-stable materials. The composition and structure of new formations for the binder and cured material itself were established using X-ray diffraction and a scanning electron microscope. The material has a high water uptake, which may be reduced using a number of different methods, the best of which is short-term impregnation with a hydrophobic material of the siloxane group. The water uptake and water absorption of compressed samples impregnated with such materials are similar to those of comparable building materials, such as lime-sand bricks, clay bricks or concrete blocks.