Calcium Silicate Products with Crushed Building and Demolition Waste

The suitability of crushed building and demolition waste as a raw material for the production of calcium silicate products has been determined. Therefore calcium silicate bricks have been produced by replacing the natural sand with crushed building and demolition waste of different sources. The mechanical properties of the bricks made with these wastes are comparable or, in some cases, even better than those of bricks with natural sand. The green shear strength of the bricks is higher. The amount of quartz and reactive SiO2 in the waste materials is high enough for the formation of tobermorite as a cementitious material between the grains. A negative aspect is the appearance of brown stains on the surface of the bricks when the waste materials are slightly contaminated with organic substances. This risk can be reduced when, besides the crushing of the waste, a washing process is also included.