Concrete building products

摘要

Concrete roof tiles having increased early strength produced by including crushed waste concrete in the cementitious mixture. For example, the increased strength is obtained if (i) crushed waste concrete is used as a replacement for aggregate; (ii) crushed waste concrete is used as a nucleating agent; and (iii) crushed waste concrete is graded such that it can be used to replace aggregate and to effect nucleation. The tiles are made from compositions comprising (i) up to 30% by weight of cementitious material and (ii) at least 70% of aggregate, with 0.1 to 20% of the aggregate comprising crushed waste concrete.