Using recycled bricks to improve the compressive strength of concrete and produce lightweight concrete

This research presents the aim of using sustainable materials like crushed bricks from the demolition of old buildings as additives to preserve the environment, reduce energy consumption, reduce the cost of concrete, improve the properties of concrete, and obtain lightweight concrete for high buildings with more fluidity for narrow places. Also, it discusses the best replacement ratios because the knowledge about them is still lake. Three mixes of concrete were used and tested. Mix-1was the standard, where the replacement of coarse aggregate with crushed brick aggregate has been used in mix-2, the mix-3 was to study the replacement of fine aggregate by powder brick. In this analysis, only two factors were taken into account: the percentage of coarse aggregate replaced by brick aggregate (from 0 to 50%) and the percentage of fine aggregate replaced by brick aggregate (from 0 to 75%).  Compressive strength was tested after curing at ages (7, and 28) days. The results showed that concrete with crushed brick aggregate reduces unit weight and increases of compressive strength of concrete. Using mix-2 increased the compressive strength by about 9.7%, and 7% at ages (7, 28) days respectively, and reduced the weight by 11%. Also, using mix-3 increased the compressive strength with high percentages of about 59%, and 61% at ages (7, and 28) days respectively, with a little percentage of reducing the weight by 2%.