The determination of optimum ratio by using recycled concrete aggregate and crumb rubber as partial sand replacement material in sand cement brick production

During the last decades, it has been recognizing that a large volume of waste with growing concerned that wastes from construction and demolition (C&D) are increasing years by years. Most waste materials are left as a landfill material or illegally dumped. The environmental impact can be reduced by making more sustainable use of this waste by the recycling process. This study aims to establish the sustainable properties for sand cement bricks using Recycled Concrete Aggregate (RCA) and Crumb Rubber (CR) as partial sand aggregate replacement materials. The objectives of this study are to determine the optimum cement-sand ratio (1:5, 1:6, and 1:7) for sand cement brick through density, compressive strength, and water absorption tests. Then, investigate the mechanical properties and durability of sand cement bricks through shrinkage and carbonation and lastly identify the optimum percentages of RCA and CR as sand aggregate replacement in sand cement bricks. The brick specimens were prepared using 15%, 30%, 45%, and 60% of RCA and 1.5%, 3.0%, 4.5%, and 6.0% of CR by volume of sand with a water-cement ratio of 0.6. The size of the RCA used to measure less than 5 mm. Hence, the size of the sieved waste CR granules used is between 0.1 to 5 mm that made it physically similar to the size of fine aggregates. The overall results revealed that the best cement-sand ratio was 1:6. The density test indicates that the average density of sand cement bricks is lower than the control bricks. Besides, the percentage of water absorption for sand cement bricks was found to be satisfactory. In a nutshell, the optimal replacement of RCA and CR was R15C1.5 with a cement-sand ratio of 1:6 as it achieved the lowest values during the drying shrinkage and carbonation tests.