Enhancing the properties of recycled aggregates for sustainable development of the construction industry

With the ultimate goal of achieving sustainable construction, it is becoming a global trend to utilize recycled aggregate (RA) from construction and demolition waste in concrete. The use of RA in concrete will lead to solving the environmental problems related to the dumping of construction and demolition waste in open areas and also conserve the fast depleting natural resources for the next generations. However, the attached mortar to the RA affects the properties of recycled aggregate concrete (RAC). Some possible remedies to overcome the drawbacks of RAC and efficiently utilize the RA are: (a) chemical and mechanical pre-treatment of RA and (b) strengthening the cement matrix itself. While the first option may be cost effective, the second alternative is costly and is not environmental advisable. Since significant quantities of construction demolition waste is dumped due to the high rate of construction in the Kingdom, it is advisable to develop cheap and reliable methods to treat the RA for its beneficial utilization in concrete. In the proposed study, removal of the attached mortar using hydrochloric acid (HCl) treatment will be investigated in addition to improving the grading of aggregates by the use of fine RA. The two-fold characters controlling the efficiency of the acid treatment are the acid concentration and soaking period. Thus, different levels of acid concentration and soaking period will be evaluated to determine the optimum concentration and time period to improve the bond between RA and the fresh mortar matrix. Also, proportions of coarse and fine RA that will lead to dene grading will be assessed. The efficiency of the proposed treatment methods will be evaluated by measuring the fresh and hardened properties and durability of RAC. The use of RA in concrete will significantly contribute to the circular economy of the Kingdom