Improving of Recycled Aggregate Quality by Thermal-mechanical-chemical Process

To save natural resources and promote the sustainable development of construction industry, the use recycled coarse aggregate (RCA) from waste concrete has been encouraged recently. However, it is widely accepted that RCA concrete has lower performance about 15% to 20% than that of natural aggregate concrete. The adhered mortar on RCA surfaces causes lower quality of RCA produced through conventional recycling process. Therefore, it is necessary to provide higher quality of RCA from waste concrete by detaching old mortar as much as possible; so that the quality of RCA concrete can be improved as well. This research proposes a thermal-mechanical-chemical process to produce better properties of RCA from waste concrete. Then, new concrete was produced by utilizing the RCA. Results indicate that the physical properties of RCA are close to natural aggregate and meet the requirement of Indonesian Standard for concrete aggregate. Furthermore, the mechanical performance of RCA concrete produced by the proposed method has better mechanical properties to that of conventional RCA. It is about 3-8% lower than the mechanical properties of natural coarse aggregate concrete.