Exprimental effect of using silica fume and fly ash on mechanical properties of recycled concretes

This paper presents the results of a laboratory study on the mechanical performance of recycled concretes prepared with incorporation of two mineral admixtures including silica fume (SF) and fly ash (FA). The recycled aggregates concrete (RAC) was prepared by using 0, 25, 50 and 100% coarse aggregate replacement. The compressive strength, splitting tensile strength (SPT) and ultrasonic pulse velocity (UPV) of concrete mixes were completed. The results showed that the pozzolanic materials cannot have a significant effect on compressive strength loss trend. In contrast, the ultimate compressive strength of recycled concretes strongly effected by pozzolanic materials. The SPT and UPV test results showed that compare with FA, the use of SF reduced the negative effect of high replaced percentage of recycled aggregates