Mechanical properties and microscopic characterization of mortar with recycled aggregate from waste road

In order to explore the practicability of recycled aggregate replacing river sand in cement mortar, the research on recycled aggregate mortar (RAM) was carried out from the aspects of mechanical properties and microstructure. Compressive test, flexural test, consistency test and scanning electron microscopy (SEM) were conducted when the ratio of river sand replaced with recycled aggregate (RSA) was 0, 20 %, 40 %, 60 %, 80 % and 100 %. The compressive test results show that recycled aggregate can reduce the brittleness index and increase the toughness of mortar. The flexural test show that the fracture energy increases with the increase of RSA. The consistency test results show that the consistency decreases slowly and then rapidly with the increase of RSA. When RSA≤ 40 %, its consistency is above 30 mm and can meet the application requirements of practical engineering. SEM tests show that after replacing the recycled aggregate with river sand, the cementation effect between hydration products and particles is more obvious. To sum up, the compressive strength, flexural strength and consistency of RAM are better than those of the benchmark group. When RSA = 40 %, the mechanical properties of RAM reach the optimal value and has high practicability.