Effect of 10% recycled sands from various storage sites on the mortar’s properties

Abstract

This study investigates the effects of using 10% of recycled sand in mortars. Using the concrete equivalent mortar approach, the reference mortar was developed from a flowable natural aggregate concrete with a C35/45 strength class. Five mortars were manufactured by replacing 10% of the natural sand with recycled sand from various recycling platforms while keeping the formulation parameters constant. The fresh state results showed that recycled mortar had an increased air content, which increased yield stress and viscosity. In addition, mortars containing 10% recycled sand showed a faster rate of flow loss over time. There was no difference between the materials in the hardening state with regard to the evolution of the hydration heat or the setting time. The relationship between the qualities of mortars and sands revealed that the air content depends on the sand’s fineness and the presence of fines with a diameter less than 63 µm. A relatively small increase in porosity and water absorption capacity was observed with a decrease in the compressive and flexural strength with no obvious change in the elastic modulus. The total shrinkage was revealed to depend on the fines content and decreases when the fines content increases.