Performance evaluation of cement mortar made of different types of recycled sand

Abstract This work investigates the potential replacement of natural sand within cement mortar via the use of recycled sand derived from excavation waste, construction and demolition waste and concrete waste. To study the mechanical properties such as compressive strength, flexural strength, hardened density, ultrasonic pulse velocity, and durability characteristics, a series of mortar mixtures is prepared by using different percentages of recycled sand (0%, 10%, 20%, 50%, 75%, and 100%). The water to cement ratio is varied to obtain a target consistency of 110% ± 5% in the flow table test, with the sand to cement ratio set at 3.553 to match field mixing conditions. Elemental and microstructural characterization of the recycled sand and mortar using advanced analytical techniques is performed on these materials. The results show a decline in compressive strength, flexural strength, water absorption, and ultrasonic pulse velocity with increasing replacement, especially when over 50%. Mortar made of recycled sand derived from construction and demolition waste achieves high compressive and flexural strengths across all replacement levels. The findings indicate that recycled sand from excavation waste and construction and demolition waste is effective for replacing natural sand in mortar applications up to 75%, while concrete waste is suitable for replacement levels up to 50%.