Comparison of the Use of Excavated Soil Recycled Fine Aggregate as a Substitute for River Sand in Mortar Mixing

Abstract

This study comparatively investigated the performance of mortar prepared using excavated soil recycled fine aggregate (ESRFA), which mainly included fine aggregate obtained by sediment separation equipment and sieving. Scanning electron microscopy (SEM) was used to analyse the size and shape of ESRFA particles. The particle size distribution of ESRFA was uneven and its sphericality was lower than that of river sand. Two series of rendering mortar mixes were prepared using identical water/cement and aggregate/cement ratios of 0.55 and 3, respectively, using river sand as fine aggregate. ESRFA was used to replace 30%, 50%, 70%, and 100% of the river sand in each mixture. The experimental results showed that the flowability of the mortar prepared with ESRFA was lower than that of the aggregate-based mortar, but the porosity, water absorption, and mechanical properties (compressive strength, flexural strength, and drying shrinkage) increased and then decreased upon increasing the ESRFA content. In conclusion, ESRFA shows potential as a partial replacement for river sand in mortar, particularly at lower substitution rates. Further research is needed to optimize the processing and application of ESRFA in concrete to enhance its performance and sustainability.