Effect of dry process manufactured sands dust on the mechanical property and durability of recycled concrete

Abstract

Manufactured sand dust, a by-product of manufactured sand production, presents a substantial environmental concern. This study explores the viability of utilizing dust derived from three distinct lithologies (diabase, tuff, and basalt) as a recycled concrete supplementary cementitious material. The investigation primarily focuses on the impact of dust type and dosage on various concrete properties, including compressive strength, drying shrinkage, susceptibility to cracking, resistance to chloride ion penetration and so on. The research findings reveal that by incorporating 10% manufactured sands dust, the concrete exhibited improved mechanical properties, as evidenced by a 13.5% increase in compressive strength and a 5.7% increase in elastic modulus compared to the control group after 90 days. When the content of manufactured sands dust in concrete is within the range of 20%, the drying shrinkage of concrete decreases, the sensitivity to cracking decreases, the crack resistance grade improves, and the solidification ability of chloride ions increases by 5%. Microstructure analysis reveals that the addition of 10% manufactured sands dust can fill larger voids in concrete, improve the internal structure of concrete, and thereby enhance durability. These results provide theoretical basis for studying the effects of manufactured sands dust on the mechanical properties and durability of recycled concrete.