Reuse of Return Concrete Slurry Waste in Concrete as Fine Aggregate

Abstract

A combination of leftover cement particles, cement hydration products, and fine aggregates make up return concrete slurry waste (RCSW). RCSW is a by-product generated during concrete production by ready-mix concrete plants and is generally identified as a waste material and generally disposed of as landfill material. Since environmental preservation is encouraged in the construction industries, achieving sustainable use of resources while producing concrete is becoming increasingly important. On the other hand, sand is extensively used in the construction industries as fine aggregate for making concrete which is extracted from rivers, pits, or artificially produced by crushing rocks. Therefore, this study has been planned to explore the possibility of the replacement of sand in mortar by RCSW. In this study, a novel technique for successfully reusing RCSW as filler material by replacing fine aggregate in cement mortar has been investigated. Mortar specimens (50 mm by 50 mm by 50 mm) were made with the replacement of natural sand by 5%, 10%, and 10.5% with RCSW. The specimens were made with different types of cement, such as CEM Type 1 (linker based cement), CEM Type II (maximum replacement of clinker by 20% with mineral admixture), 65% CEM Type 1 + 35% fly ash, 50% CEM Type I + 50% fly ash, 35% CEM Type I+65% fly ash, 65% CEM Type 1 + 35% slag, 50% CEM Type I + 50% slag, 35% CEM Type I+65% slag. The specimens were tested for compressive strength, water absorption, and sorptivity. The results revealed that RCSW can be used to replace a part of fine aggregate (sand) in mortar. By reusing RCSW for making mortar, the cost of mortar will be reduced, associated disposal problems will be solved, carbon dioxide emissions will be reduced, and eventually, it will help toward the sustainability of construction materials.