Production of concrete using reclaimed water from a ready-mix concrete batching plant: Life cycle assessment (LCA), mechanical and durability properties

Abstract

This study investigates novel methods and more sustainable techniques that have been developed to minimize the environmental damage of concrete production. The use of reclaimed water and supplementary cementitious materials in concrete can be a solution to the problems of water scarcity and excessive CO2 emissions. In this context LCA, mechanical and durability properties of concrete containing silica fume as a supplementary cementitious material (SCM) and reclaimed water as an alternative source of fresh water are studied. First several properties of concrete such as consistency, compressive strength, electrical resistance, chloride ion penetration and water penetration under pressure were measured. Then, the LCA of concrete using LCA web tool was evaluated and the global warming potential (GWP) emission rates along with air pollutants such as lead, volatile organic compounds, CO, NOX, PM10 and SO2 were determined. The results show that adding a certain level of silica fume is desirable in terms of environmental issues, cost and mechanical and durability properties of concrete. In concrete containing 5, 8 and 11% of silica fume, GWP emissions decreased by 4.9, 8 and 11.2%, respectively. On the other hand, the production of lead, volatile organic compounds (VOCs), CO, NOX and PM10 decreased by 2–12%, while SO2 production increased by 4–10%. According to the obtained results, the manufacture of concrete with the mixing ratios presented in this research in a large-scale ready-mix concrete batching plant that produces 576 tonnes concrete per year (240,000 m3/year) will lead to a reduction of GWP about 3900–8700 tonnes CO2-eq per year.