Impact of Collected and Recycled Concrete Plant Washing Water on the Physical, Chemical, and Mechanical Properties of Mortars

The management of washing water from concrete plants is a growing environmental and industrial concern due to its high alkalinity and the presence of suspended solids, chemical admixtures, and dissolved salts. This study investigates the impact of collected and recycled concrete plant washing water on the physical, chemical, and mechanical properties of mortars. Two types of wastewater were analyzed: (1) collected water (CW), obtained from settling tanks with residual suspended particles and chemical compounds, and (2) recycled water (RW), subjected to a complete treatment process including pH stabilization and solid particle removal. The effects of these waters were compared against potable water (PW) through a comprehensive experimental program evaluating the porosity, density, shrinkage, and mechanical performance of mortars. The results indicate that using CW and RW leads to increased porosity, higher shrinkage, and a reduction in compressive and flexural strength, with RW having a more pronounced impact. These changes are attributed to the chemical composition of the water, which affects cement hydration and matrix densification. Despite these drawbacks, the proper treatment and controlled usage of such waters may offer sustainable alternatives to potable water in concrete production, contributing to resource conservation and environmental sustainability.