Use of RMC Wastewater in Concrete with Admixtures for Strength Enhancement

Water is the elixir of all of our lives. India has become a water scarce country due to its rising population and its rising needs. When it comes to the construction industry, a huge amount of water is needed to both produce concrete as well as to wash the trucks after they have unloaded. This waste wash water (WWW) that is collected after the washing of trucks is high in alkalinity, TSS, TDS, etc., since it contains cementitious materials, admixtures and other impurities from the concrete and, hence, making it toxic and bringing the requirement of a prior treatment before it can be sent for disposal. In the past, scholars have tried to reuse this wash water into concrete mix, but it had resulted in a concrete with reduced strength. Hence here, in this research, we aimed to effectively reuse this wash water in concrete mix with admixtures and other strength enhancers to produce a concrete of desired strength. The wash water did not contain any harmful constituents. The w/c ratio in this study was limited to 0.3, and super plasticiser was added as 0.5% of the total weight of cement. The study involved a mix design of M₃₀ grade concrete. The strength in compression in conventional concrete was 33.4 MPa, and with the use of wash water, it was 29.87 MPa. The strength enhancement was improved with the usage of 10% Silica Fume as replacement for sand in concrete. This compensated for the strength reduction that was caused by using the wash water.