Effect of total dissolved solids-contaminated water on the properties of concrete

Abstract

Total dissolved solids (TDS) is one of the main impurities in the mixing water that can influence the properties of concrete, and therefore, the codes of practice limit the concentration of TDS in water used for producing concrete. The present study investigates the effect of TDS present in the mixing water on the properties of concrete in fresh and hardened states. Concrete mixtures were prepared using water with different selected concentrations of TDS (500, 1000, 5000, and 15000 ppm) keeping the proportions of the main ingredients invariant. Experimental tests including workability, initial setting time, air content, compressive strength, water absorption, water permeability, chloride permeability, and electrical resistivity were conducted. The results showed that the workability and initial setting time were reduced with increase in the TDS concentration, however, these properties remained within the acceptable limits as specified by ASTM C191-18a. At higher concentrations of the TDS, air content and water absorption of concrete deceased by about 31% and 6%, respectively, and compressive strength increased by about 20%, indicating positive effect of the higher concentration of TDS on the quality of concrete. However, the compressive strength was found to be slightly lower at the TDS content of 15000 ppm. Resistance against water penetration and electrical resistivity of concrete decreased slightly at higher TDS concentrations, however, water permeability class and the likelihood of reinforcement corrosion remained unaffected. The chloride permeability increased from moderate to high level when TDS concentration exceeded 1000 ppm. Based on the finding of this study, it may be concluded that the waters having TDS up to 1000 ppm can be recycled for concrete production that would benefit in cost reduction and conservation of water resources.