Investigating the appropriate quality of greywater for use in eco-friendly concrete mixing

Owing to serious limitations of freshwater, using unconventional water resources such as greywater is unavoidable. Considering the large amount of water needed for making concrete, in this research, greywater was used to mix eco-friendly concrete. To investigate the appropriate quality of greywater, synthetic and real greywater samples were prepared, and pH, total dissolved solids (TDS), chemical oxygen demand (COD), chloride (Cl − ) and sulfate (SO 4 2− ) contents were evaluated. Based on a concrete performance index, the maximum appropriate values of COD, TDS and sulfate were determined to be 119, 411 and 134 mg/l, respectively, and the water quality index should be over 67.5. The results of tests conducted on samples containing various types of greywater showed a decrease in mechanical performance, but not durability properties. The results revealed that the quality of concrete mainly depends on the quality of greywater according to the Pearson coefficient. The Pearson coefficient was generally greater than 0.4, revealing a strong correlation between greywater quality and concrete characteristics. Using a combination of greywater and potable water generally provided better performance than the use of greywater alone. Based on the results, although the use of greywater can decrease freshwater consumption, supplementary tests still need to be performed.