The Effect of Greywater and Zeolite Usage in the Construction and Curing of Plain Concrete in Different Cement Contents and Ages

Regarding the significant contribution of the concrete industry in water consumption and greenhouse gas emissions, it is necessary to study the possibility of using unconventional waters and environmental friendly materials in this industry. Accordingly, the present study was conducted to investigate 120 treatments including three levels of water quality (tap water, greywater and mixture of equal ratio of tap water and greywater), four levels of zeolite (0, 10, 20 and 30 percent of zeolite application instead of cement in the concrete mix), two levels of cement content (250 and 350 kg.m-3) and five curing ages (3, 7, 21, 56 and 90 days) in three replications by construction of 360 concrete specimens. Considering the considerable types of the experimental treatments in this study and in respect to the lack of statistical analysis in previous studies, the results of this study were analyzed based on a completely randomized design with factorial experiment using analysis of variance (ANOVA) and means comparison (LSD) tests. The results showed that the use of greywater, in whole or combined, increased the compressive strength of concrete. Also, although the application of zeolite in both cement contents generally reduced the compressive strength of concrete, the rate of change was significantly lesser in cement content 350 kg.m-3 than 250 kg.m-3, so that replacement of 10%, 20% and 30% of cement by zeolite led to decrease of the compressive strength by 15.0%, 26.1% and 34.0%, respectively; whereas in the cement content 350 kg.m-3, the changes of compressive strength of specimens were -2.4%, +5.4% and -13.7%, respectively. However, considering the significant interaction of these two factors with water type, which means the different effects of water quality and the percentage of zeolite on different contents of cement, the best level of application of zeolite and water type regarding the cement content should be selected based on in-situ mix design test.