Interaction of treated industrial wastewater and zeolite on compressive strength of plain concrete in different cement contents and curing ages

In the present study interactions of three levels of water quality (tap water, treated industrial wastewater, and a mixture of their equal ratio), four levels of zeolite application (the use of 0 %, 10 %, 20 % and 30 % of zeolite instead of cement) and two levels of cement content (250 and 350 kg m−3) on compressive strength of plain concrete over seven curing ages (3, 7, 28, 56, 90, 180, and 365 days) was investigated. For this, 504 concrete cube samples were constructed and data were analyzed using tests of analysis of variance and means comparison. Based on the statistical analysis of data, all two-, three- and four- way interactions of curing age with cement content, water type and zeolite percentage were insignificant, indicating that the variation rate of concrete compressive strength by time was not affected by mixing water type and application of zeolite and also all possible combinations of studied factors. Moreover, the results showed that the three-way interaction of cement content × water type × zeolite percentage on the compressive strength of concrete was significant. Therefore, the selection of best zeolite percentage in the mix design should be according to the mixing water type and cement content. Accordingly, simultaneous use of unconventional water as mixing water with zeolite up to 10 % in low cement content (250 kg m−3) and also with zeolite up to 20 % in the high cement content (350 kg m−3) can be recommendable.