# A Review on the Performance of Concrete Containing Non-Potable Water
## 5 Hardened Properties
### Tensile Strength  
As per the available relevant literature [10; 30], splitting tensile strength is reduced by 10-70% upon the replacement of potable water with untreated WW, depending on the type pollutants, as per Figure 10. [PERSON] et al. [30] reported that concrete with untreated WW had lower tensile strength than that of treated WW concrete. This was because the chemical properties or composition of treated WW were not far from those of potable water but were very different from those of untreated WW. [PERSON] et al. [10] blamed the reduction of tensile strength on the high amounts of organic matter, as indicated by BOD\({}_{5}\) and COD values (Figure 1). The effect of treated WW on the splitting tensile strength of concrete, reported in the available literature, is shown in Figure 10. In most of the studies, the splitting tensile strength of concrete decreased with the replacement of potable water with treated WW. [PERSON] and [PERSON] [20] reported a large decline of 35-55% in splitting tensile strength due to using treated WW. [PERSON] [30] reported a decrease of 40-70% in splitting tensile strength with the use of treated WW, while most of the studies [12; 13; 23; 31; 32; 38] showed that the splitting tensile strength of treated WW concrete was 80-110% of that of the corresponding potable water concrete. The variation in the reported effects of treated WW on tensile strength is huge because of the difference in methods and levels of treatment. The effect of different types of WW on the splitting tensile strength of concrete relative to that of potable water concrete is shown in Figure 11. The lowest relative splitting tensile strength was observed with untreated WW. On average, untreated WW concrete showed about 25% lower tensile strength than potable water concrete, whereas treated WW concrete showed an average reduction of 5% in tensile strength. The difference in tensile strength of concrete made with treated and untreated WW is mainly because of the presence of high organic matter in the latter. On the other hand, textile factory WW [10], polish filter water [12] and stone slurry WW [13] achieved 17-24% higher tensile strength than the corresponding potable water concrete. The effect of oil WW was the same as that  
Figure 10: Effect of treated WW on the splitting tensile strength of concrete relative to that of potable water concrete. of untreated WW the tensile strength, while salty water showed effects similar to those of treated WW. The relationship between splitting tensile strength (\(f_{\text{ct}}\)) and corresponding compressive strength (\(f_{\text{cm}}\)) values, reported in various studies [10; 12; 13; 20; 25; 30; 31; 32; 38], is shown in Figure 12. The relationship is derived without considering the shape and size effect of the testing samples due to lack of available studies. Moreover, the effect of WW type was also neglected in deriving the relationship. As shown in Figure 12, the variation of \(f_{\text{ct}}\) with \(f_{\text{cm}}\) follows an almost similar trend as that of the Eurocode N-1992-1-1 [46]. The predicted relationship is not strong as the coefficient of determination (R\({}^{2}\)) is below 0.7. The difference between the y-ordinate values of the predicted curve and the Eurocode curve is not significant; therefore, an established standard can be used to predict \(f_{\text{ct}}\) from \(f_{\text{cm}}\). The microstructural development affected by WW types is similarly reflected in \(f_{\text{ct}}\) and \(f_{\text{cm}}\), so both parameters can be correlated accurately with each other. Despite the fact that there are not many studies regarding the effect of WW on the flexural strength of concrete, the available data referred that WW (treated and untreated) at almost all incorporation ratios reduces the flexural strength of concrete (Figure 13). Nevertheless, this reduction has not been noted at early ages of concrete. In addition, the relationship between compressive strength and flexural strength is poor (Figure 13).