Fatigue analysis of fibrous concrete with cement additions

The flexural fatigue performance of steel-fibre-reinforced concrete containing mineral inserts is experimentally studied, to investigate the influence of limestone powder, fly ash, metakaolin and silica fume used as inserts. Using different combinations of these cement additions in binary and ternary blend systems, seven mix combinations are prepared and 168 static flexural strength tests are performed to facilitate fatigue testing. Approximately 336 beam specimens are tested to investigate the fatigue performance of different concretes in flexure. The probabilistic distribution of fatigue life of all mix combinations is found to be in agreement with the two-parameter Weibull distribution, with the correlation coefficient achieving higher values. The graphical method, method of moments and method of maximum likelihood estimates are employed to determine distribution parameters. The partial replacement of ordinary Portland cement with mineral inserts/cement additions is found to significantly reduce variability in the distribution of fatigue life. Fatigue life data are also presented in the form of traditional S–N (stress level–number of cycles to failure) diagrams and the 2 000 000 cycle fatigue strength is estimated for all mix combinations. Based on the experimental results, the mix consisting of 70% ordinary Portland cement, 20% fly ash and 10% silica fume is recommended as the most suitable.