Evaluate Statistical Significance of Compressive Strength and Ultrasonic Pulse Velocity Degradation by Water/Cement Ratio for Concrete Subjected to High Temperature

In this study, the compressive strength and UPV of concrete subjected to high temperature were statistically tested to evaluate the quantitatively significant differences in W/C ratio. Data from several existing studies that evaluated the compressive strength and ultrasonic pulse velocity(UPV) of concrete subjected to high temperature were extracted and analysed, and the range of concrete types was limited to ordinary concrete. The W/C ratio was set to four groups (W/C50, W/C40. W/C30 and W/C20). Simple linear regression analysis of temperature and mechanical properties (compressive strength and UPV) was performed, and the R-square (R2) and root mean square deviation (RMSE) of the regression model with W/C ratio were higher than the regression model without W/C ratio. The analysis of variance by W/C ratio showed that the compressive strength was significantly different by W/C ratio, but the UPV was not significantly different in all groups. The error test of the regression model showed that the regression model of temperature and compressive strength with W/C ratio satisfied normality, linearity, equality of variance and independence, but the regression model of temperature and UPV did not show a pattern that satisfied linearity, equality of variance and independence regardless of the W/C ratio.