A Freeze–Thaw Damage Evolution Equation and a Residual Strength Prediction Model for Porous Concrete Based on the Weibull Distribution Function

The service life of porous concrete (PC) structures is severely affected by freeze–thaw damage in cold regions. However, the evaluation of freeze–thaw damage of PC using experimental tests is time-consuming and inconvenient. This paper derived an equation to evaluate the freeze–thaw damage and developed a model to predict the residual strength of PC under freeze–thaw conditions based on the Weibull distribution functions. By analyzing the experimental results, the relative dynamic elastic modulus (RDME) was identified as the damage variable, which can accurately characterize the freeze–thaw damage state of PC with the advantages of convenience and nondestructiveness. Moreover, the resistance to freeze–thaw cycles of the PC blended with basalt fibers and silica fume increased by 25% compared with that without any reinforcement. Based on the damage accumulation theory, the Weibull distribution function is appropriate to be employed to describe the freeze–thaw damage evolution of PC. The model for predicting the residual strength of PC subjected to freeze–thaw cycles was verified based on a large amount of test data and had correlation coefficients R2 higher than 0.96. The proposed model also can be used to predict the residual strength of other types of PC, and provides a reference for service life prediction and safety assessment of PC structures.