Pore structure of concrete under fatigue load in areas with large temperature differences.

To study the effect of pore structure changes on the fatigue life of concrete in areas with large temperature differences, a concrete fatigue test program was designed after a temperature cycle of −50 to 70°C. Results show that temperature differences considerably influence pores with a size ranging from 0.1 to 27.98 nm. Furthermore, the fatigue life of concrete gradually decreases with the increase in the pore structure parameters of 0.1 to 27.98 nm. This result indicates that the effect of temperature difference on the fatigue life of concrete in areas with large temperature differences must not be ignored. The combined effect of temperature differences and load increases the coarsening rate of the pore structure, and the load remarkably affects pores with a size ranging from 524.26 to 10,000 nm. To characterize the pore structure of concrete under temperature cycling and fatigue load, two pore structure characteristic parameters, namely, comprehensive change rate of pore size (Sz) and pore structure complexity coefficient (Cz), are proposed. These parameters, together with the total porosity (Ptotal), form a three‐dimensional pore structure characteristic parameter and establish the relationship expression between the three‐dimensional pore structure parameters and the fatigue life of concrete (N); thus, they provide basis for the prediction of the fatigue life of concrete on the basis of pore structure. [ABSTRACT FROM AUTHOR]