EXPERIMENTAL STUDY ON COMPRESSIVE FATIGUE PERFORMANCE AND LIFE PREDICTION MODEL OF CONCRETE WITH DIFFERENT TYPES OF BINDERS AND AGGREGATES

To evaluate the effect of different binders and aggregate types on the compressive fatigue performance of concrete, three types of cementitious materials were used in the experiment: ordinary Portland cement (OPC); A high content supplementary cementitious material (SCM) composed of 30% OPC, 20% fly ash (FA), and 50% ground slag (GGBS); A base activator cementitious material (AA) composed of 50% FA and 50% GGBS, mixed with Na₂SiO₃ and Ca(OH)₂. Natural aggregate concrete (NWC) and lightweight aggregate concrete (LWC) were tested and subjected to constant stress cyclic compression tests. The maximum stress level was set at three levels, which were 75%, 80%, and 90% of the static uniaxial compressive strength of the concrete, while the minimum stress level was fixed at 10% of the static compressive strength. Based on regression analysis of experimental results, fatigue life and fatigue stress-strain curve models were established. The results show that the fatigue life of LWC is slightly lower than that of NWC, and the fatigue strain of LWC is higher than that of NWC. Compared with OPC concrete, the above rules are more prominent for SCM or AA concrete; The improved fatigue stress-strain models proposed in this article for concrete with different types of binders and aggregates have high calculation accuracy, simple calculation process, and do not require tedious iterative calculations. The research results can provide a new method for predicting the fatigue stress-strain curve and fatigue life of lightweight aggregate concrete.