Impact of Cycle Numbers on Concrete Under Variable-Temperature Dry–Wet Cycles

When a pumped storage power station utilizes its upper reservoir to store energy from a photovoltaic power plant, it often operates during periods of higher ambient temperatures. Under these conditions, the concrete panels in the upper reservoir are also hotter. The subsequent rise in the reservoir’s water level introduces a rapid temperature change and dry–wet cycles to the concrete panels, which can easily degrade the performance of these panels. While research has investigated the impact of conventional dry–wet cycles on concrete performance, studies on the effects of these cycles under variable temperatures have not yet been reported. Therefore, we conducted an optimized experimental study on variable-temperature dry–wet cycling processes, with dry:wet time ratios set at 3 h:3 h, 6 h:6 h, and 12 h:12 h. The results indicate that, after 200 cycles, the compressive strength loss rate of the concrete is three times that observed under conventional dry–wet cycles. Specifically, concrete subjected to the three tested dry:wet time ratios exhibits strength reductions of 11.25%, 22.52%, and 26.45%, respectively. When the ratio reaches 6 h:6 h, further increasing the drying and immersion times results in a similar gradual degradation effect on the strength of hydraulic concrete. Therefore, considering the time cost, a 6 h:6 h dry:wet cycle can be adopted.