Abstract: Concrete specimens with cold joints are manufactured with one-piece pouring and multiple pouring at the intervals of 0.25 d, 0.5 d, 1 d, 7 d, and 28 d to investigate their energy evolution under loads and the cycling of sulfate solution wetting and drying. The cycling effect on the strength and energy evolution are examined by conducting a uniaxial compression experiment and energy calculations. The results show that for the concrete with cold joints, the wet-dry cycling causes a first-increase-then-decrease trend in the time development of its strength, elastic strain energy, dissipation energy at damage stress, and peak stress. All these parameters present a declining tendency with the increasing pouring interval. And as the number of wet-dry cycles increases, the energy storage level Kad at damage stress first decreases and then increases, showing a larger Kad is related to higher susceptibility of concrete to damage. Thus, Kad can be used as an indicator for concrete damage early warning.

Key words: sulphate erosion, drying-wetting cycle, uniaxial compression, concrete with cold joints, energy evolution