Energy evolution of concrete with cold joint under the action of sulfate dry-wet cycles with loading

Abstract

To investigate the erosion and damage mechanism of concrete with cold joint in the cold and arid saline environment of western China, the energy evolution of concrete with cold joint under the action of sulfate dry–wet cycles was analyzed and produced concrete with cold joint at different pouring intervals. Based on uniaxial compression experiments and microscopic tests, the effect of sulfate dry–wet cycles on the strength and energy evolution pattern of concrete with cold joint is investigated and analyzed by means of energy calculation principles. Results show that the strength of concrete with cold joint, as well as the elastic strain and dissipation energies at the damage and peak stresses, tend to increase and then decrease with the increment of the number of sulfate dry–wet cycles. And a declining trend is observed as the interval between new and old concrete pours increases. Kad can be used as an early warning indicator for concrete damage by defining the ratio of the elastic strain energy Uade at the damage stress to the elastic strain energy Uae at the peak stress as the energy storage level Kad at the damage stress of concrete with cold joint. With the increase in the number of sulfate dry–wet cycles, the level of energy storage at the damage stress Kad first increases and then decreases. The concrete with cold joint first exhibits damage difficulty and then ease, that is, the higher the level of energy storage at the damage stress Kad is, the stronger the ability of concrete with cold joint to resist damage will be.