DAMAGE EVOLUTION MODEL OF EARLY DISTURBED CONCRETE UNDER SULFATE ATTACK AND ITS EXPERIMENTAL VERIFICATION

Abstract

The disturbance during the early age of the setting and hardening stage of concrete usually creates microcracks in the concrete matrix and thus decreases its strength and durability. Among the factors that affect the durability of concrete, sulfate attack is one of the important factors that cause damage. To analyze the damage development of early disturbed concrete under sulfate attack environment, the residual coefficient of flexural strength of concrete was tested by the perturbation of horizontal vibrating table. Using erosion damage factor to characterize the degree of erosion deterioration of concrete, the sulfate attack tests were carried out on the disturbed concrete. Starting from the crack initiation condition of sulfate attack, and based on the theory of microcrack nucleation and growth in the process of erosion, the statistical evolution equation of sulfate corrosion damage of concrete was obtained by using micro crack propagation to characterize the mechanical behavior of concrete after corrosion damage. Considering the influence of early disturbance on the critical stress of concrete microcrack nucleation, the damage evolution model of concrete with different disturbed conditions under sulfate attack was established, and the corrosion degree of disturbed concrete at different erosion ages was predicted. Based on the experimental data of damage factors, the damage evolution equation was fitted and the model was validated. Results demonstrate that the damage model curve fits well with the test curve of damage factor, and the correlation coefficients are above 0.98, which can reflect the damage evolution law of disturbed concrete sulfate attack. This method provides a good reference for evaluating the effect of early disturbance on the sulfate resistance of concrete. Keywords: Concrete, Disturbance, Sulfate attack, Microcrack nucleation, Damage evolution