Macro-meso degradation evolution of fully recycled coarse aggregate concrete under sulfate attack in marine environment
Libing Jin, Tian Wu, Peng Liu, Zhenhao Wang, Pin Zhou
Abstract
External sulfate attack is a major leading cause of early failure of concrete structures in marine environments. In this paper, sulfate erosion experiments were designed and a new mesoscale numerical analysis model was developed，to evaluate the deterioration pattern of sulfate erosion of fully recycled coarse aggregate concrete (FRCAC) in marine environments and promote the application of FRCAC in coastal engineering . A five-phase stochastic convex polygonal aggregate model is developed using a self-programmed program that considers the presence of different types of interfacial transition zones within the FRCAC structure to be closer to the real situation. The concentration distribution pattern of sulfate ions in FRCAC was obtained by exposing the specimens to sodium sulfate solution . The validity and practicality of the mesoscale numerical analysis model were verified by the experimental results. In addition, the evolution regularity of sulfate ions, expansion products, and expansion strains in FRCAC was further investigated by the new numerical modeling. The results can be shown that: the sulfate ion content at the identical depth improved by 21.95 % when the water-cement ratio was increased from 0.4 to 0.6. The sulfate ion content at the same depth grown by about 9 times when the surface sulfate concentration was raised from 1 % to 10 %. When the initial aluminate content was increased up to four times, the production of ettringite increased by about 3 times and the swelling strain approximately increased by 5 times.