Reactive Transport Modelling of Chloride Ingress in Saturated Coral Aggregate Concrete

Abstract

Utilizing coral aggregate concrete (CAC) for construction on remote islands can significantly reduce construction cost and period, CO2 emission, and consumption of non-renewable energy. The durability of reinforced CAC structures is critically influenced by their resistance to chloride attack. In this study, a reactive transport modelling was developed to investigate chloride ingress in CAC, in which a COMSOL-PHREEQC interface based on MATLAB language was established. The experiment from the literature was taken as a benchmark example. The results show that the developed numerical model can accurately predict chloride transport in CAC. Differing from ordinary aggregate concrete (OAC), Kuzel’s salt does not appear in cement hydrate compounds of CAC during chloride ingress. The numerical results indicate that the penetration depth of chloride in CAC gradually increases as the exposure time is prolonged. When CAC is exposed to an external chloride solution, the decrease in the pH of the pore solution affects the precipitation of Friedel’s salt, which is detrimental to the chemical binding of chloride.

Investigation on service life prediction models of reinforced concrete structures exposed to chloride laden environment

“…If the inception chloride concentration is detailed in total chloride content in concrete, a conversion period from free chloride concentration to total chloride content is required. Total chloride concentration c t is the sum of bound chloride, c b , and free chloride c, which is given by the following equation [14][15][16]: fb and β d = binding constants, k TD and k Tb = temp factors for diffusion coefficient and chloride binding, k D is the extension coefficient, c t = total chloride concentration, c b = bound chloride and c = free chloride.…”

“…The Initial corrosion stage is considered to be service life of the structure [13]. Guo investigated reactive transport modelling of chloride ingress and found that chloride ingress lowers the pH of the pore solution and influences the precipitation of Friedel salts, which is harmful to the chemical binding of concrete [14]. Yang theoretical model not only analyses the effect of chloride-induced degradation, but also the earth pressure and water forces acting on the Reinforced wall in marine environment.…”

Effect of Interface Transition Zone and Coarse Aggregate on Microscopic Diffusion Behavior of Chloride Ion

“…Yu et al [11,12] have also established a numerical model based on theoretical equation and chloride diffusion coefficient measured by test and carried out parametric analysis. Moreover, the reactive transport modelling was developed by Guo et al [13] to investigate chloride ingress in coral aggregate concrete. However, concrete is a multiphase material composed of aggregate, cement paste, ITZ and pores [14,15].…”