Experimental and computational study on chloride ion transport and corrosion inhibition mechanism of rubber concrete

Rubber concrete is an innovative environmentally-friendly building material in which waste rubber is recycled as a concrete component. Durability research of rubber concrete is an important prerequisite for its applications in marine and coastal engineering. The low-permeability and cracking-resistance characteristics of rubber demonstrate its potential to delay chloride ion penetration and corrosion-induced cracking from the perspective of material properties. However, the microstructural characteristics of rubber concrete are extremely complex, leading to uncertainties in transport process and corrosion evolution in this material. In order to promote the utilization of waste rubber in concrete and to improve durability of infrastructure in the marine environment, the chloride ion transport characteristics and corrosion inhibition mechanism of rubber concrete are systematically studied in this paper from the aspects of macroscopic experiments and microscopic simulations. In macroscopic experiments, a novel corrosion evaluation technique of rubber concrete is proposed using electrically accelerated methods and nondestructive ultrasonic testing. The experimental results show that the addition of waste rubber can effectively reduce the chloride ion diffusion coefficient, inhibit the steel corrosion and improve the durability of concrete structures. Further, in microscopic simulations, a transport model is established based on molecular dynamics to simulate the erosion of sodium chloride solution in ideal cement and rubber nanopores, revealing the transport mechanism of chloride ions in rubber concrete. The molecular dynamics simulations indicate that sodium ions and chloride ions are confined in rubber chains during the transport process, instead of forming chemical bonds at the rubber surface. (C) 2020 Elsevier Ltd. All rights reserved.