Creep, chloride, carbonation and sulphate attack on concrete

Abstract

Deterioration of concrete structures with age and environmental factors like creep, chloride, carbonation and sulphate attack in the presence of a corrosive environment leads to a decrease in their performance in terms of load-bearing capacity and serviceability. The present work attempts to develop a model for the impairment in the strength of RC beams because of the combined effects of creep and sulphate attack. It also aims at studying the individual effects of chloride carbonation attacks with the help of established deterioration models. The equations of instantaneous elastic modulus and long term creep described in Indian standard codes (IRC 112) enable modelling the deterioration of modulus of elasticity of concrete as a function of time. The influence of sulphate attack on concrete strength against time is obtained from an empirical research study. Standard numerical models are employed to understand the effects of chloride ingress and carbonation phenomena. The consequences of the aforementioned attacks on an M30 grade concrete girder beam are presented in this paper. The results showed that the creep and sulphate attacks tend to dwindle over the course of time, while the effect of the former is more dominant than that of the latter. In addition, the initiation times for carbonation and chloride attacks were estimated, and it was observed that for a pristine RC beam chloride attack is highly imminent than carbonation.