Service life modelling of carbonated reinforced concrete with supplementary cementitious materials considering early corrosion propagation

Abstract

The importance of considering corrosion propagation in service life design of carbonated concrete with supplementary cementitious materials (SCMs) has been highlighted by the decline in carbonation resistance caused by partial replacement of ordinary Portland cement (OPC) with SCMs. This study proposes a novel Carbonation-induced Early Corrosion Propagation based Service-life Assessment Model (CECP-SAM) for carbonated SCM concrete, which is characterized by the considerations of semi-carbonation zone and macrocell corrosion in corrosion propagation with an incipient crack as end of service life. Experimental and field data were used to verify CECP-SAM. The effects of exposure conditions, SCM replacements, water/binder ratio, cover thickness, rebar diameter, semi-carbonation zone and macrocell corrosion on service life are presented. Results indicate that the partial replacement of OPC with pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS) can significantly decrease service life from 66 years to 8 years and 17 years, respectively. Corrosion propagation can result in a 91% reduction in service life but service life can be extended from less than 20 years to more than 90 years by considering early corrosion propagation. Practical equations are proposed to facilitate performance-based service life design. Prescriptive limits are also provided for service lives of 50 and 100 years.