Input parameters and nomograms for service life-based design of reinforced concrete structures exposed to chlorides

Civil engineers are trying to promote the service-life-based design of reinforced concrete (RC) structures to ensure long corrosion-free service life with minimal maintenance, repair, rehabilitation, and life cycle costs. This paper highlights the difficulties in adopting the existing tools as a general practice, especially for high-performance concrete with novel materials. To overcome these difficulties, “SL-Chlor,” a MATLAB® computer program is developed to estimate service life, which uses Fick's 2nd Law of Diffusion to model chloride ingress, a major factor causing corrosion. Based on SL-Chlor, user-friendly nomograms are then developed to estimate the service life of RC structures located at various distances from the seashore. With the development of nomograms, this paper attempts to bring a new perspective to promote service life-based design with the help of user-friendly tools. The use of nomograms is demonstrated using case studies with multiple input parameters. The effect of different input parameters on service life is found to be synergistic, in the following descending order of influence: cover depth (d) > chloride diffusion coefficient (DCl) > ageing coefficient (m) [maturity constant of DCl)] > chloride threshold of the steel-cementitious system (Clth). These findings encourage not only the use of blended cements but also the implementation of 3C's (adequate cover depth, compaction, and curing, which inherently influences d, DCl, and m) to help structures achieve the desired service life.