A phenomenological model for chloride diffusion coefficient in concretes with traditional and blended binders and alternative fillers

Abstract

To minimise the environmental impact of the construction sector it has become common practice to develop mix designs that contain supplementary cementitious materials (SCMs) or alternative fillers such as recycled aggregate (RA). While it is relatively straightforward to predict the immediate environmental impact of these concretes, to develop a whole-of-life view of sustainability requires the prediction of the service-life of a reinforced concrete element. The durability of reinforced concrete is impacted by the infiltration of chloride ions which leads to the corrosion of steel reinforcement, and eventually ends the useful life of a structure. The reliable prediction of the service-life of reinforced concrete structures, and therefore the whole of life sustainability of a structure therefore requires accurate measures of the rate of diffusion of chloride ions through a wide range of different concrete types. To achieve this goal, a generic phenomenological model has been proposed that correlates the chloride diffusion coefficient with the concrete mix design, encompassing a variety of SCMs and alternative fillers such as RA or lightweight aggregates (LWA). The model, which has been calibrated using 2627 experimental observations, quantifies chloride diffusivity of concrete based on water-to-binder ratio, a binder reactivity index, meso-scale tortuosity and concrete maturity. Statistical comparisons show the model's effectiveness in predicting the chloride diffusion coefficient for diverse range of concrete mixes thereby allowing improved prediction of service-life. • Phenomenological model to describe chloride diffusion developed. • Model is calibrated using 2627 experimental observations. • Model applicable to a wide range of supplementary cementitious materials. • Model applicable to natural, recycled and lightweight aggregates.

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