THE EFFECT OF SUPPLEMENTARY CEMENTITIOUS MATERIALS, W/B RATIO AND INITIAL MOIST CURING ON CARBONATION OF CONCRETE IN A SEMI-ARID, URBAN ENVIRONMENT

摘要

This paper presents the results of a project that was undertaken to consider the effects of FA, GGBS and silica fume as supplementary cementitious materials (SCM's) in concrete, on the rate of carbonation in Johannesburg, South Africa. Concretes were prepared using CEM-I and blends of CEM-I with a range of commercially available SCM's as well as a CEM-V. These binders were used to prepare concretes with four w/b ratios. Concrete cube samples were prepared from each concrete and subjected to different initial moist curing periods before being exposed to carbonation in the natural environment. The samples were then placed in three microclimate exposure conditions. The results indicate that, all else being equal, FA, GGBS and CEM-V concretes show increased rates of carbonation. The paper also proposes a model for predicting rates of carbonation under the conditions of this study.