Lime-activation of natural pozzolan for use as supplementary cementitious material in concrete

The present work was conducted to examine the beneficial effects of activating natural pozzolan (NP) using hydrated lime (HL) for its efficient utilization in concrete. Optimum dosages of NP and HL determined based on the performance of several trial mixtures to be used in concrete as a partial replacement of ordinary Portland cement (OPC). Three mixtures were finally considered for detailed evaluation of the performance of NP-HL concrete. Activation of NP by HL increased the early- and later-age strength and decreased the depth of water penetration, coefficient of chloride diffusion, depth of carbonation, strength loss due to salt weathering, and reinforcement corrosion. Although the loss of strength due to sulfate attack and shrinkage strain increased due to the inclusion of HL, these values were less than those measured in the concrete prepared using OPC alone. In summary, the results of this study indicate that natural pozzolan can be used as a supplementary cementitious material by activating it using hydrated lime.