Effect of curing temperature in the relative decrease peak intensity of calcium hydroxide pastes for assessing pozzolanicity of supplementary cementitious materials

Abstract

Among the short-term viable alternatives for mitigating the direct emissions of carbon dioxide into the atmosphere by the cement industry, the partial replacement of Portland clinker or cement with supplementary cementitious materials (SCM) is the most efficient and conceives ecologically friendly binders. Limitations of available traditional SCMs create a demand for the exploration of alternative materials from by-products and wastes of other industries. As a result of the considerable variability in the properties between batches of these materials, it is necessary to use methods that allow the large-scale evaluation of SCMs in a fast, practical, reliable, and robust manner. This study presents the effects of increasing the curing temperature in the acceleration of the relative decrease in peak intensity (RDPI) test. The results show that samples cured at 65 °C after 3 days presented RDPI with a good indication of the reactivity level of the analyzed pozzolans. Additionally, strong correlations (R2 > 0.90) are obtained with compressive strength at 28 and 90 days. Thus, the RDPI test presents a potential for evaluating pozzolanic reactivity. However, further study is required on the SCM to CH ratio to avoid limiting the effectiveness of highly reactive pozzolans.