Effect of Cementitious Materials Composition on Heat Evolution and Strength of Concrete

Abstract

Large and massive concrete structures with high cementitious content like foundations, tunnels, bridges, dams and hydraulic structures are subjected to cracks generated and developed by internal thermal stresses and damages due to delayed ettringite formation (DEF) associated with the hydration process of cement. The Ondes bridge, Bourgogne bridge and Saint-Maurice de Beynost bridge are international examples of concrete structures damaged by delayed ettringite formation. Due to the construction expansion in Egypt and the Middle East, it was necessary to study the effect of concrete constituents on the evolution of concrete heat of hydration and the differential temperature between the core and the concrete surface, as well as the mechanical properties such as the compressive strength. In this study, the effects of six types of cement, two water-binder ratios, with two different cement contents and supplementary cementitious materials like silica fume, fly ash and metakaolin were studied. The test results of hardened concrete showed that the blast-furnace cement and moderate heat of hydration cement had an obvious effect on the hydration heat rate and concrete compressive strength compared to other tested types. Partial replacement of cement by 50 % fly ash led to a decrease in maximum hydration temperature nearly by 13-14%. Replacement of cement by 15 % metakaolin led to an increase in maximum temperature by 2.9 % comparing to reference cement. A best thermal gradient of mass concrete was observed in case of using moderate heat of hydration cement, as the maximum temperature difference was 17.5℃.