Limestone and Calcined Clay Blended Cement Used as Low-Cost Binder to Reduce Heat Production and Potential for Delayed Ettringite Formation

The use of mass concrete for the construction of infrastructure has become more prevalent in recent history. However, the use of Portland cement as a binder material for massive concrete structures is both highly expensive and can come with durability issues such as delayed ettringite formation resulting from heat produced during hydration. The use of limestone calcined clay cement binder offers a low-cost alternative to mitigate potential problems borne from construction of mass concrete. This paper presents research in which limestone and calcined clay were used as partial replacement of Portland cement to create low heat, low cost binder for mass concrete members. The specimens were evaluated for the potential for delayed ettringite formation; results were confirmed with scanning electron microscopy. Isothermal conduction calorimetry was performed at temperatures of 23 °C, 70 °C, and 85 °C which showed a reduction in heat production in paste amended with limestone calcined clay cement (LC3). The results of this study indicate that the incorporation LC3 binder of calcined clay and limestone provides higher alumina and lower sulfate which contributes to the mitigation of deleterious ettringite formation. Several conclusions were drawn from this study: LC3 can be used to create more financially viable materials for developing areas to create massive concrete structures and the concrete produced with LC3 as the concrete has a lower potential for delayed ettringite formation due to both lowered heat and chemical composition.