Comparing the Ecoefficiency of Cements Containing Calcined Clay and Limestone Filler

Abstract

Calcined clay and fillers are materials with the best chance of scalability in cement industry. However, the addition of substantial amounts of SCMs affects the reactivity and water demand of blended cements, influencing their environmental impact in use as well as their performance. So, the aim of this work is to compare the influence of substituting clinker by calcined clay and limestone filler in the ecoefficiency of blended cements. For that, an ordinary Portland cement was replaced by calcined clay and limestone filler to produce two blended cements: LC3 and LFC. Regarding reactivity, LFC and LC3 presented higher relative combined water at 91 days compared to OPC. Water demand for constant workability was higher for LC3 compared to OPC and similar to LFC, but when superplasticizer was used, both cements demanded less water than OPC. Both parameters (reactivity and water demand) affected the binder’s efficiency measured as cwf index which had a linear correlation with mechanical performance. In concern of environmental indicators, binder and carbon intensity, LFC presented the lowest indicators results for concretes with 20 and 30 MPa, LC3 for concrete with 50 MPa and OPC for concrete with 60 MPa.