Comparison of the Mechanical and Durable Behaviour of Sustainable Mortars with Reduced Cement Content with Limestone, Metakaolin, and Different Calcined Clays

The manufacture of cement clinker involves around 0.8tn of CO2 per ton of clinker being this material the most used material worldwide. The future is aimed at reducing CO2 emissions as much as possible, with the objective of reducing the clinker content used in cements by up to 70%. In this work two sustainable compositions replacing a 45 wt. % of cement by limestone, metakaolin and two morphological and compositional different calcined clays. One calcined clay is fibrillar with relatively high magnesium oxide content and the other one is laminar with high aluminium oxide content. Mechanical characterization is carried out by flexural and compression measurements and a broad durable behaviour is carried out by means migration and diffusion test against chlorides. Identical compositions with the only variation of the calcined clay used results in a very different mechanical and durable behavior. Sustainable blend with magnesium fibrillar calcined clay used presents a very promising functional response to design sustainable compositions with reduced clinker content.