Effect of Gypsum Content on the Compressive Strength of LC³ Cement

Due to environmental damage caused by the Portland cement manufacturing process, industry and academia have been required to reduce greenhouse gas emissions from the production process. The massive use of supplementary cimenticious materials (SCM’s) is one of the most viable options for reducing clinker factor and pollutant emission. LC³ cement is a type of cement that uses high additions contents, counting on the synergistic reaction between calcined clay and limestone to obtain mechanical strengths similar to those of traditional cements. This research intends to investigate the influence of the gypsum content on the compressive strength of a LC³ cement. For the accomplishment of this study six mortars were produced. In three of them the cement used was produced with 3, 5, 7% gypsum, without SCM’s. In three mortars, a 45% replacement cement was used (30% calcined clay and 15% limestone). The proportion of gypsum in these cements was 3, 5 and 7% in relation to the total mass. For the hardened state analysis, the compressive strengths were compared at the ages of 1, 3, 7, 28 and 91 days. A statistical analysis was performed on the results. From the results obtained it was possible to verify that the gypsum content influences the compressive strength of the LC³ cement. The highest mechanical strengths were obtained with the use of larger quantities of gypsum.