Investigating the Use of Lime Residuals as an Alternative in Portland Limestone Cement

Abstract

This article presents the use of lime residuals from water treatment plants and their incorporation into concrete. Through a lime-softening process, hydrated lime is added at the water treatment plant to lower water hardness from which lime residuals form. Lime residuals are mainly calcium carbonate, which make them a good addition in cement manufacturing. Specimens were cast with lime residuals at 3 and 15 % replacement dosages to determine their potential for use in manufacturing a standard cement or creating portland limestone cement. Tests were performed on three lime residual samples and available limestone products. The results showed minimal performance differences between each of the mixtures. Fresh properties (slump, air content, and unit weight) and hardened properties along with hydration microstructure (x-ray diffraction and isothermal calorimetry) were evaluated. Results showed that the use of lime residuals could be an effective alternative for powdered limestone in portland limestone cement production. In addition, long-term external sulfate attack testing was performed. Sulfate resistance decreased with increasing lime residual content.