Durability of Portland Cements Composed of Industrial Waste Fillers in an Acidic Environment

Abstract

This experimental work studies the durability of mortars made with Portland cement composed of industrial fillers: granulated slag and marble powder. Samples of normal mortar were exposed for 12 months to sulphuric acid. The evolution of crystalline phases was analyzed by XRD and minerals were observed by SEM. Microanalysis (EDS linked to SEM) confirms their chemical composition. For a low concentration of sulphate (0.05 mol/l), the results show that the hydrates of cement (CSH, CH, ettringite) seem unaffected in the interior of the sample where the sulphur is completely absent. However in the case of attack by a high concentration (0.25 mol/l) of sulphuric acid, samples develop a dense surface gypsum deposit. The mechanism of the attack is mainly due to the expansive action of gypsum.

Keywords

• durabilité, acide sulfurique, laitier, marbre