Short-term performance of sustainable silica fume mortars exposed to sulfate attack

Abstract

Nowadays, the reuse of wastes is essential in order to reach a more sustainable environment. The cement production results in CO2 emissions which significantly contribute to anthropogenic greenhouse gas emissions. One way to reduce them is by partially replacing clinker by additions, such as silica fumes or other wastes. On the other hand, the pore structure of cementitious materials has a direct influence on their service properties. One of themost popular techniques for characterizing the microstructure of those materials is mercury intrusion porosimetry. In this work, this technique has been used for studying the evolution of the pore network ofmortars with different percentages of silica fume (until 10%), which were exposed to aggressive sodium and magnesium sulfate solutions up to 90 days. Between the results of this technique, intrusion-extrusion curves and logarithms of differential intrusion volume versus pore size curves were studied. This characterization of the pore network of mortars has been complemented with the study of their compressive strength and their steady-state ionic diffusion coefficient obtained from samples' resistivity. Generally, silica fume mortars showed different performance depending on the aggressive condition, although the greatest deleterious effects were observed in the medium with presence of both magnesium and sodium sulfates.