Analytic Hierarchy Process (AHP) applied to the study of different mortars against sulfate attack

Abstract

Concrete is a material susceptible to different degradation mechanisms that can lead to the formation of expansive products resulting from external sulfate attack (ESA). In this context, supplementary cementing materials (SCMs), like fly ash, metakaolin, silica fume, and rice husk ash, have effectively suppressed the effects caused by ESA. However, each SCM may present different behavior depending on the exposure conditions, sulfate type, SO₄^2- concentration, etc. Thus, this study presents a multicriteria decision-making analysis of fixed binder content for mortars (1: 3.2 a/agl=0.60) aiming to achieve the best performance against ESA (exposure to Na₂SO₄ or MgSO₄). The criteria selected for the decision-making analysis are the sustainability impact of the mixture, economic performance, and the effect of ESA on the mechanical properties and durability of the mortars. The results indicate that the most suitable composition for aggressive environments containing Na₂SO₄ was the mortar containing 10% rice husk ash and, for exposure to MgSO₄, the use of fly ash in the same proportion.