The role of porosity in external sulphate attack
journal contributionposted on 30.01.2019, 14:54 by Tai Ikumi, Sergio Pialarissi-CavalaroSergio Pialarissi-Cavalaro, Ignacio Segura
Design codes promote a limitation of permeability (indirectly of porosity) to reduce the sulphate ingress and improve the resistance of concrete and mortar to external sulphate attack (ESA). However, porosity could also have a positive effect on durability by generating additional space to accommodate the expansive phases. The aim of this study is to evaluate the role of porosity in ESA. For that, changes at the macro-scale, phase composition and pore network are monitored for mortar compositions with different pore-size distribution. Results indicate the existence of two mechanisms: the capacity to accommodate expansive phases controls the durability during the initial stages of the attack, while at later stages durability is defined by the permeability. Results from specimens with air-entrainer suggest that the intentional increase of porosity towards maximising the capacity to accommodate expansive products might be a valid approach in order to reduce the expansive forces generated during ESA.
Support from the Spanish Ministry of Economy and Competitiveness through research project BIA2013-49106-C2-1-R is greatly acknowledged. T. Ikumi is supported by the fellowship programme FPI BES-2014-068524 of the Spanish Ministry of Economy and Competitiveness.
- Architecture, Building and Civil Engineering