Meso-scale mechanical deterioration of mortar subjected to freeze thaw cycles and sodium chloride attack

• Published in: Cement & concrete composites 2021-03, Vol.117, p.103906, Article 103906
• Main Authors: Wang, Yi, Li, Junhui, Ueda, Tamon, Zhang, Dawei, Deng, Jun
• Format: Article
• Language: English
• Subjects: Flexural strength; Freeze-thaw cycles; Meso-scale; Mortar; Sodium chloride attack
• ISSN: 0958-9465; 1873-393X
• DOI: 10.1016/j.cemconcomp.2020.103906

This paper aims to quantitatively examine the effect of sodium chloride (NaCl) on the frost-induced mechanical deterioration of mortar. After the freeze thaw cycles (FTCs), the mechanical properties of sealed specimens (70 × 30 × 5 mm) saturated with NaCl solutions were investigated. As found, the specimens with a lower water-to-cement ratio (W/C) show no clear reductions in their flexural strength and elastic modulus, while those with a higher W/C degrade gradually with increasing numbers of FTCs, even for specimens exposed to high NaCl concentrations. The connectivity of the specimens increased significantly with increasing numbers of FTCs for the pure frost damage case, whereas this variation was minimal for the case of frost damage incurred with higher NaCl concentrations. For the specimens exposed to higher NaCl concentrations, the destructive salt crystallization pressure under freezing was the main contributor to the salt frost damage and was largely attributed to the reversible formation of Friedel's salt.