Studying the bulk hydrophobization of cement mortars by the combination of alkylalkoxysilane admixture and fluoropolymer-functionalized aggregate. (15th April 2023)

• Record Type: Journal Article
• Authors: Zarzuela Sánchez, Rafael; González-Coneo, Jorge; Luna, Manuel; Díaz, Ana; Mosquera, María Jesús
• Is Part Of: Journal of building engineering. Volume 65(2023)
• Publication Date: 2023-04-15
• Subjects: Cement mortar -- Hydrophobicity -- Admixture -- Silane -- Aggregate modification; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2022.105771
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: In this work, hydrophobic mortars are produced by combining a silane-based admixture with the pre-treatment of the aggregates with an alkoxysilane-ended fluoropolymer. A comparative study is presented to determine the effect of the components, under different curing conditions, on the hydrophobicity, mechanical performance, composition and micro-structure. The combination of both strategies allows obtaining hydrophobic properties at different curing conditions, whereas the silane loses effectiveness at high humidity and the modified aggregate at low humidity. The silane hinders cement hydration and promotes gaps in the aggregate-matrix interfacial transition zone, decreasing mechanical resistance, whereas the modified aggregate changes the interfacial transition zone morphology without significant effects on resistance. The combination of both strategies partially compensates the negative impact of the silane admixture, especially when the mortars are cured at high humidity. Thus, this combination increases versatility of the mortars and poses as a potential route to address the limitations of silane admixtures. Highlights: Combined silane admixture with functionalized aggregate provides waterproofing at different curing conditions. Silane admixture hinders cement hydration and decrease matrix-aggregate cohesion. Aggregate modification with fluoropolymer has a low impact on mechanical properties. The modified aggregate loses hydrophobic effectiveness when cured at low humidity. Combination of both routes compensates the effect of silane on mechanical properties.