Sulfuric acid resistance of one-part alkali-activated mortars

By P. Sturm, G. Gluth, C. Jäger, H. Brouwers, H. Kühne. Cement and Concrete Research, 2018

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Abstract One-part alkali-activated (geopolymer) mortars based on three different silica-rich starting materials and sodium aluminate, with and without ground granulated blast furnace slag (GGBFS) addition, were tested regarding sulfuric acid resistance according to DIN 19573:2016-03 (70 days at pH = 1). Corresponding pastes were characterized by XRD, SEM, chemical analysis, 29Si MAS NMR and 1H-29Si CPMAS NMR after water storage and after acid exposure. The mortars exhibited a high resistance against sulfuric acid attack, with the best ones conforming to the requirements of DIN 19573:2016-03. The analytical results showed that this was due to precipitation of silica gel at the acid-mortar interface, which formed a mechanically stable layer that protected the subjacent mortar and thus inhibited further degradation. The addition of GGBFS decreased the acid resistance via formation of expansive calcium sulfate phases.

Subfields: Civil and Structural Engineering, Earth-Surface Processes

View Paper: https://www.semanticscholar.org/paper/743147c87b35be31f4085e88b757cdce0e736afb