Sulfuric acid resistance of one-part alkali-activated mortars. (July 2018)

• Record Type: Journal Article
• Authors: Sturm, P.; Gluth, G.J.G.; Jäger, C.; Brouwers, H.J.H.; Kühne, H.-C.
• Is Part Of: Cement and concrete research. Volume 109(2018)
• Page Start: 54
• Page End: 63
• Publication Date: 2018-07
• Subjects: Alkali activated cement (D) -- Durability (C) -- Characterization (B) -- Spectroscopy (B) -- One-part geopolymers; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2018.04.009
• Languages: English
• ISSNs: 0008-8846

Abstract

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, 29 Si MAS NMR and 1 H- 29 Si 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.