The effect of aggressive environments on the properties of a low calcium fly ash based geopolymer and the ordinary Portland cement pastes

• Published in: Materials today : proceedings Vol. 13; pp. 1169 - 1177
• Main Authors: Zerzouri Lakhssassi, M., Alehyen, S., El Alouani, M., Taibi, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2019
• Subjects: Acid resistance; Fly ash geopolymer; Ordinary Portland cement; Structural change; Sulfates resistance; Fly ash geopolymer; Sulfates resistance; Acid resistance; Structural change; Ordinary Portland cement
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2019.04.085

This paper analyzes the effects of four different aggressive environments, sulfuric acid solution (5%), magnesium sulfate solution (5 g/l), sodium sulfate (44g/l) and sodium chloride (164g/l), on the structure (durability) of fly ash based geopolymers and ordinary Portland cement. The samples were subjected to the aggressive solutions over a period of 120days. and the effects of the aggressive solutions were evaluated by visual, weight loss, and microstructural changes. It was found that the FA-GP geopolymer was poorly altered while the OPC cements are severely damaged after 120 days immersion in the 5% sulfuric acid solution. The decomposition of Portland cements in the acid solution is due to the formation of ettringite and gypsum which are very expansive materials which cause the cracking and bursting of the cement paste. The formation of ettringite and gypsum is confirmed by FT-IR and DRX analysis. The immersion in the magnesium sulfate solution, sodium sulfate and sodium chloride, caused a small change in the structure of the FA-GP and OPC, and we can conclude that the performance of FA-GP materials is higher than that of Portland cement in corrosive media.