The Effects of Aggressive Environments on the Properties of Fly Ash based Geopolymers

2nd International Conference on Innovative Materials, Structures and Technologies

Baarevi, Z.^1 ; Komljenovi, M.^1 ; Nikoli, V.^1 ; Marjanovi, N.^1

University of Belgrade, Institute for Multidisciplinary Research, Department of Materials Science, Serbia^1

关键词: Aggressive environment;    Ammonium nitrate;    Gel structures;    Geopolymer;    MAS NMR;    pH value;    Si-O-Si bond;    Sulphate solutions;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/96/1/012001/pdf
DOI  :  10.1088/1757-899X/96/1/012001

来源: IOP

【 摘 要 】

This paper analyzes the effects of two different aggressive environments, concentrated ammonium nitrate solution (480 g/dm3) and sodium sulphate solution (50 g/dm3), on the structure and mechanical strength of fly ash based geopolymers. Geopolymer samples were subjected to the aggressive solutions over a period of 365 days. It was found that exposure to the NH4NO3and Na2SO4solutions caused small decrease in geopolymer strength (10-20%). The most valuable insight into the structural changes caused by testing of the geopolymer samples in the aggressive solutions was provided by means of29Si MAS NMR. It was found that the immersion of geopolymer samples in the NH4NO3solution caused breaking of Si-O-Al bonds in the aluminosilicate geopolymer gel structure. On the other hand, treatment of the geopolymer samples with the Na2SO4solution resulted in breaking of Si-O-Si bonds in geopolymer gel structure and leaching of Si. It was concluded that the major changes in the geopolymer structure were associated with the changes in the pH values of aggressive solutions during the testing.