Effect of alkali-activation on aluminosilicate-based cementitious materials

Xiaoguang Yang1,2), Wen Ni1), Xufang Zhang1), and Yali Wang1) 1) School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China 2) Central Research Institute of Building and Construction Co. Ltd. MCC Group, Beijing 100088, China

摘 要：High-performance aluminosilicate-based cementitious materials were produced with fly ash from a coal power plant as one of the major raw materials. The structures of fly ash containing aluminosilicate-based cementitious materials were compared be-fore and after treatment by the methods of nuclear magnetic resonance （NMR） and scanning electron microscopy （SEM）. During the 28 d curing time, the compressive strength of water glass and fly ash samples increased from 9.08 MPa to 26.75 MPa. The results show that most of the stiff shells are destroyed after mechanical grinding and chemical activation. Magic angle spinning （MAS） NMR of 27Al shows that the wide peak becomes narrow and the main peak shifts to the direction of low field, indicating the decrease of polymerization degree, the enhancing of activity, the decrease of six-coordination structure, and the increase of small and symmet-rical four-coordination polyhedron structure within the aluminum-oxygen polyhedron network. Comparisons between MAS NMR of 29Si with different treatments suggest that Q0 disappears, the quantity of Q2 increases, and the quantity of Q4 decreases. The polym-erization degree of silicon-oxygen is reduced, and the potential activity of fly ash is increased.

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