Hydration Behavior and Mechanical Properties of Alkaline Excited Slag-Fly Ash-Metakaolin Geopolymer

Abstract

Abstract: By changing the ratio of slag, fly ash and metakaolin, the ternary geopolymer was prepared by alkali excitation with the compound sodium silicate. The setting time, flexural and compressive strength of ternary geopolymer were tested. XRD, SEM, EDS and DTG were used to study the morphology and composition of hydration products in the hardened paste, and the hydration process was analyzed. The results show that the ternary geopolymer is composed of calcium silicate hydrate (C-S-H), calcium aluminate silicate hydrate (C-A-S-H) and sodium aluminate silicate hydrate (N-A-S-H) gels. The higher the slag content is, the shorter the setting time of newly mixed slurry is, the more calcium gel in the hydration products is, and the higher the strength of specimen is. The 3 d compressive strength of 5 groups of specimens with slag content of 10%, 30%, 50%, 70%, 90% (mass fraction) is 2.1, 14.1, 24.2, 29.7, 37.9 MPa, respectively. The longer the curing period is, the more complete the reaction is, the more hydration products are, and the higher the strength of specimen is. When the slag content is 50%, the compressive strength of ternary geopolymer at 1, 3, 7, 28 d is 12.3, 24.2, 27.3, 36.8 MPa, respectively. When the slag content is 90% and the curing age is 28 d, the flexural and compressive strength of specimen are the highest, which are 12.0, 52.0 MPa, respectively. The short setting time of the system makes it have a broad application prospect in the field of road repair materials and 3D printing.

Key words: slag, fly ash, geopolymer, strength, microstructure, hydration process

CLC Number:

TU528

LIU Gang, DING Mingwei, LIU Jinjun, WAN Huiwen, XUE Yongjie, JIAN Shouwei. Hydration Behavior and Mechanical Properties of Alkaline Excited Slag-Fly Ash-Metakaolin Geopolymer[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(6): 2106-2114.

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