One-Part Geopolymer Prepared by Solid Composite Activator

doi:10.16552/j.cnki.issn1001-1625.2025.0593

Abstract

Abstract: Sodium silicate solution is commonly used as a liquid activator for geopolymer preparation, but its high alkalinity, high viscosity, and it is not conducive to the on-site mixing and preparation of geopolymer slurry. In this study, a one-part geopolymer was synthesized using solid composite activators including NaOH, Ca(OH)₂, and Na₂CO₃ to co-activate fly ash-slag blends. The influences of alkalinity and fly ash content on the fluidity of fresh paste and the compressive strength of hardened binder were systematically investigated. The hydration products and microstructure were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and pore structure analysis. The results indicate that with the increase of fly ash content, paste fluidity increases, setting time prolongs, and compressive strength decreases. The highest 28 d compressive strength (48.8 MPa) is achieved at 6% (mass fraction) alkalinity and 20% (mass fraction) fly ash content. Higher activator alkalinity enhances the degree of alkali-activation reaction, promotes Ca²⁺ ions leaching from slag, increases the Ca/Si molar ratio of sodium-containing calcium aluminosilicate hydrate (C-(N)-A-S-H) gel phase, and reduces the total porosity to obtain a denser microstructure. An increase in fly ash content decreases the reaction degree, lowers the Ca/Si molar ratio and significantly increases the total porosity.

Key words: one-part geopolymer, solid composite activator, fluidity, setting time, compressive strength, microstructure

CLC Number:

TU528

WANG Zhanpeng, WANG Xin, QI Le, HU Ping, YANG Tao, ZHUANG Peizhi. One-Part Geopolymer Prepared by Solid Composite Activator[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(12): 4375-4383.

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