Effect of Activator-to-Binder Ratio on Workability and Strength of Sustainable One-part Geopolymer Mortar
Anuoluwapo Sola KOLADE, Bolanle Debora IKOTUN, Damilola Oyewumi OYEJOBI
Abstract. The widespread reliance on liquid activators in geopolymer systems presents handling, storage and safety challenges that limit industrial scalability. This study addresses these limitations by developing and evaluating one-part geopolymer mortars activated with solid sodium silicate synthesized from waste glass powder and sodium hydroxide. Six mixes with activator-to-binder (AA/B) ratios ranging from 0.50 to 0.75 were prepared using high-volume fly ash and ground granulated blast furnace slag as aluminosilicate precursors. Specimens were cast in 40 × 40 × 40 mm moulds, thermally cured at 80°C for 24 hours and subsequently stored under ambient conditions for up to 28 days. Results showed that increasing the AA/B ratio reduced flow from 120% to 70% and decreased compressive and flexural strengths from 16.24 MPa and 5.02 MPa to 8.77 MPa and 3.55 MPa, respectively, due to excessive alkalinity disrupting gel cohesion and matrix densification. Regression models developed from the experimental data effectively predicted the relationship between the AA/B ratio and both fresh and hardened properties (R2 > 0.90), identifying an optimum range of 0.51 – 0.55 that achieved balanced flowability (105 – 115%) and mechanical strength (14 – 16 MPa compressive and 4 – 5 MPa flexural). Although the models were not experimentally validated, they provide a robust basis for optimizing mix design in future studies. The findings, therefore, confirm the reactivity and viability of waste-derived sodium silicate as a sustainable solid activator, offering mechanistic and predictive insights that advance the design of low-carbon, practical one-part geopolymer mortars for precast and low-to-medium performance repair applications.
Keywords
One-Part Geopolymer, Waste-Based Activator, Activator-to-Binder Ratio, Cement-Free Binder, Sustainable Mortar
Published online 4/2/2026, 9 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Anuoluwapo Sola KOLADE, Bolanle Debora IKOTUN, Damilola Oyewumi OYEJOBI, Effect of Activator-to-Binder Ratio on Workability and Strength of Sustainable One-part Geopolymer Mortar, Materials Research Proceedings, Vol. 63, pp 12-20, 2026
DOI: https://doi.org/10.21741/9781644904053-2
The article was published as article 2 of the book Advances in Cement and Concrete Research
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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