Calcium formate as a modifier agent for fly ash-based geopolymer cement

Area of Science:

• Materials Science
• Civil Engineering
• Geopolymer Chemistry

Background:

• Class F fly ash (FA) geopolymer cement requires calcium for optimal polymerization.
• Calcium deficiency in FA can lead to slow reaction rates and altered material properties.
• Portland cement (PC) systems utilize calcium formate (CF) as an accelerating agent.

Purpose of the Study:

• To investigate the impact of incorporating calcium formate (CF) into fly ash (FA) geopolymer cement.
• To determine the optimal CF content for enhancing geopolymer properties.
• To evaluate the influence of CF on air- and water-cured geopolymer specimens.

Main Methods:

• Supplementation of FA geopolymer with varying CF content (2-10 wt.%).
• Experimental testing of geopolymer specimens cured in air and water.
• Analysis using sophisticated analytical techniques to assess material properties.

Main Results:

• CF addition decreased flowability and setting time.
• Compressive strength improved with 2-8 wt.% CF addition.
• Enhanced water resistance, reduced strength loss in water, and improved transport properties were observed with 2-8 wt.% CF.
• 10 wt.% CF addition showed adverse effects.
• Optimal CF content identified at 6 wt.%, inhibiting efflorescence.
• CF facilitated C-S-H gel formation and microstructural densification.

Conclusions:

• Calcium formate (CF) is an effective additive for improving the properties of fly ash (FA) geopolymer cement.
• An optimal CF content (2-8 wt.%) enhances mechanical strength, durability, and water resistance.
• CF addition promotes C-S-H gel formation and microstructural densification, leading to improved geopolymer performance.