Research on ambient-temperature synthesis of high-strength geopolymer concrete: Parameter optimization and strength prediction model

To address the issues of poor workability, low early strength, and high-temperature curing dependence in fly ash-based geopolymer concrete, this study systematically optimized preparation parameters for geopolymer slurry, mortar, and concrete, including alkali/precursor mass ratio (L/B), sodium silicate/sodium hydroxide ratio (SS/SH), sodium silicate modulus (Ms), slag proportion, and curing methods. The research method is to optimize the aforementioned parameters based on work performance and strength indicators, and to reveal the optimization mechanism based on scanning electron microscopy and mercury intrusion testing. Results indicated‌ that optimal parameters were L/B (0.5–0.6), SS/SH (2.5:1), and sodium silicate modulus (2.3), while mortar and concrete preparation recommended cement/sand ratios of 0.6 and 0.35, respectively. ‌Furthermore‌, replacing 50% fly ash with slag can achieve room-temperature curing, and maintaining 95% humidity for 56 days followed by normal humidity can further enhanced performance. ‌Additionally‌, numerical analysis methods were used to establish the relationship equations between strength development and curing humidity, and SEM and MIP confirmed that the combination of optimal parameters and 50% fly ash substitution promoted polymerization reaction and reduced porosity. The innovation of this article lies in avoiding the problems caused by high-temperature curing of fly ash-based polymer concrete without sacrificing performance, and establishing its strength development theory. The above research results can provide strong support for promoting the engineering application of geopolymer concrete.