Prediction of Hydration Products and Pore Solution Chemistry of Fly Ash Cement
Extensive use of supplementary cementitious materials is expected in cement and construction industry not only to reduce the CO2 footprint of Portland cement but to achieve better durability performance and strength. In addition, incorporation of industrial by products including fly ash from coal fired power plant into cement and concrete reduce the environmental and economic concern related to their landfill disposal. Although the effect of fly ash on the properties and performance of concrete has been studied for decades, a quantitative understanding of the influence of fly ash on cement hydration is necessary to predict service-life of concrete structures containing fly ash cement. In this study, solid-phase assemblage and pore solution chemistry of hydrating fly ash cement is predicted based on thermodynamic considerations. The predicted results are verified with experimental data available in literature. Despite some difference in the Ca/Si and Al/Si ratios of calcium aluminosilicate hydrate, the model predicts well both qualitatively and quantitatively the hydration products and pore solution composition of fly ash cement and the blended cement containing limestone.
Keywords - Blended cement, Fly ash, Hydration products, Pore solution, Thermodynamic calculation, PHREEQC.