Preparation and characterization of carbonated high-calcium fly ash as supplementary cementitious material
Zhi Ge (Student TU Delft, Shandong University)
Xingjie Xue (Student TU Delft, Shandong University)
Haibo Fang (Student TU Delft, The Second Construction Company of China Construction Eighth Engineering Division)
Yingxuan Shao (Student TU Delft, Shandong University)
Ke Sun (Student TU Delft, Shandong University)
Hongzhi Zhang (TU Delft - Materials and Environment, Shandong University)
Branko Šavija (The Second Construction Company of China Construction Eighth Engineering Division, TU Delft - Materials and Environment)
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Abstract
This paper aims to improve the activity of high-calcium fly ash (FA) by using a wet carbonation treatment process. The results indicated that carbonation products, i.e. calcite, were attached to the surface of FA, which accelerated cement hydration primarily at the early stage. Significant improvement of early age strength and a decrease in setting time were therefore found in blended cement. Additionally, carbonation significantly reduced the amount of free calcium oxide (f-CaO) in FA, increasing its volume stability. Krstulovic-Dabic model was used to simulate the hydration process of blended paste, and the distribution of pore sizes and hydration products were also measured. Together with the filler effect of nano-sized calcite, the formation of carboaluminate phases refined the pore structure of blended paste. Furthermore, the amounts and mechanical properties of outer hydration products in blended paste increased.