Influences of Calcium and Aluminum Mineral Phases on Chloride Binding Capacity of Alkali-Activated Slag

Abstract

Abstract: In this paper, a modified alkali-activated slag cementitious material was proposed by applying calcium and alumina mineral phases (Ca(OH)₂ and γ-Al₂O₃) as partial replacement of slag, aiming at promoting the formation of Friedel's salt (F salt) in the matrix when in the presence of chloride, and improving the chloride binding capacity. The effects of calcium and aluminum mineral phase content on reaction products, chloride binding capacity and mechanical properties were discussed. The results show that the addition of calcium and aluminum mineral phases improves the chloride binding capacity of alkali-activated slag, and the mass ratio of Ca(OH)₂ to γ-Al₂O₃ is highly related to this capacity. XRD analyses show that there exists unreacted Ca(OH)₂ within the reaction products, and all those Ca(OH)₂ transform into F salt or other phases after chloride attack. It is demonstrated that the enhancement of chloride binding capacity is attributed to the formation of F salt. The compressive strength results indicate that the addition of Ca(OH)₂ exhibits a negative impact, while the γ-Al₂O₃ can compensate for the strength loss due to the Ca(OH)₂ addition.

Key words: alkali-activated cementitious material, slag, calcium and aluminum mineral phase, hydration product, chloride binding capacity

CLC Number:

TU528.01

YANG Tingli, GAO Xu, GU Qian, FAN Xiaochun, ZHU Zhaokun. Influences of Calcium and Aluminum Mineral Phases on Chloride Binding Capacity of Alkali-Activated Slag[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2022, 41(3): 878-883.

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