Enhancing Freeze-Thaw Resistance of Alkali-Activated Slag by Metakaolin

Yongheng Zhang; Yan He; Xuemin Cui; Leping Liu

doi:10.1021/acsomega.3c01600

Enhancing Freeze-Thaw Resistance of Alkali-Activated Slag by Metakaolin

ACS Omega. 2023 Jun 5;8(23):20869-20880. doi: 10.1021/acsomega.3c01600. eCollection 2023 Jun 13.

Authors

Yongheng Zhang¹, Yan He¹, Xuemin Cui¹, Leping Liu²

Affiliations

¹ School of Chemistry and Chemical Engineering and Guangxi Key Lab of Petrochemical Resource Processing and Process Intensification Technology, Guangxi University, Nanning 530004, P. R. China.
² College of Chemistry and Science, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, PR China.

Abstract

Incorporating metakaolin (MK) into slag to prepare alkali-activated materials can reduce shrinkage and improve the durability of alkali-activated slag (AAS). But its durability under freeze-thaw conditions is unknown. In this paper, the effects of MK content on the freeze-thaw properties of AAS were investigated from the perspective of gel composition and pore solution. The experimental results showed that the addition of MK generates a gel mixture of C-A-S-H and N-A-S-H with a cross-linked structure and decreases the content of bound water and pore water absorption. With the increase of alkali dosage, water absorption decreased to 0.28% and then increased to 0.97%, and the leaching rate of ions was Ca²⁺ > Al³⁺ > Na⁺ > OH^-. When the alkali dosage was 8 wt % and the MK content was 30 wt %, the compressive strength loss rate of AAS was 0.58% and the mass loss rate was 0.25% after 50 freeze-thaw cycles.