Recently, Professor Gao Xuan from the School of Materials Science and Engineering of YCIT published a research paper titled Effects of U-phase formation on early-age autogenous shrinkage of one-part alkali-activated slag（DOl:10.1016/j.cemconres.2025.107938） in Cement and Concrete Research, a top journal of building materials (ranked in the first category by the Chinese Academy of Sciences, with an impact factor of 10.9). Yancheng Institute of Technology is the first author's institution. Associate Professor Yang Tao is the corresponding author of the paper. Teacher Zhu Zheyu and Professor Zhu Huajun from YCIT Green Building Materials Research Institute provided important guidance for the related research work.
Alkali-activated slag (AAS) is a low-carbon cement-based material that has attracted significant attention from both scholars and the industrial sector worldwide. Although this cementitious material possesses excellent properties such as rapid setting, early strength, dense impermeability, and resistance to chemical erosion, it still encounters the problem of volume stability during its engineering application.
To mitigate the high shrinkage characteristic of AAS, Teacher Gao, in collaboration with Professor Zhuang Peizhi from Shandong University and Professor Zhang Zuhua from Tongji University, proposed the concept of phase design. They pointed out that the lack of sufficient crystalline phases in the cementitious materials is one of the main reasons for the poor volume stability of AAS. Promoting and controlling the formation of crystalline phases in AAS is a new approach to improving volume stability and inhibiting self-shrinkage.
Based on this, in this study, sodium-based desulfurization ash and calcium carbide slag were used as composite solid activators to prepare single-component AAS. This was to promote the formation of sodium-containing AFm-type crystalline phase (U phase) in AAS, and utilize its crystalline expansion property to compensate for the early self-shrinkage. The reaction kinetics, phase composition, pore structure and microstructure evolution were systematically characterized, and the behavior mechanism of U phase formation and shrinkage compensation in AAS was revealed.
This research was supported by the National Natural Science Foundation of China (52378257; U2001225, 52408234), the Key Research Program of the State（2022YFC3005604）, and the Excellent Young Backbone Teachers of Jiangsu Province Universities under the Blue Project of Jiangsu Province.
Literature link：
https://doi.org/10.1016/i-cemconres.2025.107938
