Efficient use of steel slag in alkali-activated fly ash-steel slag-ground granulated blast furnace slag ternary blends

• Published in: Construction & building materials Vol. 259; p. 119814
• Main Authors: Song, Weilong, Zhu, Zhiduo, Pu, Shaoyun, Wan, Yu, Huo, Wangwen, Song, Shigong, Zhang, Jun, Yao, Kai, Hu, Lele
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30-10-2020
• Subjects: Alkali-activated ternary blends; Composite additive; Pore structure; Steel slag; Strength; Composite additive; Alkali-activated ternary blends; Pore structure; Steel slag; Strength
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2020.119814

•Inclusion of SS-GGBS slightly prolonged the setting time of FA based AAP.•The optimum content of SS-GGBS with regard to flow was found to be 40%.•The brittleness of AAP can be reduced by the inclusion of SS-GGBS.•Inclusion of SS-GGBS refined the pore structure and resulted in a lower total porosity.
In order to find an effective way to use steel slag (SS), this study explored the possibility of using SS and ground granulated blast-furnace slag (GGBS) as a composite additive in alkali-activated high calcium fly ash (FA) binder. Through a series of experiments, the setting times, flow, viscosity, compressive and flexural strengths, modulus of elasticity, sorptivity and pH of pore solution of alkali-activated paste (AAP) containing different contents of SS-GGBS were investigated. Moreover, the optimization mechanism of SS-GGBS on the gel products, micro-morphology and pore structure of AAP was discussed based on multi-technical microstructural characterizations. The results showed that the setting time of AAP increased slightly with increasing SS-GGBS content due to the presence of SS. The initial flow of AAP can be improved by adding the appropriate amount of SS-GGBS. The increase in compressive strength of AAP caused by the inclusion of SS-GGBS not only was observed in the early stage but also in the later stage. In addition, the brittleness of AAP can be reduced by the addition of SS-GGBS. The optimum content of SS-GGBS with regard to the flexural strength was found to be 40%. The incorporation of SS-GGBS promoted the formation of amorphous gel products of AAP. The resulting gel products filled the capillary pores and converted them into gel pores with a smaller pore size, which refined the pore structure and resulted in a lower total porosity. The denser microstructure is one of the main reasons for the improvement of strength. This study provides a promising approach to improve the utilization potential of SS.