Insight into mechanical properties and microstructure of concrete containing steel slag and ground-granulated blast-furnace slag

Abstract

The impacts of steel slag (SS) and ground-granulated blast-furnace slag (GGBS) on the mechanical properties, hydration process, and microscopic characteristics of concrete were investigated in this study. The results show that substituting cement with SS has a negative impact on the strength; however, partial replacement of SS with GGBS could produce positive effect by facilitating the whole hydration of SS and cement. The improvement impact of GGBS on strength was small in early stages (3–28 days) and occurred mainly in the late stages (28–90 days). Meanwhile, the heat flow and cumulative hydration heat was decreased by the incorporation of SS and GGBS, in comparison to plain cement. The microscopic analysis results proved that replacing SS with GGBS could increase the whole hydration reaction degree, decrease the content of Ca(OH)₂, enhance the compactness of the interfacial transition zone (ITZ), and refine the pore structure of concrete. Furthermore, a formula was established to estimate the splitting tensile strength according to compressive strength. The finding of this study provides valuable information on the practical application of the industrial wastes in concrete.

Keywords:

• Steel slag
• ground granulated blast-furnace slag concrete
• mechanical strength
• microstructure

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study is financially supported by National Natural Science Foundation of China (Nos. 52078413 and 52278217). National Natural Science Fund for Excellent Young Scholars (52222806). Program for young and middle-aged scientific and technological innovation talents of Shaanxi Railway Institute (KJRC201903). 2020 Basic Research Project of Weinan City (ZDYF-SFGG-92).