Sulfate resistance and hydration products of steam cured steel slag blended cement mortar under dry–wet cycle

Abstract

In this investigation, the dry–wet-cycled sulfate resistance and hydration products of steam-cured and standard-cured steel-slag mortars were investigated. Strength loss, porosity change, and microstructure of mortars prepared by replacing 20% of cement with steel slag (SS) were analyzed and compared with pure cement (PC) mortars. The results revealed that SS-blended cement mortar shows worse sulfate resistance than PC mortar regardless of the initial curing condition. Steam-cured PC mortar presents inferior sulfate resistance to standard-cured PC mortar, on the contrast, steam curing improves the sulfate resistance of SS mortar, when compared with the standard-cured mortars. Besides the large amount of C-S-H gels, the formation of hemicarbonate, C-A-S-H and relative lower CH content under steam curing can account for the improved sulfate resistance of initially steam-cured SS mortars, although the high porosity caused by steam curing brings negative impact to the sulfate resistance.

Keywords:

• Steel slag
• mortar
• steam curing
• dry–wet cycle
• sulfate resistance
• hydration products

Acknowledgments

The authors would like to thank the financial support from China-Japan Joint Research Cooperative Program sponsored by Ministry of Science and technology in China (No. 2016YFE0118200), national basic research program (973 program) of China (No. 2015CB655100) and the National Natural Science Foundation of China (No. 51778132). This work is also supported by Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX17_0068).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported from the China–Japan Joint Research Cooperative Program sponsored by Ministry of Science and technology in China (No. 2016YFE0118200), National Basic Research Program (973 Program) of China (No. 2015CB655100) and the National Natural Science Foundation of China (51778132). This work is also supported by Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX17_0068).