Affiliation:
1. College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, China
2. State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
Abstract
Steel slag (SS) has been largely discharged but little utilized, causing an environmental problem in China. In this paper, SS-based composite cementitious materials with high strength were prepared by the high volume of SS (≥40%), granulated blast-furnace slag (GBFS), fly ash (FA), flue gas desulfurization gypsum (FGDG) and cement to promote the effective utilization of SS. The hydration and hardening properties were studied through setting time, compressive strength, length change, isothermal calorimetry (IC), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS) tests. The results show that SS-based composite cementitious material exhibited a lower hydration heat release, an appropriate setting time, and volume stability. The SS cementitious material with 40% SS could obtain high strength of over 65 MPa at 28 days and 80 MPa at 90 days. The strength value of > 60 MPa is present in the binder, with 50% SS at 56 days. GBFS promotes hydration reactions and the formation of AFt and C-(A)-S-H gel, thus enhancing compressive strength. FA has a beneficial effect on later strength. The small and fine pore structures contribute to the development of strength. The main hydration products of SS composite cementitious materials are C-(A)-S-H gel, and ettringite (AFt), with less Ca(OH)2. The C-(A)-S-H gel with a lower Ca/Si ratio and a higher Al/Ca ratio in cementitious material, promotes mechanical properties.
Funder
State Key Laboratory of Materials-Oriented Chemical Engineering, the National Natural Science Foundations of China
Priority Academic Program Development of Jiangsu Higher Education Institutions
Subject
General Materials Science
Reference48 articles.
1. Characteristics and cementitious properties of ladle slag fines from steel production;Shi;Cem. Concr. Res.,2002
2. Effect of replacement ratio of ferronickel slag aggregate on characteristics of cementitious mortars at different curing temperatures;Lee;Case Stud. Constr. Mat.,2023
3. Huang, Y., Yang, X., Wang, S., Liu, Z., Liu, L., and Xu, B. (2022). Evaluating Cement Treated Aggregate Base Containing Steel Slag: Mechanical Properties, Volume Stability and Environmental Impacts. Materials, 15.
4. Utilization of unprocessed steel slag as fine aggregate in normal- and high-strength concrete;Guo;Constr. Build. Mater.,2019
5. Influence of a steel slag powder-ground fly ash composite supplementary cementitious material on the chloride and sulphate resistance of mass concrete;Han;Powder Technol.,2020