Preparation and Properties Study of Steel Slag-based Low Carbon Cementitious Materials
In order to achieve carbon reduction and efficiency improvement,and improve the resource utilization rate of industrial solid waste,a new type of steel slag-based low-carbon cementitious material was prepared by using industrial solid waste such as steel slag powder,S95 slag powder,fly ash and desulfurization gypsum as raw materials.The suitable formula of steel slag-based low-carbon cementitious material was explored.The mechanical properties of mortar specimens were tested ac-cording to composite admixture for concrete(JG/T 486-2015)and cement mortar strength test method(ISO method)(GB/T 17671-2021).The composition and structure of steel slag-based low-carbon cementitious material mortar specimens were characterized by X-ray diffraction(XRD),differential thermal analysis(TG-DTA)and scanning electron microscopy(SEM),and the hydration mechanism of steel slag-based low-carbon cementitious material mortar specimens was revealed.The results show that the mechanical properties of the specimens at the ratio of 5∶5 of ordinary Portland cement and steel slag-based ad-mixture are lower than those at the ratio of 7∶3 of cement and steel slag-based admixture.Under the ratio of cement to steel slag-based admixture of 7∶3,the activity index of mortar specimens is higher than the first-level mechanical properties of com-posite admixture for concrete(JG/T 486-2015).The optimum ratio of steel slag-based low-carbon cementitious material is 7∶3 of cement and 600 mesh steel slag-based admixture.The compressive strength of the mortar specimen cured for 28 days is 47.47 MPa,and the activity index is 100.8%.In the early stage,the skeleton strength of the mortar specimen is provided by the needle-like AFt,and the AFt continue to generate in the later stage,and further grow and thicken,fill in the C—S—H,wrap and support each other,thereby improving the mechanical properties of the steel slag-based low-carbon cementitious mate-rial mortar specimen.
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