Improvement Effects and Mechanisms of Steel Slag by Binary Microorganisms

To effectively improve the stability of steel slag and promote the utilization of steel slag resources, the changes in strength, microstructure and stability before and after microbial improved steel slag were studied. The results showed that: 1) when compressive strength of original steel slag was 1.1 MPa, and the compressive strength of improved steel slag mixed with saccharomycetes, pasteurella or the mixed bacteria of the above two was 1.2 MPa, 3.1 MPa and 4.5 MPa respectively. After improvement with the mixture of the two microbes, the steel slag was of the best stability in them, and the f-CaO content was 2.86%, which met the requirements not more than 3% of GB/T 20491-2017 Steel Slag Powder Used for Cement and Concrete, but other technical indexes didn’t meet the requirments of the specification. 2) The addition of the binary microorganisms could produce CO₂ either in aerobic or anaerobic conditions, and CO₂ dissolved in water in an alkaline environment would produce CO^2-₃, which made up the lack of the mineralization capacity in the condition of less oxygen of mono-bacteria, so the steel slag modified with binary microorganisms would produce a sharper C=O absorption band and a larger area of characteristic peaks of C-S-H gel, and the CaCO₃ crystals and the C-S-H gel bodies closely coverd the surface of steel slag.