二元微生物对钢渣的改性效果及作用机制

Improvement Effects and Mechanisms of Steel Slag by Binary Microorganisms

为有效改善钢渣的安定性,推动钢渣资源化利用率,对微生物改性前、后钢渣的强度、微观结构和安定性变化开展了研究。结果表明:1)原钢渣抗压强度为1.1 MPa,加入酵母菌、巴氏菌和两者混合的二元菌改性后钢渣抗压强度分别为1.2,3.1,4.5 MPa;二元微生物改性后钢渣安定性最好,其中游离氧化钙(f-CaO)的含量为2.86%,符合GB/T 20491—2017《用于水泥和混凝土中的钢渣粉》小于3%的要求,其他指标均未达到要求。2)加入酵母菌的二元微生物在有氧或无氧的条件下都能产生CO_(2),在碱性环境下溶于水产生CO32-,弥补了一元巴氏菌少氧条件下矿化能力不足的缺陷,因此二元微生物改性后钢渣中产生了更尖锐的羰基(C=O)吸收谱带和更大面积的水化硅酸钙(C-S-H)凝胶特征峰,且其中的CaCO3晶体与C-S-H凝胶胶结体在钢渣表面形成了紧密的覆盖层。

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 CO_(2)either in aerobic or anaerobic conditions, and CO_(2)dissolved in water in an alkaline environment would produce CO32-, 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 CaCO3crystals and the C-S-H gel bodies closely coverd the surface of steel slag.