含钢渣的低熟料混凝土耐久性及水化机理研究

Study on durability and hydration mechanism of low clinker concrete containing steel slag

研究了不同钢渣掺量对C40低熟料胶凝材料混凝土的碳化、电通量、抗冻等耐久性的影响,结果表明,钢渣掺量为15%时,混凝土碳化深度最小,抗碳化等级为T-Ⅳ;抗氯离子渗透和抗冻性能在钢渣掺量为10%时最佳,分别达到Q-Ⅴ和F275等级。采用XRD、IR和SEM等手段分析了10%钢渣掺量的低熟料胶凝材料水化机理,结果表明,胶凝体系主要水化产物是水化硅酸钙(C-S-H)凝胶和钙矾石(AFt);水泥熟料和钢渣先后水化,产生的OH-维持体系的碱性环境,使矿渣中的硅(铝)氧四面体逐渐解离,在SO42-的共同作用下形成C-S-H凝胶和AFt;矿渣和钢渣的水化相互促进,使胶凝体系在后期仍然产生大量水化产物,为混凝土后期强度和密实度的提高起到了重要作用。

The influences of different content of steel slag on carbonization, electric flux and frost resistance of C40 low clinker concrete were studied. The results showed that low clinker concrete had the minimum carbonation depth and the carbonation resistance level T-Ⅳ when the content of steel slag was 15%. The resistance of concrete to chloride penetration and freezing and thawing was best when the content of steel slag was 10%, reaching level Q-Ⅴ and F275, respectively. The hydration mechanism of low clinker cementitious material containing 10% steel slag was analyzed by means of XRD, IR and SEM. The results showed that the major hydration products were calcium silicate hydrate(C-S-H) gels and ettringite(AFt). The cement clinker and steel slag were hydrated successively, then the resulting OH- gradually dissociated the silicon(aluminum) oxygen tetrahedron in blast furnace slag, and C-S-H gels and AFt were formed under the combined action of SO42-. The hydration of blast furnace slag and steel slag promoted each other, so that the cementitious system still produced a large number of hydration products in the later period, which played an important role in improving the strength and compactness of concrete in the later period.