碱性激发矿渣对水泥混凝土界面影响行为研究

Study on the Effect of Alkali-activation Slag on the Interface of Cement Concrete

针对碱激发矿渣影响水泥混凝土的力学性能和界面性能等问题,采用变掺量法,将碱激发矿渣的替代率为0%、10%、20%和30%,采用扫描电子显微镜测试分析了碱激发矿渣对水泥混凝土力学性能和微观界面特征的影响。结果表明:①碱激发矿渣水泥混凝土的轴心抗压强度随着矿渣掺量增加而降低,立方体抗压强度随着矿渣掺量增加而增加;②碱激发矿渣掺量水泥混凝土试件的峰值应力越高,应力—应变曲线越陡,低掺量试件的刚度和弹性模量较低,高掺量试件的应力—应变曲线下降斜率最小,其延性和变形能力优于其他试件,碱激发矿渣可以穿透水泥混凝土的细裂缝,从而提高基体的劈裂抗拉强度;③微观结构中存在由干燥收缩引起的微裂纹和孔隙,随着碱激发矿渣掺量增加,水泥砂浆微观结构上的微裂纹和孔洞越来越少;④高掺量试件的碱激发矿渣界面较为致密,微裂纹少,在碱激发矿渣表面和孔洞上附着较多的凝胶材料,这些凝胶材料基本沿着界面分布。

In response to the impact of alkali activated slag on the mechanical and interfacial properties of cement concrete,a variable dosage method was used,with replacement rates of 0%,10%,20%,and 30%for alkali activated slag.Scanning electron microscopy was used to test the mechanical properties and micro interfacial characteristics of alkali activated slag on cement concrete.The results show that:①the axial compressive strength of alkali activated slag cement concrete decreases with the increase of slag content,while the cubic compressive strength increases with the increase of slag content.②The higher the peak stress of cement concrete specimen with alkali activated slag content,the steeper the stress-strain curve.The stiffness and elastic modulus of the lower content sepecimen are lower,while the stress-strain curve of the higer content specimen has the smallest decreasing slope.Its ductility and deformation ability are better than other specimens.Alkali activated slag can penetrate fine cracks in cement concrete,thereby improving the splitting tensile strength of the matrix.③There are microcracks and pores caused by drying shrinkage in the microstructure.With the increase of alkali activated slag content,the number of microcracks and pores in the microstructure of cement mortar decreases.④The interface of alkali activated slag in higher group is denser than that in higer content specimen group,with fewer microcracks.More gel materials are attached to the surface of alkali activated slag and holes,and these gel materials are basically distributed along the interface.