胶粉煤矸石混凝土力学特性及微观结构试验研究

Experimental study on mechanical properties and microstructure of powdered coal gangue concrete

为探究胶粉掺量对煤矸石粗骨料混凝土力学性能的影响,设计20目橡胶颗粒掺量(0,3%,6%,9%,12%)的胶粉煤矸石混凝土,进行宏观力学试验和微观孔隙结构核磁共振试验.结果表明:胶粉掺量增加与力学强度成负相关,3%胶粉掺量影响最小,与基准组相比下降了1.3%,拟合了不同胶粉掺量对煤矸石混凝土立方体抗压强度和劈裂抗拉强度换算公式,相关性较好;胶粉的掺入降低了多害孔的孔隙占比,6%胶粉掺量使煤矸石混凝土内部有害孔分布降低了4%;数据表明,胶粉颗粒具有填充孔隙的作用,减少了多害孔的产生,优化了孔隙结构;选取对强度影响最大的因素束缚流体饱和度(关联度0.951 06)和大于0.02μm孔隙半径占比(关联度0.963 86)建立GM(1,3)模型,模型预测的平均误差为2.56%,为矿区排土场护坡材料提供可就地取材的绿色混凝土参考依据.

In order to explore the influence of rubber powder content on the mechanical properties of coal gangue coarse aggregate concrete, 20 mesh rubber particle content(0, 3%, 6%, 9% and 12%) of rubber powder coal gangue concrete was designed, and the macroscopic mechanical test and the microscopic pore structure nuclear magnetic resonance test were carried out.The results show that the increase of powder content is negatively correlated with the mechanical strength, and the effect of 3% powder content is the least, which is 1.3% lower than that of the reference group. Fitting the conversion formula of cubic compressive strength and splitting tensile strength of 20 mesh gangue concrete with different powder content has a good correlation. The addition of rubber powder reduces the proportion of harmful pores, and the content of 6% rubber powder reduces the distribution of harmful pores in gangue concrete by 4%. The data show that the rubber powder particles can fill the pores, reduce the occurrence of damage pores and optimize the pore structure. A GM(1,3) model is established by selecting the most influential factors on the strength: bound fluid saturation(correlation degree 0.951 06) and pore radius ratio greater than 0.02 μm(correlation degree 0.963 86).The average error predicted by the model is 2.56%. It provides a reference basis for the green concrete which can be used locally for the slope protection material of mine dump.