【摘要】 为探究常温条件碱激发对粉煤灰混凝土强度及其微观结构的影响，本研究利用1.2模数钠水玻璃激发不同掺量粉煤灰配制混凝土试件，通过抗压强度试验、核磁共振试验和红外光谱试验，结合分形理论研究其宏观力学性能与微观孔隙结构与物质组成的变化规律。研究发现：适量钠水玻璃有助于N-A-S-H凝胶生成，使微观结构更加致密、提高混凝土早期抗压强度。碱当量4%、粉煤灰替代率40%的微观孔隙结构最优，28 d龄期抗压强度达46.45 MPa。基于分形理论建立核磁共振和红外光谱与其分形维数的关系，将碱激发粉煤灰混凝土微观特征量化。进一步，通过灰关联熵分析发现红外光谱分形维数D_S和0～0.02μm区间的孔隙是影响抗压强度的主要因素。此外，建立了GM(1,3)混凝土抗压强度预测模型，来反映碱激发粉煤灰混凝土的微观孔结构和化学生成物对其抗压强度的影响，为提高粉煤灰在混凝土中的利用率提供理论支撑。更多还原

【Abstract】 In order to explore the effect of alkali-activated on the strength and microstructure of fly ash concrete under room temperature conditions, the fly ash concrete samples were conducted by 1.2-sodium silicate stimulator. The study focused on how the alkali-activated effects on fly ash concretes by experiments of the compressive strength test, the nuclear magnetic resonance test and FTIR spectrum test. The rules of the macro-mechanical properties related to micro-pore structure and material composition were found by the Fractal theory. An appropriate amount of sodium silicate can contribute to the formation of N-A-S-H gel, which makes a dense microstructure and improves the early compressive strength of concrete, where the compressive strength reaches 46.45 MPa at 28 days when the optimal micro-pore structure is 4% alkali equivalent and 40% fly ash substituting rate. The relationship between nuclear magnetic resonance and FTIR spectrum to fractal dimension is established based on the Fractal theory, while the microscopic characteristics of alkali-activated fly ash concrete are quantified. It was found that the fractal dimension of FTIR spectrum D_S and pores in 0～0.02 μm range are the main factors by grey correlation entropy analysis. The compressive strength prediction model of GM(1,3) concrete is established to reflect the influence of micro-pore structure and chemical products of alkali-activated fly ash concrete on the compressive strength. It provides theoretical support for improving the utilization rate of fly ash in concrete with normal temperature curing.更多还原