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针对粉煤灰充填材料早期强度低、变形量大、流动性差、泌水严重等缺陷,基于电阻率法和力学特性测试法研究3种配比粉煤灰充填材料早龄期的体积电阻率、孔隙溶液电阻率、单轴抗压强度和弹性模量随时间的变化规律;结合充填材料初始孔隙度和1 d孔隙度的测试结果,对孔隙度随时间的变化规律作进一步分析。结果表明:(1)材料的体积电阻率随时间呈升高、降低、再升高的变化规律,孔隙溶液的电阻率随时间呈先急剧下降后趋于稳定的变化规律,但材料的电阻率变化在时间上和数值上受粉煤灰掺量的影响;(2)材料的单轴抗压强度和弹性模量随水化时间的延长而增大,随粉煤灰掺量的增加而降低;(3)材料的孔隙度随水化时间的延长呈负指数规律降低,随粉煤灰掺量的增加先降低后增加;(4)在水化后期,材料的单轴抗压强度和弹性模量与其体积电阻率呈对数相关;(5)材料早龄期的水化过程可分为吸附期、溶解期、凝结期和硬化期4个阶段。研究结果为进一步了解、改善粉煤灰充填材料早龄期的物理力学特性和实现材料特性的无损检测提供了一定的理论与应用参考。
According to the shortcomings of low early strength, large deformation, poor fluidity and severe bleeding, the volume resistivity of the three kinds of fly ash filling materials in the early age was studied based on the resistivity method and the mechanical property test method. Pore fluid resistivity, uniaxial compressive strength and elastic modulus change with time; combined with the initial filling porosity and porosity of 1 d test results, the porosity variation with time for further analysis. The results show that: (1) The volume resistivity of the material increases, decreases and then increases with time, and the resistivity of the pore solution declines first and then stabilizes with time, but the resistivity of the material (2) The uniaxial compressive strength and elastic modulus of the material increase with the extension of hydration time, and decrease with the increase of fly ash content; (3) The porosity of the material decreases negatively with the extension of hydration time, and then decreases with the increase of fly ash content. (4) At the later stage of hydration, the uniaxial compressive strength and elastic modulus Volume and its volume resistivity logarithmically; (5) The hydration process of the early age of the material can be divided into four stages: adsorption, dissolution, clotting and hardening. The results provide some theoretical and application references for further understanding and improving the physical and mechanical properties of the fly ash filling material at the early age and achieving nondestructive testing of the material properties.