张小芳, 陈瑞敏, 简文彬. 2023. 水泥-矿渣-粉煤灰固化淤泥的水分转化规律及其固化机理研究[J]. 工程地质学报, 31(1): 102-112. doi: 10.13544/j.cnki.jeg.2020-378.
    引用本文: 张小芳, 陈瑞敏, 简文彬. 2023. 水泥-矿渣-粉煤灰固化淤泥的水分转化规律及其固化机理研究[J]. 工程地质学报, 31(1): 102-112. doi: 10.13544/j.cnki.jeg.2020-378.
    Zhang Xiaofang, Chen Ruimin, Jian Wenbin. 2023. Study on water conversion law and solidification mechanism of cement-slag-fly ash solidified silt[J]. Journal of Engineering Geology, 31(1): 102-112. doi: 10.13544/j.cnki.jeg.2020-378.
    Citation: Zhang Xiaofang, Chen Ruimin, Jian Wenbin. 2023. Study on water conversion law and solidification mechanism of cement-slag-fly ash solidified silt[J]. Journal of Engineering Geology, 31(1): 102-112. doi: 10.13544/j.cnki.jeg.2020-378.

    水泥-矿渣-粉煤灰固化淤泥的水分转化规律及其固化机理研究

    STUDY ON WATER CONVERSION LAW AND SOLIDIFICATION MECHANISM OF CEMENT-SLAG-FLY ASH SOLIDIFIED SILT

    • 摘要: 为研究石膏激发的水泥-矿渣-粉煤灰固化淤泥的力学强度与水分转化过程的演变规律,从本质上揭示水泥-矿渣-粉煤灰对淤泥的固化机理,通过无侧限抗压强度、抗剪强度试验探究水泥/矿渣/粉煤灰配比、固化剂掺量、养护龄期对固化淤泥土强度的影响,结合核磁共振弛豫分析(NMR)、矿物成分分析(XRD)、微观结构分析(SEM)探究结合水量、水化物种类、微观形貌随养护龄期的变化规律,并建立无侧限抗压强度qu、抗剪强度参数c、tan φ与结合水量Cw的函数关系。结果表明:14 d龄期内较高水泥配比(20%)的固化土强度显著高于低水泥配比(5%)固化土,其早强效应归功于水化物的大量生成,结合水量大幅提高,14 d龄期后5%水泥配比固化土强度增长迅速并超过20%水泥配比固化土强度。从宏观力学强度看,较高水泥配比(20%)固化土quc、tan φ均与龄期对数lg t呈线性增长关系,低水泥配比(5%)固化土则呈幂型函数关系;从微观水分转化角度分析,高低水泥配比固化土的结合水量与抗压强度、抗剪强度参数的函数关系相同,即qu-Cw、tan φ-Cw呈幂型函数增长,c-Cw存在线性关系。固化土力学强度不仅与水化物中的结合水量有关,还与水化物的结构有关,絮凝状水化物C-A-S-H逐渐形成空间网状结构,使土体结构密实,孔隙减小。

       

      Abstract: This paper investigates the relationship between the mechanical strength of the cement-slag-fly ash solidified silt excited by gypsum and the evolution of the water conversion process, and aims to essentially reveal the curing mechanism. Both the unconfined compressive strength test(UCS) and direct shear strength test(DST)were conducted to explore the effects of cementslagfly ash ratio, curing agent dosage and curing age on the strength of solidified silt. In addition, the nuclear magnetic resonance(NMR)relaxation analysis, X-ray diffraction(XRD) and scanning electron microscopy(SEM)were applied to observe the soil-water characteristics and analyze the mineral composition and the microstructure of hydration products. From the test results, the functional relationships among unconfined compression strength(qu), shear strength parameters(c, tan φ) and the combined water content(Cw)were established. Results show that during 14 days of age, the strength of solidified soil with a higher cement ratio(20%) is significantly higher than that of the low cement ratio(5%). The early developed strength effect can be attributed to hydrate formation and the greatly increasing amount of combined water. After 14 days, the strength of low cement solidified soil increases rapidly and exceeds the strength of high cement solidified soil. From the perspective of macro-mechanical strength in the specimen with higher cement content(20%), the strength parameters(qu, c, tan φ)all show a linear growth relationship with curing age(lg t), while the specimen with low cement content(5%)has a power function relationship with lg t. In contrast, from the perspective of microscopic water conversion, the relationship among the combined water content Cw, the compressive strength and the shear strength are identical in high and low cement ratio solidified soil, where, qu-Cw and tan φ-Cw increase as a power function, and c-Cw exists a linear relationship. The mechanical strength of solidified soil is not only related to the amount of combined water, but also to the structure of hydrate. The flocculated hydrate C-A-S-H gradually forms a spatial network structure, which makes the micropore structure denser and reduces the porosity.

       

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