\r章定文^{1, 2}，曹智国^{1, 2}，张 涛³，刘松玉\r^{1, 2}\r
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AuthorsHTML:\r章定文^{1, 2}，曹智国^{1, 2}，张 涛³，刘松玉\r^{1, 2}\r
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AuthorsListE:\rZhang Dingwen^{1, 2}，Cao Zhiguo^{1, 2}，Zhang Tao³，Liu Songyu\r^{1, 2}\r
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AuthorsHTMLE:\rZhang Dingwen^{1, 2}，Cao Zhiguo^{1, 2}，Zhang Tao³，Liu Songyu\r^{1, 2}\r
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Unit:\r\r1. 东南大学交通学院，南京 210096；\r
\r\r2. 江苏省城市地下工程与环境安全重点实验室，南京 210096；
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\r3. 江苏省交通规划设计院股份有限公司，南京 210014\r
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Unit_EngLish:\r1. School of Transportation，Southeast University，Nanjing 210096，China；
2. Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety，Nanjing 210096，China；
3. Jiangsu Province Communications Planning and Design Institute Limited Company，Nanjing 210014，China\r
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Abstract_Chinese:\r\r水泥固化重金属污染土在服役过程中会受到周围环境的长期物理化学侵蚀，其中二氧化碳碳化作用是影响水泥材料耐久性的一个重要因素．为确保重金属污染场地二次开发利用的安全性，通过室内加速碳化试验研究了碳化作用对水泥固化铅污染土性能的影响规律．人工配制铅污染土，采用水泥固化后进行加速碳化试验，测试碳化后试样的碳化深度、含水率、密度、强度和孔隙溶液\rpH\r值等指标，分析碳化作用对固化土各物理力学特性的影响规律，并对比分析碳化与否时固化土的矿物成分和微观结构特征．试验结果表明，固化土的碳化深度与碳化时间平方根呈近似线性关系；碳化反应消耗一定量的水分，生成碳酸钙填充于孔隙，导致碳化后试样的含水率和孔隙率降低，干密度增加；碳化作用还导致孔隙溶液\rpH\r值从\r11\r～\r12\r降低到\r8\r～\r9\r；碳化后固化土的无侧限抗压强度和变形模量均得到增长，强度增加约\r6\r%\r～\r40\r%\r，试样无侧限抗压强度与基质干密度近似线性相关，变形模量与无侧限抗压强度也呈近似线性关系，变形模量约为无侧限抗压强度的\r75\r～\r100\r倍．\rTGA\r、\rXRD\r和\rSEM\r试验从矿物成分变化和微观结构特征方面证实了碳化作用后水泥水化产物水化硅酸钙、钙矾石和氢氧化钙等向碳酸钙转化的现象，这也是固化土孔隙率降低和强度增加的主要原因．\r\r
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Abstract_English:\r\rCement-solidified heavy-metal-contaminated soils are subject to long-term physical and chemical erosion during service, and carbonation is an important factor affecting the durability of cement materials. To ensure the safety of further utilization of heavy-metal-contaminated sites, it is necessary to investigate the effect of carbonation on the performance of cement-solidified heavy-metal-contaminated soils. Artificially contaminated soils with different lead contents were solidified using cement, and the carbonation depth, water content, density, pH value, and strength of solidified samples after carbonation were investigated to understand the influence of carbonation on the physical-mechanical properties of solidified contaminated soils. The microstructural characteristics of solidified contaminated soils with or without carbonation were also explored. The results show that a linear function adapts approximately the carbonation depth with the square root of carbonation time. The carbonation reaction consumes a certain amount of water and produces calcium carbonate, which results in the reduction of the moisture content and porosity of the sample, as well as the increase in the dry density of the sample. Carbonation also leads to the reduction of the pore solution pH value from 11\r—\r12 to 8\r—\r9. The unconfined compressive strength \r(\rUCS\r)\r and deformation modulus of the samples increase after carbonation, and the strength increases by 6%\r—\r40%. The UCS of the samples relates linearly to the stromal dry density of samples. The relationship between deformation modulus and strength is also approximately linear. The deformation modulus is 75\r—\r100 times of the strength. The thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy test results of the mineral composition and microstructural features have confirmed that, after carbonation of calcium silicate hydrate, ettringite, and calcium hydroxide, the cement hydration products are converted into calcium carbonate, which is the main reason for the decrease in the porosity and the increase in the strength of solidified soils.\r\r
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Keyword_Chinese:碳化；固化/稳定化；铅污染土；碳化深度；无侧限抗压强度；微观特性\r

Keywords_English:carbonation；solidification/stabilization；lead-contaminated soil；carbonation depth；unconfined compressive strength；microstructural characteristic\r


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