Study on Environmental Durability of Solidified Lake-bottom Sediment
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摘要: 为了评价淤泥固化土的环境耐久性，采用矿渣体系的碱激发胶凝材料（矿渣粉、偏高岭土、石灰和水玻璃）和普通硅酸盐水泥为固化剂，通过开展无侧限抗压、冻融循环、Na2SO4及NaCl浸泡侵蚀、扫描电镜和EDS-Mapping试验，分析了侵蚀环境下固化淤泥土的典型水化产物、强度演变规律、质量损失率和微观结构特征，结果表明，碱激发固化淤泥内部生成的水化硅铝酸钠凝胶（N-A-S-H）能有效提高强度，但是冻融循环和浸泡侵蚀均会导致固化土强度劣化；水泥固化淤泥受硫酸盐侵蚀后，钙矾石会呈现簇状发展而产生膨胀开裂，导致强度下降；碱激发固化剂的抗氯离子能力优于硫酸根离子，综合环境耐久性优于普通硅酸盐水泥。Abstract: In order to evaluate the environmental durability of solidified lake-bottom sediment, alkali activated cementing material of slag system (slag powder, metakaolin, lime and sodium silicate) and traditional cement were used as curing agent. Through unconfined compression, freezing-thawing cycle, Na2SO4 and NaCl erosion leaching, scanning electron microscopy and EDS-Mappingtests, the typical hydrates, strength evolution, mass loss rate and microstructure characteristics of solidified sediment in erosion environment were analyzed. The results show that a large amount of hydrated sodium silicate aluminate gel（N-A-S-H）was formed in the alkali-excited solidified sediment. The freezing-thawing cycle and erosion leaching can lead to the deterioration of the strength of solidified sediment. The development of ettringite led to expansion and cracking when the cement-solidified sediment was eroded by sulfate, which resulted in the decrease of strength. The alkali-activated curing agent has better chloride ion resistance than sulfate ion and better comprehensive environmental durability than conventional Portland cement.
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Key words:
- solidified sediment /
- strength /
- freezing-thawing cycle /
- erosion /
- durability
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表 1 试验淤泥理化性质
参数 数值 比重 2.72 液限/% 50.5 塑限/% 26.3 黏土粒组 (d<0.002 mm)/ % 20.0 粉粒(0.002 mm <d< 0.075 mm)/ % 52.0 砂粒粒组 (d>0.075 mm)/% 28.0 pH 7.3 有机质含量/% 3.5 最优含水量/% 20.1 最大干密度/(g·cm−3) 2.01 
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表 2 试验材料的化学组成
% 原材料 化学成分 SiO2 Al2O3 CaO Fe2O3 MgO Na2O Loss 淤泥 58.1 18.8 4.6 5.8 2.7 2.1 6.4 水泥 22.3 4.2 64.8 2.3 2.5 1.2 1.7 偏高岭土 50.4 43.8 0.3 0.6 2.7 1.4 0.8 矿渣 49.0 12.0 32.5 2.0 3.0 0.5 1.0
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