Effect of the fly ash and lime fly ash on the mechanical properties of red clay in Guilin
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摘要: 为了研究粉煤灰和二灰掺量及养护时间对桂林红黏土的改良效果，进行了直剪试验、固结试验以及电镜扫描试验。试验结果表明，粉煤灰的掺入提高了红黏土的抗剪强度，但超过一定量（18%粉煤灰掺量）反而会降低红黏土黏聚力，各掺量粉煤灰红黏土随养护龄期的延长，抗剪强度呈先增后缓趋势。二灰改良红黏土，在早期强度剧增，且强度随养护时间增长而大幅增加，一定龄期内，二灰红黏土黏聚力随二灰掺量呈先增后减趋势。粉煤灰和二灰的掺入均增大了红黏土的压缩模量，且随养护时间的延长而逐渐增大。红黏土中随粉煤灰、石灰的加入，发生一系列物理化学反应，从微观结构分析得知土中孔隙减少，结构性较素红黏土好。Abstract: To examine the improvement effect the content and curing time of fly ash and lime fly ash on the red clay in Guilin, the direct shear tests, oedometer tests and Scanning Electron Microscope tests are conducted. The mixture of fly ash can improve the shear strength of the red clay. After over a certain amount (18% fly ash content), the cohesion of the red clay reduces. With the prolonging of the curing time, the shear strength of the red clay with different content of fly ash increases first and then increases slowly, The shear strength of lime-fly ash red clay improves rapidly in the early stage, and increases intensely with the prolonging of the curing time. The cohesive strength of the lime-fly ash red clay increases first and then decreases with the increasing lime-fly ash content. The modulus of compressibility of the red clay increases with the mixing of fly ash and lime fly ash and increases gradually with the prolonging of the curing time. With the addition of fly ash and lime, a series of physical and chemical reactions occur in the red clay. Analysis of the micro-structure show that the pores in the soil decreases, and the structure is better than the that of the plain red-clay.
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Key words:
- fly ash /
- lime fly ash /
- sheer strength /
- compressibility /
- micro-structure
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