石灰偏高岭土改良粉砂土强度特性与微观机理

以河南地区典型粉砂土为研究对象,制备不同石灰及偏高岭土掺量下的改良粉砂土试样,对其进行了无侧限抗压强度试验、扫描电镜(SEM)与X射线衍射(XRD)测试,并与水硬性石灰改良粉砂土进行对比分析.结果 表明:随着偏高岭土掺量的增加,改良粉砂土破坏应变增大,无侧限抗压强度提高,但强度增长率呈现先增加后减小的规律,并在偏高岭土掺量为4％时达到峰值;当养护龄期从7d增至28d时,石灰偏高岭土改良粉砂土的强度增长率明显高于石灰改良粉砂土.采用6％石灰+4％偏高岭土、8％石灰+4％偏高岭土可分别有效替代8％、10％的水硬性石灰;偏高岭土掺入后形成的水化产物可联结土颗粒并填充于孔隙,使改良粉砂土微观结构更加密实,具有一定的水硬性.

Strength Characteristics and Micro mechanism of Lime Metakaolin Modified Silty Soil

Taking typical silty soil in Henan area as the research subject, modified silty soil samples with different lime and metakaolin contents were prepared. Unconfined compressive strength tests, scanning electron microscopy(SEM) and X ray diffraction(XRD) tests were carried out, and the comparison analysis was made with the hydraulic lime modified silty soil. The results show that with the increase of metakaolin content, the failure strain and unconfined compressive strength of the modified silty soil increase, but the strength growth rate increases first and then decreases, which reaches the peak value when the metakaolin content is 4%. When the curing age increases from 7d to 28d, the strength growth rate of lime metakaolin modified silty soil is significantly higher than that of lime modified silty soil. 6% lime +4% metakaolin and 8% lime +4% metakaolin can effectively replace 8% and 10% hydraulic lime respectively. The hydration products formed after the incorporation of metakaolin can bond soil particles and fill in the pores, which makes the microstructure of the improved silty soil more compact and has certain hydraulicity.