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取南水北调中线工程南阳段自由膨胀率77%的中膨胀土,开展了一系列不同水泥掺灰率和不同龄期下,压实度为98%试样的物理力学特性试验。通过对素膨胀土与改性膨胀土的胀缩性、界限含水率、级配及无侧限抗压强度的对比,揭示了掺灰率及养护龄期对膨胀土改性效果的影响。试验结果表明:(1)随掺灰率的增加,改性膨胀土的胀缩性指标及反映黏土亲水性的液限和塑性指数均降低、胶粒含量减小、级配曲线随趋于平缓、无侧限抗压强度和弹性模量增加;合理的掺灰率应取6%;(2)随养护龄期的增加,胀缩性指标、液限、塑性指数、胶粒含量减小,无侧限抗压强度和弹性模量则增大。
Take middle expansive soil of Nanyang section of South-to-North Water Diversion Project with 77% free expansion rate, carried out a series of physical and mechanical properties tests of cement with different cement mixing rates and different compaction degrees of 98%. By comparing the swelling and shrinking properties, limiting moisture content, grading and unconfined compressive strength of plain expansive soils and modified expansive soils, the effects of mixing ratio and age on the modification of expansive soils are revealed. The experimental results show that: (1) With the increase of the mixing rate of ash, the expansibility index and the liquidity index and plasticity index of modified expansive soil decrease, the content of colloidal particles decreases and the gradation curve tends to Smooth, unconfined compressive strength and elastic modulus increase; reasonable mixing rate should be 6%; (2) With the increase of curing age, swelling index, liquid limit, plastic index, , Unconfined compressive strength and elastic modulus increase.