膨胀土粉煤灰改性与石灰改性对比试验研究

Test Study on Fly Ash-treated Expansive Soils Compared to Lime-treated Expansive Soils

开展了典型中膨胀土、粉煤灰改性土与石灰改性土的基本物理特性、击实特性、强度特性比较试验。试验结果表明:1)相比于未改性土,粉煤灰改性土和石灰改性土自由膨胀率、塑性指数、胶粒含量都显著降低;2)随着粉煤灰掺入比的增大,在重型击实标准下,改性土最优含水量呈增大趋势,最大干密度呈下降趋势;3)两种改性土CBR峰值都显著提高,当掺入比合适时,CBR膨胀量显著降低,改性后水稳定性较好;4)两种改性土都可同时满足规范对压实度和CBR的要求。最后探讨了与石灰相比粉煤灰改性方案的适用性与可行性。

Comparative tests on basic physical characteristics, compaction behavior, and Califomia beating ratio of typical middle expansive soils, fly ash - treated soils and Lime - treated soils have been carried out. The test results indicate that： 1 ） Compared with unmodified soils, the free swelling ratio, plastic index and clay fraction of fly ash - treated soils and Lime - treated soils decrease obviously. 2） As the fly ash quality ratio increases, the optimum water content under heavy compacting standard of improved soils increases but the maximum dry density decreases. 3） The California beating ratio peak values of two kinds of modified soils increase obviously and the CBR swelling ratio decrease obviously when the quality ratio is suitable, the water - stabilities of improved soils are better than unmodified soils. 4） Both of two kinds of modified soils can satisfy the standard requirement of the compacting degree and CBR. At last the applicability and the feasibility of the plan to use fly ash compared to lime are discussed.