In view of the unstable characteristics of expansive soil such as expansion and contraction, cement-metakaolin modified expansive soil samples were prepared. The mechanical properties and microscopic mechanism of modified expansive soil were studied by free expansion rate test, unconfined compression test, direct shear test and scanning electron microscopy (SEM). The test results show that the free expansion rate of the improved soil decreases slowly with the increase of the content of metakaolin in 7% cement improved expansive soil. The compressive strength and shear strength increased first and then decreased, and the improvement effect was the best when the content of metakaolin was 4%. The incorporation of metakaolin accelerates cement hydration, increases gel content, optimizes pore structure, and enhances mechanical properties. The effect of cement-metakaolin on expansive soil is remarkable. The test results show that the free expansion rate of the improved soil decreases slowly with the increase of the content of metakaolin in 7% cement improved expansive soil. The compressive strength and shear strength increased first and then decreased, and the improvement effect was the best when the content of metakaolin was 4%. The incorporation of metakaolin accelerates cement hydration, increases gel content, optimizes pore structure, and enhances mechanical properties. The effect of cement-metakaolin on expansive soil is remarkable.

Yuguo Zhang, Zhaobin Zhang, Chunhao Zhao, Zilai Zhang, Jinshuai Kou, Zhan Jing. Experimental Study on Engineering Characteristics of Cement-metakaolin Composite Modified Expansive Soil. Academic Journal of Architecture and Geotechnical Engineering (2024) Vol. 6, Issue 4: 62-69. https://doi.org/10.25236/AJAGE.2024.060410.

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