Ground Improvement Using Soil-Cement Method: A Case Study with Laboratory Testing and In-Situ Verification for a Highway Project in Southern Vietnam

Abstract

This article presents the experimental unconfined compressive strength results of soil-cement columns to improve the soft soil gained by Tan Son Nhat-Binh Loi Outer Ring Road Project, located in Ho Chi Minh City, Vietnam. Initially, in the laboratory, two cement materials were chosen to stabilize the soil with different depths, including Stable Soil cement and tower (60%) slag cement. The specimens were prepared by mixing method. Three trial ratios of cement content (i.g. 160 kg/m³, 200 kg/m³, and 240 kg/m³) mixed into soil which obtained from 3m, 6m, 9m, 12m and 15m depths from in-situ. All specimens were cured at the age of 7-, 14-, 28-day with the temperature of 20±3°C. The laboratory test results revealed that the Stable Soil cement has a greater unconfined compressive strength than tower (60%) slag cement and it was suitable with soil condition in this area, irrespective of the curing time and depth. Based on obtained results from three trial cement ratios, the target cement content of 240 kg/m³ was satisfied not only a required compressive strength (≥ 24 kgf/cm²) but also a low-cost. In site, the deep mixing method was applied to produce soil-cement columns. The unconfined compressive strength of core specimens was tested at various depths of 3m, 6m, 9m, 12m, and 15m for test piles and official piles. The obtained results are expected to provide an experience for further design and construction in Ho Chi Minh city and its vicinity.