The Field Quality Assessment of Soft Ground Improvement Using Soil Cement Mixing Technology in Ho Chi Minh City Vietnam

Abstract

The Soil Cement Mixing technology (SCM) was employed to create soilcrete columns to improve soft ground and soilcrete retaining walls for excavation to construct reservoirs Ho Chi Minh City, Vietnam. However, several core samples taken in various field soilcrete columns appeared visually non-uniform material and had unexpectedly low strength during the field quality evaluation. The quality of the massive construction was questionable and needs to be further assessment. The available data such as the soil investigation before the construction, design documents, pilot columns, field quality data, and mixing machine data were obtained. The several field, laboratory tests, and additional soil investigation after the construction were conducted. The core sampling in the field soilcrete columns, the river water and groundwater tests, and the strength of the soilcrete specimens made in the laboratory were performed. The results of the robust analyses from the all data indicates that the very high organic content of the in-situ soil, the low pH of the river water, and the low cement content of 220 kg/m³ were the key factors causing low quality of the field soilcrete columns created by the massive construction. The invalidated operation parameters of the mixing machines which were different from those of the machine used for the pilot tests were also convinced by a significant cause of the low field quality soilcrete.