Publication Abstract

DFI - PFSF Piling & Ground Improvement Conference 2022 Proceedings, (DFI and PFSF)

Comparison of Cement Injection Options for Deep Mixing
Chew Soon Hoe, Audrey H. M. Yim, Juan Wei Koh, Say Cheong Ng, Kok Eng Chua, Lionel Ang, Pei Ling Goh, Yi Shan Toh and Zi Xiang Gng

Deep mixing (DM) is widely used to improve the strength and stiffness of soil. When installed in an earth bund used to retain water, the DM columns are needed to improve the stability of the slope and act as a low permeability barrier for seepage cut-off. In this application, the permeability properties of the treated soil must be considered, on top of strength requirements. One concern in DM construction is the uniformity along the DM column. Good mixing processes and a sound quality assurance and quality control (QA/QC) programme are crucial to ensure good quality DM columns that fulfil both strength and permeability requirements. For DM construction, there are two options in which cement can be injected into and mixed with the soil during penetration of soil mixing tool (penetration injection) or during retrieval of soil mixing tool (withdrawal injection). In this paper, a trial was conducted with DM columns constructed by these two injection options. Cored samples were collected and tested. This paper investigates the effect of injection options on the uniformity and quality of the DM column with respect to different soil types and operating parameters. An appropriate QA/QC programme has been developed and proposed for actual construction.

 article #3836; publication #1076 (IC-2021)