DFI Journal - The Journal of the Deep Foundations Institute

Volume 9, Issue 1, May 2015
DOI: 10.1179/1937525515Y.0000000002

All Journal papers are free to DFI members.
If you are a member, please click on the "Login" link at the top of this page to to download this paper.

Not a member? Join here to get access to all papers or click the purchase button below to access this paper only.

Performance of Biocemented Sydney Sand Using Ex Situ Mixing Technique
Article Type: Research Paper

Duraisamy, Y. & Airey, D. W.


This paper describes a small-scale demonstration of an ex situ mixing technique that uses biocementation as an alternative to existing ground improvement techniques. The main objective of this research is to improve the strength and the stiffness of loose sand. Biocemented sand specimens have been produced by mixing a urease producing bacteria with nutrients and Sydney sand. Triaxial test with bender elements and the physical model test are conducted to investigate calcium carbonate precipitation and the properties of the soil. The model foundation tests have been performed at 1 g in a cylindrical tank with diameter of 600 mm. The tank has been filled with loose Sydney sand and a cemented column of 38 mm in diameter has been created in the center of the tank. A footing of 90 mm diameter has been placed on the sand surface and loaded to large displacements. The ability of the biocemented column made by ex situ mixing to significantly improve the foundation response is well demonstrated. Triaxial test performed on biocemented specimens also showed significant strength and stiffness increase over uncemented specimens. These tests confirmed the feasibility of using ex situ mixing technique to induce biocementation and provide valuable insight into the factors that must be considered in developing field applications.

bio-cement, deep soil mixing, physical model, urea hydrolysis, calcite precipitation, ground improvement