Annotated Summary
Li, B. (2015). Geotechnical properties of biocement treated sand and clay. Doctoral dissertation, Nanyang Technological University, Singapore. Retrieved from https://hdl.handle.net/10356/62560
This thesis focuses on the applications of microbially induced calcium carbonate precipitation(MICP) in Singapore, which includes a feasibility study on using biocement to improve the mechanical properties(shear strength and compressive strength) of clay as well as sand. Evaluation of different implementations of MICP for soil was made, and in particular, the results obtained from using injection techniques to simulate those anticipated in practice yielded cementation efficiency of more than 90% in sand. The strength of MICP treated clay was also evaluated, and results for unconfined compression strength fell within the range of 150% - 400% gain when compared to the initial. The thesis highlighted that even though the initial cost estimates for the chemicals supersedes that of conventional cement, material cost can be lowered by ordering chemicals on an industrial scale.
The thesis provides useful information for our research project on the use of biocement to strengthen weak soils during underground construction. From the aspect of sustainability, the precipitation of calcium carbonate from the above-mentioned MICP process, as shown by the research in the article, is a CO2 sequestering reaction. This would make biocement serve two purposes: Strengthen soil and eliminate CO2 from the atmosphere. While the experiments were only performed and tested in a lab setting, the thesis still provides useful information and statistics on the stabilization of soil using MICP, which is a relevant aspect for our research project.
Commented on Syahmi's, Ardini's, Sharif's, Ken's, Jaime's Annotated Summary on 31/03/20
Hi Brien,
ReplyDeleteIt is really an interesting annotated summary and it is well-versed in the applications of MICP. But one thing come to my mind is, if I'm not wrong, you are using grouting methods to strengthen the weak soil but I wonder where will be the cement grout injected to as there'll be buildings around and if it is happened to be inside the buildings, is there any affects as the buildings are on problematic soils?
Overall, well done for your annotated summary.
With regards,
Thazin
Hi Thazin thank you for your reply! Well actually the injection of the solution is into the ground and forced to flow through the soil highlighted to be experiencing differential settlement by an artificially induced pressure head difference. By this technique, the injection can occur from the soil outside the base concrete slab supporting the structure. The solution being highly liquid also helps by ensuring full saturation of the soil underneath the said structure. This method is used to improve the soil and cannot be used to repair the existing damages in the building. Hope this is enough to clear up the doubts you had!
DeleteHi Brien,
ReplyDeleteYour annotated summary was very interesting and informative. The flow was consistently well throughout the summary.
A question is what is the current cost for implementing the biocement in a small-scale?
I would love to see this project come into fruition in the future.
Warm regards,
Muhd Sharifuddin
Hi Sharif thank you for your reply! The sad thing is for small scale testing, the materials and chemicals required becomes quite costly because we can only source them from chemical suppliers in small quantities. However with the help of an educational institute, i am pretty sure that the chemicals could be purchased at a much more palatable cost.
DeleteHowever for the implementation of the technology in the field, cost estimates ranging anywhere from 50 cents to 9 dollars per meter cube of treated soil is to be expected. Thank you for your reply!
since chemicals purchased in bulk tends to be much cheaper.