MECHANISMS OF CEMENTATION OF AUSTRALIAN ROAD BASES USING MICP

Author(s): Hannah Porter, Navdeep Dhami and Abhijit Mukherjee
Paper category: Proceedings
Book title: Proceedings of the Final Conference of RILEM 253-MCI Microorganisms-Cementitious Materials Interactions Volume II
Editor(s): Alexandra Bertron and Henk Jonkers
ISBN: 978-2-35158-207-7 (Set)
ISBN: 978-2-35158-210-7 (Volume 2)
e-ISBN: 978-2-35158-206-0
Publisher: RILEM Publications SARL
Publication year: 2018
Pages: 521-531
Total Pages: 308
Language : English

Abstract: Microbially Induced Calcium Carbonate Precipitation, (MICP) is a natural ‘cementing’ process observable in the formation of stromatolites and corals. During MICP carbonate crystals form bridges between soil particles, forming cementation that reduces porosity and increases strength and stiffness of the material. The technology has the potential to improve longevity and reduce embodied energy of nearly a million kilometre long Australian roads. However, its applicability in a substrate of widely varying particle size and in conjunction with cement stabilizers must be ensured. This paper evaluaes the mechanisms of MICP cementation in a substrate of road bases with a particle size distribution from 0.2mm to 20mm. The effect of MICP treatment and its effect on material with cement stabilization has been demonsrated. Bulk properties of the stabilized road bas have been characterised using unconfined compressive tests. The micro scale have been characterised using a combination of nano indentation and microscopy. It is noticed that the bacterial cells secure themselves in the grooves of the substrate and act as the nucleation site for the growth of the calcium carbonate crystals. Through quantitative energy dispersive X-ray scans the mechanism of cementing of the grains has be established. It was revealed that the bridging efficincy of MICP is higher in substrates with wider particle size distribution. This effect was found to improve even further in case of cement stabilised substrate due to improved packing and surface coating with finer particles. The results of this paper provide a fundamental explanation of the nucleation of carbonate crystals within granular substrate matrix as well as the improvement in cementing efficacy of MICP in cement stabilized substrate material.

Online publication : 2018
Publication type : full_text
Public price (Euros) : 0.00