Abstract:
The growing concerns over climate change and the move towards sustainable, cost-
effective road development have resulted in the development of bio-based construction
methods. Microbial induced calcium carbonate precipitation (MICP) binds material through
the formation of calcite bridges between soil grains. Current MICP treatment techniques,
however, are not compatible with road construction processes. Due to this the Council for
Scientific and Industrial Research (CSIR) has started investigating bio-stabiliser treatment
techniques for road construction. The objective of this paper is to present Unconfinded
compressive strength (UCS) results for a G8 material stabilised using in-situ bacteria
present in the soil. After 10 days of cementation solution treatments a UCS dry result of
1.16MPa was achieved. No wet UCS results were, however, produced as all the samples
disintegrated. The decision was made to supplement MICP with 0.7% cement. Not only did
UCS wet results show a 100% increase compared with MICP only treated samples, but
the UCS dry results were comparable to adding 2.5% cement to the G8 material. Partial
replacement of cement with MICP during stabilisation could lead to an overall reduction in
the amount of cement used in road construction without compromising strength, which will
have a positive environmental and economic impact.
