Large-Scale Bio-Cementation Test to Improve Sub-Structures of Existing Asphalt and Concrete Roadways

A large-scale bio-cementation experiment was conducted to evaluate the feasibility of microbially induced calcite precipitation (MICP) using a bioaugmentation approach with Sporosarcina pasteurii for improving the sub-structures of existing asphalt and concrete roadways. A 1.2 m x 1.2 m soil filled reactor was used, containing a 23-cm-thick layer of sand treated with five injection ports, spaced 0.3 m apart. The sand layer was sandwiched between two layers of coarse gravel, with a 2.5-cm thick grout slab on top, simulating the impermeable road surface. The MICP treatment was applied daily over 8 days. To monitor improvement, biogeochemical changes were assessed by collecting fluids from the reactor through four ports at the corners of the model. Changes to the mechanical properties were monitored both spatially and temporally using California Bearing Ratio (CBR) through testing ports on the surface. A pasteurizing waste treatment system was developed to deactivate the bio-waste. This paper outlines the design and construction of the sand box and discusses the method development. Further details will be provided regarding the injection strategy and treatment process.