Nature-based solutions applied to unpaved roads engineering (NATURE)

Dr Mariana Ramos Chrusciak,
Universidade Federal de Roraima, Brazil

Dr Bruna de Carvalho Faria Lima Lopes
Newcastle University

Research problem: Unpaved roads are integral to many developing countries’ road network systems. The construction and maintenance of these roads have to overcome two main challenges. Firstly, most of these roads are built with local soils lacking the necessary construction characteristics. Lastly, erosion needs to be controlled.

Innovation/novelty: Most MICP research has focused on adding ureolysis bacteria to soil. This is problematic because it produces toxic by-products, and the survivability of exogenous bacteria, among other reasons, restricts the development of the technology. Our research tackles these issues by exploring bio-stimulated denitrifying MICP bacteria.

Proposed solution: The conventional solutions for soil stabilisation and erosion control are not sustainable. Thus, we are proposing the use of bio-stimulated Microbial Induced Calcite Precipitation (MICP) instead. MICP is a bio-geotechnical ground improvement technique that has been demonstrated to be effective in increasing the mechanical characteristics of the soil.

Research Methodology: Firstly, soil samples collected at a road test site in Brazil will be characterised. Then, enrichment media will be investigated to increase calcite production. The load capacity and erosive susceptibility of untreated and stimulated samples will be assessed. Finally, instrumentation and treatment of the test site will take place.

Practical application and implications:  Our proposal could be a feasible alternative to develop sustainable infrastructure in cities that are difficult to access in the Amazon region. The possible implications of our research could extend beyond cost and environmental savings. This could indirectly impact the population by improving their well-being.

Assumptions:  The two research questions this research aims to answer are RQ1: Could bio-cementation produced by bio-stimulated denitrifying MICP help stabilise erosion of embankment margins of unpaved roads? RQ2: Could bio-cementation produced by bio-stimulated denitrifying MICP stabilise and reinforce unpaved roads?

Scope and limitations: Deliverable 1 (D1): Enrichment media protocol for denitrifying MICP that maximises calcite precipitation production. D2: Comparison of load capacity and erosion susceptibility between untreated and stimulated denitrifying MICP-treated samples. D3: Installation of field instrumentation and denitrifying MICP treatment in the test site. D4: Final report.