Carbon Footprints Assessment of RBI Grade 81 Stabilized Pavements using Life-Cycle Approach

Objectives: To reduce the life-cycle carbon footprint of a flexible pavement using RBI grade 81, a patented natural soil stabilizer. Methods: This paper outlines the common guidelines for estimation of greenhouse gas emissions associated with a pavement as per the Indian environmental conditions. California Bearing Ratio (CBR) tests were carried out on subgrade soil treated with diverse proportions of RBI grade 81. Greenhouse gas emissions due to the initial construction phase and maintenance activities over a 20 year life cycle were assessed and compared for RBI grade 81 treated and non-treated subgrades. Key sources of carbon footprint considered were construction materials and transportation with construction equipments having negligible contribution. Findings: Studies reveal significant improvement in the CBR of the subgrade soil leading to reduction of pavement layer thicknesses thereby limiting the requirements of resources that is to say materials, fuel and machinery. The total CO₂ emissions were reduced from 910.9 tonnes to 750.8 tonnes per km length of a four lane dual carriageway road by treating the subgrade soil with 4% RBI grade 81. The production of materials and transportation used to construct the project account for 93% and 7% of the total CO₂ emissions throughout the life cycle of the pavement. Improvements: Use of RBI grade 81 results in attenuation of greenhouse gas emissions which were found consequential in amassing of carbon credits, a step towards safeguarding the environment for the future generations to come.