Life Cycle Greenhouse Gas Analysis of Foam Stabilizing Base

Foam stabilized base (FSB) is a cold asphalt recycled mix, which uses 100% reclaimed asphalt pavement (RAP) or a combination of RAP and crushed concrete pavement with 2 to 2.5% of foamed asphalt binder. The production process involves injecting 1 to 2% water into hot asphalt binder in a patented foaming chamber to develop foams that are 10 to 15 times the original volume of the asphalt cement. In additional to its cost advantage, foam stabilized base is more environmentally friendly than traditional bitumen stabilizers due to a reduction in natural resources, energy consumption during production and construction, and emissions of greenhouse gases (GHG). The application of FSB could help asset owners to meet their sustainability objectives and comply with relative regulatory requirements. This paper presents a life cycle analysis (LCA) of GHG emissions from FSB production and construction. The analysis assesses the environmental impacts of FSB compared with other alternative designs over the entire life cycle of pavement assets, including site preparation, raw material extraction and transportation, installation and construction, operations and maintenance, and asset demolition. Based on the analysis of a set of design alternatives and project cases, it is shown that FSB could reduce GHG emissions by up to 69.5% from project construction. This presentation is useful for 1) those who wish to understand the FSB material, pavement design, and construction; 2) designers and contractors who want to benchmark their design and construction options; 3) state and local agencies, which are increasingly mandated to improve their environmentally friendly engineering practices; and 4) researchers who wish to identify ways of improving construction designs and processes that reduce long-term GHG emissions.