Environmental Impact Analysis of Low-Carbon Road-Foundation Layers

Abstract

Emissions reduction and energy certifications of products are critical current issues. Both industry trends and the general public opinion are showing an increased concern about what is “sustainable,” “green,” or “energy-efficient”. Many processes and raw materials especially referring to industrial products have been analyzed to determine their environmental impacts, and “green certifications” and “eco-labels” are starting to be used by industries and companies, especially in Europe. This article presents a methodology designed to compute the carbon footprint of the stabilization of in situ soils with hydraulic binders and compares the results with the traditional supply of non-renewable resources used to build road foundation layers. The analysis is conducted by computing the emissions related to all processes (and equipment) involved in both in situ and traditional methods. A sensitivity analysis of the hauling distance of virgin aggregates (the most critical activity in the traditional process) assesses the influence of transportation activities on the entire construction process. The analysis shows that improving in situ soils through cement stabilization can save more than 80% in emissions if compared to the supply of traditional granular layers (assuming embodied energies are not considered). A “sustainable road pavement” should certainly consider the reuse of in situ soils to limit emissions during construction activities.