Application of the ecorce m tool to investigate pavement premature failure on South African roads

Abstract

Minimising the consumption of materials, energy and water during construction, and evaluating environmental impact indicators and finding ways of reducing environmental impact indicators can help to build sustainable road networks in South Africa. Ecorce M is a tool that was developed by the French Institute of Science and Technology for Transport, Spatial Planning, Development and Networks (IFSTTAR) in collaboration with CEREMA of the French Ministry of Ecology, Sustainable Development and Energy (MEDDE). This tool deals with construction and structural maintenance of pavements, installation of foundation layers, preparation of upper part of earthworks and construction of fills. It identifies and evaluates possible measures for improving the environment and it provides Life Cycle Inventory. This tool further provides environmental indicators and yields environmental indicators relative to the earthworks undertaken from an overall perspective. The Ecorce M tool is used in this research to measure consumption of materials, energy and water. It is also used to calculate the values of environmental impact produced by indicators during road construction and rehabilitation. Ecorce M reduces the consumption of materials, water and energy by means of evaluating impacts and assessing environmental impact indicators in road construction. These environmental impact indicators are calculated by identifying and quantifying the flows of energy and materials. Inputs used on this study comprise data gathered from a project that took place in Klerksdorp, namely the Patchwork, Rehabilitation and Reseal of Road P3/ 4 (N12) from Road R503 to Archbishop Desmont Tutu Street Phase 2. The inputs that have been taken into account are: geometry of each layer, composition and mass density of the component layer material, hauling distances and unit consumption values for construction vehicles. The outcomes achieved include, but are not limited to, the amount of material consumption, energy consumption and water consumption. The emissions produced for the following indicators have also been achieved: greenhouse effect indicator; acidification potential, eutrophication indicator; tropospheric ozone; toxicity and eco-toxicity indicators. Most of materials consumption occurs during materials extraction, most of the energy is consumed during processing of aggregates and most of the water is consumed during mixing and processing layer works. Most of the environmental impact indicators result from materials used with 54% on average, and machinery used weighs 46% on average.