A marked trend in road construction is the more systematic consideration of the influence of the activity not only on the environment but also on staff, road users and residents. This requires an improvement in knowledge and the more effective application of techniques accompanied by increasingly large-scale measures to reduce their overall impact. Colas is actively committed to the aims of sustainable development and in this framework hasdeveloped a procedure for manufacturing what are commonly known as warm mixes. The objective is to reduce energy consumption and greenhouse gas emissions, and also emissions of fumes which may be unpleasant for road users, residents and laying teams. This process was undertaken in a strictly-managed framework, with strong constraints on the targeted results, in particular a reduction of 40degreeC in the manufacturing and laying temperature of tnatives for producing environmentally friendly energy saving mixes. Both of these are based on the control of binder rheology. The first focuses principally on the viscosity of the binder and the other mainly involves themanufacturing process. The selection of a final mix temperature in excessof 100degreeC and the complete elimination of water guarantees a level of perforventional hot mixes. Moreover, these mixes can be laid using existing industrial plant directly, which limits the investment required and facilitates their large-scale deployment. These mixes retain their workability when laid using conventional techniques. They have been tested successfully for a 3 year period under all possible worksite conditions and with intense heavy vehicle traffic. They have been monitored by the technical services of central government and their performance has proved completely satisfactory. In particular, emissions of fumes have been reduced to the great satisfaction of all involved and energy consumption measurements confirm the estimates that were made in the framework of a partial life cycle analysis of the products. The findings show a reduction in energy consumption during manufacture of at least 18% and a 20% reduction in greenhouse gas emissions. For the covering abstract see ITRD E139491.
Abstract