New surface-dressing binders are required for treating difficult road sites where vehicles turn or brake. Conventional bituminous binders lack the cohesive strength necessary to retain chippings under the shear stresses imposed. On the other hand, current types of epoxy-resin-based binders, which are able to cope with high stresses, are too expensive for all but the most severe sites where large savings from reducing skidding accidents compensate for their high initial cost. The properties and performances of a wide variety of new binders are being studied at the laboratory. This report describes two road experiments with new, probably cheaper, thermosetting binders containing smaller proportions of epoxy-resin. In the first the performances of 7 binders were compared by laying small areas of surface dressing at the approach to a roundabout. Four of these performed well enough to be tested further in full-scale road experiments. So far, one full-scale experiment has been laid using one of these binders, and after 16 months of trafficking it is still performing well. (Author/publisher)
Abstract