The publication in 1972 of road note no 39, 'recommendations for road surface dressing' provided engineers with up-to-date guidance on surface dressing specifications necessary to cater for the wide range of traffic conditions and types of road surface encountered. Research on surface dressing continues to develop new techniques and materials and this report gives details of a series of full-scale road trials and experiments designed to provide information on which to base revised and expanded recommendations. The three topics that have been investigated are: (1) surface dressings on concrete roads. (2) the use of cut-back bitumen and low-temperature-carbonisation tars as binders on roads in lane traffic category 2 (1000-2000 cvd). (3) the use of class k1-70 cationic bitumen emulsions as binders in road surface dressing. Recommendations proposed for the future revision of road note no 39 as a result of these investigations include the use of single surface dressings on concrete and confirmation of the use of cut-back bitumen and low-temperature-carbonisation tars on roads carrying traffic in category 2 (1000-2000 cvd). a proposed innovation is the expansion of the road note to include rates of spread of cationic bitumen emulsions for use on roads carrying less than 1000 commercial vehicles per day (categories 3, 4 and 5 of road note no 39). (Author/publisher)
Abstract