Standard cold-opened mixtures, characterized by the high number of gaps or openings (>20%), low refined content (<5% go through a 2.5mm-sieve) and a very low filler content (<2% go through a 0.08mm-sieve) have long been used in Spain, at a volume ranging between 2 and 2.5 million tons, basically as a rolling layer in medium volume and high volume roads. The fine-tuning of these new types of cationic emulsions, polymer-modified asphalts, associated with high quality sand and cement, has paved the way for a new generation of cold-opened mixtures with significantly improved mechanical characteristics such as stability and resistance to acceptably high tangential efforts, even immediately after laying down the mixture. Its application, with a maximum sand and cement size of 12 mm, in thin layers on surface renovation public works of ageing pavements, provides a rolling surface with excellent drainage features, macrotexture and resistance to skidding. This paper describes the treatment undertaken in 1991, consistent with the application of a 3-cm thick layer of a bituminous cold-opened mixture made with an average rolling emulsion with modified binder over a surface of 120,000m2 of the A-4 autoroute between Sevilla and Cdiz. This paper also describes the materials, the design method used, as well as the initial superficial and drainage features and their evolution over time. Its performance over the years confirms the fact that these modern cold-opened mixtures can be used without any problem on high-speed roadways. (A)
Samenvatting