SPECIAL BITUMINOUS SURFACES ON ROADS

THE EXPERIENCE OF THE UNUSUALLY HOT SUMMER OF 1976 HAS SHOWN THAT MORE SIGNIFICANCE SHOULD BE ATTACHED TO THE DESIRED COMPOSITION OF BITUMINOUS MIXES AND TO LAYING TECHNIQUES. ON THE BASIS OF COMPLETED TESTS, REFERENCES ARE MADE TO METHODS BY WHICH THE PRODUCTION AND LAYING OF BITUMINOUS MIXES MAY BE IMPROVED, PARTLY BEYOND THE FRAMEWORK OF TECHNICAL SPECIFICATIONS AND GUIDES WHEN PARTICULAR STRESSES ARE CAUSED BY THE CHANNELLING OF HEAVILY LOADED TRAFFIC (AS ON UPHILL STRETCHES, AREAS IN THE VICINITY OF INTERSECTIONS, BUS LAY-BYS AND BRIDGE SURFACES). THE USE OF A HARDER BINDER IN 8.5 CM THICK LAYERS, INCREASING THE QUANTITY OF CHIPPINGS AND OF THE LARGE AGGREGATE IN WEARING SURFACES AND INCREASED USE OF ROLLED GUSSASPHALT ARE ALL SUGGESTED. AT THE SAME TIME MODIFIED BINDERS ARE CALLED FOR WHICH EITHER POSITIVELY INFLUENCE THE ELASTIC BEHAVIOUR OR THE COMPRESSIVE AND SHEAR STRENGTH AND ALSO THE USE OF SPECIAL FILLERS ARE MENTIONED. BY MEANS OF EXAMPLES FROM ENGLAND AND FRANCE, WHERE PARTICULARLY HARD STONE AND MODIFIED BINDERS ARE USED, IT IS SHOWN HOW SKID-RESISTANCE CAN BE IMPROVED.