TVBIT 6 - "GUSSASPHALT AND MASTIC ASPHALT"

THE ISSUE IN 1975 OF TVBIT 6 TAKES ACCOUNT OF THE PROGRESS SINCE 1960 WITH THIS CONSTRUCTION METHOD. TVBIT 7/71 REGULATED CONTRACTUAL MATTERS SUCH AS ACCEPTANCE, GUARANTEES AND FINAL ACCOUNTS. IN ADDITION THE BMV INTRODUCED IN 1975 A NEW STANDARD (RSTO 75) GOVERNING THE STRUCTURE OF BITUMINOUS PAVEMENTS. THE CHANGES COMPARED WITH TVBIT 6/60 CONCERN AMONG OTHER THINGS GREATER PERMISSIBLE GRADIENTS IN LAYING, THE STIPULATION THAT THE BASE MUST ONLY BE FREE FROM ICE AND SNOW AND MAY NOT HAVE A CONTINUOUS COVERING OF WATER, THAT BINDER COMPLYING WITH TVBIT 3 MAY NOT BE USED, AND THAT THE ASPHALT MUST BE HIGHLY STABLE AND MUST CONTAIN EITHER A MINIMUM PROPORTION OF VOIDS OF 6-10% BY VOL OR HAVE A VERY LOW VOID CONTENT (LESS THAN 2% BY VOL). GUSSASPHALT IS CLASSIFIED ACCORDING TO MAXIMUM AGGREGATE SIZE (0/5, 0/8 AND 0/11), FORMERLY ACCORDING TO GRIT CONTENT. ONLY BITUMEN B45 CONTAINING AT LEAST 2% BY WEIGHT OF TRINIDAD-EPURE IS USED. PAVING THICKNESS AND MAXIMUM AGGREGATE SIZE ARE RELATED. SMALLER TEST INDENTATIONS ARE NOW REQUIRED, WHICH MEANS A STIFFER FORMULATION AND HIGHER PERMISSIBLE MIXING TEMPERATURES (NOW 200-250 DEGREE C). MUCH SPACE IS DEVOTED TO INITIAL SURFACE ROUGHNESS, FOR WHICH A NUMBER OF METHODS ARE GIVEN. THE PROBLEM OF ELIMINATING RUTS HAS BEEN SOLVED SUCCESSFULLY IN A TEST CARRIED OUT IN 1971. FURTHER CONSTRUCTIONS OF VARIOUS THICKNESSES (1-7 MM) AND ROLLING WITH STEEL OR RUBBER-TIRED ROLLERS HAVE CONFIRMED THE SUCCESS ON NEWLY CONSTRUCTED STRETCHES. FINALLY THE DEFORMATION DAMAGE DURING THE 1976 HEAT WAVE IS DISCUSSED. RECOMMENDATIONS FOR REMEDIAL MEASURES ARE CURRENTLY BEING PREPARED. IN PRACTICE THE USE OF GUSSASPHALT WITH COPIOUS CHIPPINGS AND THOROUGH ROLLING OFFERS THE MOST ADVANTAGES.