SUPPLEMENT TO THE RESEARCH PROJECT 7.77 ENTITLED "LABORATORY DETERMINATION OF THE SUSCEPTIBILITY OF BITUMINOUS MIXTURES TO SUBSEQUENT COMPACTION"

ERGAENZUNGSANTRAG ZUM FORSCHUNGSAUFTRAG 7.77 "ERFASSUNG DER NACHVERDICHTUNGSWILLIGKEIT BITUMINOESER MISCHUNGEN IM LABORATORIUM"

BY MEANS OF THE EXISTING GYRATOR TESTING MACHINE THE DECREASE IN THE VOIDS CONTENT IN RELATION TO THE NUMBER OF REVOLUTIONS AND SIMULTANEOUSLY THE CHANGE IN THE GYRATOR ANGLE CAN BE DETERMINED. FOR EVALUATING THE SUSCEPTIBILITY OF A BITUMINOUS MIXTURE TO COMPACTION, KNOWLEDGE OF THE DECREASE IN VOIDS AND THE ANGLE ALONE IS NOT SUFFICIENT. MOREOVER THE SIZE OF THE ANGLE IN DEGREES IN ASSOCIATION WITH THE DECREASE IN VOIDS ONLY ALLOWS A COMPARATIVE EVALUATION, AND NO COEFFICIENT IS OBTAINED WHICH COULD BE EXPRESSED IN TECHNICAL UNITS. THE ROLLER BEARING STRESSES ALSO HAVE TO BE DETERMINED, AND A DEVICE IS AVAILABLE WHICH ALLOWS THE TEMPERATURE OF THE INCORPORATED SAMPLE TO BE KEPT LARGELY CONSTANT DURING THE COURSE OF THE TEST. TO EVALUATE THE BEHAVIOUR OF THE MIXTURE THE IMPORTANT MEASURED VALUES (ROLLER BEARING STRESS, GYRATOR ANGLE AND HEIGHT OF THE SAMPLE) HAVE TO BE RECORDED ON PAPER TAPE AFTER EACH GYRATOR REVOLUTION; THIS TAPE HAS TO BE ABLE TO BE TRANSFERRED DIRECTLY TO A COMPUTER FOR EVALUATION. SUPERSEDES IRRD RESEARCH PROJECT NO 56010.