MECHANICAL PROPERTIES OF ASPHALT MATERIALS AND STRUCTURAL DESIGN OF ASPHALT ROADS

Abstract

NUMEROUS PROPOSED RATIONAL APPROACHES TO BITUMINOUS ROAD DESIGN CONTRIBUTED BY PREVIOUS INVESTIGATORS ARE REVIEWED. THE MECHANICAL PROPERTIES AND THE TEST METHODS FOR THE PROPERTIES OF MATERIALS ENTERING INTO CONSTRUCTION OF ROAD CARPETS ARE DISCUSSED. THE CHARACTERISTICS OF ASPHALTS AND AGGREGATES WHICH AFFECT BOTH THE ELASTIC AND PLASTIC BEHAVIOR OF MIXTURES ARE DESCRIBED. THE PROBLEM OF ANALYZING THE PROPERTIES AND FUNCTIONS OF BASE COURSES, SUB-BASES, AND SUB-SOIL LAYERS ARE DISCUSSED. DESIGN METHODS FOR ROAD CONSTRUCTIONS ARE PRESENTED. DESIGNS FOR THE ENTIRE LAYERS SYSTEM FOR STATIC LOADS AND THE DESIGN FOR ONLY THE ROAD CARPET FOR STATIC LOADS ARE DISCUSSED IN DETAIL. IT IS SHOWN THAT FOR SAND SHEET, TENSILE STRENGTH DECREASES WITH INCREASED DURATION OF LOADING IRRESPECTIVE OF TEMPERATURE. BONDING STRENGTH DECREASES WITH AN INCREASE IN THE NUMBER OF LOAD REPETITIONS APPLIED TO THE SPECIMEN. THIS INDICATES THE EFFECT OF FATIGUE. IT IS CONCLUDED THAT TO AVOID CRACKED FORMATION, THE LOWEST F/B RATIO COMPATIBLE WITH OTHER CRITERIA SHOULD BE EMPLOYED.