TEMPERATURE CONDITIONS IN BITUMINOUS CONCRETE SURFACINGS AT A SITE NEAR MELBOURNE DURING A PERIOD OF THREE YEARS

THE TEMPERATURES AT DIFFERENT DEPTHS IN TWO BITUMINOUS CONCRETE SURFACINGS HAVE BEEN RECORDED OVER A THREE-YEAR PERIOD AT A TEST SITE NEAR MELBOURNE. THE RECORDED DATA WERE ANALYZED FOR: (1) ANNUAL VARIATION OF TEMPERATURE INCLUDING MAXIMUM AND MINIMUM TEMPERATURES RECORDED, (2) SEASONAL VARIATION OF TEMPERATURE, AND (3) DAILY VARIATION OF TEMPERATURE. RESULTS OF AN ANALYSIS OF THE DATA FOR THE FIRST YEAR OF OPERATION WERE PUBLISHED AND THE ANALYSIS FOR THE LONGER PERIOD REPORTED HERE CONFIRMS THAT THESE RESULTS WERE REPRESENTATIVE. TEMPERATURE CONDITIONS IN THE FIRST YEAR WERE SLIGHTLY MORE EXTREME THAN THOSE ENCOUNTERED IN THE OTHER TWO. THE IMPLICATIONS OF THE OBSERVED MAXIMUM RATES OF COOLING OF THE 1-1/2 IN. BITUMINOUS CONCRETE LAYER ON THE POSSIBILITY OF THE CRACKING OF THE LAYER FROM STRESSES INDUCED BY THERMAL CONTRACTION ARE DISCUSSED. CRACKING BY THIS MECHANISM ALONE IS POSSIBLE IF THE LAYER ATTAINS A SUFFICIENTLY HIGH MODULUS (OR LOW COMPLIANCE) AT LOW AMBIENT TEMPERATURE AFTER IT HAS BEEN IN SERVICE FOR SOME TIME. TENSILE STRESSES PRODUCED BY HEAVY VEHICLES MOVING OVER THE LAYER WILL AUGMENT THOSE PRODUCED BY THERMAL CONTRACTION SO THAT CRACKING IN SERVICE CAN BE EXPECTED AT A LOWER MODULUS. /AUTHOR/