METHODS FOR CALCULATING TEMPERATURE PROFILES OF HOT-MIX ASPHALT CONCRETE AS RELATED TO THE CONSTRUCTION OF ASPHALT PAVEMENTS

METHODS OF PREDICTING THE TEMPERATURE OF HOT-MIX ASPHALT CONCRETE, AS A FUNCTION OF TIME AND PLACE, IN THE MIX FROM THE MOMENT IT LEAVES THE PAVER UNTIL COMPACTION TO SPECIFIED DENSITY IS COMPLETED WERE INVESTIGATED TO PROVIDE A MEANS FOR ENVIRONMENTAL CONDITIONS THAT MAY BE MARGINAL WITH RESPECT TO OBTAINING ADEQUATE COMPACTION AND TO STIMULATE THE DEVELOPMENT OF PROCEDURES FOR OBTAINING ADEQUATE COMPACTION UNDER ADVERSE ENVIRONMENTAL CONDITIONS. A NUMERICAL OR FINITE DIFFERENCE SOLUTION WAS USED AS THE BASIS FOR A COMPUTER PROGRAM FOR CALCULATING TEMPERATURES AS A FUNCTION OF TIME, PLACE IN THE MIX, AND VARIOUS ENVIRONMENTAL CONDITIONS. FOR USE IN THE COMPUTER PROGRAM, DATA FOR WIND VELOCITIES WERE CONVERTED TO BIOT NUMBERS AND DATA FOR SOLAR ALTITUDE WERE CONVERTED TO SOLAR RADIANT FLUX. CONSTANT PHYSICAL PROPERTIES FOR THE MIX AND BASE WERE ASSUMED AND USED DIRECTLY FOR DATA INPUT TO THE COMPUTER PROGRAM. THE EFFECT OF WIND VELOCITY, SOLAR RADIATION AND ATMOSPHERIC TEMPERATURE IS GREATER ON MIX TEMPERATURES NEAR THE UPPER SURFACE OF THE MIX THAN ON MIX TEMPERATURES NEAR THE LOWER SURFACE OF THE MIX. INITIAL BASE TEMPERATURE DISTRUBITION AFFECTS TEMPERATURES NEAR THE LOWER SURFACE OF THE MIX TO A MUCH GREATER EXTENT THAN IT AFFECTS TEMPERATURES NEAR THE UPPER SURFACE. STUDY RESULTS INDICATE THAT TEMPERATURES OF THE HOT-MIX ASPHALT CONCRETE NEAR THE LOWER SURFACE DECREASE MORE RAPIDLY THAN TEMPERATURES NEAR THE UPPER SURFACE. SINCE COMPACTIVE EFFORT IS LESS NEAR THE LOWER SURFACE, TEMPERATURES NEAR THE LOWER SURFACE ARE OF PARTICULAR SIGNIFICANCE IN OBTAINING SPECIFIC DENSITIES. THE NUMERICAL METHOD OF DETERMINING THE TEMPERATURE DISTRIBUTION IN HOT-MIX ASPHALT CONCRETE LENDS ITSELF WELL TO COMPUTER PROGRAMMING AND PROVIDES A MEANS OF INVESTIGATING THE EFFECT OF AN ALMOST LIMITLESS NUMBER OF ENVIRONMENTAL CONDITIONS ON THE COOLING OF HOT-MIX ASPHALT CONCRETE DURING CONSTRUCTION.