Methods for calculating temperature profiles of hot-mix asphalt concrete as related to the construction of asphalt pavements

Abstract

Temperature is an important v a riab le in the compaction of hot-mix a sp h alt concrete.Cooling ra te s d iff e r s ig n if ic a n tly and a ff e c t the allow able time for compaction to sp e c ifie d density,, The a b i l i t y to p re d ic t mix tem perature fo r any environment, time, and place in the mix is of considerable importance in estim ating the allow able time for compaction a f t e r placement of the mix.Mathematical expressions describe the flow of heat or thermal energy from the hot-mix asphalt concrete to the upper and lox-zer -su rfac e s of the mix.Environmental or boundary conditions: wind v e lo c ity , i n i t i a l base tem perature, so la r ra d ia tio n , and time a ffe c t the flow of thermal energy to the upper and lower surfaces of the mix.I n te r a c tio n of the conductive, r a d ia tiv e , and convective modes of therm al energy con tro ls the flow of heat from the upper surface to the atmosphere, w hile the conductive mode of tra n s fe r alone co n tro ls the flow of heat from the lower surface to the baseG A numerical or f i n i t e d iffe re n c e so lu tio n was used as the b asis for a computer program for c a lc u la tin g tem peratures as a function of time, place in the mix, and various environmental co n d itio n s.For use in the computer program, data for wind v e lo c itie s were converted to Biot numbers, and data for so la r a lt it u d e were converted to s o la r-ra d ia n t flux.Constant physical i i i