Investigation of the Microstructural Mechanisms of Relaxation and Fracture Healing in Asphalt
Annual rept. 15 Aug 90-15 Sep 91
TEXAS TRANSPORTATION INST COLLEGE STATION
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Three research issues are addressed 1 establishment of a mechanism of chemical healing of microcracks within the process zone preceding the macrocrack, 2 establishment of the mechanism or mechanisms of relaxation and creep in asphalt cements of various types and 3 establishment of a formal tie between permanent strain in asphalt concrete and cyclic loading and the creep compliance function. A methodology has been developed by which to quantify the degree of fracture healing that occurs in asphalt concrete. The methodology has been verified by testing thirteen different asphalts with widely varying compositions and chemistries. This method of establishing the amount of fracture healing that occurs in asphalt concrete as the result of rest periods is being used to establish the microstructural mechanism responsible for fracture healing. Rheo-optics and infrared analysis using a Fourier transport infrared spectrometer are being used to establish the microstructural composition of asphalt cements that influence or control the creep, relaxation and fracture healing processes.
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