LOW TEMPERATURE TRANSVERSE CRACKS IN ASPHALT PAVEMENT IN INTERIOR ALASKA. FINAL REPORT

The formation and dynamics of low temperature transverse cracks in asphalt pavement have been investigated. Caliper measurements of crack movements showed that the average movement was 14.21 mm with a maximum movement of 27.86 mm for a one year period. A lag in crack response to air temperatures suggests that the movement of the cracks is controlled, not only by the asphalt pavement but by all the material in the top 2 m of the embankment. The cracks returned to within 1 mm of their previous widths over a period of a year. Average crack spacing was 23.6 m with a general trend of increased crack movement with an increase in average crack spacing. Pavement surface elevations near cracks were about 1.1-1.2 cm higher (relative to the nearby pavement) in February as compared to the following June. The linear thermal expansion coefficients of twelve samples recovered from asphalt pavement ranged from 17.2 to 22.3 times 10 to the minus 6 power per deg C with an average value near 19.8 times 10 to the minus 6 power per deg C. Predicted pavement cracking temperatures for three pavements in the Fairbanks area are colder than -50 deg C. Crack observations in the Deadhorse Airport runway suggest that the position and severity of low temperature transverse asphalt pavement cracks can be controlled by introducing transverse zones of weakness into the pavement and/or underlying embankment.