FATIGUE AND ELASTIC CHARACTERISTICS OF ASPHALTIC CONCRETE MIXES --14TH ARRB CONFERENCE, 28 AUGUST - 2 SEPTEMBER, 1988, CANBERRA, ACT, AUSTRALIA; PROC. PARTS 1 - 8

A laboratory investigation was undertaken to determine the effect of several variables on the fatigue life and mix stiffness of three commonly used continuously graded asphaltic concrete mixes by the road construction authority. A repeated flexure machine operating in controlled stress mode was used to test rectangular beams of about 50 mm square. The factors investigated were bitumen content and viscosity class, air voids, loading time, temperature and tensile stress. The effects of these factors on mix stiffness were shown to agree with work reported by others. The stiffness doubles for every 7 per cent decrease in air voids and and every 7 per cent decrease in temperature. For asphaltic concrete temperatures between 10-30 degrees celsius, mix stiffness cn be reliably estimated from the shell (1978) procedure. Stiffness values at various traffic speeds are given for a use in mechanistic pavement design. The data suggests that the shell fatigue life relationships adopted in the naasra pavement design guide tend to underestimate field performance for thin (less than 50 mm) asphaltic concrete surface pavements but are satisfactory for full depth and deep strength asphaltic concrete pavements. No changes to the naasra guide fatigue relationships are recommended at this stage (a). For the covering record of the conference, see IRRD no 808936.