Laboratory fatigue performance evaluation of different field laid asphalt mixtures

Fatigue associated distresses are considered to be one of the major causes of failure in flexible pavement. Continuum micro cracking and healing in the pavement as a result of repeated traffic leads to micro damage, which ultimately coalesce into macrocracking. In the present study, fatigue performance of 12 asphalt mixtures has been investigated using 4-point flexural beam fatigue testing. Specimens were extracted from the field laid asphalt mixes. The purpose of this work is to assess the toughness of different field laid asphalt mixtures in laboratory fatigue testing. Two different types of aggregate gradations (coarse and fine), three different types of fillers (stone dust, cement and sand) and two different grades of bitumen (60/70 and 80/100 penetration grade) have been used to make asphalt mix samples. It has been observed that asphalt mix with composition of finer gradation, stone dust as filler and 80/100 penetration grade bitumen showed more fatigue life compared to other mixes. Also, slope coefficients (K2) obtained from the fatigue curves of different mixes ranges from 2.03 to 4.25, which is in line with what has been reported by other researchers. Present study revealed that asphalt mixture prepared with stone dust as filler, yielded highest fatigue life of asphalt mixtures compared to other filler types. Reasonable correlation exists between the fatigue coefficients (K1 and K2).