Monitoring the Stiffness Variation of Asphalt Concrete through the Fatigue Life

Abstract

The flexural stiffness of asphalt concrete is considered as an essential parameter in the sustainability of the pavement. However, the stiffness starts to decline at an early age and throughout the service life of the pavement. Such decline in the properties is related to the dynamic loading and environmental influence. An attempt has been made in the present work to monitor the variation in the flexural stiffness of asphalt concrete through its fatigue life. Asphalt concrete mixture was prepared with its optimum binder requirement in the laboratory and compacted into a slab mold with roller compaction. Beam specimens were obtained and tested for fatigue life with the aid of dynamic flexural stresses. Three levels of constant strain of (750, 400, and 250) microstrain have been implemented while the specimens were tested at (5, 20, and 30) ℃ environment. The test results indicated that at failure, the flexural stiffness decline by (99.3, 92, and 95) % while the fatigue life of asphalt concrete increase by (90, 50, and 150) % for specimens practicing constant strain levels of (250, 400, and 750) microstrain respectively when the testing environment changes from (5 to 20) ℃. However, the flexural stiffness decline by (96.6, 90, and 95) % while the fatigue life of asphalt concrete increase by (15.6, 14, and 233) folds for specimens practicing constant strain levels of (250, 400, and 750) microstrain respectively when the testing environment changes from (5 to 30) ℃.