Characterisation of asphalt pavement materials

The main objective of this research work was to characterise the performancerelated properties of asphalt mixtures (rutting, and cracking) through dynamictesting. Appropriate analytical and experimental procedures were developed todetermine the elastic moduli and resistance of asphalt concrete to permanentdeformation and fatigue cracking through a routine test program. A repeated loadingapparatus called MATTA (Material Testing Apparatus) along with a direct tensiontest device developed in the School of Civil Engineering were used in this researchstudy.A dense graded asphalt with one type of aggregate having a maximum size of 20mm along with four binder types (C-170, C-320, Multigrade, and Cariphalte) wereused. Two types of equipment were used for compaction of the specimens. Gyropacwas used for manufacturing cylindrical specimens for the resilient test, creep test,indirect tensile fatigue, and direct tension tests. A new Shear Box apparatus wasemployed to manufacture rectangular beams for the four point beam testing.This experimental study investigated the effect of mix variables, temperature, anda polymer additive (SBS) on the mechanical properties of different asphalt mixes.Indirect repeated tensile resilient modulus test and uniaxial repeated creep tests werecarried out to characterise the resilient and plastic behaviour of asphalt concrete. APhenomenological approach was used to characterise the fatigue behaviour ofasphalt concrete. Furthermore, two mechanistic methods, fracture mechanics anddissipated energy approach were employed to characterise fatigue behaviour ofasphalt concrete using the four point beam test.Models were developed to estimate the resilient modulus of several asphalt mixesat different temperatures and rise times. It was found that a polymer modified binder( Cariphalte) significantly enhanced the resistance of asphalt concrete to permanentdeformation (rutting). It was also found that the indirect tensile fatigue test could beused to characterise the fatigue behaviour of asphalt concrete providing, a quick andaffordable test method. A new approach for the definition of the failure point and thenumber of repetitions to crack initiation and crack propagation were developed. Itwas found that dissipated energy could be used to obtain fatigue properties ofasphalt concrete without performing a time consuming fatigue test. A surrogatemodel chosen from limited mixes was developed to estimate the fatigue life ofasphalt mixes based on initial mix stiffness and initial phase angle. A new simpleand affordable approach was used to apply fracture mechanics principles in order todetermine crack initiation and crack propagation of asphalt concrete as well as theparameters needed by Paris' law