Modeling of interface bonding of bituminous pavement layers for tropical climate

The bonding strength of bituminous layers is an element of paramount consequence, as it defines the structural performance of flexible pavement layers. Failure to establish the required strength will lead to the occurrence of pavement distresses. This study was conducted in pursuance of the aims of identifying and further analyzing the significant parameters affecting interface bonding strength. Type of tack coat, application rate and residual application rate of tack coat, curing time, and surface macro-texture were determined as the parameters, upon the examination of past studies. Another parameter which had not been subjected to prior examination- the absorbed emulsion content was also discovered. Furthering the research, correlations of these parameters were studied based on field data and laboratory data. Field data were collected from in situ tests, namely the sand patch test and test methods which estimate rate of application, and the absorbed emulsion content test, conducted on actual road construction projects, while laboratory data comprised of interface shear strength of pavement core samples which were evaluated through the Moratuwa Interface Shear Strength Tester (MISST): a device that had been designed in line with the research especially for the purpose of evaluating interface shear strength of pavement core samples. Established on the observations, a final model capable of evaluating interface shear strength of bituminous pavement layers was developed based on application rate determined by geotextile pads and corrected absorbed emulsion content computed through a past study: significant parameters affecting interface shear strength. It was thus observed that interface shear strength increases when the application rate estimated by the geotextile pads decreases, and when the corrected absorbed emulsion content increase