Development of Asphalt Pull out Tester for Investigation of Tack Coat Adhesiveness

Tack coat is a bituminous product applied to provide sufficient bond between pavement layers in which the bond strength maybe quantify through shearing, tensile or torsional mechanism. A system capable to determine the quality of tack coat in term of the tensile property is always interested for the adhesion study. A prototype device using tensile mechanism was developed to evaluate the quality of the bituminous product. The objective of the work is to examine the developed system in performing laboratory testing on tack coat applications. Two asphalt binders (PEN80/100 and PG76) were evaluated using the developed device at 3 application rates (low, medium and high), 2 contact plate diameters (50mm and 100mm) and 2 confinement loads (6kg and 12kg) on the resulting tensile strength. For the tested variables, the ANOVA test results indicated that all variables possessed significant effect on the resulting tensile strength except for confinement load. The F-statistic of the ANOVA test further concluded that specimen diameter was the most significant factor followed by application rates and the binder types. The tensile strength tested on 50mm specimen was generally higher than 100mm specimen. For binder PG76, reduction in tensile strength was observed with increasing amount of dosage while for binder PEN80/100, maximum tensile strength appeared at minimum dosage application. For this trend however, it was worthwhile to note that from the mass loss analysis, it was found that binder PG76 failed due to adhesive failure, and that the determined tensile strength do not reflect the true tensile strength of the material.