Investigation of the Relation between Adhesion and Water Sensitivity Test Results

The relation between the results of adhesion and water sensitivity tests was investigated. The tests were performed according to the relevant European standards. Two paving grade bitumens (PGB) with different gradations were used in combination with three adhesion additives and basic, neutral and acidic coarse aggregate. It was concluded that each of the additives enhanced the evaluation of the adhesion regardless of the type of binder and aggregate. All the additives combined with PGB 35/50 improved the water sensitivity results. A better result with PGB 50/70 was observed with only one additive. It was noted that an assessment of the efficiency of an adhesion additive based on a change in the water sensitivity value (ITSR) can contradict a change in the indirect tensile strength. The expected reduction in values with an increase in the coarse aggregate acidity was only confirmed for the adhesion test. The change in the ITSR and the indirect tensile strength of dry and wet samples did not fit the expectations. The correlation between the results of the adhesion and water sensitivity test was low and could not be recommended for predicting the indirect tensile strength of asphalt from rolling bottle test results.