Utilization of fatigue test to predict stripping of asphalt concrete mixtures

Abstract

Stripping is the separation of the asphalt cement film from the aggregate surface due to the action of moisture. Three types of aggregate: crushed limestone, uncrushed valley gravel, and crushed basalt, asphalt cement, and two anti-stripping additives: hydrated lime and a polyamine liquid additive were used. The stripping potential is evaluated by a Fatigue test using the Universal Testing Machine. Marshall specimens were prepared with optimum asphalt and 6-8% air voids, with; no additive, hydrated lime dosages of (1.5-2.0%) by weight of aggregate and the polyamine dosage of (0.75-1.0 %) by weight of asphalt. High saturation degree 60 - 80% of the air voids volume was used. It was concluded that aggregate type is the most significant variable that affects the stripping. The anti-stripping agents are effective in cases where the potential of stripping is high. All aggregates types have shown a tendency for stripping at a high degree of saturation. Limestone showed the best stripping resistance, better than valley gravel and basalt. The results indicated that cycles to failure at a given strain (1000 micro-strain) were improved as the accumulated strain for all mixtures. The use of the fatigue test gives a necessary indicator of the performance of moisture potential and additive effects.