Fatigue Design Criteria for Low Noise Surfaces

Internationally low noise porous asphalts (PA) are typically laid on top of structural asphalt layers. In New Zealand structural asphalt is generally prohibitively expensive and PA is used directly on chipseal-surfaced unbound granular pavements. Two accelerated pavement tests funded by Land Transport New Zealand were undertaken at the Canterbury Accelerated Pavement Testing Indoor Facility in 2004–2005. The first test was to develop a horizontal tensile strain vs. fatigue life curve and establish a relationship between base course surface curvature and fatigue life. The second test evaluated the extension of fatigue life by initial trafficking rather than using enhanced binders in PA. The outcomes of the project suggest that the Austroads Pavement Rehabilitation Guide is very conservative in predicting fatigue and that deformation leads to surface failure before fatigue occurs. Pavements sealed with low noise surfaces could tolerate more deflection if initial trafficking was undertaken.