Permeability Measurements of Reinforced Asphalt Overlays

Rutting, fatigue and thermal cracking are the most prominent pavement degradation observed in Canada. The presence of cracks on the surface allows water to seep into the pavement structure and accelerate its degradation. One of the options to remove cracks is to mill a thin layer and replace it with a new layer. Unfortunately, reflective cracking reappears very quickly on the surface. It is, however, possible to add a layer of reinforcement, a geotextile (paving fabric), or a geogrid that can help resolve this problem. The objective of this study is to investigate the effect of the addition of an impregnated paving fabric over a cracked surface. To do that, a new test was developed to simulate the crack propagation in the lab when a paving fabric is used. Permeability tests were then performed on cracked specimens to evaluate if the paving fabric can still function as a waterproofing layer even if the asphalt is cracked below and above it. Finally, rutting resistance tests were done to check if the paving fabric impacts this property. The results have shown that the developed test setup for cracking propagation with a paving fabric works very well. It was demonstrated that even with a crack width of 6 mm on the surface mix, the overall system remains waterproof, which means that water will not accelerate the pavement degradation. However, the rutting test has shown that the presence of paving fabric has a negative effect on the rutting resistance. Overall, the results show that the use of impregnated paving fabric over a cracked surface does increase the rehabilitated pavement performance.