PAC, short for porous asphalt concrete, is a popular type of asphalt as top layer or wearing course for motorways in The Netherlands. Less hydroplaning, less trouble due to splashing water and also less sound of vehicles roaring over it. All because the material is porous: coarse granulate ‘glued’ to each other by a small amount of bitumen. Due to the interconnected ‘porous’ cavities, rainwater can drain away easily and car noises can be absorbed to some extent.

But the porous structure of VAC adversely makes the material sensitive to loosening granulate. This phenomenon, known as ravelling, shortens the life span of the top layer – certainly when compared to dense asphalt concrete. This booklet describes the phenomenon ravelling, its causes and possible solutions in the form of self healing asphalt. After all, if the material is able to repair itself, maintenance will be necessary on a lower level, reducing road construction and, hence, traffic jams. A new generation of pavements with a high added value will become within reach. Besides technical matters, also financial aspects of self healing asphalt are dealt with.

Here you can download the bilingual (both Dutch and English) booklet Self healing in road construction as a PDF file. You can find parts of this booklet about road composition, asphalt, PAC and bitumen, as well as the vision of the future in brief as separate downloads in PDF format.

Published as:
Self healing in road construction, a bilingual publication (Dutch/English) of Rijkswaterstaat, publication number DVS1110, November 2010, 60 pages.

External link:
Click here for the website of Rijkswaterstaat (Dutch Public Works and Water Management).