Immediately upon being laid, new asphalt pavement begins the process of oxidation. This is the reaction of oxygen exposure wherein molecular processes begin the process of creating bonding sites or layers within the asphalt itself. This allows for the asphalt molecules to search and find bonds that help it to maintain its stable state for maximum efficiency. 
As this is an ongoing process, over time the tighter and tighter bonding of these molecules can result in the pavement becoming stiffer and more brittle and subject to cracking, potholes and other failures, possibly even resulting in costly drainage issues. An example of the effects of asphalt oxidation can be seen in the severe cracking of this asphalt parking lot showing a web of asphalt cracking issues and drainage damage therein.
By taking proactive measures you can reduce the rate of asphalt oxidation. Implementing a strict scheduling of asphalt sealcoating can reduce oxidation by as much as 75% if initiated within the first two years of being lain. Asphalt should be resealed about once every three years, depending upon usage and vehicular load, to maintain their appearance and protect them. For more severe cases of asphalt deterioration such a severe cracking and spider web-cracks in a large area, then asphalt crack filling should be performed first before sealcoating. Sealcoating asphalt that has already oxidized will not bring back its elastic properties.
