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PASER Evaluation 3 <br /> Asphalt pavement distress <br /> PASER uses visual inspection to evaluate pavement surface conditions. The key <br /> to a useful evaluation is identifying different types of pavement distress and <br /> linking them to a cause. Understanding the cause for current conditions is <br /> extremely important in selecting an appropriate maintenance or rehabilitation <br /> technique. <br /> There are four major categories of common asphalt pavement surface <br /> distress: <br /> Surface defects <br /> Raveling, flushing, polishing. <br /> Surface deformation <br /> Rutting, distortion rippling and shoving, settling, frost heave. <br /> Cracks <br /> Transverse, reflection, slippage, longitudinal, block, and alligator cracks. <br /> Patches and potholes <br /> Deterioration has two general causes: environmental due to weathering and <br /> aging, and structural caused by repeated traffic loadings. <br /> Obviously, most pavement deterioration results from both environmental and <br /> structural causes. However, it is important to try to distinguish between the <br /> two in order to select the most effective rehabilitation techniques. <br /> The rate at which pavement deteriorates depends on its environment, traffic <br /> loading conditions, original construction quality, and interim maintenance <br /> procedures. Poor quality materials or poor construction procedures can <br /> significantly reduce the life of a pavement. As a result, two pavements <br /> constructed at the same time may have significantly different lives, or certain <br /> portions of a pavement may deteriorate more rapidly than others. On the other <br /> hand, timely and effective maintenance can extend a pavement's life. Crack <br /> sealing and seal coating can reduce the effect of moisture in aging of asphalt <br /> pavement. <br /> With all of these variables, it is easy to see why pavements deteriorate at <br /> various rates and why we find them in various stages of disrepair. Recognizing <br /> defects and understanding their causes helps us rate pavement condition and <br /> select cost-effective repairs. The pavement defects shown on the following <br /> pages provide a background for this process. <br /> Periodic inspection is necessary to provide current and useful evaluation data. <br /> it is recommended that PASER ratings be updated every two years, and an <br /> annual update is even better. <br />