Paving 101

Liberty Township streets are evaluated annually using an asphalt pavement rating form and a 0-10 scoring scale based on the pavement conditions. The following factors are rated: age of asphalt, transverse cracking, longitudinal cracking, alligator cracking, shrinkage cracking and overall ride quality. Each year, a list of streets to be evaluated is created. The streets receive two separate ratings by Liberty Township personnel. The two scores are merged to obtain an average score. The higher the rating, the greater the pavement distress. See below the types of resurfacing options Liberty Township uses.  

Types of Paving

Crack Sealing

This type of paving treatment is for roads showing signs of minor pavement distress. Pavement cracking without some type of preservation program can lead to costly road repairs due to water entering these cracks and eventually causing potholes or pavement subgrade issues. The method of preventative maintenance used by Liberty Township to address the cracking is first to blow out any loose debris from the crack and then apply a hot poly-fiber sealant into the crack. This "crack sealing" treatment is mostly used for pavement surfaces that are scheduled for resurfacing within a 3 - 5 year period. By completing this type of pavement preservation, asphalt life can be extended and costly restoration avoided. Many local maintenance departments also utilize this method of treatment as well.

Black Mat Paving/Micro Surfacing

This type of paving treatment is used on streets that show minor levels of pavement distress such as polished aggregate or minor cracking but no potholes or large areas of cracking. Black mat is a thin 1/8 - 1/4 inch layer of small aggregate and asphalt polymer and is applied as a cold mix paving. Black Mat paving restores surfaces without the need to mill existing surfaces that are structurally sound and show minor levels of distress. Black mat paving costs are approximately 60% less than standard overlay resurfacing; therefore this method serves as the primary paving option for Liberty Township in order to remain cognizant of the taxpayers' money.

Standard Overlay Resurfacing
This type of paving treatment is considered when pavement conditions score high, during ratings indicating excessive distress such as alligator cracking, potholes, etc. Overlay paving consists of milling 1 - 1.5" of the existing pavement to allow for the new pavement to match existing curb while keeping the crown in the roadway for proper drainage. Grindings are swept and a tack coat material is applied to help bond the new asphalt to the milled surface. Approximately 1 - 1.5" of surface asphalt is applied and compacted using a roller. 

It's important to note paving standards are based on a 18 - 20 year life; however many factors play a part in the breakdown or detriment of pavement life including traffic volume, traffic type and climate conditions.