| Description |
When applied at the right time, Hot Mix Asphalt (HMA) Thin Lift Treatments (TLTs) extend the life of flexible pavements. Correct application depends largely upon pavement condition and rate of deterioration. State Highway Agencies (SHAs) utilize an Open Grade Surface Course (OGSC), Dense Grade Asphalt (DGA), and Stone Matrix Asphalt (SMA) for TLTs. No criteria currently exist to select the best performing mix for factors such as traffic, climate, previous road conditions, and prior treatment methods. Additionally, TLT performance is largely dependent upon local climate conditions and individual state Pavement Management Systems (PMSs). Thus, performance evaluation needs to be done at the local level. This study assessed the early performance of TLTs in Utah by measuring surface cracking within the first two years of service life. This study evaluated 14 TLTs, consisting of eight OGSC, four DGA, and two SMA mixes. Pavement Condition Indices (PCIs), deterioration rate, failure thresholds, and expected design lives identified five early failures. Four of five of these failures resulted from cold temperature thermal cracking. A comparison made from local TLTs to national TLTs, monitored through the Federal Highway Administration’s (FHWA) Long Term Pavement Project, showed a much higher failure rate for the nationally treated roads of 87% to 36%. Cold-temperature related cracking was the predominant early distress type found, both locally and nationally. |
