4 INTRODUCTION An asphalt concrete pavement section typically consists of three primary layers over native subgrade soil: 1. Surface course (asphalt concrete pavement). 2. Base course (engineered roadbase). 3. Subbase course (granular soil). These layers work together to support vehicular traffic. They are referred to as a flexible pavement section because they have the ability to resist cracking while deflect under traffic loads and expanding and contracting with temperature changes. However, even the best-designed and best-constructed pavement sections require maintenance. Many factors can lead to pavement distresses. They can be related to the pavement section itself (design or workmanship issues), the underlying native subgrade soil, environmental effects such as sun and water, physical damage such as cuts to install utilities, settling utility trenches, unexpected traffic loading, frost heave (expansion of wet fine-grained soil that freezes) or just the passage of time that leads to the asphalt becoming more brittle and years of traffic loading. Identifying the cause of distress helps make good use of money spent on treatments applied to address them.
RkJQdWJsaXNoZXIy ODQxMjUw