HMA Mix Types The most common type of flexible pavement surfacing in the U.S. is hot mix asphalt (HMA). Hot mix asphalt is known by many different names such as hot mix, asphalt concrete (AC or ACP), asphalt, blacktop or bitumen. For clarity, this Guide makes a...
Aggregate “Aggregate” is a collective term for sand, gravel and crushed stone mineral materials in their natural or processed state (NSSGA 1991). In 2009, the U.S. produced nearly 2 billion tons of aggregate at a value of about $17.2 billion. Roads and...
WAPA Design Checklist This page puts forth some basic guidance for use when designing HMA pavements and is meant to be used as a checklist. When designing a pavement, the guidance listed here should at least be considered. The guidance contained on this page is not...
Top Down Cracking Top down cracking appears to be a common mode of HMA pavement distress in at least several states and countries. Traditionally, pavement cracking is thought to initiate at the bottom of the HMA layer where the tensile bending stresses are the...
Pavement Evaluation Categories Pavement performance is a function of its relative ability to serve traffic over a period of time. Typically, a system of objective measurements is used to quantify a pavement’s condition and performance. These systems are used to...
