Evaluating the field performance of asphalt mixtures in the lab

The National Cooperative Highway Research Program (NCHRP) is developing advanced pavement technology that Supports the Federal Highway Administration's (FHWA) mission to achieve long-lived asphalt pavements. One of these advanced technologies is the Simple Performance Tester (SPT), which evaluates asphalt mixtures to determine their response to permanent deformation (rutting) and fatigue cracking. FHWA is supporting NCHRP's research by evaluating how well the SPT works in a field laboratory environment. Highway engineers have been looking for a simpl e, inexpensive, and accurate performance test for hot-mix asphalt (HMA) since HMA first came into use in the late 19th century. One of the first tests was the Hubbard-Field method, developed in the 1920s, which measured the strength of the asphalt by using a punching shear load to test for failure.