Several pavement failures have been observed to be initiated at or near the surface of the hot-mix asphalt layers and some of them propagate downward through the surface layer (top-down cracking). These modes of failure are affected by heavy vehicular loading configuration, pavement structure and their interaction at the tire-pavement contact. This paper documents an experimental investigation ...

The dynamic modulus (|E*|) is one of the primary hot-mix asphalt (HMA) material property inputs at all three hierarchical levels in the new Mechanistic-empirical pavement design guide (MEPDG). The existing |E*| prediction models were developed mainly from regression analysis of an |E*| database obtained from laboratory testing over many years and, in general, lack the necessary accuracy for mak...

The National Center for Asphalt Technology (NCAT) completed a roundrobin study in March to determine the accuracy and precision of the NCAT asphalt content tester. The Center has conducted research since 1990 to develop this test method for determining asphalt content of hot mix asphalt (HMA) mixtures by ignition (See the fall, 1994, issue of Asphalt Technology News). In the ignition method, a ...