The relationship between surface cracking and the structural capacity of both thin and thick pavement structures was invesigated using field data from the fhwa pavement testing facility test sections.The test sections were loaded with the accelerated loading facility. Surface cracking was evaluated in terms of lineal cracking and aasho class 2 and 3 cracking; structural capacity was evaluated in terms of peak deflections and backcalculated moduli of the asphalt concrete layer under falling weight deflectometer testing. The field dataindicated a definite lag between the loss of structural capacity and the appearance of surface cracking for both thin and thick pavements. Because a structural capacity loss may exist before cracks appeared on the surface, the use of surface cracking to indicate structural condition may be misleading in several cases. Field data on peak deflections indicated that the deflection ratio may reach a value of2 before any surface cracking appears and a value of 3 before any aasho class 2 and 3 cracking appears on the surface. The backcalculated moduli of the asphalt layer were reduced by 50% before any linealcracking or aasho class 2 and 3 cracking appeared on the surface. This paper appears in transportation research record no. 1227, Rigid and flexible pavement design and analysis: unbound granular materials, tire pressures, backcalculation, and design methods.
Samenvatting