Effects of construction cracks on the design of asphalt pavements

Compaction of asphalt mix has been recognized as one of the most important factors that affect the long-term performance of the pavement. Problems experienced in compacting asphalt mixes have generally been ascribed to the mix. Roller "checking," the result of compaction with steel rollers, has been disregarded or considered as irrelevant. Compaction based on a new concept, using a soft plate, avoids roller checking, as demonstrated by a series of side-by-side field tests with steel and pneumatic rollers. The surface cracks initiated by the steel wheel roller may provide an explanation for the often reported phenomenon of early deterioration of asphalt pavements. Finite element analyses of pavement structures with roller-induced cracks have shown significantly higher tensile stresses than the corresponding stresses in otherwise identical uncracked pavements. The analytical findings are supported by indirect tensile and stress fatigue tests results obtained in the laboratory from asphalt samples compacted in the field. The test samples were recovered from pavements compacted either by existing compaction equipment and technique or by the new soft plate method. Key words: asphalt, crack, compaction, fatigue, finite element, tensile strength testing, pavement.