| Reflective cracking, a common distress that affects composite pavements is caused by cyclical movements in the underlying concrete base that is overlaid with hot-mix-asphalt in reaction to climate and traffic conditions. In an attempt to prevent or control reflective cracking the saw and seal method, which involves making saw cuts in the overlaying asphalt across and along the direction of travel and sealing with a compressible rubberized low modulus sealant, is studied for its effectiveness in composite pavements in Washington DC. In the 4 ½ year field study, the widths of the fifteen transverse and seven longitudinal saw-cut measurement points in the hot-mix-asphalt overlay were measured every three months. Multiple regression analyses and statistical tests of significance were conducted to determine the statistical relationship between the changes in mean daily air temperature, average daily traffic, pavement age and the variations of the saw-cut widths. The interactions of changes in mean daily air temperature and average daily traffic (ADT) had a statistically significant impact on variations in transverse and longitudinal saw-cut widths accounting for 95.7% and 91.4% of variations respectively. Pavement age also had a significant impact but was excluded due to multicollinearity with ADT. In conjunction with the statistical analyses, a visual condition comparison with the adjacent untreated pavement section showed that, the saw and seal method effectively controlled reflective cracking in the composite pavement. |
