Exploring the use of the saw and seal method for mitigation of reflective cracking in composite pavements

Abstract

Reflective cracking, a common distress that affects composite highway pavements, is caused by cyclical movements of the underlying concrete base that is overlaid with hot-mix-asphalt in reaction to climatic and traffic conditions. A saw and seal method, which involves making saw cuts in the overlaying asphalt, (above the concrete joints) and sealing them with a compressible rubberized low modulus material, was studied for its effectiveness in mitigating reflective cracking in newly constructed pavements in Washington DC. In the 4½ year field study, the widths of the transverse and longitudinal saw-cuts made in the hot-mix-asphalt overlay were measured every three months at 22 saw-cut points. 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 sawcut widths. The interactions of changes in mean daily air temperature and 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 a similar adjacent pavement section built without any saw-cut treatments showed that the saw and seal method effectively controlled reflective cracking in the composite pavement.

Performance Comparison of Break and Seat and Rubblization Rehabilitation Techniques for Reflection-Crack Mitigation: Case Study in Louisiana

“…Sawing and sealing HMA overlays at joint locations is a crack-control technique, where saw cuts are created on the overlying HMA layer directly above the joints in the underlying PCC layer and then filled with a low-modulus rubberized sealant ( 2 , 3 ). The low-modulus sealant prevents moisture intrusion and stops incompressible objects getting into the base and subgrade layers.…”

“…The low-modulus sealant prevents moisture intrusion and stops incompressible objects getting into the base and subgrade layers. Further, it absorbs the movements in the underlying PCC layer caused by traffic and periodic temperature changes ( 3 ). Researchers have demonstrated in a previous study that the saw and seal method of reflection-crack prevention has the potential to improve the service life of a typical composite pavement by 4 years ( 4 ).…”