TREATMENTS FOR REDUCTION OF REFLECTIVE CRACKING OF ASPHALT OVERLAYS ON JOINTED-CONCRETE PAVEMENTS IN GEORGIA

For the past 6 years, the Georgia Department of Transportation has placed emphasis on the rehabilitation of the concrete pavement sections of the Interstate system. Many of these sections were resurfaced with asphaltic concrete. One of the problems that had to be addressed was that of reflective cracking of the joints into the overlay. A research project began in 1976, which consisted of placing 16 asphalt overlay test sections with various treatments on an existing jointed-concrete pavement on I-85 north of Atlanta. The treatments consisted of two nonwoven fabrics and sections with strips of a waterproofing membrane. The treatments were repeated for each of three overlay thicknesses. The philosophy behind the experiment was that no treatment would completely stop reflective cracking, but it would provide a waterproofing barrier to prevent surface water from entering the pavement system and thereby cause pumping of the concrete pavement. The waterproofing membrane was included in the experiment for this purpose and was placed in strips over the joints and cracks while the fabrics were placed full width. In 1979, additional test sections were placed on I-85 south of Atlanta to evaluate three types of waterproofing membranes and a nonwoven fabric. The fabric material was placed in strips rather than full width in this experiment. Overlay thicknesses of 2 and 4 in. were placed over the test sections. The performance to date indicates that the treatments reduced the rate of reflective cracking for the 4- and 6-in.-thick overlay sections. Some improvement was also obtained with the 2-in. overlay section, and the best performance was obtained with the waterproofing membrane. (Author)