| General Conclusions The goal of the study was to determine the effectiveness of spray applied sealers. The user survey, the collected laboratory and field data, and the field observations all confirmed that a defined application strategy of fog seals is a cost-effective tool for pavement preservation. The seals appeared to protect the surface by reducing permeability to moisture for several years after application. Visual comparisons with control sections showed water running off of sealed surfaces instead of penetrating. Fog sealing decreased friction, but original skid resistance returned over time. Sanding after application increased the friction levels significantly. The portable CTM and DFT devices appear to be a reasonable surrogate for full scale friction testing. However, the friction results were higher on the Reclamite sections using both portable and full scale testing than might be predicted from a simple spinning tire field test using a rear-wheel drive pick-up truck. Rheological testing showed the high temperature modulus of binder within 3/8 inch of the surface was reduced by those sealers containing rejuvenator oils, as long as the pavement was permeable enough for the emulsion to penetrate. None of the rheological data showed significant differences in the stiffness of the binder or the corresponding dense-graded mix more than ½-inch deep in the pavement. Of course better penetration can be expected for open-graded HMA or asphalt-rubber mixes. Mixture testing, however, was too variable to draw conclusions for any open mixes. It appears one of the roles of the spray applied seals is as a sacrificial layer to address surface cracking. The sealers were generally inexpensive and yet effective in providing protection to pavements and prolonging service life. The primary constraint to the use of sealers on dense HMA mixes appears to be a loss in friction following application. Sealers can also prolong the life of seal coats and open-graded mixes, where concerns with friction loss are considerably fewer. Specific conclusions may be found in each of the “Lessons Learned” sections on the pages of this website. |