Rejuvenating Fog Seal Research

On June 18 and 19, 2007, Caltrans District 9 (D9) placed six rejuvenator seal test sections to preserve a  section in the eastbound number two lane ( right lane), often used by trucks, on  Highway 58 between PM 123.3 and 125.1 east of Mojave, California in Kern County .  This roadway is 4-lane divided freeway with a 65 MPH speed limit.  The weather during the application was dry with light winds.  

The California skid test (CT372) and ASTM E274 locked wheel skid trailer were used to evaluate friction before and after treatment application. Two of the 6 treatments (CRF and Reclamite) were sanded after application to blot excess emulsion. The skid numbers dropped about 30 % after the application of the treatments. 

Cores were obtained before and after treatments to determine if the rejuvenators softened the upper millimeters of existing pavement.  The bending beam rheometer (BBR) stiffness and m-value testing showed the CRF and PASS-QB products softened the existing pavement; however, this finding is unexpected based on previous experience by the monitoring team.  The CQS-1h emulsion significantly increased the stiffness of the pavement. The dynamic shear rheometer (DSR) test method was too variable (coefficient of variation of about 50%) to determine if there was any statistical difference between the treatments and the control sections.

In the summer of 2011, a follow-up survey was completed and additional testing conducted. The results of the survey showed that the treatments have improved the performance compared to the control with some treatments softening the existing pavement more than others

This is the initial phase of further planned testing. Conclusions cannot be drawn until further work is done and the remaining test sections are completed.