MIX AND STRUCTURE OF I-710'S LONG-LASTING PAVEMENT

California's I-710 project includes full-depth asphalt concrete sections, which replace portland cement concrete (PCC), and asphalt concrete overlays on cracked and seated PCC. The asphalt mix and pavement section structural designs rely on technologies developed in the Strategic Highway Research Program (SHRP) and employ innovative construction specifications, as well as requirements stemming from the work of the California Department of Transportation (Caltrans) Accelerated Pavement Testing (CAL/APT) Program. The original pavement section consisted of PCC, cement-treated base, and aggregate base and subbase. The pavement, which opened to traffic in 1952, was in poor condition, since it had not received any overlays before the reconstruction. Rehabilitation included two strategies: (1) Crack and seat the PCC and apply an asphalt concrete overlay; and (2) If an overlay would cause the clearance under a structure to fall short of the minimum, replace the PCC pavement with full-depth asphalt concrete sections, lowering the grade to provide the required clearance. This article provides details concerning the asphalt mixes, the structural sections and the system of checks and controls. Caltrans, the Asphalt Pavement Association of California, and the University of California, Berkeley partnered in determining the designs and the construction requirements. The partnership provided opportunities to implement new ideas and research results on a project for which traditional approaches were insufficient.