Suggested Citation:
Mateos, Angel, Irwin M. Guada, John T. Harvey (2026)

Assessment of Field Performance of Rubberized HMA with RAP Pilot Projects—Year 3

. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-26-28

Abstract:

This technical memorandum presents the results of a visual assessment of five pilot projects constructed by Caltrans between 2022 and 2023 as part of a Caltrans-industry initiative aimed at evaluating the feasibility of using 10% reclaimed asphalt pavement (RAP), by aggregate replacement, in rubberized hot mix asphalt–gap-graded (RHMA-G) mixes, which is currently not permitted under Caltrans standard specifications. Each pilot project included a section constructed with RHMA-G incorporating 10% RAP while the remainder of the project was built with a conventional RHMA-G containing no RAP. The visual assessments were conducted between October 2025 and January 2026, when the projects had been in service for approximately 2.4 to 3.1 years. The assessment included, for each pilot project, a 0.4-0.6 miles long section built with RHMA-G with 10% RAP and an adjacent section, either immediately upstream or downstream, built with conventional RHMA-G without RAP. Overall, both RHMA-G mixes—with and without RAP—performed satisfactorily across the five pilot projects. In three projects, no significant distresses were observed in either of the two mixes. In the remaining two projects, cracking was observed; however, the extent of cracking was greater in the sections without RAP than in the sections with RAP. The satisfactory preliminary performance of the mixes with RAP across the five pilot projects supports the continued use of 10% RAP in RHMA-G.