RAP and RAS in HMA Pilot Project on SBD 215: Material Testing, Observations, and Findings

A pilot project for the inclusion of high percentages of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) was built on State Route 215 in San Bernardino County in September 2022. Five mixes were included in short test sections: (1) a controlmix with no recycled asphalt shingles (RAS) or RAP, (2) a mix with 25% RAP and recycling agent (RA), (3) a mix with 30% RAP and RA, (4) a mix with 35% RAP and RA, and (5) a mix with 40% RAP and RA. A sixth mix, which was a typically used mix with 23% RAP, was used for construction of the rest of the overall project. This technical memorandum presents the laboratory test results from plant mix produced for job mix formula verification and from one or two quality assurance (QA) samples, depending on the test, taken during test section construction as well as observations of plant production and construction. Only the control mix binder consisting of the virgin PG 64-28M base binder and the mix with PG 58-34M, 25% RAP, and RA passed the delta Tc specification. There is FHWA guidance and past UCPRC experience with other polymer-modified Caltrans mixes that indicate delta Tc may not be a good parameter to use with modified binders. The mixes with 30%, 35%, and 40% RAP and RA and the mainline mix did not meet the PG specification low temperature limit. All the mixes easily passed the IDEAL-CT (cracking tolerance) index number. Construction QA sampled binder test results indicated that the PG 58-34M binder was used for the control mix with no RAP instead of the specified PG 64-28M binder. Results are presented for volumetric tests, flexural and axial dynamic modulus tests, repeated load triaxial tests, flexural fatigue tests, Hamburg Wheel-Track tests, and IDEAL-CT tests with reheated and medium-term oven aged samples reported in terms of the IDEAL-CT index and indirect tensile strength.