Development of Mix Designs for Minimally Refined Reclaimed Asphalt Pavement (RAP) Concrete for Florida Concrete Test Road

The main objective was to develop mix designs for concrete incorporating minimally processed reclaimed asphalt pavement (RAP) materials to be used in the Florida Concrete Test Road. The laboratory program was conducted in two phases. Phase I involved testing of twelve (12) trial mixes to identify feasible mixes which could meet the Florida Department of Transportation (FDOT) specification requirements for pavement concrete. Based on the preliminary test results from the trial mixes, ten (10) production mixes were identified and evaluated more extensively in Phase II to establish the optimum concrete mixes incorporating RAP to be recommended. Concrete mixtures, with 0% to 40% RAP as aggregate replacement and using 20% fly ash and 50% slag as cement replacement, were designed using the optimized aggregate gradation (OAG) technique instead of the American Concrete Institute (ACI) method. Among the RAP concrete evaluated, the 20% RAP concrete mixes with 0%, 20% fly ash, and 50% slag as cement replacement were able to meet Florida Department of Transportation’s (FDOT) over-design compressive strength of 29 MPa (4200 psi) at 28 days. Using 20% and 40% RAP in concrete could result in saving in the total cost of aggregate by 9% and 17%, respectively. When the RAP is not refined (e.g., no washing of RAP, and no separating of coarse and fine portions), it is recommended that 20% of RAP can be used as aggregate replacement in pavement concrete.