Evaluation of Cemented and Fly Ash Treated Recycled Asphalt Pavement and Aggregates for Base Construction

摘要

Many entities currently use recycled asphalt pavement (RAP) and other aggregates as base material, temporary haul roads, and, in the case of RAP, hot mix asphalt construction. Several states currently allow the use of RAP combined with cement for a stabilized base course under both asphalt and concrete pavements. Currently, there is disagreement on what properties are required, and how to test the cement and fly ash treated RAP for both asphalt and concrete pavement structures. The objective of this study was to determine feasibility of cement and fly ash treated RAP and other aggregates as a structural layer for both portland cement concrete and hot mix asphalt pavement systems. A 610 limestone from Kentucky was used as the reference material. Other materials used in the study include: Mexican 610 limestone, gravel and limestone based RAP, and blended calcium sulfate (BCS). Samples were prepared with three cement and fly ash contents and tested for compression and flexural strength. Length changes specimens were also produced and the resilient modulus was measured. Mixtures achieving 150 and 300 psi are capable of being produced with 4 to 8 percent portland cement and 10 to 20 percent class C fly ash. The compacted specimens achieved equal to or up to two and a half times greater compressive strength than those samples that were uncompacted. The reference and Mexican 610 limestones produced much higher strengths compared to the RAP BCS mixtures. The BCS mixtures proved adequate in terms of shrinkage, strength, and did not fall apart when stored in the 100 percent humidity room or underwater for the requisite 14-day cure period for the length change test. The resilient modulus results were similar across all samples, but no discernible trend could be determined, most likely due to the test containing only one sample for analysis.