Five test methods to evaluate moisture sensitivity and the performance of lime in hot mix asphalt pavement.

摘要

Five test procedures were used to evaluate five mechanical properties and one material property before and after multiple cycles of moisture conditioning for 15 hot mix asphalt (HMA) mixtures. Hydrated lime as an aggregate treatment was used in 12 of the mixes in an effort to enhance mixture properties. An analysis of variance through statistical methods was used to compare the HMA mixes and rank the best method for introducing lime to the HMA mixtures.; The 15 HMA mixtures were comprised from two aggregate sources and three grades of asphalt binder. Lime treating consisted of dry lime added to damp aggregates or the application of a lime slurry. In addition, lime treated mixes were subjected to either zero or 48 hours of marination.; Multiple cycles of freeze-thaw conditioning were implemented as an accelerated moisture damage technique. Moisture sensitivity of the mixtures was evaluated by statistically comparing mixture properties before and after moisture conditioning.; A diametral loading resilient modulus test was used to evaluate the stiffness of the mixtures. A modified version of AASHTO T-283, indirect diametral loading split tensile test, was used to appraise each mixture's tensile strength property. The repeated shear at constant height derived from the Superpave Simple Shear Test (SST) apparatus assessed each mixture's shear strain property. The Thermal Stress Restrained Specimen Test (TSRST) evaluated both a material and mechanical property. These measured properties were the coldest temperature which caused the specimen to yield in tension. A repeated axial load, triaxial test was used to evaluate the mixture's accumulation of axial strain.; The analysis shows that mechanical and material properties for unconditioned, lime treated mixtures and untreated mixtures are relatively the same. After moisture conditioning, the mechanical properties of untreated mixes are severely reduced in comparison to the lime treated mixtures. The evaluation for a superior performing mix to resist moisture sensitivity among the four methods of lime application was statistically inconclusive. In ranking the four methods of lime treatment by their ability to retain mechanical or material properties while being subjected to moisture conditioning, dry lime added to moist aggregates, marinated for 48 hours was shown to have superior performance.