The growing demand for performance testing within the asphalt industry accentuates the need to have consistent handling, sample preparation, and storage of asphalt mixture test specimens. As more agencies are moving to balanced mix design (BMD) and implementing performance tests, there is an urgent need to standardize the fabrication practices of asphalt specimens to avoid disputes between agencies and contractors. One major gap identified in NCHRP Synthesis 552: Practices for Fabricating Asphalt Specimens for Performance Testing in Laboratories is the effect of the storage practices of loose mixtures and compacted specimens on the mixture aging, which further affects the mixture performance. Therefore, the inconsistent storage practices will result in disputes between agencies and contractors regarding the BMD properties during the mix design and quality acceptance. To address this issue, this study will focus on defining aging terms related to sample storage and establishing suitable storage practices based on the storage-related effects on mixture properties. The proposed practices will minimize the disputes among agencies and contractors regarding the mixture properties. This study will provide recommendations to supplement current materials standards regarding the mix design and performance testing to promote the implementation of BMD.

The objective of this research is to assess the impact of storage time of loose mixtures and compacted specimens on performance properties of asphalt mixtures. The main outcome from this study will be a recommendation for an AASHTO Standard Practice on storage requirements for asphalt mixture performance tests. This will include storage time and conditions (e.g., sealed vs. unsealed, type of container, location of container, temperature, humidity) for loose mixtures, compacted bulk specimens, and prepared test specimens. This study will focus on plant-produced mixtures targeting the acceptance process and will also verify storage impacts on laboratory- versus plant-produced mixtures from both a cracking and rutting performance standpoint.