Evaluation and Improvement of Bituminous Maintenance Mixtures (1377-1F)

The objective of this study was to provide the Texas Department of Transportation with a means to assure quality of cold-applied asphalt stabilized maintenance mixtures. Samples of 17 different maintenance mixtures were obtained from across the state and 14 of these were stockpiled at Texas A&M's Riverside Campus. These materials were evaluated in terms of field aging and field workability. To evaluate the aging of the field materials, laboratory tests were performed to determine resilient moduli, tensile strength and extracted binder properties. Findings indicated that only minimal aging occurred in most of the mixtures in a six-month period.|The workability of the stockpiled field materials was subjectively evaluated and compared to laboratory measurements aimed at quantifying workability. Comparisons of field ratings to laboratory measurements indicated that there was no clear relationship.|Two test procedures were evaluated regarding their potential to quantify the workability of HMCL asphaltic mixtures: (1) a biaxial compression test, and (2) unconfined compression test. Test results indicated that both procedures provide a relatively good measure of workability.|Two laboratory aging procedures were evaluated for their ability to predict workability of a stockpiled maintenance mixture after 6 months of stockpile aging.|Test protocol and acceptance criteria were developed to estimate the relative ability of a maintenance mixture to retain adequate workability after outdoor stockpile storage.