Volumetric Properties of Stone Mastic Asphalt Mixtures Containing Tear Off Shingles

Stone Mastic Asphalt (SMA) is a tough, stable, rut-resistant mixture that relies on stone-to-stone contact to provide strength and a rich mortar binder to provide durability. The design of an SMA is critical in providing an aggregate grading that will be compatible with the high bitumen content that provides durability without binder drainage. This project investigates the use of tear-off shingles in SMA to produce economic mixtures. The mixture containing shingles were compared to control mixes (without shingles), but with fibers at the same level as those mixtures containing shingles. As per Superpave method of mix design all mixes met the air void ratio at N (design) and N (max). SMA mixtures were tested using Marshall Method for stability and flow. Mix design results showed that all required volumetric properties can be achieved with lower binder content if shingles can be added to SMA mixes. The critical property in SMA (the draindown) was controlled and the tensile strength ratio was improved by using tear-off shingles.