Assessing Tensile and Shear Properties of Aged and Recycled Sustainable Pavement

The effect of two types of recycling agents on aging after recycling properties of asphalt concrete , and the effect of accelerated aging (Short and Long -Term) on physical properties for aged and recycled asphalt concrete were investigated. The preparation of asphaltic mixtures involves the use of penetration grade (40-50) asphalt cement, mineral aggregate with 12.5 mm nominal maximum size, ordinary Portland cement as mineral filler. Specimens were prepared at optimum asphalt content and at asphalt contents of 0.5 percent above, and below optimum using Marshal Method. Mixtures have been subjected to indirect tensile test at 25oC, 40oC, and 60oC and double punch test. Aged specimens were prepared by subjecting the loose asphalt concrete mix to (short-term aging); the mixture was then compacted and subjected to long-term aging process. Recycled mixture was prepared from short and long-term aged asphalt concrete using two different recycling agents at (1.5%) by weight of mixture. The recycled asphalt concrete was subjected to accelerate short and long-term aging. It was found that using (soft asphalt cement blended with silica fume) as a recycling agent revealed better performance than the other type of recycling agent. Short and long-term aging after recycling shows that Indirect tensile strength at 25˚C, was less than that of recycled mix by 43%, while it increases by 16.5% and 78% when tested at 40 and 60 ˚C respectively; Punching shear strength was higher than that of recycled mixed by 34% at optimum asphalt content.