Evaluation of Longitudinal Cracks in Flexible Pavements with SMA Surfacing Layer

Stone Matrix Asphalt is a sort of hot mix asphalt that is used to increase pavement resistance against rutting. According to their high initial construcion cost, SMA mixtures are usually used in heavy traffic areas. Although these mixtures have more binder than conventional asphalt mixtures, special attention is required for their resistance to fatigue cracking, because traffic level in pavements with SMA surfacing layer is high. According to the new design guide for flexible pavements, damage of top-down fatigue cracking is considered in pavement design, so it is desirable to investigate the effects of SMA layer thickness, subgrade condition, climatic condition and base layer thickness on the longitudinal cracking (top-down) that is created in pavements with SMA surfacing layer. The results obtained from MEPDG software show that the cracks are more when subgrade layer strength is higher. Furthermore, by increasing the thickness of SMA layer, longitudinal cracks increase at first and then decrease.