PERFORMANCE EVALUATION OF STONE MASTIC ASPHALT (SMA)

Abstract

In Pakistan on National Highways with the flexible pavements the phenomena of rutting is a very common distress. This distress in roads is caused by many factors including but not limited to increase in temperature and the design techniques adopted. Road problems are not only occurring because of the increase in the traffic on roads but it also may be due to reason of poor pavement designs and structures. Pre-mature rutting phenomena and the poor selection of the aggregate gradations may also be one of the reasons of the poor road pavements. All this ultimately leads towards the loss of capital investment and makes it very difficult and uncomfortable to travel on a road section. Marshal Mix Design technique is one of the methods for finding the volumetric properties of asphalt mix. 60/70 ARL Bitumen and Marghalla crush are best suited for the making of Stone Mastic Asphalt (SMA). The addition of additive changes the behavior of asphalt and reduces the viscous nature of it. Stone mastic asphalt (SMA) using Sasobit is considered effective solution in heavily trafficked areas because of the larger single size aggregate that can be used with the increased bitumen thus controlling rutting susceptibility. Comparison of 12.7mm NMA gradation and 9.5 mm NMA gradation shows that SMA gives better results using higher gradations and the addition of Sasobit will improve the results and properties of SMA and does not change the trends in the results of higher and lower gradations.