Application Study On The Ultrathin Thin SMA-5 Gradation Design And Pavement Performance

SMA has been used for over ten years in China. To date almost all of the SMA mixes have had either a 13.2 or 16.0mm nominal maximum aggregate size (NMAS) . For a variety of reasons, the reseach and application are less toward thiner 4.75mm NMAS SMA both here and abroad, and new specifications don't relate to thin SMA-5 mixture. The existence of thin SMA mix could be beneficia because it can be placed in thinner lifts, could be used as part of a preventative maintenance program, and should be more workable.Study showed that thin SMA-5 could be successfully designed to have stone-on-stone contact and confirmed that thin SMA was rut resistant.The objective of this study was to research the 4.75 NMAS SMA mix to suit the climate and traffic level and material properties of Jing-Qin expressway.Contents include aggregate, design procedure and pavement performance and construction technics.The dissertation firstly analyses the mechanical and structural characteristics of tradional SMA and thin SMA. Secondly discusses Aggregate Crushing Value Test in technical specifications, and tests the 2.36mm~4.75mm aggregates with different percentage of Flat and Elongated Particl, an analysis is made of the influence of different percentages of F&E particles on Aggregate Crushing Value and air voids, water stability, high temperature stability, slip resistant performance and percent aggregate breakdown in SMA-5 asphalt mixture. And supplies a Aggregate Crushing Value Test ways for little sizes contact ggregates. Then based on laboratory test for SMA-5 gradation counted with different control siebe size, an analysis is made of Marshall volume index and pavement performance in SMA-5 asphalt mixture. The results showed that the gradation and asphalt content significantly affected VMA and VCAmix, and the gradation's more. In addition, a sieve size of 2.36 mm was confirmed as being the appropriate breakpoint between coarse and fine aggregate for 4.75mm NMAS SMA, and the cumulative percentage passing the 2.36mm sieve is between 28 and percent.Combining with the construction of Jing-Qin expressway, the construction technics of SMA are discussed.