Contrast Research Of Gyratory Compaction Method And Marshall Compaction Method In The Mix Design Of Asphalt Pavement

Along with the booming development of our country's highway transportation business , the highway construction change with each passing day, and especially since the reform and opening, the construction of our country's high-grade highway have got a sharply development. The asphalt pavement has the advantages of high strength, good smoothness, and high durability and so on, so it has got an extensive adoption, and has an occupation of above 80% of the high-grade highway pavement. Because of continuous increment of traffic volume and vehicle tonnage, the road appears a great deal of ruts, wraps and cracks before attaining service life, which seriously influences the safety and comfort of the transportation. This puts forward higher requests to structure, material and other kinds of function of asphalt pavement, and brings us a new topic, "how to choose high quality material, design more reasonable pavement structure, and put forward a scientific and dependable design method of mixture". The Marshall Compaction method is one of the asphalt mixture design methods which generally accepted in the world, but along with the continuously applied of this method in the laboratory and construction site, many engineering and technical personnel all discover that those indexes got from Marshall Compaction method can't truly imitate various functions of realistic pavement under using. First of all, Marshall Compaction Device needs compacted models, can't really reflect the kneading and rolling effects of road roller and vehicle loads to the asphalt pavement; Second, the compaction work of Marshall Compaction Device is not enough, if just depending on adding compaction times to increase compaction work, then it will make some stones fall into pieces in compaction process, the asphalt pavement under construction and using is rarely been stroked.We should continuously look for mixture design method aiming to raise the capability of pavement, and exploit equipments and devices which match this method, sequentially reduce ruts, low temperature cracks and fatigue cracks in asphalt pavement. The Superpave is a bran-new, extensive asphalt mixture design and analyse system, and a fruit of the American Highway Strategic Research Plan (SHRP). The equipments matched with it is Gyratory Compactor, the compaction process of it is much nearer to the actual state of the pavement under loading. The Superpave Gyratory Compactor (SGC) can carry on compaction with two kinds of modes which are by times of compaction and by the height of model, and can collect the height of model at different compaction times, in order to calculate the compactness of model correspond to times of compaction. It is due to the better emulation and superiority of data collection of the Gyratory Compactor that makes it become an ideal tool in making asphalt mixture models.Our country hasn't brought Superpave asphalt mixture design method into criterion. The Superpave asphalt mixture design and analytical system was excogitated on the basis of American weather, environment and the load circumstance, as for whether it can be applied in our country still needs study and analysis of science researcher. A set of equipments needed by this system is also very expensive and the price is about $ 330,000. In this kind of circumstance, the universal application of Superpave asphalt mixture design and analytical system in our country is difficult. How to put together this system and our country existing condition is a problem that we should take prior consideration, looking for the relationship between Gyratory Compaction method and Marshall Compaction method also seems to be especially important, and then designs more high-quality asphalt mixture.This paper analyzed the compaction molding principle of Superpave asphalt mixture; Thoroughly studied Superpave asphalt mixture design and analytical system; Carrying on mixture ratio design of AC-13, AC-16 asphalt mixture by Superpave asphalt mixture design and analytical system, and carrying on road usage performance analysis; Carrying on mixture ratio design of AC-13, AC-16 asphalt mixture by Marshall Compaction method, and evaluating the merits and shortcomings of those two methods; Carry on contrast experimental research on those two methods, and looking for the relation curve of them.This paper carried on systematical research and analysis of the Superpave asphalt mixture design system, and made a great deal of experiments combining the maintenance item of Chang-Ping expressway, its main conclusions as follows:1.The Superpave asphalt mixture design system has a certain instruction meaning for our country's asphalt mixture design, the molding method by Superpave Gyratory Compactor is more reasonable than by Marshall Compaction method, although it hasn't been brought into our country's criterion and got a widespread adoption, but its molding method and design thought is worthy of our reference.2.The Superpave asphalt mixture design system rules control points and restricted area, and appears superfluous fine sand in the restricted area, will form a weak aggregate framework, usually lowers the strength of asphalt mixture ,and subsequently influences road usage performance. This is more strict and scientific than our country's former 0.45 power diagrams.3.The high temperature stability, low temperature anti-crack performance and water stability and other indexes of asphalt mixture which designed by Superpave asphalt mixture design system meet our country's requests, but the indexes of asphalt mixture designed by Marshall Compaction method can not necessarily completely meet the requests of Superpave. From this point of view, Superpave design method replacing of Marshall Compaction method is an inevitable trend.4.The adopted design void ratio in asphalt mixture design by Superpave asphalt mixture design system is 4%.For dense gradation asphalt mixture (AC, ATB, SMA), Our country's void ratio is between 3%-6%, for open gradation asphalt mixture (Drainage Asphalt Wearing Course, Drainage Asphalt Macadam Base) the design void ratio is bigger than 18%, the design void ratio of semi-open gradation asphalt mixture (asphalt macadam) is between 6%-12%. So this paper thinks Superpave asphalt mixture design system is greatly worthy of reference for our country's dense gradation asphalt mixture design ,whether the design method is suitable for open and semi-open gradation asphalt mixture or not need scholars' study and research.5.By contrast research on Gyratory Compaction method and Marshall Compaction method, seeking after the relationship curves of some decisive indexes between these two methods, in order to instruct the design and construction of asphalt mixture.