| The adoption of crumb rubber modified asphalt not only can improve the performance of asphalt at high or low temperature,reduce the asphalt pavement cracking and aging, improve the safety for vehicle drives and road service life, but also do not increase the cost, combining can make a contribution to the recovery of the discarded rubber and environmental protection .Therefore, the research and application of crumb rubber modified asphalt has become an important study aspect in developed countries.Coarse crumb rubber is apt to deposit in asphalt. Finer crumb rubber can dissolve more easily in asphalt. So the effect of using finer crumb rubber to modify asphalt could be better. However, the finer crumb rubber is more expensive. In fact, we should take both technology and economy into consideration.As rude rubber has a linear structure like a chain, its physical and mechanical performance is low and unstable. It can't be used as rubber product. So people always use the sulphurized rubber. The sulphuriza -tion ,just we call it, it means that the structure of the rude rubber transformed from linear form to cubic net form meanwhile its physical and mechanical performance also changed. In fact, sulphurization is the reaction proceedings of the form of the rubber chain .After the rude rubber changed into sulphurized rubber, its plastic property has been lost. So it can't be used directly. In order to reuse it ,we should make the rubber powder recover some performance of rude rubber.Under high temperature and evaporable water,sulphurized rubber can be oxidated and divided. So the large net structure of rubber was destructed and formed smaller net structure or linear structure. And then it became easy to dissolve in asphalt. By that the asphalt has been modified. In order to get better modification effect, it is necessary that the rubber powder not deposit. We should notice the temperature and period of the producing. The temperature usually be controlled within 150℃～160℃. Because under this temperature scope crumb rubber and asphalt can be mixed evenly and the asphalt can not aged.Both crumb rubber and asphalt are elastic high molecular material. Their characteristics are very similar. In order to improve crumb rubber mixing degree in asphalt, asphalt need to be heated to get a certain temperature , and asphalt and crumb rubber need be blended strongly. So the main technology is the optimum composition of reaction temperature,period and mixing speed. The principle of controlling optimum composi -tion is similar viscidity principle which means that more similar are the viscidity of asphalt and crumb rubber ,more easily the crumb rubber be mixed in asphalt. When crumb rubber asphalt has maximum viscidity ,the rubber powder is apt to dissolve in asphalt, and then they form the continuous net structure. And at this time the temperature and period is the optimum temperature and period.This text has studied the basic performance of crumb rubber modified asphalt and asphalt mixture through experiments, obtaining the data of different amount of crumb rubber addition to asphalt in order to find the prime dosage. On this basis, the performance of crumb rubber modified asphalt mixture has been examined. It was showed that the high temperature reliability, temperature sensitivity, low temperature anti- cracking performance etc of crumb rubber modified asphalt are all prior to unmodified asphalt, making the performance of the asphalt improved obviously. It has come to the research goal that we schedule to.The text has made a important improvement for the wet method of crumb rubber modified asphalt, and designed a equipment of crumb rubber modified asphalt which was first created in our country compound with the intermittent type mixture by oneself. Through a set of high speed shear type mixture equipment, rubber powder can be scattered in asphalt without deposition and eduction. It has higher production efficiency and better modifying effection.After the indoors experiments, we paved crumb rub... |
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