# Silane Modification of Crumb Rubber on the Rheological Properties of Rubberized Asphalt
## 1 Introduction  
Rubberized asphalt (AR) has been developed well in recent years, not only because of the huge consumption of waste tires for manufacturing the crumb rubber (CR), but also the presentation of excellent road performance in the road engineering. According to domestic and overseas research, AR mixture pavement, due to its great high temperature anti-rutting ability, low temperature anti-cracking ability, fatigue resistance ability, and water resistance ability, has been widely popularized and used in many countries [1; 2; 3; 4; 5; 6]. However, during real construction of this type of pavement, there is an urgent problem needing to be solved. Researchers and constructors find that CR would gradually segregate from the top asphalt and sink to the bottom during all mixing, transporting, and construction procedures, which finally results in uneven road performance of pavement, such as sweeping (extensive oil), rutting, and aging. All these diseases may be accrued at the very beginning and be harmful to the long-term servicing [7; 8; 9].  
In current studies, constructors and researchers have paid more attention to the adhesion situations between the acid aggregate or the fiber additive and asphalt. Limestone powder and anti-stripping agent are widely used to heighten the bonding state that asphalt tightly grafts on the granite aggregate surface. Besides this, KH-550 (c-ammonia propyl triethoxysilane), a kind of silane coupling agent, is adopted to modify the basalt fiber to enhance the rheological properties of the basalt fiber-reinforced asphalt nucilage [10; 11; 9; 12]. The purpose of the above research is to improve the interfacial property between modifier (aggregate, additive) and base material, and in the meantime to acquire a stronger composite with better performance resisting harsh environments. However, there have been fewstudies carried out about crumb rubber surface silane modification and its influences on the macroscopic properties of rubberized asphalt.  
At present, mechanisms of KH-550 modification are very clear [9; 13; 14; 15]. When materials requiring silane modification are mixed with KH-550 solution, KH-550 grafts on the materials' surface through chemical reactions by its organic functional groups. Then, when this silane modified material is mixed with the base material, the inorganic functional groups of KH-550 on the surface of the modified material can dehydrate and condensate with the hydroxyls on the surface of the base material, so that the silane modified material and the base material can be firmly bonded together.  
In this study, the most important purpose is to acquire a uniformly \"suspended\" state of the CR in the asphalt to ensure that modified AR (MAR) has a better road performance. This study adopts KH-550 as the silane coupling agent to prepare the silane modified CR (MCR) and then prepares several asphalt samples incorporating CR and MCR. High and low temperature mechanical properties of asphalt samples are evaluated by rheology tests, and mechanisms of KH-550 on CR and MCR on the asphalt are studied separately. The present research provides an important approach for population and application of CR surface modifications in road construction.