بررسي تاثير انواع الياف تثبيت كننده بر خواص خستگي مخلوطهاي آسفالتي با استخوان بندي سنگدانه اي

Fiber Stabilizers Effects on Fatigue Properties of Stone Matrix Asphalt

In early 1970s European road industry felt a need for a pavement that resists rutting, wearing out and damage caused by heavy traffic load and studded tires. In order to address this need, officials have developed Stone Matrix Asphalt (SMA). High value of coarse aggregate, use of large amount of asphalt binder and thickness of asphalt film around the course aggregate in SMA are the main reasons for drain down, flushing and bleeding during the storage, transportation and placing. Therefore to reduce these weakness points, stabilizers for thickening of binder and increasing the viscosity are used. Fibers are one of the materials used for this purpose, that is, fibers are used to reinforce and stabilize this mixture. Common types of fibers used for these applications are cellulose and mineral. The aim of present paper is to investigate the feasibility of using acrylic, jute, polyester, polypropylene and viscous fibers as stabilizers and to determine their effect on drain down and fatigue strength of the mixtures. In this experimental research, mixtures containing cellulose fibers have higher asphalt content than synthetic fibers, therefore synthetic fibers are more economical. By reducing the amount of the most expensive constituents of an asphalt mixture (asphalt binder), the result would lead to construct more cost effective pavements. Also mixtures containing synthetic fibers have higher drain down potential compared to cellulose fibers. Flexural stiffness of different mixtures was decreased with increasing of strain level especially in higher strain level. One type of fiber stabilizer showed significant effect in fatigue life of stone matrix asphalt mixtures. Keywords: SMA mixtures, fibers, Marshal Stiffness Index, flexural stiffness, fatigue life.