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Using of Reclaimed Asphalt Pavement (RAP) has been become indispensable in most of the world nations as for its many benefits as significant cost savings and provide environmental benefits. Many factors such as virgin materials, binder content, availability of RAP, viscosity of binder and extent of deterioration had important role in effecting on Optimum percentage of RAP. In this study, effect of using RAP on the asphalt mixture properties and the its optimum ratio was determined to achieve the objective of the study. The glass fiber (GS) was used as additives to improve the asphalt mixture. It has been observed from the previous researches that the optimum percentage of reclaimed asphalt use is not determiner and is disagreed from project to project. So, different percentages of RAP was (25%, 50%, 75%, 100%) by weight of aggregate were added as well as using the additive GS at optimum bitumen content. The study is revealed that untreated 100% RAP materials are not good as a bituminous mix. and was showed that mix prepared with 25% RAP gave nearly the same physical and strength parameters as virgin bituminous mix. From results of study, the use of RAP until (%50) as a maximum percentage in unmodified asphalt mixture course sustained good results. To achieve better performance, the percentage of 25% RAP was used with percentage of 0.26% GS. This mix achieved the specification requirements and ensured the degree of better performance for paving. The economical evaluation of using percentage of 25% RAP with percentage of 0.26% GS was also studied. The results indicated that, about 21% of the cost was saved. [ABSTRACT FROM AUTHOR]

• Effect of RAP and glass fiber on fracture behaviors of UTFC were investigated. • The size-independent fracture energy was obtained considering the tail part of the load–displacement curve. • Two new parameters, cracking resistance index and balanced cracking index, were adopted to characterize the fracture performance. Ultra-thin friction course (UTFC) presents excellent performance in preventative maintenance of asphalt pavement. UTFC could be also used as the wearing course of newly constructed pavements. This study investigated the effects of reclaimed asphalt pavement (RAP) and glass fiber on the fracture behaviors of UTFC at the low and intermediate temperatures. At the low temperature (-10℃), fracture energy, stress intensity factor and cracking resistance index (CRI) were obtained to present the fracture behaviors of three types of UTFC mixtures. At the intermediate temperature (25℃), the size-independent fracture energy considering the tail part of the load–displacement curves were obtained. Besides, J-integral, cracking resistance index (CRI) and balanced cracking index (BCI) were obtained to characterize the intermediate fracture performance. Results indicated that at −10 ℃, the incorporation of RAP weakened the fracture resistance of UTFC; while the addition of glass fiber could counteract the adverse effect of RAP. Besides, CRI value of UTFC with glass fiber was the largest, indicating the superior fracture resistance at the low temperature. At 25 ℃, UTFC presented the best cracking resistance in terms of fracture energy, J-integral, CRI values and BCI values, indicating the incorporation of RAP could deteriorate the fracture resistance at the intermediate temperature. When both RAP and glass fiber were added in UTFC, the fracture performance was deteriorated furtherly, which may be possibly caused by the non-uniform distribution of fiber. On the other hand, the bonding strength between fiber and asphalt could be mitigated when temperature increased from −10 ℃ to 25 ℃. The size-independent fracture energy of UTFC was the largest, indicating the superior fracture resistance, followed by UTFC-50% RAP-F and UTFC. It was also reported that the incorporation of fiber improved the ability to tolerate deformation. [ABSTRACT FROM AUTHOR]