توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Effect of LDPE in Rutting Characteristics of Asphalt Concrete mixtures
اطلاعات انتشار: نهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۶
In recent years, different kinds of polymers such as SBS, SBR, Sasobit, etc have been used to modify the properties of asphalt binders. These additives can change the mechanical properties of Asphalt Concrete (AC) mixtures to some extent but most of them are expensive and the blending process with bitumenrequires special equipment and conditions. In this paper the use of low–density polyethylene (LDPE) in enhancing the AC mixture properties is discussed. In comparison with other polymer modifiers, the LDPE is relatively cheaper in the Iran market. It also does not require any special condition in mixing with bitumen. Based on the tests conducted and the model presented in this research, the results suggest that adding LDPE can improve the rutting characteristics of asphalt concrete<\div>

۲Laboratory evaluation properties of HMA modified with carbon Nano tube
اطلاعات انتشار: دومین کنفرانس ملی مصالح و سازه های نوین در مهندسی عمران، سال
تعداد صفحات: ۹
In this study, along the lines of the use of different polymeric and non–polymeric materials in improving the characteristics of bitumen and asphalt mixtures, carbon Nano–tube as a new material is used to increase the life and improve the performance of asphalt mixtures due to its unique properties (100 times more resistant than steel) and the fact that its molecular structure is very close to that of bitumen. For preparing bitumen modified with carbon Nano–tube, it is necessary to specify the appropriate conditions of mixing this material with bitumen. Therefore, to meet this need, three different types of mixer and for each of which three states of combination are considered. For the samples mixed by the ultrasonic mixer, it is observed that the Nano–materials are uniformly and separately from each other (without being agglomerated) spread in bitumen. The use of Nano–materials improves the classic properties of bitumen (softening point, penetration degree and so on) in comparison to the base bitumen. In the next step, the asphalt samples are prepared using the modified bitumen and then, their Marshall stability, indirect tensile strength, and rutting are investigated. In addition, the resistance and performance of these samples in to water (moisture sensitivity) is surveyed since the issue of contacting with water is inevitable for asphalt mixtures due to water penetration into the asphalt through the pore of pavements and also water penetration and leakage through slits and cracks on pavements.<\div>

۳The Effects of Styrene–Butadiene–Styrene (SBS) Polymers on the Improvement of Mechanical Properties of Hot Mix Asphalt (HMA)
نویسنده(ها): ، ،
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۷
In recent decades, using polymers to improve bitumen properties is increasing. In 1960`s the copolymerization techniques developed and Styrene – Butadiene – Styrene (SBS), one of themost effective additives which has plastic and thermoplastic properties at the same time, has been offered in bitumen market. This polymer will improve the properties of bitumen both in high (FBP= 130c) and low (FBP=–38 c) temperatures, then it is practicable for all weather conditions and itsperformance will be satisfying in both conditions. In this research the effects of SBS polymer on bitumen and asphalt was studied. Pastexaminations shows that SBS polymer will decrease the Frass breaking point and lose weight of bitumen and also increase the softening point and penetration grade of it. SBS polymer also improves the properties of asphalt, including the increase of MarshallResistance and flow of asphalt mixtures; but it has no considerable effect on specific gravity of asphalt; and at the same time decreases the optimal bitumen percentage of asphalt.<\div>

۴Comparative Study of Bitumen Modified by SBS andLDPE (LD–LF0200& LH–0075)
نویسنده(ها):
اطلاعات انتشار: کنفرانس بین المللی عمران، معماری و زیرساخت های شهری، سال
تعداد صفحات: ۶
In recent years, different kinds of polymers have been used to modify properties of asphalt mixtures, among them SBS is one of the most widely used which can extremely improve the mechanical properties of asphalt mixtures and bitumen. In order to study the performance of asphalt modified by SBS and the low–density polyethylene (LDPE), one type of SBS and LDPE and one kind of base asphalts are selected according to SHRPindex, and performances of combination of modified asphalt at different percents of modifiers are evaluated. The properties of the LDPE–modified bitumen were compared to mixture with different contents of styrene–butadiene–styrene (SBS) modified–bitumen. The tests showed that to achieve the same performance, as with SBS modified mixture. the LDPE–content must be use a bit higher than SBS. 6%–LDPE(LD–LF0200& LH–0075) modification was determined as the most suitable content according to both binder and mixture tests. ButLPDE is an internal (Iran) production and a very cheap polymer by comparison with SBS.<\div>

۵NANOTECHNOLOGY IN PAVEMENT (review paper)
نویسنده(ها):
اطلاعات انتشار: کنفرانس بین المللی عمران، معماری و زیرساخت های شهری، سال
تعداد صفحات: ۱۳
To date, nanotechnology applications and advances in the construction and building materials fields have been uneven. The application of nanotechnology in various applied fields is receiving widespread attention. Definitions of nanotechnology, including nanoscience and nano–engineering in civil engineer, are provided. This paper reviews the state of the field of nanotechnology in asphalt and concrete pavement engineer.<\div>

۶Introducing New Methods of Safety Improvement and Hazard Reduction in Roadwork Sites
نویسنده(ها): ،
اطلاعات انتشار: دومین کنفرانس بین المللی یافته های نوین پژوهشی در مهندسی عمران، معماری و مدیریت شهری، سال
تعداد صفحات: ۵
Implementing executive and traffic operations in operating roads ,must provide safety of drivers ( safety of road users ) undertakers and operatives ( site safety ) as well as , ability of providing safe and smooth traffic riding considering suitable performance speed in implementing of tasks . With respect to this matter and considering lack of checking whole aspects from codes and occasionally existing safety regulations in our country indicating insufficient forecasting in notification of drivers before work zone and lack of directing traffic and lack of providing suitable procedure in case of deviation or entering of vehicles to the work zone ( due to lack of drivers' attention and or vehicles mechanical failure ) , this article intends to introduce new systems of shock– reduction and supporting work zone with approach of decreasing damages inflicted to the deviated vehicles to possible minimum content and increasing safety of roadwork zone<\div>

۷The Effect of Carbon Nano–tube on the Fatigue Life of Asphalt Mixtures
نویسنده(ها): ، ، ،
اطلاعات انتشار: International Journal of Transportation Engineering، دوم،شماره۱، Summer ۲۰۱۴، سال
تعداد صفحات: ۱۶
The fatigue cracks are observed in asphalt surfaces much more than ruts. This paper deals with the influence of carbon nano–tube on the fatigue life of asphalt mixtures. These samples are made up of the slabs cut by the asphalt cutting saw. Fatigue beams contain 0, 0.3, 0.6, 0.9, 1.2, and 1.5 percent of Carbon Nano–tube. The fatigue experiment was conducted using a 4–point semi sinusoidal loading on a flexural beam for a constant strain (600 micro–strain) at 20oC. The end of these samples, fatigue life is assumed to be when 50% reduction in the initial rigidity happens. The results show that with an increase in the percentage of carbon nano–tube in the fatigue samples, the fatigue life of asphalt mixtures and the amount of cumulative dissipated energy increase noticeably, and the rate of damage propagation is reduced. Also rut depth, Fracture Energy density, Marshall Stability, Indirect Tensile strength have been improved excellently.

۸Performance Evaluation of Nano–silica Modified Bitumen
اطلاعات انتشار: International Journal of Transportation Engineering، سوم،شماره۱، Summer ۲۰۱۵، سال
تعداد صفحات: ۱۲
In this study, different contents of Nano–silica, 2 wt.%, 4 wt.% and 6 wt.%, have been added to bitumen to modify the physical, mechanical and rheological properties of warm mix asphalt (WMA). WMA is containing 2 wt.% of Sasobit (mixture of long–chain hydrocarbons). Various quality control tests have been carried out to characterize the modified bitumen and WMA. The rheological investigations showed that the complex modulus of base bitumen increases by increasing the percentage of Nano–silica from 2 to 6 wt%. Phase angle and rut factor for the Nano–silica modified bitumen have also decreased significantly. From rheological analysis, 6 wt% Nano–silica has been selected as the optimum content. Results of investigations on the asphalt mixtures demonstrated the fact that by increasing Nano–silica content, the quality of the warm mix asphalt has been improved. By increasing the Nano–silica content, the resilient modulus of WMA has increased; as such, the pavement response under the traffic loading has decreased. By adding Nano–silica to the Sasobit WMA, the depth of cracking has decreased dramatically. So, fatigue life of WMA has been extended in the presence of Nano–silica. Also, the results of wheel tracking test demonstrated that the rutting depth of modified samples have been reduced. The results on WMA showed that 6 wt.% of Nano–silica is the optimum content. This result was in compliance with the rheological investigations.
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