@article { author = {Ameri, M. and Jarrahi, A. and Jarrahi, A. and منصوریان, احمد and منصوریان, احمد}, title = {Laboratory Assessment of Temperature Effects on the Strength of Recycled Asphalt Concrete Mixture}, journal = {Journal of Transportation Research}, volume = {4}, number = {3}, pages = {-}, year = {2007}, publisher = {}, issn = {1735-3459}, eissn = {2008-3351}, doi = {}, abstract = {Crushed asphalt is made by recycling of asphalt pavements (by crushing or milling the old materials). This material may be used in making new asphalt mixes. Using crushed asphalt in making new asphalt, reduces the consumption of new materials and thus results some savings in capital as well as natural resources. The main objective of heating the crushed asphalt in the process of hot mix recycling is to change the hard state of asphalt to soft and liquid state and thus making the possibility of segregation of the aggregates in the asphalt mix. Not to mention that too much heating may also result corrosion or burning of the bitumen. Meanwhile heating the asphalt less than the required time, may result incomplete mixing of crushed asphalt components with aggregates and new bitumen materials. In this paper the effect of temperature changes and heating periods of crushed asphalt on some parameters like real gravity, Marshall Stability and indirect tensile strength of recycled crushed asphalt have been evaluated. Also the Marshall Stability and indirect tensile strength of recycled asphalt mix have been compared to similar amounts in the ordinary asphalt mixes. The obtained results are as follows: 1- Heating time and heating temperature of crushed asphalt influence the real gravity, Marshall Stability and indirect tensile strength of the asphalt mix. These influences are meaningful, by other words; the occurred changes in the mentioned parameters are not accidental, but affected by the developed changes in time and temperature of heating process. 2- Taking into account the Marshall Stability diagrams and indirect tensile strength of asphalt mixes on the basis of heating time and temperature parameters of crushed asphalt, it is considered that the average amounts of both parameters, at the heating time of four hours and heating temperature of 160◦ have reached their maximum level. By other words, those parameters that are indicative of hardness and strength of asphalt mix, at the mentioned time and temperature have reached their maximum level. 3- Results show that the recycled asphalt mix has had considerable Marshall Stability and tensile strength. For instance the Marshall Stability of the recycled asphalt mix at 4-hour heating time and 175◦ heating temperature has approximately reached 3700 Kg. Also the indirect tensile strength of the asphalt mix at 4-hour heating time and 160◦ temperature has approximately reached 26 Kg/cm2. Comparison of the mentioned amounts with the same amounts in ordinary mix asphalt (without crushed asphalt) it can be resulted that making use of crushed asphalt in asphalt mix increases the strength and hardness of the asphalt mix to a considerable extent. 4- Relatively intensive slump of real gravity, Marshall Stability and indirect tensile strength diagrams at the point of 8-hour heating time and 175◦ temperature shows that at the mentioned point the properties of asphalt mix have considerably changed. The reason for these changes is developing considerable changes in the properties of crushed asphalt, due to the high temperature and long period of heating.}, keywords = {urban environment,Traffic pollution,traffic demand model,lead and cadmium distribution,roadside soil pollution}, title_fa = {بررسی آزمایشگاهی تأثیر دمای اختلاط مصالح خرده آسفالت بر برخی معیارهای مقاومتی مخلوط بتن آسفالتی گرم}, abstract_fa = {مهم ترین هدف از حرارت دادن مصالح خرده آسفالت در فرآیند طرح اختلاط بازیافت گرم، تغییر حالت قیر خرده آسفالت از حالت سخت و جامد به حالت نرم و مایع و به تبع آن آزاد کردن مصالح سنگی خرده آسفالت از یکدیگر است. باید توجه داشت که حرارت بیش از حد، ممکن است باعث فرسوده شدن و یا سوختن قیر شود. در ضمن حرارت دهی کمتر از حد مناسب نیز باعث ممانعت از اختلاط کامل مصالح خرده آسفالت با مصالح سنگی و قیر جدید در فرآیند اختلاط می شود. در این مقاله اثر تغییرات دما و مدت زمان حرارت دهی مصالح خرده آسفالت بر پارامترهای وزن مخصوص حقیقی، مقاومت مارشال و مقاومت کششی غیر مستقیم مخلوط آسفالتی بازیافت شده مورد ارزیابی قرار گرفته و تأثیر آن بر پارامترهای موصوف مشخص شده است. همچنین مقادیر مقاومت مارشال و مقاومت کششی غیر مستقیم مخلوط آسفالتی بازیافت شده با مقادیر متناظر در مخلوط آسفالتی معمولی (بدون خرده آسفالت) مورد مقایسه قرار گرفته است. نتایج به دست آمده در این پژوهش حاکی از آن است که افزایش مدت زمان و دمای حرارت دهی مصالح خرده آسفالت به میزان قابل ملاحظه ای باعث افزایش پارامترهای مقاومت مارشال و مقاومت کششی غیر مستقیم مخلوط آسفالتی می شود. همچنین مخلوط آسفالتی بازیافت شده نسبت به مخلوط آسفالتی معمولی مقادیر مقاومت مارشال و مقاومت کششی قابل توجهی از خود نشان داده است.}, keywords_fa = {خرده آسفالت,وزن مخصوص حقیقی,مقاومت مارشال,مقاومت کششی,حرارت,قیر}, url = {https://www.trijournal.ir/article_11384.html}, eprint = {https://www.trijournal.ir/article_11384_dc26a16f387d2548e8f0a3cccaa12c84.pdf} }