7305

6811

كارشناسي ارشد

راه و ترابري

اصفهان: دانشگاه صنعتي اصفهان، دانشكده عمران

1391

دوازده، 83ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

مهدي ابطحي، بهروز كوشا

27/8/91

مسعود مير محمد صادقي، كياچهربهفرنيا

1396/09/21

كتابنامه

عمران

مهندسي عمران

ID6811

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Analytical Empirical Investigation of Bleeding Mechanism In Asphalt Mixtures Hamed Khosravi h khosravi@cv iut ac ir Date of Submission September 8 2012 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Dr Sayed Mahdi Abtahi mabtahi@cc iut ac ir Supervisor Dr Behrooz koosha cgkoosha @cc iut ac ir Abstract Bleeding is one of the most common failures of asphalt pavements in tropical countries Bleeding can be dangerous because of reducing skid resistance of the vehicles especiallywhen the pavement surface is wet Bleeding has been dealt with in the asphalt concreteliterature as occurring mostly due to poor construction practices and other than empirical andqualitative observations there have not been any attempts to understand its mechanism The aim of this study was to evaluate the analytical empirical bleeding mechanism inasphalt mixtures This evaluation is based on the distribution of air voids in asphalt mixtures An x ray computed tomography system was used to capture the internal structure of thespecimens and image analysis techniques were used to quantify the air void distribution Twodifferent methods were conducted in this study The rst method was conventional method based on extraction tests were performed according to the standard ASTM D2172 andincluding preparing specimens impact loading static loading and extraction test The secondmethod was carried out based on image analysis that after the specimen was initially scannedusing X Ray CT dynamic loading was applied by UTM 5KN at temperatures of 5 25 40 and60 C Static loading test was applied by uniaxial compressive machine at temperatures of 25 40 and 60 C The specimens were scanned after loading again Image processing and analysissoftware were used to quantify the air void distribution in X ray CT images The softwarequanti es the vertical distribution of air along the depth of each specimen by calculating thepercent area on each CT image X ray CT along with image analysis techniques were shown to provide a non destructiveand accurate tool to analyze the air void distribution in asphalt mixes According to the stress strain results obtained from dynamic loading and variations of air voids distribution inspecimens can be expressed asphalt mixtures under low frequency loading have more strainand less air voids On the other hand it can be concluded that the pavement under heavy trucktraffic is more likely to bleeding due to reduced air voids in asphalt mixture Also accordingto changes in air voids distribution under thermal loading conditions 5 25 40 and 60 C canbe concluded at low temperature asphalt cement behaves like an elastic solid and withincreasing temperature this behavior will tend towards plastic manner Key Words Asphalt mixture Bleeding Air voids Image analysis X ray CT

مهدي ابطحي، بهروز كوشا

مسعود مير محمد صادقي، كياچهربهفرنيا