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Article
PREDICTION OF RESILIENT MODULUS MODEL FOR WEARING ASPHALT PAVEMENT LAYER

Author: Miami M. Hilal
Journal: KUFA JOURNAL OF ENGINEERING مجلة الكوفة الهندسية ISSN: 25230018 Year: 2018 Volume: 9 Issue: 4 Pages: 65-87
Publisher: University of Kufa جامعة الكوفة

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Abstract

Resilient modulus for pavement layers is a key design parameter for pavement systems and permits for determination of how the pavement system will react to traffic loadings. It can be defined shortly as elastic modulus of a material under repeated loads. Several factors have effects on the elastic modulus of the layers of asphalt pavements. The indirect repeated axial load test was carried out by using the pneumatic repeated load system (PRLS) at Transportation Laboratory at Baghdad University to test seventy two cylindrical specimens prepared by the gyratory device. SPSS program was used to predict the resilient modulus model which contains many factors like asphalt content, asphalt viscosity, air voids, surface area, and temperature. Multiple linear regression is used to build the model of resilient modulus because it is a function of more than independent variables. F statistical significance value from the results of ANOVA table is smaller than 0.05 in the predicted model then the independent variables in the predicted model explain the variation in the resilient modulus variable. The coefficient of determination (R2) is 0.886 for the predicted model which is referred to a very good relation obtained. The predicted model shows that the modulus of resilience is highly affected by variation of temperature and moderately by viscosity of the asphalt whereas the stress level, types of filler, and the asphalt content have smaller effect on resilient modulus. The predicted model shows that there is a positive relationship among the resilient modulus and the two variables viscosity and the surface area whereas the three variables temperature, asphalt content, and air voids have inverse relationship with resilient modulus. Two asphalt types (40-50) and (60-70) from Dora refinery were used; the average value of resilient modulus corresponding to asphalt grade (40- 50) is almost 21.331% times the value for asphalt grade (60-70). Three asphalt contents (optimum asphalt content, optimum asphalt content±0.5) were used; when the content of asphalt was increased from 4% to 4.5%, the average resilient modulus decreased by 2.923% whereas increasing the percent of asphalt content from 4.5 to 5 the average resilient modulus decreased by 1.737%. Two types of mineral fillers (cement and limestone) were used, and when cement was used as mineral filler, the average resilient modulus increased by 4.422% rather than using limestone as filler in the asphalt mixture. Three temperatures for test were used 10, 25, and 40 oC. The results showed that when temperature was increased from 10 to 25 ◦C, the average resilient modulus decreases by 65.738%; whereas when the test temperature was increased from 25 to 40 oC, the average resilient moduli decreased by 97.715%. The results also showed that the average resilient modulus increased by 9.69% when the stress level increased from 6.5 psi to 13 psi.


Article
Evaluation of Asphalt Pavement Using Ground Penetration Radar
تقييم التبليط الاسفلتي باستخدام تقنية رادار الاختراق الارضى

Authors: Miami M. Hilal --- Nawar A. Abd-Alsattar
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2013 Volume: 31 Issue: 21 Part (A) Engineering Pages: 478-488
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This paper presents a status report on evaluation of the asphalt pavement using the ground penetration radar device (GPR) in one of the University of Technology streets about 92 m length. The technique of GPR is a nondestructive geophysical method that gives information about the thickness of asphalt pavement layers, existence of drainage pipes, rutting places and produces a continuous cross-sectional profile or record of subsurface features without drilling, probing, or digging.Three samples of asphalt were taken from different places of the street. The thickness of asphalt layers were measured from these samples. One of the samples consists of two layers and the others of one layer.Comparison of the two results of the thickness from the device and the sample indicate that there was very slight difference between them.

هذا البحث يقدم تقريراً عن استخدام تقنية رادار الاختراق الارضي كوسيلة لتقييم التبليط الاسفلتي حيث قمنا باخذ مقطع من طريق طوله 92 متر في احد شوارع الجامعة التكنولوجية. تقنية الرادار الارضي هي طريقة جيوفيزيائية غير متلفة حيث انها تمكننا من الحصول على العديد من المعلومات منها سمك الطبقات للتبليط وكذلك وجود انابيب تصريف المياه والاماكن التي فيها هطول في الطبقات وكذلك انشاء مقطع عرضي وطولي مستمر للطريق من غير حدوث اضرار في سطح الطريق كالحفر.وفي نفس المقطع قمنا بفحص الطريق من خلال اخذ ثلاث عينات اسفلتية في اماكن متفرقة من الطريق وقد تمكنا من معرفة سمك طبقات التبليط من هذه العينات وقد ظهر لدينا عينة واحدة تتكون من طبقتين تبليط والعينات الاخرى تتكون من طبقة واحدة هذا يدل ان الطريق قد تعرض الى اعادة تبليط عن طريق اعادة اكساء من خلال وضع طبقة من مادة رابطة ومن ثم وضع طبقات التبليط.من خلال مقارنتنا لنتائج الفحصين الحقلي والنظري نجد هناك فرق بسيط جداً في قياس السمك مابين العينة والجهاز.

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