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Article
Evaluation of Job-Mix Formula Tolerances as Related to Asphalt Mixtures Properties
تقييم التغاير لمعادلة المزج بالنسبة لخواص الخلطات الاسفلتية

Authors: Mohammed Qadir Ismael . محمد قادر اسماعيل --- Reem Fouad Ahmed Al-Harjan ريم فؤاد احمد الحرجان
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2018 Volume: 24 Issue: 5 Pages: 124-144
Publisher: Baghdad University جامعة بغداد

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Abstract

The current Iraqi standard specifications for roads and bridges allowed the prepared Job-Mix Formula for asphalt mixtures to witness some tolerances with regard to the following: coarse aggregate gradation by ± 6.0 %, fine aggregate gradation by ± 4.0 %, filler gradation by ± 2.0 %, asphalt cement content by ± 0.3 % and mixing temperature by ± 15 oC. The objective of this work is to evaluate the behavior of asphalt mixtures prepared by different aggregates gradations (12.5 mm nominal maximum size) that fabricated by several asphalt contents (40-50 grade) and various mixing temperature. All the tolerances specified in the specifications are taken into account, furthermore, the zones beyond these tolerances are also observed. The evaluation process is illustrated by volumetric properties such as density, air voids, voids in mineral aggregate and voids filled with asphalt. Marshall test is carried out to find stability and flow values. The resistance to moisture effect is investigated by conducting the compressive test for dry and water immersed conditions to find the index of retained strength. The experimental results supported the recommendations to increase tolerances of coarse and fine aggregate gradations to ± 7.0 % and ± 5.0 % respectively. The optimum asphalt content tolerance can be increased to ± 0.5 %. The tolerances of filler gradation and mixing temperature are preferable to keep their current values.

تسمح المواصفات القياسية العراقية الحالية للطرق والجسور لمعادلة المزج المعدة للخلطات الاسفلتية ان تشهد بعض التغاير بالنسبة للاتي: تدرج الركام الخشن ±6.0%, تدرج الركام الناعم ±4.0%, تدرج الحشوة ±2.0%, محتوى السمنت الاسفلتي ±0.3% وحرارة المزج ±15oC. الهدف من هذا العمل هو تقييم تصرف الخلطات الاسفلتية المعدة بتدرجات مختلفة للركام (12.5مم مقاس اسمي اقصى) والمصنعة بمحتويات اسفلت متعددة (درجة 40-50) وبحرارة مزج متعددة. تم اخذ جميع التغاير المحدد بالمواصفة بنظر الاعتبار. توضح عملية التقييم بالخواص الحجمية كالكثافة, الفراغات الهوائية, فراغات الركام والفراغات المملؤة بالأسفلت. تم اجراء فحص مارشال لإيجاد قيم الثبوتية والزحف. تم التحقق من تأثير مقاومة الرطوبة بأجراء فحص الانضغاط للحالة الجافة والمغمورة بالماء لإيجاد معامل القوة المتبقية. النتائج العملية أسندت التوصيات بزيادة التغاير للركام الخشن والناعم الى ±7.0% و±5.0% على التوالي. من الممكن زيادة تغاير محتوى الاسفلت الامثل الى ±0.5%. من المفضل ان يحتفظ تغاير الحشوة وحرارة المزج بقيمهم الحالية.


Article
EXPERIMENTAL STUDYING THE EFFECT OF ADDING STYRENE BUTADIENE STYRENE POLYMER (SBS) ON THE MECHANICAL PROPERTIES OF HOT MIXTURE ASPHALT
دراسة عملية لتأثير إضافة بوليمر (SBS) على الخصائص الميكانيكية للخلطة الإسفلتية الحارة

Author: Ali Fadhil Naser
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 5 Pages: 33-47
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The objective of this research is to study the effect of adding Styrene Butadiene Styrene polymer SBS as a modifier on the mechanical properties of asphalt binder and hot mixtures asphalt (HMA) and to compare between the properties of the modified and unmodified asphalt binder and hot mixture asphalt (HMA) which is used in the rehabilitation of Baghdad province and Al-Basra province highway by paving the surface course of highway for areas suffers from problems such as rutting and cracks. There are two stages were used in the laboratory tests on asphalt binder and hot mixture asphalt (HMA). The first stage is used laboratory tests without using SBS polymer with asphalt and the second stage is used SBS Polymer with asphalt as an additive material. The results of asphalt binder tests show that the using of SBS Polymer with asphalt binder lead to improve the mechanical properties of asphalt binder. According to penetration test, the grade of asphalt is decreased from 61 and 62 to 39. The flash point, the ductility, and viscosity are increased and the solubility is decreased. The results of hot mixture asphalt test show that the adding of SBS polymer lead to improve the mechanical properties of modified hot mixture asphalt. Therefore, the Marshall stability for modified hot mixtures asphalt is increased for all samples. Therefore, the resistance to plastic flow and the load carrying capacity is improved by approximate more than 60%. The others Marshall properties such as Marshall flow, Marshall density, and Marshal air voids are improved. Therefore, the recommendation of this study is to use the modified hot mixture asphalt that is using Styrene Butadiene Styrene polymer SBS in the paving of new flexible pavement layers and in rehabilitation of the surface course of the old flexible pavement.


Article
Improvement of the Specification of the Asphalt Concrete Overlay by Using Polypropylene

Author: Hayder Salman Khudhair
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2018 Volume: 26 Issue: 6 Pages: 199-219
Publisher: Babylon University جامعة بابل

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Abstract

The research aims to prepare high-performance asphalt concrete with good specifications for using in asphalt concrete overlay can resist deformations and problems faced and increase its age service. Used all of polypropylene particles as an additive to the asphalt concrete type (AC 60-70) by six ratios (1, 2, 3, 4, 5 and 7) % of optimum asphalt content weight, as an additive for asphalt mixture with a maximum size of the aggregate (19mm). Study the effect of these additions on the volumetric and the mechanical properties of the asphalt concrete and evaluate its performance through Marshall Method test by take at least three specimens of ratio tested. The results showed that the use of polypropylene particles improvethe performance and specifications of asphalt concrete and increase the ability to resist deformations that are exposed, where it was concluded that the addition of ratio (4%) of the weight of the asphalt of polypropylene gives optimum improvement of the performance of the asphalt concrete overlay, where Marshall stability is increased by 47% and flow decreased by 17% compared to untreated mixtures respectively, with volumetric properties within limitations of the specifications.

يهدف البحث إلىإعداد خلطة إسفلتية عالية الأداء تتمتع بمواصفات جيده لاستخدامها في طبقة التقوية تستطيع مقاومة المشاكل والعيوب التي تتعرض لها وتزيد من عمرها الخدمي. حيث استخدمت حبيبات البولي بروبلين كماده مضافة للرابط الإسفلتينوع. ((AC 60-70بسته نسب (1, 2, 3, 4, 5, 7) % من وزن النسبة المثلى للإسفلت مع استخدام ركام ذو المقاس الأعظم 19 ملم. تم دراسة تأثير هذه الإضافات على الخصائص الحجمية والميكانيكية وتقييم أداء الخلطة باستخدام فحص مارشال وبأخذ مالايقل عن 3 نماذج لكل نسبة. بينت الدراسة ان استخدام 4% من حبيبات البولي بروبلين من وزن الإسفلت المثلى أعطت التحسين الأمثل بالاداء مقارنة مع الخلطة المرجعية غير المعالجة حيث زاد ثبات مارشال بنسبة 47% ونقص مقدار الانسياب بمقدار 17% مقارنه بالخلطة المرجعية. كما بينت النتائج ان اضافة مثل هكذا نسبة اعطت خلطة ذات مواصفات حجمية ضمن حدود المواصفة.

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