Characterizing the properties of sustainable semi-flexible pavement produced with polymer modified bitumen

Semi-Flexible Pavement (SFP) is a composite type of pavement produced by manufacturing of porous asphalt mixes using open graded aggregate gradation to create 20-35% of voids filled with grout (cement paste, cement mortar, etc.….). The resulting pavement has the flexibility of asphalt pavement and some strength of concrete pavement. The current study focused on investigation of using widely available (in Iraq) waste material namely Rice Husk Ash (RHA) to replace the Ordinary Portland Cement (OPC) partially in grout, also, using Polymer Modified Bitumen (PMB) to develop Open-Graded Asphalt (OGA) pavement without using cellulous fibre. The study focused on assessment of mechanical properties of the obtained SFP mixes with and without PMB. The results of study showed that using of PMB increased the Marshall Stability up to 100% and indirect tensile strength up to 50%. The Marshall Retained Stability gave about 90% which is quite higher the minimum required limit (70%). The results also revealed that RHA can be used as replacement for the OPC in SFP mixes. All investigated percentages showed satisfactory mechanical properties

Evaluation for the effect of pavement type on the total life cost and environmental aspects of roads

There are several types of pavements which have been constructed around the world; flexible and rigid pavement. These pavements have major differences in terms of materials and construction process, giving the differences in their compositions and production process, each one of these pavements has some strength and weak points. The current study presents detailed comparison between these two pavements from the perspectives of the total life cost and environmental aspects using software Athena pavement Life Cycle Assessment (LCA). The assessment using LCA software is based on the construction materials, the construction and maintenance process as well as the machines and vehicles used during the construction, and the life cycle of pavement. Two majors streets were selected for the purpose of the comparison, the first street is called the street of coaches station in Al-Diwaniyah city and the second street is Om Al-Kheil street. The street of coaches station was constructed with composite pavement layers (full rigid pavement layers covered by 5 cm flexible pavement layer). On the other hand, the street of Om Al-Kheil was constructed with full layers of flexible pavement. The results of Life Cycle Cost Analysis (LCCA) showed that initial construction cost of composite pavement is higher than that of flexible pavement by 31%, while the total maintenance cost for flexible pavement is about 24 % more than of composite pavement. The diesel oil and gasoline had consumed by higher quantities during the preparation and construction stages of flexible pavement compared with composite pavement. Therefore, the environmental impact and gases emissions is more consumed during the construction of flexible pavement

Production of Hard Grade Bitumen for Using in High Modulus Asphalt Concrete

قد تتعرض الخرسانة الاسفلتية الاعتيادية لعدة اضرار مثل شقوق الكلل والتخدد وتتفاقم درجة هذه الاضرار مع الظروف المناخية القاسية والحمل المروري المتكرر. يمكن اعتبار الخلطة الاسفلتية العالية المرونة المصممة وفقا للطريقة الفرنسية (EME)) أحد الحلول المهمة للحد من هذه الاضرار. ان انتاج هذا النوع من الخليط يتطلب اسفلت (كمادة رابطة) عالي الصلابة. البحث الحالي يتضمن طريقة جديدة لأنتاج الاسفلت بتدرج اختراق نوع hard)) ليلائم متطلبات الاسفلت العالي الصلابة المستخدم لأنتاج الخلطة الاسفلتية العالية المرونة المصممة وفقا للطريقة الفرنسية. العمل المختبري يتضمن خلط البوليمر ومصلبه مع الاسفلت الاعتيادي لأنتاج الاسفلت الجديد العالي الصلابة. نظرا لأن شقوق الكلل هي أكثر المخاوف المتعلقة بالأسفلت (كمادة رابطة) العالي الصلابة والخلطة الاسفلتية العالية المرونة، لذلك تمت إضافة حبيبات المطاط الى الاسفلت المنتج العالي الصلابة لتحسين أداء التبليط في مقاومة شقوق الكلل. تم اجراء اختباري مطياف الاشعة تحت الحمراء ومسح المجهر الالكتروني للأسفلت الاعتيادي وللأسفلت العالي الصلابة. كانت القيمة المثلى المختارة للمضافات لانتاج الاسفلت العالي الصلابة المستخدم في الخلطة الاسفلتية العالية المرونة هي 4% و0.4% من وزن الاسفلت للنوفولاك والهكسامين على التوالي، بينما نسبة حبيبات المطاط لتحسين المرونة هي 0.5%. أظهرت نتائج الاختبارات المجهرية والاشعة تحت الحمراء للاسفلت المنتج حدوث تداخلا ميكانيكيا بين الاسفلت والمضافات أدى الى تحسن كبير في الخواص الميكانيكة للاسفلت المنتج. الاسفلت المنتج قد حقق متطلبات الاسفلت العالي الصلابة وبالتالي يمكن استخدامه في انتاج الخلطة الاسفلتية العالية المرونة المصممة وفق الطريقة الفرنسية.The conventional Hot Mix Asphalt (HMA) may suffer from several distress such as fatigue cracks and rutting. These distresses increase with severe climate conditions and reputation of traffic load. The High Modulus Asphalt Concrete (HMAC) designed according to the French method (EME) can be considered as one of the important solutions for these distresses. The production of HMAC requires hard grade bitumen. The current research involved a novel way to produce hard grade bitumen (asphalt binder) to be consonant with the requirements of hard grade bitumen used for a HMAC. The experimental work involved mixing polymer and cross-linking agent with conventional bitumen to get the new bitumen. Since the most concern with hard grade bitumen and HMAC is the fatigue cracks, Crumb Rubber (CR) was added to the obtained bitumen to improve the fatigue performance of the pavement. Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electronic Microscope (SEM) tests were carried out on the conventional and hard grade bitumen. The optimal value of additives was selected to meet the requirement of hard grade bitumen was 4% Novolac from weight of bitumen and 10 % of Hexamine from weight of Novolac (i.e. 0.4% of weight of bitumen), while the selected CR ratio to improve flexibility was 0.5% from weight of bitumen. FTIR and SEM test results showed that a mechanical interaction was occurring between the bitumen and the additives leads to greatly improve the mechanical properties of resulting bitumen. The obtained bitumen is satisfied to required standards and can be used for HMAC according to French method

Qualitative Evaluation for Asphalt Binder Modified with SBS Polymer

Solutions for safer, more durable infrastructure are required in light of increasing traffic and severe weather in Iraq. The most significant road conservation and maintenance challenges are the pavement's low resistance to dynamic loads and short service life. As a result, vast sums of money are spent annually to enhance the road service capacities in Iraq. Thermoplastic electrometric polymers for bitumen modification create long-lasting, cost-effective roadways. This study aims to determine how the mechanical properties of neat asphalt binder change when styrene butadiene styrene (SBS) is added as a modifier. The current research investigates adding three percentages of SBS (3, 5, and 7% of the weight of bitumen). Both neat and polymer-modified bitumen (PMB) were subjected to a series of physical laboratory and Superpave tests, including a dynamic shear rheometer tester (DSR) and a storage stability test. In addition, a chemical analysis test was conducted to identify any change in the neat binder chemical composition due to the addition of SBS polymer. The results indicated that 5% of SBS polymer was the optimum addition percentage to the local asphalt in Iraq. Additionally, it reduced the susceptibility of bitumen to temperature changes and enhanced its characteristics in all laboratory tests. The obtained PMB significantly improved rutting and fatigue factors compared to the neat asphalt binder. Based on the DSR tester and the storage stability test, the ratio of 5% SBS met the requirements of class PG76-10, used in the central and southern governorates of Iraq. Using SBS polymer on the surface course in Iraq reduces road damage due to the scorching summer sun, reduces the likelihood of rutting and fatigue cracking, and works well in hot regions, resulting in roads that last longer, provide comfortable riding, and require less maintenance

Investigation the effect of newly used polymer modified bitumen on the performance of hot mix asphalt containing reclaimed asphalt pavement

The current research focuses on investigating the effect of using reclaimed asphalt pavement (RAP) on performance of hot mix asphalt (HMA) prepared with polymer modified bitumen (PMB) binder. This PMB used for the first time with HMA contained RAP. The mechanical properties and performance of HMA were assessed using several standard tests including Marshall, indirect tensile strength, creep compliance, and wheel track test. The RAP replacement was conducted up to 70% of total aggregate in HMA with an increment of 10%. The results of investigation showed, that the use of PMB binder prepared by addition novolac (phenol formaldehyde solid resin) and hexamine to conventional bitumen, significantly improved the performance of HMA contained RAP. Also, the optimum percentage of RAP replacement was found to be 50% of total aggregate in HMA. For this level of replacement, the rut depth reduced up to 38% of its original value