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ثلاث برامج تصميم انابيب ودكت وسيكرومتري تحفة من أخوكم ductlator

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  1. [41]
    حيدر علي خورشيد
    حيدر علي خورشيد غير متواجد حالياً
    عضو


    تاريخ التسجيل: Dec 2006
    المشاركات: 40
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    بانتظار دخولك اخ ductlator

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  2. [42]
    مهندس/علي
    مهندس/علي غير متواجد حالياً
    عضو فعال جداً
    الصورة الرمزية مهندس/علي


    تاريخ التسجيل: May 2006
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    الف شكر بس ياريت نبزة شرح عن الموضوع او عن البرنامج

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    من السهل أن ترى الناس على حقيقتهم ..ومن الصعب أن ترى نفسك على حقيقتها !

  3. [43]
    يوسف جابر
    يوسف جابر غير متواجد حالياً
    عضو فعال


    تاريخ التسجيل: May 2006
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    مشكوووووووووور

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  4. [44]
    المهيب بن علي
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    تاريخ التسجيل: Jun 2007
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    الف شكر لك ياأخي الكريم

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  5. [45]
    محمد الباهدلي
    محمد الباهدلي غير متواجد حالياً
    عضو


    تاريخ التسجيل: Oct 2006
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  6. [46]
    khajan2003
    khajan2003 غير متواجد حالياً
    جديد


    تاريخ التسجيل: Jun 2007
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    بارك الله فيك ودعائى لوالديك

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  7. [47]
    رائد احمد
    رائد احمد غير متواجد حالياً
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    الصورة الرمزية رائد احمد


    تاريخ التسجيل: May 2007
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    Standard SpecificationforPublic Works Improvements

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  8. [48]
    رائد احمد
    رائد احمد غير متواجد حالياً
    عضو
    الصورة الرمزية رائد احمد


    تاريخ التسجيل: May 2007
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    1. INTRODUCTIONEnvironmental awareness has been increasing rapidly over the past years. Extensivemeasures like air pollution reduction targets set by the European Union with the Kyotoprotocol have encouraged efforts to reduce pollution.Warm Mix Asphalt (WMA), a new paving technology that originated in Europe,is one of those efforts. It allows a reduction in the temperatures at which asphalt mixesare produced and placed. Its benefits are reduction in energy consumption and reducedemissions from burning fuels, fumes and odors generated at the production plant and thepaving site. This paper investigates the potential use of warm mix asphalt in cold weatherconditions and specifically how countries like Iceland, with such conditions, can benefitfrom this technology. Early research and marketing efforts have mainly focused on theenvironmental benefits and the reduced energy consumption of the technology and not asmuch on how it functions in cold weather paving.The primary objective of this research is to find out whether warm mix asphalt isa viable option for the paving industry in Iceland. In the process of answering thatquestion, warm mix asphalt’s advantages and disadvantages compared to traditional hotmix asphalt (HMA) are explored and the question of whether warm mix asphalt is aviable paving option for cold weather conditions in general is also answered. Theconclusions of this paper are primarily drawn from a literature review that was conductedon warm mix asphalt to evaluate what is known about its performance and a survey thatwas conducted in Iceland by sending a questionnaire to professionals in the industry.Conditions and paving practices in Iceland are also explored to give an understanding ofcommon paving issues in Iceland. Hopefully this paper can assist potential warm mixasphalt users in cold weather regions to understand the basic differences in the availablemethods and how they are differently suitable for the different situations that can comeup in cold weather paving.22. BACKGROUND2.1 HISTORY OF WARM MIX ASPHALTThe discussion of lowering the heat used to produce asphalt mixes is not new. The idea ofsaving energy and lowering emissions in the asphalt industry has been discussed fordecades.In 1956, Dr. Ladis H. Csanyi, a professor at Iowa State University, realized thepotential of foamed bitumen for use as a soil binder. Since then, foamed asphalttechnology, which allows lower mixing temperatures, has been used successfully in manycountries. The original process consisted of injecting steam into hot bitumen. In 1968,Mobil Oil Australia, which had acquired the patent rights for Csanyi’s invention,modified the original process by adding cold water rather than steam into the hotbitumen. The bitumen foaming process then became more practical. [1]In 1994, Maccarone examined developments in cold mixed asphalt based on theuse of foamed bitumen and very high binder ******* emulsions. He wrote that around theworld the use of cold mixes for use on roadworks are gaining greater acceptance. Suchsystems are energy efficient and environmentally friendly. Cold mixes do not emithydrocarbons and use less fuel in manufacturing. [2]Despite many good properties, cold mixes have not affected hot mix asphalt’sposition as the primary road surfacing material because they have not achieved the sameoverall long-term performance as hot mixes.In 1999, Jenkins et al. introduced a new process, half-warm foamed bitumentreatment. Their paper explores the considerations and possible benefits of heating a widevariety of aggregates to temperatures above ambient but below 100°C before theapplication of foamed bitumen. [3]A warm asphalt mix process (WAM) has been developed in Europe and wasreported by Harrison and Christodulaki at the First International Conference of AsphaltPavements in Sydney, 2000. A more complete report was given by Koenders et al. at theEurobitume congress in 2000. [4] Their paper describes an innovative warm mixture3process that was tested in the laboratory and evaluated in large-scale field trials (inNorway, the UK and the Netherlands) with particular reference to the production andlaying of dense graded wearing courses. [5] Their work resulted in the development ofWAM Foam, Warm Asphalt Mix with foamed bitumen. [6]At the Eurobitume congress in 2004, Barthel et al. introduced the use of asynthetic zeolite additive to produce warm mix asphalt. The zeolite creates a foamingeffect that results in a higher workability of the mix. [7]Warm mixes have received some attention in Europe and Australia since around2000. The pavement industry in North America started to give warm mixes some interesta few years later and in June 2005 the National Center for Asphalt Technology (NCAT)published two reports about the use of Sasobit, a synthetic wax, and Aspha-min, asynthetic zeolite, in warm mix asphalt. [8,9]2.2 POTENTIAL WARM MIX ASPHALT BENEFITSIn the following sections, the benefits that are usually publicized in literature as WMA’smain benefits and issues are briefly discussed. These are the emissions reductions,reduced energy consumption and decreased viscosity.2.2.1 Energy ConsumptionThe reduction in energy consumption is the most obvious benefit of WMA and isgenerally marketed and discussed in literature as one of the two main benefits of WMA.Studies have shown that energy consumption reductions of about 30% can be achievedby lowering the production temperatures at the asphalt plant. The reduction in energyconsumption reduces the cost of the asphalt production but there can also be an addedcost involved in using the WMA process, i.e. for additives and/or equipmentmodification. How much that additional cost is depends on the WMA method used.Another side benefit of the reduction in production temperatures sometimes mentioned isless wear and tear of the asphalt plant. [10]

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  9. [49]
    اشرف الشافعى
    اشرف الشافعى غير متواجد حالياً
    عضو فعال
    الصورة الرمزية اشرف الشافعى


    تاريخ التسجيل: Jul 2007
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    عمل جميل جزاكم الله خير الجزاء

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  10. [50]
    ductlator
    ductlator غير متواجد حالياً
    عضو فعال جداً
    الصورة الرمزية ductlator


    تاريخ التسجيل: Jul 2006
    المشاركات: 373
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