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Register a new userThe Possibility Of Using The Recycled Concrete Aggregates In Hot Mix Asphalt
امكانية استخدام الحصويات البيتونية معادة التدوير في الخلطات الاسفلتية الساخنة
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استطاعت الحصويات البيتونية معادة التدوير ان تأخذ مكان الحصويات الطبيعية لتنفيذ الردميات المنتخبة و طبقتي الاساس و ما تحت الاساس الحصوية للطرق و المطارات في كثير من دول العالم. و هناك شبه اجماع من قبل عدد كبير من الباحثين و الدارسين حول امكانية استخدام RCA في خلطات البيتون الاسمنتي للعناصر غير الانشائية . اما في مجال الخلطات الاسفلتية الساخنة للطرق Hot Mix Asphalte(HMA), فمازال استثمار هذه الحصويات قيد البحث و النقاش, و ذلك بسبب ما تتميز به هذه الحصويات من زيادة المسامية و ارتفاع نسبة التشرب اضافة الى عدم التجانس, الامر الذي سينعكس سلبا على المواصفات الفيزيائية و الميكانيكية للمجبول الاسفلتي الساخن. تم في هذا البحث اجراء دراسة لامكانية استخدام الحصويات البيتونية المعاد تدويرها في الخلطات الاسفلتية الساخنة Hot Mix Asphalte(HMA) لتنفيذ طبقة الاساس البيتوميني للطرق, و ذلك من خلال اجراء اختبارات مارشال على خلطات اسفلتية تم تحضيرها باستعمال نسب مختلفة من الحصويات معادة التدوير, حيث بينت نتائج اختبارات مارشال بأنه يمكن لخلطات الاسفلت الساخن ان تحقق شروط استخدامها لتنفيذ طبقة الاساس البيتوميني للطرق على ان لا تزيد فيها كمية الحصويات البيتونية معادة التدوير عن 50%, و ذلك وفق متطلبات دفتر الشروط و المواصفات العامة لأعمال الطرق و الجسور في الجمهورية العربية السورية.
The recycled concrete aggregate RCA was able to take the place of the vierge & natural aggregate NA, embankments elected,to implement the base&subbase road layaers and airports in many country of the world.furthermore, there is almost consensus by a large of reshershers and scholars about the possibility of using RCA in mix cement concrete for non-structural elements .whil,the using of RCA in the hot mix asphalt HMA still under discussion and debate, due its high porosity , high water absorption, and its heterogeneity which reflected negatively on the mechanical and physical properties of the HMA This research discusses stadying the possibility of using the recycled concrete aggregates in hot mix asphalt HMA, for the implementation of the bas layer bituminous road , by the application of the marshall tests on hot mixtures asphalts have ben prepared using different ratios of recycled concrete aggregates. The results of marshall testes showed that the HMA prepared with amount of recycled concrete aggregates less than 50%,can be used to implement the base layer bituminous road,according to the general terms and specifications book for road works and bridges in the syrien arab republic.
References used
O'MAHONY, M.M. Recycled Of Materials In Civil Engineering. A Thesis Submitted To The University Of Oxford For The Degree Of Doctor Of Philosophy New College Trinity Term 1990
FderalHigway AdministrationFHWA : Recycled Materials Policy Administrator'smessage.2002
FderalHigway AdministrationFHWA:Transportation Applications Of Recycled Concrete Aggregate.FHWA, State of the Practice National Review -September 2004
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The large increase in the volume of demolition concrete waste and its impact on the
environment has led to reconsider of using concrete demolition rubble as a partial or a
whole alternative of natural aggregates to produce new concrete which has th
e required
properties to use in engineering constructions[1]. With the possibility of improving the
mechanical properties of this concrete by processing this aggregates before using it or
support this concrete with fiber to improve its structural behavior.
This research deals with the study of the replacement the natural aggregates used in
concrete with recycled concrete aggregates resulting from the demolition rubble ,
according to different replacement ratiosranging between 0 % -25 % -50 % -75 % -100%
and the impact on the concrete behavior with a natural aggregates and determine the
optimal replacementpercentage.
The results showed a relative decrease in the concrete resistance on the simple
pressure , limited decrease in the volumetric mass also, and a slight adjustment to the
behavior of concrete under the loading effect by increasing the replacement proportion of
the natural aggregateswith recycled concrete aggregates..
The recycling of debris, is considered as one of the most important resources for
constructing base &subbase road layers in many countries.
There are two problems for RCA: first, the considerable size it takes up when
collected and second, its low
technical properties. The second problem appears in
countries which don't have natural quarries and they have to use RCA in certain fields
(concrete mixes, asphalt mixes, granular road layers).
This research discuses preparing RCA aggregates, by recycling the concrete waste,
which comes from Al-Sallima landfill, near to Damascus city. Then many tests are carried
out to study the effect of changing the aggregate's size on their mechanical & physical
properties, and also to study the possibility of using these aggregates in constructing base
&subbase road layers.
As a result, it has been found that we can use RCA for constructing unbound base
&subbase road layers, and the mechanical & physical properties of these RCA get better
when the aggregate's size gets smaller, except in Proctor test. In this test, Proctor density
and optimum moisture content get better when aggregate's size gets bigger.
Asphalt concrete is used in the surface layer of road paving and is widely used around the
world. Asphalt concrete consists of coarse aggregate , fine aggregate, filler and asphalt
binder. Fly ash FA is one of the main wastes of coal-fired thermal
and coal-fired power
plants and is available in large quantities and has no use. The aim of this study is to
evaluate the possibility of using fly ash as a filler material in hot asphalt mixtures and to
use it as an alternative to natural fillers by performing laboratory work in which the asphalt
mixture is designed and the optimal ratio of asphalt is determined . Then replace the filler
material with 0, 25, 50, 75 and 100% with fly ash . The results showed that Marshall's
stability values increased with increased replacement ratio and observed that Marshall's
hardness values were decreased while remaining within the tolerable limits of the
specifications. The study concluded that fly ash can be used as a filler in asphalt mixtures.
Using different alternative materials in concrete mix, and expanding the area of using these materials, is considered very important from scientific, economic, and environmental point of view. Especially the diversity in number of used aggregates. As
a result, reduction in the cost of transportation saving the environment, and improving the properties of concrete mix may occur Basalt lava, and volcanic cines are widely present in Syria, but using lava is limited because the
studies about Syrian basalt were not enough. The lack of proper mills or crushers to grind basalt to be good to prepare concrete mix. As a result, the investment of using Syrian basalt in preparing concrete mix was very limited.
Investigating, and classifying the basalt quarries, is needed to find out if the Syrian basalt is convenient to prepare concrete mix, or bitumen mix.
The purpose of this research in to use the natural resources in different Syrian areas in better engineering,environmental,and economical ways through the improvement of engineering
sides, increasing the capability of concrete structures, better investment of quarries in Syria, and to get more economical benefit with minimum cost. In this research, an experimental study was achieved to evaluate the basalt in north Syria according to international standards and codes. The composition of basalt Ore was determined by petrogrphic study, with focus on the content of olivine in basalt, and the degree of deterioration.
This research presents new procedures to calculate the aggregates weight and the water requirement to realize a controlled concrete mixing design, where the aggregates proportion is defined by numerical method according to referential curve draw as r
eferring to the proposed fine aggregate ratio and the required water will be calculated as referring to the aggregates surface area. The results showed the facility and the reliability of the proposed design procedures.
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