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Register a new userThe Effect of Changing Aggregate's Size on its Mechanical & Physical Properties and the Possibility of Using it in Base &Sub base Road Layers
تأثير تغير حجوم الحصويات البيتونية المدورة RCA على خواصها الفيزيائية و الميكانكية و امكانية استخدامها في انشاء طبقات الأساس و ما تحت الأساس الطرقي
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تعتبر عملية تدوير نفايات الهدم و البناء البيتونية من أهم مصادر الحصويات، لتنفيذ طبقات الأساس و ما تحت الأساس الطرقي في العديد من دول العالم. تتأثر الخواص الفيزيائية و الميكانكية لـلحصويات البيتونية المدورة RCA بعدد كبير من العوامل, و تشير كافة الأبحاث السابقة إلى أن الحصويات البيتونية المدورة ذات خواص فيزيائية و ميكانكية أدنى بالمقارنة مع الحصويات البكر. و تكمن المشكلة في الكميات الكبيرة لنفايات الهدم و البناء البيتونية ، و بالتالي فهي تشغل مساحات كبيرة من الأراضي، و لابد من تدويرها و استثمارها بالشكل الأمثل رغم خواصها الفيزيائية و الميكانكية المتدنية. يتناول هذا البحث عملية تحضير الحصويات البيتونية المدورة RCA، الناتجة من تدوير ركام بيتوني تم احضاره من مكب السليمة قرب مدينة دمشق. و من ثم اخضاع هذه الحصويات للاختبارات المناسبة، و ذلك من أجل دراسة تأثير تغير حجوم الحصويات على خواصها الفيزيائية و الميكانكية (الأوزان النوعية, التشرب بالماء, كثافة بروكتور، مقاومة الاهتراء)، بالإضافة إلى دراسة امكانية استخدام هذه الحصويات في مجال انشاء طبقات الأساس و ما تحت الأساس الطرقي في بلدنا. و بالنتيجة تبين أن كافة عينات حصويات RCA المدروسة تحقق الشروط الفنية المطلوبة لاستخدامها في انشاء طبقتي الاساس و ما تحت الأساس الطرقي. كما بينت نتائج الاختبارات زيادة مقاومة الاهتراء (لوس انجلوس) كلما كانت الحصويات ذات حبيبات اقل خشونة، بينما اظهرت نتائج اختبار بروكتور (زيادة الكثافة الجافة العظمى و انخفاض الرطوبة المثلى) مع الخلطات ذات التدرج الأكثر خشونة.
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.
References used
Fderal Higway Administration FHWA : Recycled Materials Policy Administrator'smessage.2002
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
MALESEV.M.;RADONJANIN.V.;MARINKOVIC.S., Recycled Concrete as Aggregate for Structural Concrete Production . Sustainability 2010
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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.
The accelerated structural expansion in most countries has resulted in a major problem related to providing the necessary concrete for these buildings. Besides, the buildings that have become out of service recently has posed a real problem represent
ed in demolishing them creating a large amount of hard-to-manage aggregate.
The necessity to get rid of the aggregate have opened up the possibilities for attempting to use it as a relative substitute for the natural aggregate. The research focuses on recycling these aggregate in an attempt to use them in producing concrete and other construction materials. The research deals with one of the mechanisms of benefiting from these recycled aggregate through using them in producing concrete through treating the aggregate produced from demolition, and mixing them in quantities that reflect their actual ratio. The results are of great importance economically and environmentally.
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..
With the rapid growth of the size of the data stored in the cloud systems, the need for
effective data processing becomes critical and urgent. This research introduces a study of
the most important characteristics of databases management systems: H
ive, SQLMR, and
MariaDB Galera. Hive is a cloud database management system. SQLMR is a hybrid
system, which depends on the integration between the cloud and traditional systems
capabilities. While MariaDB Galera is a traditional database management system
developed to cope with the cloud characteristics. In this research, we show the most
important developments that have been on those systems, and then we compare their
performance in data processing based on the execution time of query operations with the
change of the volume of data. That is to identify the performance of those systems
practically and to know the developing requirements for access to optimized data
management system, and to help users in the selection of the database system that achieves
their requirements in terms of availability and scalability.
This research deals with producing structural lightweight aggregates concrete (the
density is less than 1920kg/m3 and compressive strength is more than 17.2Mpa according
to ACI 213R-03) by using scoria aggregates. Several concrete mixes have been d
esigned
with different proportions of scoria aggregates. The cement content (c=450 kg/m3), the
ratio (w/c = 0.36) were kept constant in all the mixes.
Different tests were performed to determine some properties of product concrete
such as density, compressive strength and splitting tensile strength. The density of product
concrete was in the range of (1752-1917 kg/m3), compressive strength was in the range of
(22.2-32.8Mpa), and the splitting strength was in the range of (2.3-3.2Mpa). The study
demonstrated the possibility of production concrete achieved the Requirements of the
American code ACI 213R-03 for structural lightweight concrete.
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