There are various types of industrial fibers such as: (polypropylene fiber, fiberglass, silica fume powder, etc..). These fibers are used widely as additives for improving concrete strength. We study in our research the effect of each of polypropylen
e fibers, steel fibers, and silica fume powder, on two kinds of concrete mix the first ordinary mix and the second is mix other with Mazar sand. We found after the studying of mechanical properties for those mixes that a slight improvement on tensile strength of concrete has
occurred, an increasing of compression strength of concrete has happened, and the failure style has changed according to the type of additive compared with concrete without additive.
The Roller Compacted Concrete (RCC) offers a different concept in the creation of pavement and concrete dams it’s dry Beaton (Zero Abrams slump), with a low water content, and includes of dense mix consisting of graded coarse aggregate, and cementati
ons materials, and water, this makes it so difficult to compact it in big thicknesses layers without using large energy rollers compactors. concrete conveys by trucks, placed and compacted by using equipment asphalt pavement. The main advantage of this technique is in reducing the completion time and cost savings in labor and the possibility of replacing traditional materials in road paving. It also provides a solid surface smooth and polished, and would facilitate the operations of traffic expected in all circumstances and various factors such as axial loads and environmental conditions.
This paper presents a new technology for the manufacture of Roller compacted concrete samples by applying a mechanism of Vibro-compaction pressure on samples of fresh concrete. It had Been manufactured concrete samples differ from their limestone filler content, and after conducting an analytical study of the results of tests of these samples has been reached to ideal feller content for this type of concrete by reliance on the mechanical strength and speed of evolution with time as criteria for the basic design.
Slabs are considered one of the most exposed elements to disasters and deformities
that can be clear to the viewer. These deformities are reflected as sign of defects that
appear clearly on big slabs. So, here comes the importance of applying and d
esigning
accurate slabs.
The purpose of this research is stating the need for persistent efforts to get a better
form of the slabs in order to increase their ability to be able to carry any outside extra
weights without the appearance of any deformities that might take place during the period
of investing the building. When deformities happen, they have bad effect on the beauty
and main function (purpose) of the building.
This research includes an experimental study for the real applicable slabs under our
supervision, in addition to a theoretical study about the deflection appearing on the slabs
by taking into consideration the plastic specifications of the concrete and the formation of
cracks.
This research aims at constructing reflexive deflections in the slabs during the
construction period and measuring the actual deformities and watching them through a
period of time, then comparing them with the theoretical expected deformities.
The findings that we could get at the end of our research are supposed to play a main
role in choosing the best design for the mandate slabs and at the same time getting the best
value for the reflexive deflection that can be used in the slab to make it better functionally
and to increase its ability to resist the outside applied weights. We hope this is just a start
for more research in this field.
Recently, the methods and theories of the structural and technicalevaluation for
cracked buildings have been developed because of different reasons (Natural disasters,
wars, the oldness… etc.) That was due to urgent need for right evaluation proces
s,
understand the structural and function status of the building and make the right decision.
The research includes the clarification of the importance of building structural
evaluation in addition to the basis and criteria of cracked buildings classification regarding
their structural and technical status.
The structural and technical evaluation for concrete building is considered as nonrepetitive
unique process, which has its particularity due to its link with large group of
indicators ( concrete natural and structure- structural system - the natural and intensity of
failures and cracks …etc.) Therefore, the evaluation process based on groups of
measurements, tests and views. The personal experience of the engineer has an important
role at evaluation process.
The research includes the preparation of scientific methodology to evolution process
and designing structural and technical evaluation software to evaluate cracked buildings
and limit the personal and mood role of the engineer during evaluation process. In addition
to that, the software will include applications from the real situations.
يستعرض هذا البحث دراسة الحالة الإجهادية – التشوهية للعناصر المكونة من أنابيب فولاذية مملوءة
بالبيتون تحت تأثير الضغط اللامركزي. و تبيّن أن هذه العناصر تبدأ بفقدان استقرارها عندما تصل
التشوهات اللدنة قيمها الحدية، و الموافقة لحالة توازن العزوم الخار
جية مع العزوم الداخلية.
و لقد تم تعيين العلاقات الحرجة للأنبوب الفولاذي المملوء بالبيتون في حالة حدوث السيلان من طرفي
المقطع باستخدام طريقة جداءات لاغرانج غير المعينة. إضافة إلى ذلك تمّ اقتراح شكل جديد للعلاقة
الرياضية (ε(f = σ اللاخطية لعمل النواة البيتونية و الذي يأخذ بالحسبان تغيّر المقاومات المختلفة
للبيتون.
In this research paper, engineering properties of structural elements
formed of combined metalic sections are compared with the suggested
structural element made of steel pipes full of concrete.
Such a comparison is carried out for bending and tor
sion carrying
capacities of above mentioned elements with the same height and crosssection.
Structural characteristics and material properties of steel pipes full of
concrete are presented.
The Study of stress state created in concrete pipes using the general
principles of structures mechanics is presented. A special relation to
determine the carrying capacity of the concrete pipe under various levels
of axial compression is suggested.
Theoretical results got on the basis of Euler equation are compared with
experimental results of special specimen tested in laboratory. A good
agreement between theoretical and experimental results is demonstrated.
