الفهرس 
Chapter (1): introductionOnly 14 pages are availabe for public view
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Abstract
Concrete, typically composed of gravel, sand, water, and Portland cement,
is an extremely versatile building material that is used extensively worldwide.
Reinforced concrete is very strong and can be cast in nearly any desired shape.
Unfortunately, significant environmental problems result from the manufacture of Portland cement. Worldwide, the manufacture of Portland cement accounts for 6-7 % of the total carbon dioxide (CO₂) produced by humans.
Fortunately, many waste products can be substituted for large portions of
Portland cement to improve the concrete’s environmental characteristics. For instant, fly ash, consisting mostly of silica, alumina, and iron, forms a compound similar to Portland cement when mixed with lime and water.
The proposed study aims to investigate steel-concrete bond behavior in
different concrete mixes proportioned using blended cements. Different fine
powders are available to replace relatively high fractions of Portland cement to produce blended cements. In this study dolomite powder is used as cement replacement along with either silica fume or fly ash. The main parameters of the study include: the composition of the blended cement and the reinforcing bar diameter. The bond behavior is evaluated by means of pull-out tests to determine the influence of the test parameters on steel-concrete bond
characteristics by evaluating the bond strength and the load-slip diagrams.
This thesis consists of five chapters:-
CHAPTER (1): Introduction
This chapter presents an introduction about concrete and its importance as a
construction material and an overview on Portland cement as the main
component of concrete and the economic and environmental influence of cement
industry. Also presents an overview on the research scope and objectives and the different chapters of the thesis.
CHAPTER (2): Literature Review
This chapter reports and discusses the most recent finding of previous
research work and the methods of testing and recommendations and it includes the theoretical and practical previous research works addressing the subject of the current study and concerned with the properties of composite cement and its fields of application.
CHAPTER (3): Experimental Work
This chapter describes the materials used; testing of materials, concrete
mixes design and manufacturing of test specimens, the curing and testing
procedure of specimens.
CHAPTER (4): Analysis of Test Results
This chapter contains the experimental results of test specimens and a
comprehensive analysis to demonstrate the influence of the different test
parameters.
CHAPTER (5): Conclusions and recommendations
This chapter summarizes the main conclusions and recommendations based
on the available test results and can be concluded in:
1- The results demonstrated beneficial effect of the dolomite powder on the
rheology of concrete as a consequence of improved particle size distribution.
The fine particles replace part of the voids between the coarser particles,
making more water available as an additional ”internal lubricant”.
2- The use of dolomite powder reduced the compressive strength of concrete
when used to replace cement without compensation of the amount of water
as the powder acted as diluents of the cement.
3- The better 28 – day compressive strength results can be obtained when silica fume is used along with dolomite powder to replace cement. The use of
either dolomite powder or fly ash or their combinations has a negative effect
on the 28 – day compressive strength.
4- The optimum replacement combination to achieve optimum compressive and
tensile strength comprises 5 percent dolomite powder and 7 percent silica
fume.
5- The chemical adhesion mechanism was negatively affected due to cement
replacement for all replacement ratios and combinations. While the 5 percent
dolomite powder replacement resulted in a relatively moderate reduction.
6- The bond strength continued to decrease as the dolomite powder replacement ratio increased. The use of silica fume did not provide significant increase or decrease in the bond strength. On the other hand, the use of 15% fly ash along with 5 percent dolomite powder maintained a bond strength level comparable to that when 7% of silica fume was used with the same dolomite powder ratio.
7- Concrete mixes containing either 5% dolomite powder or 15% fly ash along
with 5% dolomite powder have the potential of developing satisfactory bond strength levels provided that the water – to – cement ratio is reduced to
maintain the same consistency of the control mix.