1. Presentation about Reinforced concrete
Islamic university – Gaza
Faculty of Engineering
Civil Engineering department
Presentation about Reinforced concrete
Done By:
Rasha Qandeel
Eman El Batta
Heba Al Nazly
Samah AL Halees
Somaia Mkhimer To
Dr. Basel Hamad
Reinforced concrete

2. Content Introduction The Functional Requirements
Structural Materials and Their Engineering Properties
Structural concrete material
Historical development of structural concrete
Component of concrete
Concrete Properties and Specifications
Steel Reinforcement
Mechanics of reinforced concrete
Conclusion

3. Introduction
What is the reason of the wide using of reinforced concrete in all over the world ?
This will be discuss in the presentation .

4. Functional Requirements of the construction materials
Strength
Toughness
Stiffness
Human comfort and safety
Economy
Environmental impacts

5. Structural concrete material
Historical development of structural concrete
Oldest concrete from the Stone Age around 7000 B.C. was discovered in 1985 in the Southern Galilee, Palestine.
The extensive use of structural concrete began at the turn of the twentieth century where lot of developments has occurred in the theory, design and construction .

6. Component of concrete
Cement
Water
Aggregate
Admixtures

7. Cement
Cement is produced by grinding limestone to fine powder and mixing it with clay in proportion of two part of limestone to one part of clay.
There are many types of cement , the mainly used are :
Portland-pozzolan cements
Rapid hardening cements
White cements
Slag cements

8. Water
The water must be free of organic contaminants. Potable water is generally acceptable.
Water-cement ratios affect the strength of concrete; Low ratios generally make concrete stronger. A water-cement content by weight between 0.40 and
Table (1): Maximum permissible water: cement ratios
Water : cement ratio by weight
Compressive strength, fc'
Air-entrained-concrete
Non-air-entrained concrete
0.54
0.67
2,500 psi [17MPa]
0.46
0.58
3,000 psi [20MPa]
0.40
0.51
3,500 psi [24MPa]
0.35
0.44
4,000 psi [28MPa]
……..
0.38
4,500 psi [32MPa]

10. Aggregate Aggregate is composed 70 - 80 % of concrete
Aggregate is a term referred to cursed rock or gravel and sand Crushed rock or gravel are called course aggregate.
Sand is called fine aggregate.
Aggregate is composed % of concrete
Aggregate may be divided into two main types :
natural aggregate
artificial aggregate
Aggregate must satisfied the required properties as:
Shape and texture
Size and gradation
The maximum size of aggregate is specified in the Building Code as
(a) 1/5 of the narrowest dimension between sides of forms
(b) 1/3 the depth of slabs
(c) 3/4 the minimum space between reinforcing bars

11. Admixture:
Admixtures are often used in concrete to obtain specific characteristic in its fresh or hardened states
The needs of using admixture:
Improve workability and strength.
To increase durability of concrete .
To accelerate the initial set of concrete .

12. Concrete Properties and Specifications
Compressive Strength and Grade of Concrete:
Preparing samples
Stress strain diagrame
(kg/cm2)
Grade
300
B300
280
B280
250
B250
Compressive strength test
Table (2) Grade of concrete

13. Tensile Strength of Concrete
The concrete is weak in tension reason , that is The tensile strength of concrete denoted by fct is only about 8 to 15% of its compressive strength ,So its neglected in reinforced concrete design.

14. Modulus of Elasticity of Concrete:
Modulus of Elasticity is defined as a ratio between normal stress to corresponding stress
E =
Ec= 15100
Unit Weight of Concrete:
The unit weight of concrete WC varies from about 2320 kg/ m3 to 2480 kg/ m3, an average value of 2400 kg/ m3 is usually considered. The unit weight of reinforced concrete depends on the steel ratio and is usually taken 2500 kg/ m3. This value is usually used in computing the own weight of reinforced concrete elements.

15. Advantages and Disadvantages of concrete as a construction material:
Easy and speed of construction.
Abundance of its constituents
Concrete toughness and structural strength make it withstand heavy loads.
Concrete is a durable material need little maintenance.
Good fire resistance.
Reduce thermal losses and provide sound insulation.
Concrete is a water resistance.
Concrete is an environmentally friendly material.
And for other reasons.
Disadvantages of concrete as a construction material
Low strength to weight ratio
low tensile strength
chemical attacks

16. Steel Reinforcement
Weak of concrete in tension region is the reason for using reinforced bars .
The addition of steel reinforcement which is characterized by its high tensile strength in the tension region is chosen for this reason:
To improve the resistance in the tension region.
Increase ductility of concrete.
Steel and concrete have similar thermal expansion coefficient.
Good bond between the steel reinforcement and the concrete.

17. Mechanics of reinforced concreteft fc fs
Mechanics of reinforced concrete beams.
Brittle flexural failure of Plain concrete beam.
Brittle shear failure of Plain concrete beam.
Prevention of failure in reinforced concrete beam
Prevention of failure in prestressed concrete beam
Prestressing force
Use of longitudinal and shear reinforcement to prevent the failure. The resulting composite material is called reinforced concrete.

18. Conclusion
Concrete has a good properties to use as a construction material for this reason it has a wide using in all over the world
Using of steel reinforcement bars to resist tension force in the tension region
The combination of concrete and steel provide anew material has a good property called reinforced concrete.

19. Thank you for your attention