Presentation aboutPresentation about Reinforced concreteReinforced concrete

Done By:Done By: Rasha QandeelRasha Qandeel Eman El BattaEman El Batta Heba Al NazlyHeba Al Nazly Samah AL Halees Samah AL Halees Somaia MkhimerSomaia Mkhimer

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Dr. Basel HamadDr. Basel Hamad

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teIslamic university – Gaza

Faculty of Engineering

Civil Engineering department

ContentContent

IntroductionIntroductionThe Functional RequirementsThe Functional RequirementsStructural Materials and Their Engineering Properties Structural Materials and Their Engineering Properties Structural concrete materialStructural concrete materialHistorical development of structural concreteHistorical development of structural concreteComponent of concreteComponent of concreteConcrete Properties and SpecificationsConcrete Properties and SpecificationsSteel Reinforcement Steel Reinforcement Mechanics of reinforced concreteMechanics of reinforced concreteConclusionConclusion

IntroductionWhat is the reason of the wide using of reinforced concrete in all over the world ?

This will be discuss in the presentation .

Functional Requirements of the construction materials

Strength

Toughness

Stiffness

Human comfort and safety

Economy

Environmental impacts

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 .

Component of concrete

Cement Water

Aggregate Admixtures

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

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 0.50 .

Table (1): Maximum permissible water: cement ratios

Compressive strength,

fc'

Water : cement ratio by weight

Non-air-entrained concrete

Air-entrained-concrete

2,500 psi [17MPa]

0.670.54

3,000 psi [20MPa]

0.580.46

3,500 psi [24MPa]

0.510.40

4,000 psi [28MPa]

0.440.35

4,500 psi [32MPa]

0.38……..

Aggregate 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 70 - 80 % 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

Admixture:

The needs of using admixture:

• Improve workability and strength.

• To increase durability of concrete .

• To accelerate the initial set of concrete .

Admixtures are often used in concrete to obtain specific characteristic in its fresh or hardened states

Concrete Properties and Specifications

Compressive Strength and Grade of Concrete:

Grade (kg/cm2)

B300300

B280280

B250250

Preparing samples

Compressive strength test

Stress strain diagrame

Table (2) Grade of concrete

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.

Modulus of Elasticity of Concrete:

Modulus of Elasticity is defined as a ratio between normal stress to corresponding stress

E=

Ec= 15100 'fc

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.

Advantages and Disadvantages of concrete as a construction material:

Advantages of concrete• 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

Steel ReinforcementWeak 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.

Mechanics of reinforced concrete

ft

fc

ft

fc

fs

ft

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.

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.

Thank you for your attention