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

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

Introduction What 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 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]

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 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: 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 .

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

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 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: 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 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.

Mechanics of reinforced concrete ft 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.

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.

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