Plain cement concrete has very low tensile strength. To improve the tensile strength of concrete, some sort of reinforcement is needed which can take up the tensile stresses developed in the structure. The most common type of reinforcement is in the form of steel bars which are quite strong in tension.

The reinforcing steel is placed in the forms and fresh concrete is poured around it. This solidified composite mass is called as Reinforced cement concrete and is abbreviated as R.C.C. Thus, Reinforced cement concrete is a composite material which is made up of concrete and steel reinforcement. The steel reinforcement, generally in the form of steel bars, are placed in the tensile zone of the structure and take up the tensile stresses. R.C.C. is a versatile construction material which is strong in compression as well as tension. The use of reinforcement in concrete not only increase its strength but also helps in preventing the temperature and shrinkage stresses.

The composite action of steel and concrete in a reinforced concrete section is dependent on the following important factors :

(i) The bond between steel and concrete.

(ii) Prevention of corrosion of steel bars embedded in the concrete.

(iii) Practically equal thermal expansion of both concrete and steel.

1.2.1. Uses of Reinforced Concrete

Reinforced cement concrete has innumerable uses in construction some of which are listed below :

1. Buildings

2. Flyovers

3. Water Tanks

4. Road and Rail Bridges

5. Chimneys and Towers

6. Retaining Walls

7. Bunkers and Silos

In this Article Learn : Various methods used for the design of R.C.C. structures,Working stress method,Load factor or ultimate load method,Limit state method, The main drawbacks of the working stress method of design,the advantages of Ultimate load method,The main limitations of the ultimate load method,The two important limit states to be considered in design:Limit State of Collapse,Limit State of Serviceability. DESIGN PHILOSOPHIES Design of any R.C.C. member comprises of the following : (i) To decide the size (dimensions) of the member and the amount of reinforcement required. (ii) To check whether the adopted section will perform safely and satisfactory during the life time of the structure. Various methods used for the design of R.C.C. structures are as follows : (i) Working stress method. (ii) Load factor or ultimate load method. (iii) Limit state method. Working Stress method This method of design was the oldest one. It is based on the…

In this Article: Learn Types of loads on R.C.C. Structures, Dead loads, Live loads or imposed loads, Wind loads, Snow Loads,Earthquake loads. See also The loads coming on the foundations TYPES OF LOADS ON R.C.C. STRUCTURES Structures are designed to withstand various types of loads. The various types of loads expected on a structure are as follows : (i) Dead loads (ii) Live loads or imposed loads (iii) Wind loads (iv) Snow loads (v) Earthquake loads Dead Loads Dead loads are due to self weight of the structure. Dead loads are the permanent loads which are always present. Dead loads depends upon the unit weight of the material. Dead loads includes, the self weight of walls, floors beams, columns etc. and also the permanent fixtures present in the structure. The unit weight of commonly used building materials are given in the code IS 875 (part-I)-1987. The unit weights of…

Content of this Article : Reinforcing material, Suitability of Steel as Reinforcing Material, charectristic strength of steel and types of steel reinforcement REINFORCING MATERIAL Concrete is weak in tension and it is to be reinforced properly with suitable material. The purpose of providing reinforcement in R.C.C. is : To take up all the tensile stresses developed in the structure. To increase the strength of concrete sections. To prevent the propagation of cracks developed due to temperature and shrinkage stresses. To make the sections thinner as compare to plain concrete section. To fulfill above criteria the reinforcing material should satisfy the following requirements : The reinforcing material should develop a perfect bond with concrete to transfer stresses from one material to other. It should have high tensile strength. It should be cheap, easily available and durable. The coefficient of thermal expansion of the reinforcing material should be nearly same as that…

Concrete Mix Proportioning Concrete Mix Proportioning Concrete Mix Proportioning : The determine of the proportions of cement, aggregates and water to attain the desired strength and properties such as workability, durability etc., is called as concrete mix proportioning. The design of concrete mix is classified into following two types by IS 456:2000 (Clause 9) : (1) Nominal mix concrete (2) Design mix concrete. Nominal Mix Concrete A concrete mix in which the proportions of cement, aggregate and water are adopted is called as nominal mix. It is not necessary that such a mix will give the desired strength and properties. For example, nominal mix proportions of M15 is 1:2:4. Nominal mix is not used for grades higher than M20. It is used for ordinary concrete works only. As per IS 456:2000 (Clause 9.3.1). The proportional of materials for nominal mix concrete shall be in accordance with the following Table…

Conetnt of This Article Properties of concrete : compressive strength,work-ability,Workability depends upon the following factors, The work ability can be measured by the following tests, Workability Requirements for Different Works,Durability Different Exposures with Normal Weight 20 mm Aggregates,Tensile Strength, Modulus of Elasticity, Poisson's Ratio, Creep, creep coefficient, Shrinkage, Freezing and Thawing, percentage of en trained air for nominal maximum size of aggregate, Sulfate, Attack Various Types of Environment Exposure Conditions See also: Requirements of good concrete mix and Grades of concrete Properties of concrete in plastic and hardened state Water cement ratio and slump test CEMENT CONCRETE AND ITS INGREDIENTS Properties of Concrete The properties of concrete depend upon the properties and proportions of its ingredients. The following are the important properties of concrete which are used in the design : Compressive Strength The compressive strength of concrete is determined by the cube test. The characteristic compressive strength of…

Content of this article: Concrete making materials Cement: Ordinary portland cement, Rapid hardening Portland cement, Low heat Portland cement, Portland slag cement, Sulfate resisting cement, Portland pozzolana cement, white cement, Aggregate and Water Concrete Making Materials (1) Cement Cement is the only chemically active ingredient of concrete which shows binding properties after reacting with water. It consist of silicates and aluminates of calcium which form a hardened mass after mixing with water. This type of cement is also known as hydraulic cement. There are many types of cements available in market, some of which are explained below : (i) Ordinary Portland Cement Ordinary portland cement (OPC) is commonly used in construction. The Bureau of Indian Standard has classified OPC in three grades. This classification is based on the compressive strength of cement-sand mortar cubes. The face area of these cubes shall be 50 cm2. The cube is made of 1…

In this article : Learn Plain cement concrete, Reinforced cement concrete, Composite action of steel and concrete, Uses of Reinforced concrete, Advantages of R.C.C. ,Disdvantages of R.C.C. Plain Cement Concrete Plain Cement Concrete is a hardened mass obtained from a mixture of cement, sand, gravel and water in definite proportions. These ingredients are mixed together to form a plastic mass which is poured into desired shape moulds called as forms. This plastic mass hardens on setting and we get plain cement concrete. The hardening of this mixture is caused by a chemical reaction between cement and water. Plain cement concrete has good compressive strength but very little tensile strength, thus limiting its use in construction. Plain concrete is used where good compressive strength and weight are the main requirements and tensile stress are very low. Reinforced Cement Concrete Plain cement concrete has very low tensile strength. To improve the tensile…