Concrete and Reinforced Concrete...

Concrete and Reinforced Concrete Concrete is a composite building material made from a mixture of sand, gravel, crushed rock, or other aggregates (coarse and fine) held together in a stone like mass with a binder such as cement and water. The stone like mass is formed due to the hydration of cement and eventually due to its hardening. Sometimes one or more admixtures (plasticizers, super plasticizers, accelerators, retarders, pazolonic materials, air entertaining agents, fibers, polymers and silica furies) are added to change certain characteristics of the concrete such as its workability, durability, and time of hardening. Hardened concrete has a high compressive strength and a very low tensile strength. Concrete is one of the most popular materials for buildings because it has high compressive strength, flexibility in its form and it is widely available. The history of concrete usage dates back for over a thousand years. Contemporary cement concrete has been used since the early nineteenth century with the development of Portland cement. Despite the high compressive strength, concrete has limited tensile strength, only around 10 % of its compressive strength and zero strength after cracks develop. In the late nineteenth century, reinforcement materials, such as iron or steel rods, began to be used to increase the tensile strength of concrete. Today concrete is generally strengthened using steel bars known as reinforcement bars (rebars in short) in the tension zone. Such elements are known as ‘reinforced concrete’.  In the reinforced concrete, concrete and steel deform together and hence ribbed reinforcing bars are used for increasing the capacity to resist bond stresses. Reinforced concrete can be moulded to any complex shape using suitable form work. It has high durability, better appearance, fire resistance and is economical. It is a combination of concrete and steel wherein...