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...

Fusion Bonded Epoxy Coated Reinforcement Bar...

Fusion Bonded Epoxy Coated Reinforcement Bar Fusion bonded epoxy coating, also known as fusion bond epoxy powder coating and commonly referred to as FBE coating, is an epoxy based powder coating that is widely used to protect concrete reinforcement bars from corrosion. FBE coatings are thermoset polymer coatings. The most widely used types include acrylic, vinyl, epoxy, nylon, polyester, and urethane. Most popular for reinforcement bars is epoxy coating. The name fusion bond epoxy is due to resin cross linking and the application method, which is different from a conventional paint. FBE coatings are 100 % solid coatings applied as dry powders and formed into a film by heating. The fusion bonded epoxy coating process for reinforcement bars was developed in United States in 1960s and its use was strongly recommended in coastal areas. Since Its introduction, FBE coating formulations had gone through vast improvements and developments. Today, various types of FBE coatings, which are tailor made to meet various requirements are available. Modern application techniques for applying powders fall into four basic categories. These are (i) fluidized bed process, (ii) electrostatic bed process, (iii) electrostatic spray process, and (iv) plasma spray process. The electrostatic spray process is the most commonly used method of applying powders. In this process, the electrically conductive and grounded object is sprayed with charged, non conducting powder particles. The charged particles are attracted to the substrate and cling to it. The epoxy powder is applied by electrostatic spray on hot steel on preset temperature level. The powder, when in contact with hot bar, melts flows, gels, cures, cools and produces a well adhered continuous corrosion resistant protective coating. The thermosetting of the epoxy is an irreversible process and provides a good protection to reinforcement bars against corrosion. It prevents attack of chloride ion on the metallic surface and the occurrence...