Properties of Concrete in Plastic State 1. Essential Qualities The quality of the hardened concrete is largely dependent on the quality of the plastic concrete. The curing process also contributes to attainment of the specified design criteria. Because the consistency of the mix may vary, careful adherence to design criteria is extremely important. When the … Read more
Concrete Placing As with the handling of concrete, certain fundamental considerations govern placing techniques. First and perhaps foremost is the need to avoid segregation of the concrete caused by improper techniques. Second is the need to ensure thorough compaction of the concrete. The manner in which concrete is placed can have a significant influence on … Read more
What is Compaction of Concrete? Compaction of concrete is one of the important site operations that together enable the fresh concrete to reach its potential design strength, density and low permeability. Properly carried out it ensures that concrete fully surrounds and protects the reinforcement, tendons and cast-in inserts. It also has a direct impact on … Read more
Role of Steel in Concrete Reinforced concrete is a material that combines concrete and some form of reinforcement into a composite whole. Whilst steel bars, wires and mesh are by far the most widely used forms of reinforcement, other materials are used in special applications, e.g. carbon-filament reinforcement and steel fibres. Concrete has a high … Read more
What is Contraction Joint? A contraction joint is one in which the two concrete surfaces are free to move away from one another as a result of shrinkage or thermal movement. Relative movement in the plane of the joint is prevented. Why to Provide Contraction Joint? As concrete hardens and dries out, it shrinks. Unless … Read more
Mix Concrete Manually Proper mixing of concrete ingredient is very much necessary as it affects the quality of concrete in its fresh state as well as in hardened state. A concrete is said to be well mixed if it fulfills the following requirements. Concrete mix should be uniform in colour Concrete should achieve proper consistency … Read more
Cracks in Hardened Concrete Cracking in concrete after setting occurs for a variety of reasons. The two most common forms of cracking in hardened concrete are crazing and drying shrinkage cracking. 1. Crazing This is best described as a network of very fine cobweb-like or alligator-skin cracks, which appear on the surface of concrete after … Read more
What is Efflorescence in Concrete? Efflorescence in concrete simply means appearance of white colored powdered material on the concrete surface. Efflorescence is the formation of salt deposits, usually white, on or near the surface of concrete after it has been finished and causing a change in the appearance. Light-coloured concrete shows the deposit much less … Read more
Fly Ash Fly ash or pulverized fuel ash (PFA) is the residue from the combustion of pulverized coal collected by mechanical or electrostatic separators from the flue gases or power plants. It constitutes about 75 per cent of the total ash produced. The properties and composition of fly ash vary widely, not only between different … Read more
Concrete Repair Chemicals Chemicals that are used to repair damaged sections or members of any concrete structure is called concrete repair chemicals. Concrete repair chemicals are of various types. While some are used for increasing bond strength between old concrete and new concrete; others are used for water repellant or corrosion resistance purpose. Depending upon … Read more