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
How to Cure Concrete in Cold Weather? Curing concrete becomes a more challenging job in colder days. Heavy snowfall and excessive humidity in the air are a few typical sights of the winter season which prevent concrete slabs from hardening properly in time. When temperature goes below 0 degree Celsius or minus 7 degree Celsius, … Read more
No Fines Concrete No fines concrete is one type of light weight concrete. As the name indicates, this a concrete mix without fine aggregate or sand. This type of concrete consists of only water, cement and coarse aggregate. Important Notes on No fines Concrete Normally coarse aggregates passing 20 mm sieve and retained on 10 … Read more
Special Materials in Concrete Industry 1. Ferrocement Ferrocement is a type of reinforced concrete composed of concrete with small aggregate (or coarse cement mortar), 12 to 30 mm thick, reinforced with a minimum of two layers of small diameter, orthogonally woven wire mesh separated by 3 to 6 mm diameter galvanized spacer wires or weld … Read more
Corrosion of Concrete Reinforcement Corrosion is a chemical process of destruction of material because of its reaction with the environmental conditions. The most predominant among various factors of corrosion is the atmospheric corrosion which causes the rusting of steel. Appreciable corrosion only starts when the relative humidity of the air exceeds around 65%. In dry, … Read more