Posted By:Infra Bazaar
INTRODUCTION: Concrete is a strong element and a vitally important thing which is used in several individual and commercial buildings. It solidifies and hardens after mixing with water and placement due to a chemical process which is known as hydration. It binds other building materials together. It is a material extensively used in the construction process and is made by mixing aggregate, cement, small stones, sand, gravel and water. All the components bond together, to create a stone-like material.
The Romans invented the hydraulic cement-based concrete. The British improved upon it and popularized it in the modern world. The Pantheon in Rome is one of the finest examples of Roman architecture that has survived to this day and has a 42-meter-diameter dome made of poured concrete.
Concrete is used to make pavements, architectural structures, foundations, motorways, roads, and bridges, overpasses, parking structures, walls and footings for gates, fences and poles. It is most used man-made material.
HOW IT WORKS
The material grows together from a moldable liquid into a hard, rigid solid. In the world today, concrete has become a fact of modern life. 6 billion tons of concrete is used around the world each year. The addition of sand, fine aggregates and coarse aggregates of up to a few centimetres makes concrete. It is a porous material, whose properties depend on its different kinds of pore space. There are air voids that are entrapped in the mixing process, the capillary pores, which are spaces occupied by water from mixing.
Concrete has compressible strength, which is related to the overall porosity of the cement paste and the amount and form of the aggregates.
Concrete in the present infrastructure has been deteriorating at a fast pace due to the corrosion of reinforcing steel coming from the including chloride and other ions from road salts, marine areas and ground soils.
Nowadays the focus is on the transport aspect of concrete which includes diffusivity, permeability, and absorption. Concrete is a complex composite, which needs an improvement, monitoring and control.
The amount of water in the mix is compared with the amount of cement is called the water/cement ratio. The lower the water-cement ratio, the stronger is the concrete. It has higher strength and less permeability. The qualities expected of it are resistance to freezing and thawing and deicing chemicals, water-tightness, low permeability, wear resistance, and tough strength.
Admixtures are additions to the mix which are used to achieve certain goals. When Accelerating admixture-accelerators are added to concrete they reduce setting time of the concrete and accelerate strength. The amount of reduction in setting time varies. The Retarding admixtures are often used in hot weather conditions to delay setting time. The use of Fly ash reduces the heat generated by the concrete
Thus concrete is versatile and a widely used construction material, which provides for durable, resilient and sustainable end products and serves the humanity in a big way.