What is Concrete ?
Concrete is a construction material composed of cement, fine aggregates (sand) and coarse aggregates mixed with water which hardens with time. Portland cement is the mostly used type of cement for production of concrete.
There are different types of binding material is used other than cement such as lime for lime concrete and bitumen for asphalt concrete which is used for road construction.
Ingredients of Concrete
1. Binding material: Most commonly used binding material for concrete is Portland cement. Other binding materials used for this purpose, are lime, fly ash, silica fume etc. The selection of cement for concrete is depend on the “cement properties.
2. Aggregate: Two types of aggregates are used in concrete. Coarse aggregate and Fine aggregate.
Coarse aggregate: Big sizes aggregates in concrete are coarse aggregates. The size of it
varies between 1/2″ to 1.5″ depending on concrete mix design. Generally, crushed stone or brick chips are used as coarse aggregate.
Fine aggregate: The smaller size aggregates in concrete are Fine aggregates. The FM
(Fineness Modulus) of fine aggregates can be between 1.2 to 2.5 depending on mix design. We use sand as fine aggregate in concrete.
3. Water: The most important concrete ingredient is water. Water can decrease and increase the concrete strength depending on its using. Water just starts and continues the chemical reaction of cement. High water content in concrete mix increases the workability of concrete but decreases the strength. On the contrary, low water content increase the concrete strength but makes concrete less workable.
Qualities of Good Concrete
Strong: The concrete should be strong in compression and it will be weak in tension. And concrete used in a construction of load carrying for different structures same like dames, construction of bridges, pair and abutment of bridges etc. In these structure we must be used steel bar with concrete to extend the strength of concrete. Then it will be able to resist the loads.
Durability: The concrete should be able to against of weather action, such a wind, rain, storm and variation of temperature. So when we used the concrete in the construction of dames, sewer line or in sea water then it should be able to withstand of the action of chemical salts. Then the concrete will be safe from environmental problems.
Watertight: When we use the concrete In Construction of water like culvert , retaining wall , dames or in water canal so in these construction the use of concrete is very necessary so there for the concrete must be watertight the against of water. If the concrete is not watertight with
Workability: The concrete must be easily workable in using of construction. For that we have to use the water in limit. Then concrete will be workable and strong. But if the water ratio is max in the concrete so it’s making segregation of course aggregate and fine aggregate. And the max water ratio result is also bleeding of concrete. When the concrete making bleeding then the concrete strength is becomes loss.
Density: The concrete must be compacted and there should be no voids or hollow left in the concrete. And the weight of concrete must be 3000kg/cu meter. So that is the good quality of concrete.
Resist to Wear and Tear: When we used concrete in the construction of road and floor, so the concrete must be able abrasive for well. If the concrete is not able to resist with different problems so that will be not the good properties of concrete.
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