Concrete is a building material consisting of cement, fine aggregate (sand), and coarse aggregate mixed with water that solidifies over time. Portland cement is the commonly used type of cement for concrete production. Concrete technology covered the properties of concrete and its practical applications.
In building construction, concrete technology is used to build foundations, columns, beams, panels, and load-bearing elements.
There are different types of bonding materials other than cement such as lime for calcareous concrete and bitumen for asphalt concrete used in road construction.
Different types of cement are used for concrete works that have different properties and applications. Some types of cement are Portland Pozzulana Cement (PPC), Rapid hardening cement, Sulfate-resistant cement etc.
The materials are mixed in specific proportions to obtain the required strength. The strength of the mixture is determined as M5, M10, M15, M20, M25, M30, etc., where M denotes Mix, 5, 10, 15 etc. as its strength in kN / sq.m. In the United States, the strength of concrete is determined in the PSI and is the pound per square inch.
The ratio of aqueous cement plays an important role affecting various characteristics such as operability, strength and durability. A sufficient percentage of cement and water is required to produce the applicable concrete.
When the water is mixed with the materials, the cement reacts with the water and the water begins to react. This reaction helps the components to form a solid matrix that bonds the materials together in a stone-like substance.
Concrete can be cast in any shape. Since it is a plastic material in a new condition, different shapes and sizes of shapes or molding molds are used to provide various shapes such as rectangular and circular etc.
There are different types of additives that are used to provide certain properties. Additives such as pozolan or super plasticizer are included in the mixture to improve the physical properties of the wet mixture or the final material.
Various types of concrete are manufactured these days to build buildings and structures. These have special characteristics and features that improve construction quality as per the requirements.
The concrete components are cement, sand, aggregates and water. A mixture of cement and water is called Portland whenever you paste. Therefore, concrete can be called as a mixture of dough, sand and aggregate. Sometimes rocks are used instead of rubble.
The cement paste covers the surface of fine and rough aggregates when well mixed and bonded. Shortly after mixing the components, the water reaction that provides strength and the solid rocky concrete is obtained.
What is the degree of compressive strength?
The degree of strength and hardness indicates its required strength for construction. For example, the M30 grade indicates that the compression strength required for construction is 30 MPa. The first letter in row “M” is the mixture and 30 is the required strength in MPa.
Based on different laboratory tests, concrete grade is offered in Mix Proportions. For example, for the M30 grade, the mixture ratio can be 1: 1: 2, where 1 is the cement ratio, 1 is the sand ratio and 2 is the ratio of coarse aggregate based on the size or weight of the material.
Force is measured using a cube or a concrete cylinder by civil engineers at the construction site. The cube or cylinders are manufactured during the casting process of the structural member and after hardening it is treated for 28 days. Then a pressure force test is performed to find the strength.
The normal grades of concrete are M15, M20, M25 etc. To build reinforced concrete, a lower M20 grade of concrete is used.
How is concrete made?
Concrete is manufactured or mixed in proportion to w.r.t. The amount of cement. There are two types of concrete mixtures, i.e. the nominal mixture and the design mixture. The nominal mixture is used for ordinary construction works such as small apartment buildings. The most popular nominal mix is in a ratio of 1: 2: 4.
Designed concrete is the one whose mixture ratios are finished based on various laboratory tests on the cylinder or cube of its compressive strength. This process is also called mix design. These tests are conducted to find a suitable mixture based on locally available materials to obtain the required strength, according to the structural design. Mixed design offers economy of ingredients.
Depending on the quantity and quality required, the appropriate mixing method is chosen. In manual mixing, all ingredients are placed on a flat surface, water is added and mixed with hand tools. In mixing the machine, different types of machines are used. In this case, the ingredients are added in the amount required to mix and produce fresh concrete.
Once properly mixed, they are transported to a casting site and poured into molds. Various types of molds are available, which are chosen depending on the usage.
Cast concrete is allowed to put molds on time based on the type of structural member to gain sufficient strength.
After the molds are removed, the treatment is carried out in various ways to compensate for the loss of moisture due to evaporation. Requires moisture reaction and strength gain. Therefore, treatment generally continues for at least 7 days after removing the molds.
Types of concrete construction
Concrete is generally used in two types of construction, i.e. simple concrete construction and reinforced concrete construction. In simple concrete construction, it is poured and poured without using any reinforcement. This is used when only the structural member is exposed to pressure forces and not bending.
When a structural member is bent, reinforcements are required to withstand the organ of tension forces because it is very weak in tension compared to pressure. In general, the strength of a concrete in tension is only 10% of its compressive strength.
It is used as building material for almost all kinds of structures such as residential concrete buildings, industrial structures, dams, roads, tunnels, multi-storey buildings, skyscrapers, bridges, sidewalks, highways, etc.
An example of famous and large concrete structures, the Hoover Dam, the Panama Canal and the Roman Pantheon. It is the largest man-made building material used in construction.