What Is Concrete?
Concrete is a composite material made by mixing different material like cement, sand, aggregate & water with or without admixture
Concrete is the most widely used and popular construction material, although no construction can be done without the use of concrete.
Concrete is the oldest and most used man-made material on earth. Its most common construction material extensively used for buildings, bridges, roads, and dams. Its uses range from structural applications to sidewalk ways, curbs, pipes, and drains.
Read More: Concrete Material Calculator
Ingredients of Concrete
Cement is the main binder material used to bind other building concrete materials together. It is used for making mortar and concrete during the construction process.
2. Coarse Aggregate
Coarse Aggregate forms the major body of concrete. The aggregates contribute to the overall strength of the concrete by increasing density.
3. Fine Aggregate (Sand)
fine aggregate such as sand used to fill in the spaces left between the large coarse aggregate and to “lock” the larger pieces together. Sand helps in reducing the quantity of cement paste required and decreases the amount of shrinkage that could occur.
Admixtures are added to enhance or to modify the properties of fresh & hardened concrete. (Plasticizers, retarders)
it is the key ingredient, which when mixed with cement, forms a paste that binds the aggregate together. The water contributes to the hardening of concrete through a process called hydration. Its role is major in concrete because the strength of concrete extensively depends on water to cement ratio and it is the critical factor in the production of “perfect” concrete.
6. Fly Ash
Fly ash use in concrete improves the workability of plastic concrete and the strength and durability of hardened concrete. Fly ash use is also cost-effective. Fly ash added to concrete to reduce the amount of cement required for concrete, which contributes to considerable saving of cement and cost of concrete making.
How to Make Concrete
Steps of making concrete are given below
1) Decide ratio of concrete (1:1.5:3 or 1:2:4).
2) Take out the material as per ration like,
1 – For cement (take 50 kg)
1.5 – Sand (take 50 x 1.5 = 75 kg)
3 – Aggregate (take 50 x 3 = 150 kg)
3) These two methods of mixing concrete mixing and machine mixing.
4) First, add coarse aggregate on the floor and over it add sand then spread cement over it. Mix this ingredient well at least for 2 minutes.
5) After that add water according to the water-cement ratio.
6) Mix all materials well until well mix concrete is ready to be used.
Workability of concrete is the property of freshly mixed concrete which measures the ease and homogeneity with which it can be mixed, placed, consolidated, and finished as per ACI.
It means the ability of concrete to flow. The concrete made with good consistency will increase workability and performance. The concrete having good consistency helps in reducing the placing and compaction efforts and reduces the time of concreting work.
It can be defined as the separation of the constituent materials of concrete.
It is sometimes correlated to the property of water gains in concrete. It is a specific form of segregation, in which some of the water from the concrete comes out to the surface of the concrete, being of the lowest specific gravity among all the ingredients of concrete.
5. Setting Time
It is the time required by concrete to get sufficient hardness. It generally correlated to the setting time of cement.
6. Unit Weight
A normal weight concrete weighs 2400 kg per cubic meter or 145 lbs per cubic foot (3915 lbs per cubic yard).
Types of Concrete Test
The following are an important tests of concrete,
1) Test on Fresh Concrete
2) Test on Harden Concrete
- Compressive strength test (most common)
- Modulus of Elasticity
- Split-tension test
- Flexural strength test
- Rebound hammer test
- Penetration resistance test
- The ultrasonic pulse velocity test
- Maturity test
Types of Concrete
- Normal Strength Concrete
- Plain or Ordinary Concrete
- Reinforced Concrete
- Prestressed Concrete
- Precast Concrete
- Light – Weight Concrete
- High-Density Concrete
- Air Entrained Concrete
- Ready Mix Concrete
- Polymer Concrete
- Polymer concrete
- Polymer cement concrete
- Polymer impregnated concrete
- High-Strength Concrete
- High-Performance Concrete
- Self – Consolidated Concrete
- Shotcrete Concrete
- Pervious Concrete
- Vacuum Concrete
- Pumped Concrete
- Stamped Concrete
- Asphalt Concrete
- Roller Compacted Concrete
- Rapid Strength Concrete
- Glass Concrete
Factors Affecting Cost of Concrete
The cost of concrete depends on various factors like,
- Ingredient of concrete
- Quality of material like cement, sand & aggregate.
- Availability of materials.
- Labor cost.
- Method of making – hand mix or machine mix.
- Site mix or ready mix concrete.
- Grade of concrete.
- Depending on the above factors the average cost of concrete around the world is about 50 $ to 80 $ per Cubic meter.
- The cost of concrete is $108 per cubic yard in the USA
Read More: How To Calculate Cost Of Concrete Work
Advantages of Concrete
Following are the advantages of concrete,
- Availability of concrete ingredients easily.
- it can be easily handled and can be molded in any shape.
- it can be easily transported from one place to another place where it is required by truck mixer before the initial set takes place.
- Ability to pump/spray to fill into cracks and lining of tunnels.
- When reinforced, all types of structures are made possible from an ordinary lintel to massive flyovers
- Monolithic character gives a better appearance and much rigidity to the structure.
- The property of concrete possessing high compressive strength makes a concrete structure more economical than that a steel structure.
Disadvantages of Concrete
Following are the disadvantages,
- It is required to be reinforced to avoid cracks due to low tensile strength.
- For a long span of structure like slabs, expansion joints are required to be provided if there is a large temperature variance in the area.
- Construction joints are provided to avoid cracks due to drying shrinkage and moisture expansion.
- Soluble salts in concrete cause efflorescence if moisture reacts with them.
- The Portland cement used in concrete sometimes gets integrated into the presence of alkalies, sulfates, etc.
- Sustained loads develop creep in structures.
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