There is main Properties of concrete featured in this article. In the concrete, there is always increase strength with age. After the casting, everyday the concrete increases its strength. Where it can be shown that a member will not receive its full load within 28 days after the casting of its member the characteristic strength of the member may be increased by multiplying with a factor e.g. factor for loading after 12 months is 1.2. The properties of concrete is follows,
Properties of Concrete
Concrete has a number of properties, including:
It is main The properties of concrete. Since the concrete is weak in tension, provision of steel is there due to this reason. But still it shows some tensile strength. The tensile strength of concrete may be obtained from the formula given as, Flexural Strength fct = 0.7√fck N/mm².
The properties of concrete is compressive strength. In general, the compressive strength of concrete is known as mechanical strength of concrete. The normal range of the compressive strength varies from 25MPa to 40Mpa. In high performance concrete, the compressive strength is more than 50Mp depending on the grades of concrete. M20 Grade concrete is one of which a 150mm cube of concrete cured for 28 days under standard testing conditions will yield at a compressive stress of 20N/mm².
Characteristic Strength means the strength of material below which not more than 5% of the test results are expected to fail.
Grades of concrete:
Concrete is known by its grade like M20, M25 etc. in which letter M refers to concrete mix and number 20, 25 denotes the specified compressive strength (fck) of 150mm cube at 28 days, expressed in N/mm2. Thus, concrete is known by its compressive strength. M20 and M25 are the most common grades of concrete, and higher grades of concrete should be used for severe, very severe and extreme environments. For the complete article click grades of concrete.
The change of shape due to presence of load in concrete is known as the Elastic deformation. The value is calculated using IS codes.
In the absence of test data the value of EC = 5000√fck.
Shrinkage of Concrete :
The total shrinkage of concrete is dependent mainly upon the total amount of water present in the concrete at the time of mixing and to a lesser extent on the cement content. The approximate value of shrinkage strain may be taken as 0.0003.
This is defined as a time dependent deformation at elevated temperature and under constant stress.
For concrete creep depends on
- Size of the member
- Environmental conditions.
- Stress in concrete
- Age at loading.
- Duration of loading.
The Unit Weight:
The unit weight of concrete varies from 23 to 26 KN/m2. The unit weight of plain and reinforced concrete as specified by IS:456 are 24 KN/m3 and 25 KN/m3 respectively. Generally for the calculation is taken as 25 KN/m3
The presence of pores in the concrete with reference to solids, is known as porosity. Basically it is the measure of percentage of pores present in concrete. The value of porosity for the conventional concrete is 9% to 10%.
It is nothing but the expansion of concrete due to temperature. Due to temperature variations the thermal expansion of concrete is happened.The value may range from 0.6 x 10-⁵/⁰c – 1.3 x 10-⁵/⁰c.
Durability of concrete is its ability to resist its disintegration and decay. One of the chief characteristics influencing durability of concrete is its permeability to increase of water and other potentially deleterious materials. Concrete is extremely resistant to chemical and physical attack.
Resistance to fire is known as fire resistance of concrete. Basically concrete does not burn but it fails due cracks and failure of other elements in fire. The concrete can with stand in fire up to 4-6 hours in fire, after that it collapse.
Some of the least important properties of concrete: