NEWS | SOFTWARE | SHEET
Concrete and its properties
There are various factors which affect the properties of concrete. These factors range from mix proportion of cement, sand, aggregates and water. Proportions of these materials are applied to manage the different concrete properties which are mentioned below.
Properties of Concrete:
- Grades (M20, M25, M30 etc.)
- Compressive strength
- Characteristic Strength
- Tensile strength
- Durability
- Creep
- Shrinkage
- Unit weight
- Modular Ratio
- Poisson’s ratio
Grades of concrete: Concrete is recognized with its different grades like M15, M20 etc. Here letter M stands for concrete mix and number 15, 20 stands for the indicated compressive strength (fck) of 150mm cube at 28 days that is presented as N/mm2. So, concrete is identified with its compressive strength. M20 and M25 are considered as the mostly recognized grades of concrete.
Compressive strength of concrete: Similar to load, the strength of the concrete should also be considered that differs significantly for the equivalent concrete mix. So, a single representative value, called characteristic strength is applied.
Characteristic strength of concrete: It is described as the value of the strength under which not over 5% of the test results are anticipated to fall (i.e. there is 95% chance of obtaining this value only 5% of not obtaining the same).
Characteristic strength of concrete in flexural member
It is assumed as 0.67 times the strength of concrete cube.
Design strength (fd) and partial safety factor for material strength
The strength that is considered for the determination of design is called as design strength and is presented as below:-
Design strength (fd) = characteristic strength/ partial safety factor for material strength
The value of partial safety factor is based on the type of material and upon the type of limit state. As per IS code, partial safety factor will be as 1.5 for concrete and 1.15 for steel.
Design strength of concrete in member = 0.45fck
To read the complete article, go through the follow link theconstructor.org
