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Wednesday, 12 August 2015

APPLICATION OF CONSTRUCTION MATERIALS

Application of Construction materials 

Concrete

Concrete is used in construction areas. it is mixture of Portland cement & water with a definite quantity of sand or stone. This mixture is called cement paste. The strength of cement paste depends on the relative quantity or proportion of water & cement.

Timber

Timber is used in construction and furniture works. It is used in high class joinery & general joinery. It is also used in structural grade .there are some common applications of timber for example
  1. Windows, doors & stairs
  2. Architectural structures
  3. Craft items & turnery
  4. Framing
  5. External structures & landscaping,
  6. Fitting & trims

Steel 

  1. Steel is used in construction areas for example
  2. Reinforced concrete
  3. Bridge deck plates
  4. Educations & hospitals building
  5. Offices & tunnels
  6. Bridges, station & buildings

Specification of construction materials (concrete, timber, steel) regarding their performance in use

Specification of construction materials

Steel

The suitable specification of steel depends on application areas. If we consider for construction application, the main factor of steel is its strength. There are so many types of grades of steel.
There are so many types of ASTM specification.

For example 
For hot rolled product – ASTM A36/A36M
For sheet –    ASTM 606, for bolt, nut & washers- ASTM A307

Concrete

The specification of concrete for construction field should be as per standard
IST EN206-1, this standard gives the whole information about specification, production & application of concrete in construction areas.

Timber

Timbers are widely using these days in construction areas; there is some required specification for timber. 

For example
  1. Moisture: moisture should be less than 20%.
  2. Grades: Timer grades as per standard BS EN 14081, timbers are graded according to some properties like Fissures, knots & slope of grain against the allowable limit.
  3. Strength: it is property of timber to apply resistance against yielding under the action of different type of loads.
  4. Dimension & tolerances: it should be as per requirement and design.


Stress-strain diagram of steel and concrete

Behavior of steel structural under load 

From stress strain diagram, we can find the below information.
Point A is called as proportionality limit, up to this point hook’s law will be followed and stress will be directional proportional to strain.
Point B - Elastic limit, up to this point the deformation will be elastic.
Point C – Ultimate stress, it is the maximum value of stress in stress – strain diagram.
Point D- it is the fracture point, up to this point the material will have only elastic & plastic deformation ,but at this point fracture or rupture take place.

So we may know that behavior of steel under load will be as ductile material because there is elastic and plastic deformation before rupture.

Behavior of concrete under load

In case of concrete as we can see the diagram

There is no plastic elongation under load before fracture, so it is as brittle material.

Stress and strain diagram for Timber 

Timber is also well known brittle material so its stress & strain diagram will be same as above, there will be no plastic elongation before rupture, and its stress and strain diagram will be same as of concrete.

Conclusion

Before selection any material we have to know that application area , that means where we are going to use and properties are required over there. 

So before selection any material we should know all the details required by application areas.

For example in case of construction of this house we should know that it requires insulating material in order to reduce the loss of heat.  It requires ventilation system and we have also information about the required capacity of ventilation system so accordingly we can quote the materials.

What types of load are present and what is the atmospheric condition we can select the materials.
So in one sentence we can say the selection of materials is governed by demand and application areas.

Let us see 

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