concrete technology

1. CONCRETE TECHNOLOGY
Presented By :-Nihar Ranjan Mohanta

2. OUTLINES:
• Introduction
• Indian Standard Code for Design
• Various Design Methods
• Application of Limit State Method
• Future scope
• References

3. INTRODUCTION
Concrete is one of the greatest inventions in the field of construction industry,
with nearly three billion tons used worldwide consistently. It has a wide range
of applications since it offers noteworthy strength at a tolerably negligible
exertion. Nowadays, concrete is prepared easily in huge quantities by mixing
the four locally available ingredients. Concrete is a composite material
composed of Coarse aggregate, fine aggregate (sand) cement and water. a
building material made from a mixture of broken stone or gravel, sand,
cement, and water, which can be spread or poured into moulds and forms a
stone-like mass on hardening

4. Constituents of concrete
Cement
A cement is a binder, a substance used in construction that sets, hardens and
adheres to other materials, binding them together.
Coarse Aggregate
Coarse aggregates are particles greater than 4.75mm, but generally range
between 9.5mm to 37.5mm in diameter. They can either be from Primary,
Secondary or Recycled sources.
Fine Aggregate
Fine aggregates are the aggregates whose size is less than 4.75 mm.
Example: Sand is used as fine aggregate in the preparation of concrete and
cement mortar.

5. Water
Almost any natural water that is drinkable and has no pronounced taste
or odor may be used as mixing water for concrete. Excessive impurities in
mixing water not only may affect setting time and concrete strength, but
can also cause efflorescence, staining, corrosion of reinforcement, volume
instability, and reduced durability.
Concrete properties
Concrete has relatively high compressive strength, but significantly
lower tensile strength, and as such is usually reinforced with materials that
are strong in tension (often steel). The elasticity of concrete is relatively
constant at low stress levels but starts decreasing at higher stress levels as
matrix cracking develops.

6. TESTING OF CONCRETE
Following are the various test performed on concrete
1. Test on workability
• Slump test
• Compacting factor test
• Flow table test
• Vee-bee consistometer method
2. Test on compressive strength
3. Test on flexural strength
4. Test on fresh concrete
5. Test cement content of hardened concrete

7. IS CODE FOR DESIGN OF
CONCRETE
IS 456:2000
• IS 456: 2000 is Indian National Building Code.
• Provide guidelines for the design and construction of structures.
• Evolved from the collective wisdom of expert structural engineers.
• Periodically revised to bring them in line with current research, and often,
current trends.

8. VARIOUS DESIGN METHODS
Three philosophies for the design of reinforced concrete.
• Working Stress Method
• Ultimate Strength Method
• Limit State method
Working Stress Method
The method basically assumes that the structural material behaves as a
linear elastic manner, and that adequate safety can be ensured by suitably
restricting the stresses in the material induced by the expected
working loads on the structure.

9. Ultimate Strength Method
In this method, ultimate or collapse load is used as design load. The
ultimate loads are obtained by increasing the working/service loads suitably
by some factors. These factors which are multiplied by the
working loads to obtain ultimate loads are called as load factors.
Limit State method
Limit state design (LSD), also known as load and resistance factor design
refers to a design method used in structural engineering. A limit state is a
condition of a structure beyond which it no longer fulfills the relevant
design criteria.

10. Application of Limit State Method
Limit state concept
The aim of this method is that the structure should be able to withstand
safely all the load that are liable to act on it throughout its life and it should
also satisfy the serviceability requirements of limiting deflection and
cracking.
Limit state is defined as the acceptable limit of safety and serviceability
requirements before failure. The most important limit states which are
considered in design as are follows:
(i) Limit state of collapse.
(ii) Limit state of serviceability
Limit State of Collapse
This limit state is also called as strength limit state as it corresponds to the
maximum load carrying capacity i.e., the safety requirements of the
structure. The limit state of collapse is assessed from collapse of the whole
or part of the structure. As per this limit state, the resistance to bending,
shear, torsion and axial loads at every section shall not be less than that
produced by the most unfavorable combination of loads on that structure.

11. The following limit states of collapse are considered in design:
(i) Limit state of collapse in flexure (bending)
(ii) Limit state of collapse in compression
(iii) Limit state of collapse in shear
(iv) Limit state of collapse in torsion.
Limit State of Serviceability
A structure is of no use if it is not serviceable. Thus, this limit state is introduced
to prevent excessive deflection and cracking. It ensure the satisfactory
performance of the structure at working loads. It is estimated on the basis of
elastic theory or working stress method because deformation is of significance
under working load and not at collapse. Limit state of serviceability of following
limit states:
(i) Limit state of deflection
(ii) Limit state of cracking
(iii) Limit state of vibration
The structure should be designed which considering all the appropriate limit state
of safety and serviceability and on the basis of most critical limit state and then
checked for all other limit states.

12. DESIGN OF VARIOUS STRUCTURES
With the help of Limit state method in accordance with IS
456:2000 we can able to design various concrete structures as
follows.
• Design of Singly reinforced beams.
• Design of doubly reinforced beams
• design of Flanged beams
• design of one way and two way slabs
• design of staircases
• Design of short and long columns
• Design of footings
• Design of Retaining walls

13. REFERENCES
• Reinforced Concrete structure design by B C Punmia. Laxmi
Publications.
• Design of Concrete Structures By N.Krishan Raju, CBS
Publication and Distribution Pvt.Ltd.
• Reinforced Concrete Design by Devdas Menon and S. Pillai,
McGrawHill Education.
• Design of reinforced concrete by N subramanian , oxford
publication.
• Reinforced Concrete Vol 1 by H. J. Shah, Charotar
Publishing House Pvt. Ltd

14. Thank you