Its for Civil Engineering Students In Subject of Concrete Technology

1. QUALITY CONTROL OF CONCRETE
Prepared by:
Shivkumar M. Goti

2. What is concrete?
Concrete is a most widely used construction material, Commonly
made by mixing of Cement with Fine Aggregate , Coarse Aggregate, Water
and Admixture.
What is quality of concrete?
For the building structure to be durable, more strength and also
for aesthetic, accomplishing a quality concrete is of supreme importance.
This is because the vital factor which determines or makes a building look
elegant, gives a building more strength and durability the concrete’s
quality.

3. Quality control application in concrete construction
Mechanical properties of the reinforcement to be used.
Dimension of the reinforcement.
Location of the reinforcement in construction before concrete poured.
Location of pre-stressing ducts.
Properties of the cement used in the concrete.
Properties of the concrete mix designed of use in the structure.
Control of the coarse aggregates and fine aggregates going into the concrete.
Mixing of the concrete.

4. Quality control application in concrete construction
Transport of the concrete to the construction site.
Slump of the concrete.
Pouring of the concrete.
Control of water addition.
Vibration/Compaction of the concrete.
Preparation of areas where different concrete pours are done.
Control of compression test samples
Control of formwork removal.

5. Where does quality control begin?
It begins in the production of material used in concrete ( Sampling and
Testing):
•Portland Cement
•Pozzolana
•Coarse and Fine Aggregate
Uniformity of concrete production will be no greater than the uniformity of
materials used in the concrete.

6. How does quality control continue?
Handling and stockpiling
Batching and Mixing
Sampling and testing fresh concrete
•Slump
•Air Content
•Unit weight
•Temperature
Transporting and Placing the freshly mixed concrete.

7. To know the quality of concrete,
we can do the several tests.
 Tests on Fresh Concrete
• The Slump test
• The Compacting Factor Test
 Tests on Hardened Concrete
• Compression Test
• Tensile Strength Test(Split Cylinder Test)
• Flexural Strength Test

8. Tests on Fresh Concrete
(1)The Slump Test
The mould for the slump test has the shape of frustum of a cone, 300mm
high, the Diameter of the base is 200 mm and at the top is 100mm.
If the slump is:
•25-50 =Low Workability
•50-100 =Medium Workability
•100-150 = High Workability

9. The Compacting Factor Test
•Compacting factor is less than 0.75 = low workability concrete.
•Compacting factor is less than 0.92 = High workability concrete.

10. Tests on harden Concrete
(a)Compression Test
To determine the characteristic strength of the concrete. Size of concrete cylinder is
150mm Dia 300mm long.
Compression test of concrete Cylinder

11. Tensile Strength Test(Split Cylinder Test)
when the cylinder split the tensile strength of concrete is determined.

12. Flexural Strength Test
Test to determine the tensile strength of concrete in flexure have been largely
superseded by the indirect tensile strength test, although it is still specified
occasionally on pavement and other similar projects where the strength of concrete
in flexure, or bending, is of prime importance.

13. Cement
A mixture of compounds made by burning limestone and clay
together at very high temperature ragging from 1400 C to 1500 C . The
production of Portland Cement begins with the quarrying of
limestone.CaCO3.Then Mixed with Clay(or Shale),sand and iron ore and ground
together to form a homogenous powder.
Material Used in Concrete

14. Water
Water is the key ingredient. When water mixed with a cement, forms a paste
that binds the aggregates together. water causes the hardening of concrete through
process call hydration. The water needs to be pure in order to prevent side reaction
from occurring which may weaken the concrete or otherwise interfere with hydration
process. The ratio of cement and water is the most critical factor in the production of
‘perfect’ concrete. Too much water can reduces concrete strength but high workability.
Too little water will make the concrete unworkable but high strength.

15. Aggregate
Chemically inert, solid bodies, held together by the cement. Come in
various shapes, sizes and material ranging from fine particles of sand to large,
coarse rock. Soft, porous aggregate can result in weak concrete with low wear
resistance. Hard aggregate can make strong concrete with high resistance to
abrasion. Should be clean, Hard and strong, Usually washed to remove any Dust,
Silt, Clay, Organic matter.

16. Admixtures
A material ,other than aggregate ,cement and water added in small
quantities to the mix in order to produce some desired modification, either to the
physical or chemical properties of the mix or of the hardened product. The most
common admixture affect plasticity, air entrainment and curing time.