Quality control of concrete

Prepared By:
Shivkumar M. Goti
CONCRETE
TECHNOLOGY
QUALITY CONTROL OF CONCRETE

2
Index
Sr.No Title Page No.
1 Introduction 3
2 Quality control application in concrete construction 4
3 Where does quality control begin? 4
4 How does quality control continue? 5
5 To know the quality of concrete,
We can do the several tests.
5
6 Material Used in Concrete 10
7 Reference 12

3
Introduction
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.
Low strength and low durable concrete structures have damaged millions of lives and
properties in past decades. So, in order to achieve a quality and a durable building structure,
maintaining the quality and standard of concrete is paramount.
Quality is perceived differently by different people. Yet, everyone understands what is
meant by “quality”. In a manufactured product, the customer as a user recognizes the quality of
fit, finish, appearance, function, and performance.
The quality of service may be rated based on the degree of satisfaction by the customer
receiving the service. The relevant dictionary meaning of quality is “the degree of Excellence”

4
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.
 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.
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.

5
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.
To know the quality of concrete,
We can do the several tests.
(1) Tests on Fresh Concrete
a) The Slump test
b) The Compacting Factor Test
(2) Tests on Hardened Concrete
a) Compression Test
b) Tensile Strength Test(Split Cylinder Test)
c) Flexural Strength Test

6
(1)Tests on Fresh Concrete
(a) The Slump Test
The mound 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

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(b)The Compacting Factor Test
 Compacting factor is less than 0.75 = low workability concrete.
 Compacting factor is less than 0.92 = High workability concrete.
Compacting Factor Machine

8
(2)Tests on Fresh Concrete
(a)CompressionTest
To determine the characteristic strength of the concrete. Size of concrete
cylinder is 150mm dia 300mm long.
Compression test of concrete Cylinder
(b)Tensile Strength Test (Split Cylinder Test)
When the cylinder split the tensile strength of concrete is determined.

9
(c) 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.

10
Material Used in Concrete
1) Cement
2) Water
3) Aggregate
4) Admixture
(1) Cement
A mixture of compounds made by burning limestone and clay together at very
high temperature ragging from 1400 ®C to 1500 ®Cather 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.
(2) 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.

11
(3) 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.
(4) 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.

12
Reference
Books
 Concrete Technology (R. P. Rethaliya)
 Concrete Technology (M. S. Shetty)
Web Sites
 www.concretenetwork.com
 www.constructionlearning.com
 www.scribd.com

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