This document provides an overview of concrete technology. It defines cement and concrete and describes their composition and manufacturing processes. It discusses the properties and types of cement and concrete, how workability is measured, and testing methods for fresh and hardened concrete, including compressive strength, slump, and rebound hammer tests. The document also outlines the processes for mixing, transporting, placing, compacting, curing, and finishing concrete.

1. UNIT – I
CONCRETE TECHNOLOGY

2. SYNOPIS
 CEMENT : Definition, Grades, Types, Manufacture, Testing
 CONCRETE : Definition
 Manufacture - batching, mixing , transporting, placing, compaction,
curing, finishing
 Testing – fresh & hardened (non-destructive)
 Quality of concrete
 Application
 Concrete Chemicals
 MIX DESIGN : BIS & ACI method

3. Cement
Definition
 Cement is a substance acts as a binding agent for materials.
 It is obtained by burning the mixture of calcareous material such as
limestone and argillaceous materials such as clay at a high
temperature.
 There are two main constituents in portland cement:
 Argillaceous materials - clay
 Calcareous materials – calcium carbonate.

4. Composition of ordinary cement
INGRIDENT PERCENT
Lime 62
Silica 22
Alumina 5
Calcium sulphate 4
Iron oxide 3
Magnesia 2
Sulphur 1
Alkalies 1

5. Setting action of cement
 When water is added to cement, ingredients of cement react
chemically with water and forms chemical compounds which impart
strength to the cement. This is known as setting action of cement.
 Chemical compounds produced are
 Tricalcium aluminate
 Tricalcium silicate
 Dicalcium silicate
 Tetra –calcium alumino ferrite.
 Usually cement attains about 70% of its final strength in 28 days and
about 90% of its final strength in one year or so.

6. Manufacture of portland cement
There are three operations involved in manufacture of portland
cement:
 Mixing of raw materials
 Burning
 Grinding
Mixing of raw materials
There are two methods in mixing of raw materials of cement:
 Dry process
 Wet process.

7. Argillaceous
material
crushing
Fine grinding
storage
Calcareous
material
crushing
Fine grinding
storage
Mixing in correct
proportion
Dry process

8. Storage tanks for raw mix
Rotary kiln
Formation of clinkers
cooler
Grinding of clinkers in ball
mills and tube mills
Storage in silos
Weighing &packing in bags
distribution
gypsum
Coal dust

9. Wet process
Calcareous material
limestone
Argillaceous material
clay
crushing crushing
storage storage
channel
Grinding mill
Formation of slurry

10. Correcting basin
Storage tank
pumping
Rotary kiln
Formation of clinkers
cooler
Grinding of clinkers in ball mills
Storage in silos
Weighing and packing in bags
distribution
gypsum
Coal dust

11. Burning
 Burning is carried out in rotary kiln.
 Diameter of kiln is 250-300 cm, length is 90-120 m and inclined about 1 in
20 to 30.
 It is supported on rollers.
 Refractory lining is provided on the inner surface.
 Slurry is injected at upper end and it descends to burning zone carbon-
dioxide gets evaporated and forms nodules.
 Temperature is about 1500-1700 c.
 In burning zone the lime and clay in the slurry get chemically fused to form
hard balls of portland cement known as clinkers (Size 5 to 10mm).

12. Rotary kiln
from storage tank
slurry dust nodules
rotary arrangement coal dust
burning
zone
refactoy
lining air
Support cooler
clinkers

13. Grinding
 Grinding is done in ball mills and tube mills.
 Gypsum is added about 3 to 4 percent during grinding.
 Gypsum controls initial setting time of cement.
 Finely ground cement is stored in silos.
 It is weighed and packed in bags.
 Each bag contains 50Kg of cement.
 The bags are stored in dry places.

15. Properties of cement
 It is an excellent binding material.
 Gives strength to masonry.
 Possesses a good plasticity.
 Offers a good resistance to moisture.
 Easily workable.
 It hardens quickly after addition of water.
 The colour of cement should be uniform.
 Cement should be free from lumps.
 Cement should feel smooth when touched or rubbed in between
fingers.

16.  If a small quantity of cement is thrown into a bucket of water, it should
sink and should not float on the surface.
 Average compressive strength of cement mortar should not be lass than
11.5 N/mm2 at 3days and 17.5 N/mm2 at 7days.
 Average tensile strength of cement mortar should not be less than 2 N/mm2 at
3days and 2.5 N/mm2 at 7days.
 The initial setting time should not be less than 30 mins and final setting time
should not be more than 600 mins.
 The loss of ignition should be within 4%
 The specific surface of cement should not be less than 2250 cm2 /gm.
 If the cement is sieved on 90 micron sieve for 15 mins, the residue by weight
should be within 10%.

17. Uses of cement
 It is used for constructing engineering structures such as dams,
bridges, storage reservoirs.
 Used for making joints for pipes, drains.
 Used for preparation of foundations, footpath.
 Used for manufacture of precast pipes, fencing posts.
 Used for masonry work, plastering, pointing.
 Used for laying floors, roofs and constructing lintels.
 Used for protecting the structures from weather.

18. Types of cement
 Quick setting cement
 Low heat cement
 High alumina cement
 Expanding cement
 Rapid hardening cement
 Acid resistant cement
 Sulphate resisting cement
 White cement
 Coloured cement
 Blast furnace cement
 Pozzolana cement
 Air – entraining cement
 Masonry cement
 Oil-well cement
 Redi-set cement
 High strength cement
 Hydrophobic cement

19. Testing of cement
Testing of cement can be brought under two categories:
• Field testing
• Laboratory testing
 Field testing – sufficient to subject the cement to field tests when it is
used for minor works.
 Open the bag and take a look at the cement. There should not be any
visible lumps. The colour of the cement should normally be greenish
grey.
 Thrust your hand into the cement bag. It must give you a cool feeling.
 Take a pinch of cement and feel between the fingers. It should give a
smooth and gritty feelings.

20.  Take a handful of cement and throw it on a bucket full of water, the
particles should float for some time before they sink.
 Take about 100 grams of cement and a small quantity of water and
make a stiff paste (cake should not disturb when take into the water)
 Laboratory testing - for using cement in major works, the laboratory
test are carried out.
The following are carried out in laboratory:
 Fineness test (sieve analysis)
 Setting time test(standard consistency)
 Strength test(compressive strength)
 Soundness test(le chatelier)
 Heat of hydration test(vacuum flask method)
 Chemical composition test

21.  Strength test:
 Compressive strength is most important.
 The standard sand is used for finding the strength of cement.
Fineness test
 Fineness of cement is important bearing on the rate of hydration and
on rate of gain of strength.
 Finer cement offers a greater surface area and hence faster and greater
the development of strength.
 Fineness of cement is tested in two ways:
 By sieving.
 By determination of specific surface by air- permeability.

22. Setting time test
 An arbitrary division has been made for the setting time of cement as
initial setting and final setting time.
 Initial setting time- is the time elapsed between the moment that the
water is added to the cement to the time that the paste starts losing its
plasticity.
 Final setting time – the time elapsed between the moment the water
is added to the cement and the time when the paste has completely
lost its plasticity and has sufficient firmness to resist pressure.
 The test is carried out in vicat apparatus.

24. Concrete
Definition
 Concrete may be defined as a building material obtained by mixing cement,
fine, coarse aggregates and water in suitable proportions.
 It is plastic mixture after curing it becomes hard mass.
 The coarse aggregates are broken stone, broken bricks or gravel, the fine
aggregate is sand or surki and the binding material is lime or cement.
 Fresh concrete or plastic is a freshly mixed material which can be moulded into
any shape.
 The relative quantities of cement, aggregates and water together control the
properties in the wet state as well as in the hardened state.
Constituents of Concrete
Cement
Fine aggregate and Coarse aggregate
Water

25. Advantages of Concrete
It is plastic when freshly prepared and can be moulded to any shape.
Concrete does not lose its strength with age and does not require
maintenance.
The proportion of mix can be suitable designed to give concrete of
required strength.
It is durable and not affected by weather.
It affords quickness and ease of a construction.
It can be given various finishes.
Concrete is water repellent and can be made water proof.
Concrete can be made fire proof or light weight or chemical resistant by
using suitable admixtures.

26. Properties of Concrete
Concrete has high compressive strength depends on the proportion of
cement, sand, coarse aggregates and water used.
It hardens with age and process of hardening continuous for long time
even after it has attained sufficient strength, but the rate of hardening
decreases with age.
It is free from corrosion and atmospheric effects.
It is weak in tension. Steel reinforcement is placed in cement concrete at
suitable places to take up the tensile stresses called as RCC.
It shrinks in the initial stage and during hardening. This can be minimized
by proper curing.

27. Workability
The property of freshly mixed concrete which determines the ease and
homogenous with which it can be mixed, placed, compacted and finished
Factors Affecting Workability
 Water content
 Mix proportions
 Size of aggregates
 Shape of aggregates
 Surface texture of aggregates
 Grading of aggregates
 Use of admixtures

28. Water content
 Water content in a given volume of concrete will have significant
influences on the workability.
 Higher the water content, higher be the fluidity which affects
workability.
Mix proportion
 Aggregate/cement ratio is an important factor influences workability.
 Higher the aggregate/cement ratio, leaner is the concrete.
Size of aggregate
 Bigger the size of the aggregate, less is the surface area and less is the
amount of water.
 It will give better workability.

29. Shape of aggregate
 The shape of aggregate influences workability.
 Angular, elongated or flaky aggregate makes the concrete harsh when
compared with rounded aggregates.
Surface texture
 The total surface area of rough textured aggregate is more than the
surface area of smooth rounded aggregate of same volume.
Grading of aggregate
 It influences maximum workability.
 Better the grading, less the void content and higher the workability.
Use of aggregate
Use of air-entraining and pozzolanic material gives better
workability.

30. Measurement of workability
The following tests are commonly employed to measure workability:
 Slump test – K Slumper
 Compacting factor test - Compacting factor apparatus
 Flow test – Flow table
 Kelly ball test – Kelly ball
 Vee bee consistometer test- VBR
Segregation : Separation of the constituent materials of concrete
Bleeding : Water from the concrete comes out of the surface of the concrete
Water Cement ratio : Ratio of weight of water used to that of cement. It
depends upon strength, workability and method of compaction

31. Process of manufacture of concrete
The various stages of manufacture of concrete are:
 Batching
 Mixing
 Transporting
 Placing
 Compacting
 Curing
 Finishing

32. Batching
 The measurement of materials for making concrete is known as
batching.
 Volume batching – Gauge box
 Weigh batching – weight machine
Mixing
 Mixing of materials is essential for the production of uniform concrete.
 There are two methods for mixing concrete:
 Hand mixing
 Machine mixing.

34. Transporting concrete
 Concrete can be transporting by a variety of methods and equipments.
 Mortar pan
 Wheel barrow, Hand cart
 Bucket and Rope way
 Truck mixer and Dumpers
 Belt conveyors
 Chute
 Skip and Hoist
 Pumps and Pipeline

35. Placing concrete
 Placing concrete within earth mould.
e.g.: foundation concrete for a wall or column.
 Placing concrete within large earth mould or timber plank formwork.
e.g.: road slab and airfield slab.
 Placing concrete in layers within timber or steel shutters.
e.g.: mass concrete in dam construction or construction of concrete
abutment or pier.
 Placing concrete within usual from work.
e.g.: columns, beams and floors.
 Placing concrete under water.

36. Compaction of concrete
 Compaction of concrete is the process adopted for expelling the entrapped air
from the concrete.
 Hand compaction:
 Rodding
 Ramming
 Tamping.
 Compaction by vibration
 Internal vibrator (needle vibrator)
 Formwork vibrator (external vibrator)
 Table vibrator
 Platform vibrator
 Surface vibrator (screed vibrator).
 Compaction by pressure and jolting
 Compaction by spinning.

37. Curing of concrete
 Curing is the process of maintaining a satisfactorily moisture content
and favorable temperature.
The following are the curing methods:
 Water curing
 Membrane curing
 Application of heat
 Miscellaneous
Water curing
Water curing can be done in the following:
 Immersion
 Ponding
 Spraying
 Wet covering

38. Membrane curing
 Bituminous compounds
 Polyethylene
 Waterproof paper
 Rubber.
Application of heat
 The exposure of concrete to higher temperature can be done in the
following manner:
 Steam curing at ordinary pressure
 Steam curing at high pressure
 Curing by infra-red radiation
 Electrical curing.

39. Miscellaneous methods of curing
 Calcium chloride is used as a surface coating or as a admixture.
Finishing
 Finishing operation is the last operation in making concrete.
 Surface finish can be grouped as follows:
 Formwork finishes – centering work
 Surface treatment
 Applied finishes.
 Miscellaneous Finishes : Non - Slip Finish, Coloured finish, Water
resistant floor finish

41. Tests of fresh concrete
 Slump test
 Kelly ball test.
Tests on hardened concrete
Non-destructive testing-does not cause any destructive of the element.
Semi-destructive testing-cause negligible damage of the element.
Non-destructive testing:
 Rebound hammer test.
 Ultrasonic pulse velocity test.
Semi-destructive testing:
Windsor probe test

42. Rebound hammer test
 It consists of spring-controlled mass that slides on a plunger within
tubular housing.
 When the plunger is pressed the spring controlled mass rebounds.
 Depends on surface hardness of concrete.
 Related to compressive strength.
 The rebound is read on graduated scale and the value is designated as
“rebound number” or “rebound index”.

43. Uses:
 It is used for estimating the compressive strength.
 Establishing the uniformity of concrete.
 Assessing the quality of one element of concrete in relation to another.
Limitations:
 Results are affected by the angle of test, surface smoothness, and mix
proportion.
 It is only suitable for close-textured concrete.

44. Rebound hammer
concrete impact spring compression spring
surface
plunger hammer
mass housing

46. Types of concrete
 Normal density
 Air-entraining
 Polymer concrete composites
 Sulphur impregnate concrete
 Fibre reinforced concrete(FRC).
 Roller compacted concrete
 Super plasticized
 Coloured
 Pumped
 Ready mixed concrete(RMC)
 Ferro cement
 Light weight
 Recycled
 Heavy weight
 No slump
 No fine
 Vacuum
 Spinned
 Hot

47. FRC
 Composite material consisting of mixture of cement mortar and
discontinuous discrete, uniformly dispersed suitable fibres.
Types:
a) SFRC- steel fibre reinforced concrete
b) CFRC- carbon fibre reinforced concrete
c) GFRC- glass fibre reinforced concrete
d) HFRC- hybrid fibre reinforced concrete.
 SFRC- steel fibre reinforced concrete
 Made up of rusted steel.
 Used in road pavements, bridge decks.

48.  CFRC- carbon fibre reinforced concrete
 Has high tensile strength.
 Durability.
 HFRC- hybrid fibre reinforced concrete
 Made up of polypropylene, nylon fibres, asbestos.
 Durability
 High tensile strength.

49. Quality of concrete
 Good workability
 No segregation
 No bleeding
 High strength
 Durability
 Impermeability
 Elasticity
 Shrinkage
 Least thermal expansion.

50. Advantages of concrete
Availability of concrete is easy.
Easy handling.
Easy transportation.
More economical.
Monolithic character gives better appearance.
Disadvantages of concrete
Expansion joints are required.
Construction joints are provided to avoid cracks.
Sustain loads develops creep in structure.
Due to low tensile strength, concrete is required to be reinforced to avoid
cracks.
Soluble salts in concrete cause efflorescence of moisture reacts with them.

51. Concrete chemicals
 They are used in cement as an additive, in mortar and concrete as
admixtures.
 Such additives and admixtures is called as concrete chemicals or
construction chemicals.
It includes the following materials:
 Plasticizers and super plasticizers.
 Retarding plasticizers and retarders.
 Accelerating plasticizers and accelerators.
 Air-entraining agent.
 Water proofing material.
 Polymer bonding agents.

52.  Floor hardness and dust proofers.
 Concrete curing compounds.
 Polymer mortar for repair and maintenance.
 Adhesive for tiles, marbles and granite.
 Mould releasing agents.
 Grouting agents.
 Decorative and protective paint.
 Concrete repair system.
 Installation aids.

53. Queries:
Two marks:
 What is cement and list out its chemical composition?
 What are the process of cement manufacturing?
 What are the methods of testing in cement?
 What is meant by workability?
 What is concrete and explain mix proportion of concrete?
 What are the testing methods involved in fresh concrete and
hardened concrete?
 What are the qualities of concrete?
 Describe the advantage of concrete?
 Describe the disadvantages of concrete?
 What Is meant by concrete chemicals?

54. 16 marks:
 Describe the manufacturing of cement(dry and wet process)?
 What are the different types of cement? explain their properties and
uses?
 Describe the field testing and laboratory testing method in cement?
 Explain in detail the process of concrete manufacturing?
 Explain the method of non-destructive testing in detail?
 What tests are used to determine the workability of fresh concrete?
explain in detail:
 What are the different types of concrete? explain their properties and
uses?
 Explain the various types of concrete chemicals in detail?

55. Thank you