1. UNIT I CONCRETE MAKING MATERIALS
SNS COLLEGE OF TECHNOLOGY (An Autonomous Institution) Coimbatore- 35
CONCRETE TECHNOLOGY
UNIT I
CONCRETE MAKING MATERIALS
P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I

2. WHAT IS CONCRETE TECHNOLOGY?
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3. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
TECHNOLOGY DEALS WITH
making concrete.
Casting concrete.
Ensuring efficient casting.
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4. WHAT IS CONCRETE MAKING MATERIAL?
Cement.
Fine aggregate.
Coarse aggregate.
Admixtures.
Water.
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5. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
CEMENT
What is cement?
Material with adhesive & cohesive properties.
What is the function of cement?
To bind the fine & coarse aggregate together
To fill voids in between fine & coarse aggregate particle form a compact mass.
Why is it called "Portland" cement?
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6. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
COMPOSITION OF CEMENT
Calcium Oxide (CaO) = 60 – 65%
Silica (SiO2) = 20 – 25%
Aluminum Oxide = %
Ferrous Oxide = 2 – 4 %
Magnesium Oxide = 1 – 3 %
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7. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
COMPOSITION
Lime (CaO)
60-66%
Excess reduces strength and make cement disintegrate and in less amount reduces strength and makes it quick setting.
Silica (SiO2)
17-25%
Provides strength to cement
Alumina (Al2O3)
3-8%
Helps in quick setting
Calcium Sulphate (Gypsum)
Enhances initial setting of cement
Iron Oxide
2-6%
Gives color, Strength and hardness.
Sulphur trioxide (SO3)
1-3%
Provides soundness
Alkali Oxides (Na2O and K2O) %
in excess makes cement efflorescent
Magnesium Oxide (MgO)
1-5%
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8. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
What type of mixture can be created using cement ?
Cement Grout
Cement Mortar
Cement concrete
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9. MANUFACTURING OF CEMENT:
(1) Mixing and crushing of raw materials
Dry process
Wet process
(2) Burning
(3) Grinding
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10. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
MANUFACTURE OF CEMENT
At present 93% of cement production in India is based on modern and environment-friendly dry process technology and only 7% of the capacity is based on old wet and semi-dry process technology.
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11. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I

12. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
clinker
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13. FOUR MAIN COMPOUNDS OF PORTLAND CEMENT
Tricalcium silicate (C3S) (25-50%)
Dicalcium silicate (C2S) (25-45%)
Tricalcium aluminate(C3A) (5-12%)
Tetracalcium alumino ferrite (C4AF) (6-12%)
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14. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
TO CHECK THE QUALITY OF CEMENT IN THE FILED: ( PHYSICAL PROPERTIES)
Colour greenish grey.
One feels cool by thrusting one’s hand in the cement bag.
It is smooth when rubbed in between fingers.
A handful of cement thrown in a bucket of water should float.
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15. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Presence of Lumps
It should free from hard lumps.
It is due to the absorption of moisture from atmosphere.
If a bag contains lumps it should be rejected.
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16. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
QUALITY TESTS OF CEMENT: (1) Fineness Test (2) Soundness test (3) Consistency test / setting time test (4) Compressive strength test
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17. SIEVE TEST(FINENESS TEST)
PROCEDURE:
Take correctly 100grams of cement on a standard IS sieve No.9
Break down the air-set lumps & sieve it &weigh it.
This weight shall not exceed 10% for ordinary cement.
Sieve test is rarely used.
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18. STANDARD CONSISTENCY TEST
The standard consistency of a cement paste is defined as that consistency which will permit a Vicat plunger having 10 mm diameter and 50 mm length to penetrate to a depth of mm from the top of the mould.
USE:
Used to find out the percentage of water required to produce a cement paste of standard consistency.
This is also called normal consistency (CPNC).
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19. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
PROCEDURE
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20. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
SETTING TIME TEST
An arbitrary division has been made for the setting time of cement.
Initial setting time &
Final setting time.
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21. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
INITIAL SETTING TIME
The time elapsed between the moment that the water is added to the cement, to the time that the paste starts losing its plasticity.
Normally a minimum of 30min has maintained for mixing & handling operations.
It should not be less than 30min.
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22. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
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 attained sufficient firmness to resist certain definite pressure.
It should not exceed 10hours.
So that it is avoided from least vulnerable to damages from external activities.
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23. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
(2) Consistency Test /Setting Time Test :
This test is performed to determine the quantity of water required to produce a cement paste of standard or normal consistency.
Standard consistency of cement paste may be defined as the consistency which permits the Vicate’s plunger (10 mm, 40 to 50 mm in length) to penetrate to a point 5 mm to 7 mm from the bottom ( or 35 mm to 33 mm from top) of Vicat mould. When the cement paste is tested within the gauging time ( 3 to 5 minutes) after the cement is thoroughly mixed with water.
Vicat apparatus is used for performing this test.
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24. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
(3) Setting Time Test:
In cement hardening process, two instants are very important, i.e. initial setting and final setting.
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25. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Initial Setting Time:
The process elapsing between the time when water is added to the cement and the time at which the needle ( 1 mm square or 1.13 mm dia., 50 mm in length) fails to pierce the test block ( 80 mm dia. and 40 mm high) by about 5 mm, is known as Initial Setting Time of Cement.
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26. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Final Setting Time:
The process elapsing between the time when water is added to the cement and the time at which a needle used for testing final setting upon applying gently to the surface of the test block, makes an impression thereon, while the attachment of the needle fails to do so, is known as final Setting Time of Cement.
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27. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Compressive strength
Mortar of cement & sand is prepared, 1:3.
Water is added, water cement ratio 0.4/bag
It is placed in moulds & form cubes of sides 70.6 or 76 mm.
The cement required is 185 or 235g
Compacted in vibrating machine in 2 min.
Moulds placed in damp cabin for 24 hrs
Specimens are removed & placed in water for curing.
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28. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
It is tested in compressive testing machine after 3 and 7 days.
Every side is calculated and average is taken.
For 3 days: > 115 kg/cm2 or 11.5 N/mm2
for 7 days: > 175 kg/cm2 or 17.5 N/mm2
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29. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Types of Cement
Depending upon our requirements i.e. using it at a suitable place, we use different types of cement.
Rapid Hardening or High early strength Cement
Quick setting Cement
High Alumina Cement
Portland Slag Cement
Low Heat Cement
Air Entraining Cement
White Cement
Coloured Cement
Portland Pozzolona Cement
Sulphate resisting cement
Hydrophobic cement
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30. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Rapid Hardening Cement
Strength faster than OPC
contains more of Tri-Calcium Silicate and is more finely grounded.
unsuitable for massive concrete.
It is used for the Structures which are Subjected to loads early e.g. Roads, Bridges.
Quick Setting cement
adding small %age of aluminium sulphate (Al2SO4) which accelerates the setting action.
Its Initial Setting Time is 5 minutes and the Final Setting Time is not more 30 minutes.
It is required for lying under water or in running water.
High Alumina Cement
burning of bauxite ore and lime stone in correct proportions and at high temperature.
It develops Strength Rapidly.
It is of black colour and resists well the attack of chemicals especially of sulphates and sea water.
Its initial setting takes more than 2 hours and the final set takes place immediately thereafter.
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31. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Portland Slag Cement
Obtained by mixing clinker, gypsum and granulated slag in a proper proportion.
It has lesser heat of hydration and has better resistance of soils, sulphates of alkali metals, alumina and iron. It has better resistance to acidic water. This type of cement is mostly used in Marine Works.
Low Heat Cement
Controlled by keeping the percentage of Tri-Calcium Silicate and that of Tri-Calcium Aluminate low.
It is not very suitable for Ordinary structures
It will also need more curing.
Air Entraining Cement
OPC mixed with some air entraining agents.
The common air entraining agents are oils, fats and fatty acids etc.
However because of air entrainment the strength of concrete reduces and as such the quantity of air so entrained should not exceed 5%.
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32. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
SULPHATE RESISTING CEMENT:
In certain regions/areas where water and soil may have alkaline contents and O.P.C is liable to disintegrate, because of unfavorable chemical reaction between cement and water, S.R.C is used.
This cement contains a low %age of C3A not more than 5%.
This cement requires longer period of curing.
It develops strength slowly, but ultimately it is as strong as O.P.C.
HYDROPHOBIC CEMENT
Obtained by adding water repellant film forming substances like stearic acid, boric acid, oleic acid and pentachlorophenol to OPC during grinding of cement clinker.
Prevent the entry of atmospheric moisture and the film breaks down when the concrete is mixed and then the normal hydration takes place
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33. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
AGGREGATE
Inert materials which are mixed with binding material such as cement or lime
Used as filler in mortar and concrete.
Occupy about 70% to 80% of the volume of concrete
Fine Aggregate
Diameter< 4.75mm
Coarse Aggregate
Diameter > 4.75mm
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34. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Uses Of Aggregates
Concrete
Roads
Railway
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35. CLASSIFICATION OF AGGREGATE
Classification based on source:
Natural aggregates
Manufactured
(synthetics) aggregates
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36. Classification According to Size
Fine Aggregates
Coarse Aggregate
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37. Types of Fine Aggregates
Sand
Stone dust
Cinder
Surkhi
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38. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Sand
little particles of silica.
Larger particles – gravel
Smaller particles - silt or clay.
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39. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Types of Sand
Pit Sand
River Sand
Sea Sand
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40. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Pit Sand
It is found as deposited in soil and is to be excavated out
It should be free from organic matter and clay
the best fine aggregate for use in mortar and concrete.
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41. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
River Sand
Obtained from the banks and beds of rivers. It may be fine or coarse.
Fine sand - found mixed with silt and clay so it should be washed before use.
Coarse sand is generally clean and excellent for use especially for plastering.
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42. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Sea Sand
Consists of fine rounded grains of brown colour.
Contains salts and while using that in mortar, etc, causes disintegration of the work in which it is used.
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43. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Stone Dust
Obtained by crushing the waste stones of quarries to the particular size of sand.
Sand obtained from by crushing a good quality stone is excellent fine aggregate.
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44. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Cinder
Cinder is the slag from a metal furnace. Before use this slag we crushed this so that its size remains in fine aggregate.
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45. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Surkhi
Surkhi is finely powdered burnt clay and generally made from slightly under burnt bricks.
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46. Types of coarse Aggregates
Stone Ballast
Gravel
Brick Ballast
Clinker
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47. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Stone Ballast
Stone ballast produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers.
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48. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Gravel
obtained from river beds, quarries and sea shores.
obtained from sea shores should be well washed with fresh water before use in order to remove the impurities which may be clay, salts ,silt,etc.
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49. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Brick Ballast
For unimportant works we can use brick ballast in concrete as coarse aggregates. For this purpose well burned bricks are chosen.
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50. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
CLASSIFICATION BASED ON UNIT WEIGHT: Aggregates are classified as Light-weight, Heavy-weight and Normal-weight aggregate depending on weight and specific gravity.
AGGREGATE
SPECIFIC GRAVITY
UNIT WEIGHT (kN/m3)
BULK DENSITY (kN/m3)
EXAMPLE
normal-weight
23-26
sand
heavy-weight
25-29
>20.80
Scrap iron
light-weight 12
<11.20
dolomite
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51. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
CLASSIFICATION BASED ON SHAPE: The shape of aggregates is an important characteristic, since it affect the workability of concrete.
CLASSIFICATION
EXAMPLE
Rounded
River or seashore gravels
Partly rounded
Pit sands & Gravels
Angular
Crushed Rocks
Flaky
Laminated rocks
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52. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
FLAT
ELONGATED
ANGULAR
ROUND
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53. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
CLASSIFICATION BASED ON SUFACE TEXTURE: measure of the smoothness and roughness of aggregate..
CLASSIFICATION
EXAMPLES
Glassy
Black flint
Smooth
Gravel, Marble
Granular
Sandstone
Rough
Basalt
Crystalline
Granite
Honeycombed & Porous
Brick, slag
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54. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
SMOOTH
ROUGH
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55. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
GOOD QUALITIES OF AN IDEAL AGGREGATE:
An ideal aggregate used for the manufacturing of concrete and mortar, should meet the following requirements.
(1) It should consist of natural stones, gravels and sand or in various combinations of these materials.
(2) It should be hard, strong and durable.
(3) It should be dense, clear and free from any coating.
(4) It should be free from injurious vegetable matters.
(5) It should not contain flaky (angular) and elongated pieces.
(6) It should not contain any material liable to attack steel reinforcement in case of reinforced concrete.
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56. Physical properties of aggregates
Strength
Hardness
Toughness
Durability
Porosity
Water absorption
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57. Strength of aggregates
In practice, majority of normal aggregates are considerably stronger than concrete
A good average value of crushing strength of aggregates is 200N/mm2.
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58. Hardness of aggregates
Hardness of aggregates is the ability of the aggregate to withstand wear or load or applied pressure.
This hardness is depending on the type of parent rock
The test that can obtain the hardness is the abrassion test.
A satisfactory aggregate should have an abrassion value of not more than 30% for aggregates used for wearing surfaces and 50% for aggregates used for non wearing surfaces.
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59. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Toughness
Is the resistance of aggregate to failure by impact.
This can be determined by aggregate impact test.
The aggregate impact value shall not exceed 45% by weight for aggregate used for concrete other than those used for wearing surfaces and 30% for concrete for wearing surfaces.
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60. Durability of aggregates
Durability is ability of the aggregate to withstand external or internal damaging attack or in other words the soundness of aggregate.
This can be obtained by carrying out the Soundness test.
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61. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Porosity
Aggregate normally have pores of various sizes.
Aggregates will absorb water when it is dry but normally release water in the concrete mix when it is wet.
The amount of water and its rate of permeation depends on the size and volume of aggregate
Since the aggregate comprises 75% of the concrete volume, it is essential to note that porosity of an aggregate contribute to the overall porosity of concrete.
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62. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
IMPACT VALUE TEST
The aggregate impact value gives a relative measure of the resistance of an aggregate to sudden shock or impact. The impact value is some times used as an alternative to its crushing value. Material passing 12.5mm and retained on 10mm sieve is taken.
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63. AGGREGATE CRUSHING VALUE:-
The aggregate crushing value gives a relative measure of resistance of an aggregate to crushing under a gradually applied compressive load. The aggregate crushing strength value is useful factor to know the behavior of aggregates when subjected to wear. CRUSHING VALUE=weight of fraction passing the sieve total weight of sample
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64. AGGREGATE ABRASION VALUE:-
The aggregate abrasion value gives a relative measure of resistance of an aggregate to wear when it is rotated in a cylinder along with some abrasive charge
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65. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
SIEVE ANALYSIS
Sieve analysis is also called as Particle size value.
In determination of the proportions of the
particles with in certain ranges in an aggregate
by separation on various sieves of different size
openings, may be defined as sieve analysis.
FINENESS MODULUS= cumulative % of agg retained on each sieve
100
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66. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I

67. SPECIFIC GRAVITY OF AGG.
Sp.Gr.=
Weight of Agg. (WA)
Weight of an equal volume of water (VA*ρw) ρA
Density of Agg. WA = =
VA*ρw ρw
Density of Water
Sp.Gr. is used in certain computations for concrete mix design or control work, such as, absolute volume of aggregate in concrete. It is not a measure of the quality of aggregate.
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68. FLAKINESS & ELONGATION INDEX
FLAKINESS INDEX= weight of particle passing through the gauge weight of sample ELONGATION INDEX=weight of particle retained on length gauge
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69. P.THARANI CE314/CONCRETE TECHNOLOGY/ UNIT I
Water
It reacts with the cement to form binder that hardens and bonds the aggregates together
Lubricates the fresh concrete enabling it to be placed into position and compacted.
Good water is essential for quality concrete.
It should be good enough to drink--free of trash, organic matter and excessive chemicals and/or minerals.
The strength and other properties of concrete are highly dependent on the amount of water and the water-cement ratio.
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