Portland cement concrete is an artificial rock composed of aggregates, water, and a cementing agent like Portland cement. Portland cement is produced by burning and grinding a mixture of limestone, silica, alumina, and iron. The major constituents of Portland cement are compounds like C3S, C2S, C3A, and C4AF that form during burning and fusion and influence properties like strength. Concrete is composed of cement, water, fine aggregate, coarse aggregate, and sometimes admixtures. Admixtures are added during mixing to improve properties and aid construction. Curing protects concrete from moisture loss and temperature extremes to ensure proper strength development.

1. Portland Cement Concrete
BUILDING MATERIALS

2. Portland Cement Concrete
 Portland cement concrete is a “concrete”, or
artificial rock composed of aggregates, water,
and a cementing agent.
 Portland cement=(Limestone +Silica
+Alumina +Iron) are mixed
 Burned
 Ground (grind)
 Main component is Lime (60%-75%)

3. The major constituents of Portland
cement are as follows
The above constituents chemical reactions during burning and
fusion, combine to form the following compounds are

4. The cement compounds produced are:
 C3S
 C2S
 C3A
 C4AF
Percentage of each depends on required properties:
 Rate of hydration
 Amount of heat given off
 Chemical attack

5. Characteristics of the Portland cement
compounds
 C3S: hardness rapidly, responsible for the initial set &
early strength.
 C2S: hydrates slowly, low heat of hydration
 C3S + C2S: responsible for the strength of concrete
 C3A: reacts very quickly
 C4AF: reduce temperature required during burning in
the kiln
 C3A&C3S: rate of release of heat is greatest

6. Types of Portland cement
 I : Normal
 II: Moderate, moderate resistance to sulfate
 III: High early strength, in case where early
high strength is required.
 IV: Low heat of hydration, (slow reacting)
 V: Sulfate resisting

7. Types of Portland cement
.

8. Properties of Portland cement
1. Fineness: govern rate of hydration
2. Setting
3. Compressive strength
4. Tensile strength=10% of compressive
strength

9. Properties of Portland cement
concrete
 W/C ratio (w/c=0.4-0.7)
 Water is required in the mixture for two
purposes:
1. Hydration
2. Workability

10. Properties of Portland cement
concrete
3- Compressive strength
 The strength at 3,7,and 14 days is about
40%,60%, and 75% respectively of 28 day
strength.
4- tensile strength= 10% compressive strength.

11. Materials
 Concrete composed of:
1. cement
2. water
3. fine aggregate
4. coarse aggregate
5. admixtures.

12. Materials
Water
1. Drinkable
2. No definite taste or odor
3. Municipal Water Supply
4. Ice can be used in hot weather but during mixing it
should fully melted.
ASTM C1602, Standard Specification for Mixing Water
Used in the Production of Hydraulic Cement Concrete

13. Normal-Weight Aggregate
Most common aggregates
Sand
Gravel
Crushed stone
Produce normal-weight concrete
2200 to 2400 kg/m3
ASTM C 33

14. According to Size:
Fine aggregate: d ≤ 5 mm
Coarse aggregate: d > 5 mm

15. Fine Aggregate
• Sand and/or crushed
stone dust
• < 5 mm
• F.A. content usually
35% to 45% by mass
or volume of total
aggregate

16. Coarse Aggregate
• Gravel and crushed
stone
• > 5 mm
• typically between
9.5 and 37.5 mm

17. Aggregate Characteristics and Tests
Characteristic Test
Abrasion resistance
ASTM C 131 (AASHTO T 96), ASTM C 535,
ASTM C 779
Freeze-thaw resistance
ASTM C 666 (AASHTO T 161), ASTM C 682,
AASHTO T 103
Sulfate resistance ASTM C 88 (AASHTO T 104)
Particle shape and
surface texture
ASTM C 295, ASTM D 3398
Grading
ASTM C 117 (AASHTO T 11), ASTM C 136
(AASHTO T 27)
Fine aggregate
degradation
ASTM C 1137
Void content ASTM C 1252 (AASHTO T 304)
Bulk density ASTM C 29 (AASHTO T 19)

18. Aggregate Characteristics and Tests
Characteristic Test
Relative density
ASTM C 127 (AASHTO T 85)—fine aggregate
ASTM C 128 (AASHTO T 84)—coarse aggregate
Absorption and surface
moisture
ASTM C 70, ASTM C 127 (AASHTO T 85), ASTM
C 128 (AASHTO T 84), ASTM C 566 (AASHTO T
255)
Strength
ASTM C 39 (AASHTO T 22), ASTM C 78
(AASHTO T 97)
Def. of constituents ASTM C 125, ASTM C 294
Aggregate constituents
ASTM C 40 (AASHTO T 21), ASTM C 87
(AASHTO T 71), ASTM C 117 (AASHTO T 11),
ASTM C 123 (AASHTO T 113), ASTM C 142
(AASHTO T 112), ASTM C 295
Alkali Resistance
ASTM C 227, ASTM C 289, ASTM C 295, ASTM C
342, ASTM C 586, ASTM C 1260 (AASHTO T 303),
ASTM C 1293

19. Aggregates
Minimum amount of fine
aggregates passing 300
micro m and 150 micro m
10% & 20% respectively is
required to insure
smoothness

20. Aggregates
 Cement paste must cover each particle
 The larger size of aggregate, the more
economical the concrete is. This is because
there will be less voids space between
aggregates to be filled with expensive paste
concrete.

21. Aggregates
 The larger of size aggregates the less need
of water, so the more strength of concrete, or
the less amount of needed cement.

22. Aggregates
 Fineness Modulus:
Sum. of accumulative %retained or 9.5mm, 4.75mm,
2.36mm, 1.18mm, 6.00micro m, 300micro m and 150
micro m sieves divided by 100.
 To ensure that an aggregate does not fall beyond to the
coarse or fine side of the limits for sieves sizes.
 Useful in choosing proportions in trial mixes.

23. According to Unit Weight:
Heavy weight agg.: Hematite, Magnetite
Specific Gravity, Gs > 2.8
Normal weight agg.:Gravel, sand, crushed
stone 2.8 < Gs < 2.4
Light weight agg.:Expanded perlite, burned
clay Gs < 2.4

24. Uses Of Aggregates
Concrete
Roads
Railway

25. Any chemical / substance added to
cement during its manufacture to
improve the quality of concrete or to
obtain any desired effect on concrete
is called Additive.
Any substance added to concrete
during its mixing to improve its quality
in a desired way is called Admixture.
Additive and Admixtures
Reference: Additive and Admixtures from Concrete.
Structures byZ.A Siddiqi

26. Admixtures
Purposes:
 To improve the concrete properties
 To aid in construction procedures
 To provide economy

27. The admixtures may be of the following
general types:
 Accelerators.
 Set-retarders.
 Plasticizers or water-reducers.
 Super-plasticizers.
 Cementing admixtures.
 Gas forming or air-entraining agents.
 Bonding admixtures.
 Sealing agents.

28. 1. Accelerators
 The admixtures that accelerate the hardening
of concrete in order to get development of
early strength are called accelerators.
 Quick-setting admixtures are also available
which cause flash set, such as washing soda or
sodium carbonate.

29. 2. Set-Retarders
 These admixtures cause delay in setting of
concrete.
 These are useful for mass concreting,
concreting in hot weather, improving the
construction joints and for obtaining special
architectural surface finishes.

30. 3. Plasticizers Or Water- Reducers
 These admixtures reduce the amount of water
required for a desired workability.
 This reduction in the water-cement ratio
increases the strength of concrete.
4. Super-Plasticizers
 These are used to make flowing concrete that can
be compacted into difficult places without any
vibrations.
These are helpful in maintaining very low water /
cement ratios and to achieve very high strength
concrete.

31. 5. Cementing Admixtures
Pozzolans are the materials that provide
cementitious properties and may replace
cement up to about 40 per cent.
Volcanic ash, pumicite, opaline shales,
calcined diatomaceous earth, burnt clay, fly
ash and pulverized fuel ash (PFA) may act as
pozzolanas.
6. Gas Forming Or Air Entraining Admixtures
 Gas forming admixtures are used to liberate gas in
fresh concrete so as to form aerated or foam
concrete, which is lightweight and provides
better thermal insulation.
 To improve resistance against frost action

32. 7. Bonding Admixtures
These admixtures improve the bond of fresh
concrete with the already hardened
concrete.
8. Sealing Agents
These admixtures reduce the capillary
absorption of water by the concrete.

33. Curing
Curing is the process in which the concrete is
protected from loss of moisture and kept within a
reasonable temperature range
 To ensure the quality of the finished product
 Low temperature slow the rate of hydration
 Excessive evaporation of water = surface shrinkage =
cracks.

34. Methods of curing
 Ponding
 Sprinkling
 Wet covering (burlap)
 Water proof paper
 Plastic film
 Membrane
 Steam curing
A period of 7 days is often specified

35. Mixing & transporting of concrete
 Generally 70-100 revolutions at the mixing speed
(6-8 rpm) are required.
 Concrete must discharged from ready mixed trucks
within 1 1/2 hours or 300 drum revolutions
(whichever comes first) according to ATSM
requirement.
 Concrete should poured closer to its final position
and not allowed to fall freely to avoid segregation.
 Vibration: consolidate the concrete and fill all voids.
 Over vibration: for about 15 seconds will cause
segregation in concrete.

36. Concrete Vibrator
A vibrator is a mechanical device to generate
vibrations.
It is used to liberate voids from the concrete and
densify the concrete.
Types
1. Needle Vibrator
2. Surface Vibrator
3. Vibrating Table

37. Joints
 Expansion Joints: The joints
provided to accommodate the
expansion of adjacent parts in a
building are known as expansion
joints.
 Contraction joints The joints
introduced in concrete structures to
localize shrinkage movements are
known as contraction joints.
 Construction joints are placed at
stopping places in the process of
construction.

38. Lime
Lime is one of the most important and largely
used building materials. In fact, it used to be the
main cementing material before the advent of
Portland cement.
Its proportion in cement is used in the production
of cement carefully.
It is used to reduce acidity in water.
It is also used in agriculture to remove soil acidity

39. Mortar
Mortar is a workable paste used to bind
construction blocks together and fill the gaps
between them.