Cement and cement concrete

1. CEMENT AND CEMENT
CONCRETE
Guided by
Prof. Manish Jain
Prepared by
Rohit Galani

2. CEMENT
 Cement is the costliest and most
important ingredient of concrete.
 Cement has cohesive and adhesive
properties which make him capable of
bonding the materials.
 The cements of interest in the making of
concrete have the property of setting
and hardening under water by virtue of
chemical reaction with it are, therefore
called Hydraulic Cement.
 Hydraulic cements consist of mainly of
silicate, sand aluminates of lime and can
be classified broadly as natural cements.
For e.g. Portland cement, high alumina
cement, etc.

3. CHEMICAL COMPOSITION OF CEMENT
 Cement mainly consists of lime, sand, alumina, and iron oxide. The
major compounds of cement are classified as follows:
Tricalcium Silicate (C₃S) : 50±5%
Dicalcium Silicate (C₂S) : 30±5%
Tricalcium Aluminate (C₃A) : 9±4%
Tetracalcium Aluminoferrite (C₄AF) : 12±3%
Free Lime : 1±.5%

4. Different Types Of CEMENT
 Ordinary Portland cement
 (i) Ordinary Portland cement 33 Grade- IS 269:1989
 (ii) Ordinary Portland Cement 43 Grade- IS 8112:1989
 (iii) Ordinary Portland Cement 53 Grade- IS 12269:1987
 Rapid Hardening Cement - IS 8041:1990
 Sulphate Resisting Cement –IS 12330:1998
 Quick setting Cement
 Low Heat Cement –IS 12600:1989
 Portland Pozzolana Cement – IS 1489 (Part-1) 1991 (Fly ash based)
 Air Entraining Cement
 Colored Cement - (White Cement IS 8042:1989)
 Expansive Cement
 High Alumina Cement- IS 6452:1989

5. CONCRETE
 Concrete is a composite material composed of
gravels or crushed stones (coarse aggregate),
sand (fine aggregate) and hydrated cement
(binder),and imparts considerable hardness to
the mixture.
 The cement reacts chemically with the water
and other ingredients to form a hard matrix
which binds all the materials together into a
durable stone-like material that has many uses.
 Sometimes, additives such as pozzolans or super
plasticizers are included in the mixture
 Most concrete is poured with reinforcing
materials (such as rebar) embedded to provide
tensile strength, yielding reinforced concrete.

6. Properties Of Concrete
 Compressive strength
 Tensile strength
 Elastic Deformation
 Shrinkage

7. Compressive Strength
 Compressive strength is defined as the measured maximum resistance
of a concrete or mortar specimen to an axial load, usually expressed
in PSI(pound per square inch) at an age of 28days.
 Concrete compressive strength depends upon many factors:-
-Quality & Proportions of the ingredients
-The curing environment
 The grades are designated by one letter M (for mix) and a number
from 10 to 80 indicating the characteristic compressive strength (fck)
in N/mm2.
 As per IS 456 (Table 2), concrete has three groups as (i) ordinary
concrete (M 10 to M 20), (ii) standard concrete (M 25 to M 55) and (iii)
high strength concrete (M 60 to M 80).
Note: The following grade of concrete are generally used in highway
pavements and are M30 M35 M40 M45.

8. Tensile Strength
 Concrete is not normally resist to direct tension, the knowledge of
tensile strength is use to estimate to load under which cracking will
develop.
 This is due to its influence on the formation of cracks and its
propagation to the tension side of reinforced concrete flexural
member.
 The tensile strength of concrete is relatively low.
 The flexural and splitting tensile strengths are obtained as described
in IS 516 and IS 5816, respectively.
 However, the following expression gives an estimation of flexural
strength (fcr) of concrete from its characteristic compressive strength.
fcr = 0.7 𝑓ck in N/mm2

9. Elastic
Deformation
 It is seen that the initial
tangent modulus is much
higher than Et (tangent modulus
inelastic respectively)
components of strain. The
initial tangent modulus Ec in
N/mm2 is estimated from
Ec = 5000 𝑓ck
 The initial tangent modulus Ec
is also known as short term
static modulus of elasticity of
concrete in N/mm2 and is used
to calculate the elastic
deflections.

10. Shrinkage
 Shrinkage is the time dependent deformation, generally
compressive in nature.
 The constituents of concrete, size of the member and
environmental conditions are the factors on which the
total shrinkage of concrete depends. However, the total
shrinkage is most influenced by the total amount of water
present in the concrete at the time of mixing for a given
humidity and temperature.
 The approximate value of the total shrinkage strain for
design is taken as 0.0003

11. Additives & Admixture Admixtures are chemicals which are added to concrete at the mixing stage to
modify some properties of the mix.
 The reason of using admixtures in concrete are as follows:
To Improve Durability.
Water Reduction in the Mix without changing workability.
To produce High Strength Concrete.
Accelerate the rate of strength development at early stages.
Strength Enhancement.
Crack Control (shrinkage reduction)
To improve pump ability.
Finish Enhancement.
Early Strength and Reduced Permeability.
Produce a fluid backfill, which flows easily and is self-leveling.
To reduce the total cost of the materials used in concrete.

12. Type of Admixture
 Plasticizers (water-reducing agent):When concrete of high
workability without using excess of water is required
then, Plasticizers are used. The main types of plasticizers
are: LignoSulphates based, Melamine Sulphate based, and
Naphthalene Sulphate based.
 Super plasticizers (high range water reducers):The use of
plasticizer is practiced for production of flowing, self
levelling, self-compacting and for the production of high
strength concrete and high performance concrete. Super-
plasticizer are chemical compounds such as modified lingo
Sulphates (MLS), sulphonated melamine formaldehyde
(SMF), sulphonated naphthalene formaldehyde (SNF) and
other polycarboxylate based materials.

13. Type of Admixture
(contd)
 Retarders: They are used when delay in setting time is
required to ensure sufficient placement, vibration or
compaction. Commonly known retarders calcium
Sulphate, hydroxylated carboxylic acids, sugars, acids or
salts of acids.
 Accelerators: Accelerators work by accelerating cement
hydration, which results in shortened setting times and
increased early age strengths, particularly in cooler
temperatures. For e.g.. Calcium chloride

14. Types of concrete used in pavement
construction:
 High strength concrete
 High performance concrete
 Stamped concrete
 Fibre reinforced concrete
 Self Compacting concrete

15. High strength concrete
 High strength concrete has a compressive strength greater than 40
MPa (6800 psi). Recently, this strength has rose to 50 to 60 MPa and its
use has increase in construction of high-rise bldg. and long span
bridges. High strength concrete is made by lowering the w/c ratio to
0.35 or lower.
 Often silica fume is added to prevent the formation of free calcium
hydroxide crystals in the cement matrix, which reduce the strength at
the cement-aggregate bond.
 Low w/c ratios and use of silica fume make concrete less workable,
which is particularly likely to be perform in high-strength concrete
applications where dense rebar cages are likely to be used.
 To compensate for reduced workability, super-plasticizers are
commonly added to high-strength mixtures.

16. High Performance concrete
 HPC is being vastly used for highway pavement due to potential
economic benefits that can be derived from early strength gain of
HPC, it reduced permeability, increased water or abrasion resistance
to steel studded tires and improved freeze-thaw durability.
 Different types of HPC are being considered for pavement repairs for
early opening of traffic, bridge deck overlays, etc.
 A durable concrete called fast track concrete designed to give high
strength at very early stage without using special materials or
techniques has been developed.
 Fast track concrete paving (FTCP) technology can be used for
complete pavement reconstruction, partial replacement by an inlay of
atleast one lane, strengthening of existing bituminous or concrete
pavements by a concrete overlay, rapid maintainence and
reconstruction processes, and air-field pavement.
 Benefits of applying FTCP is to reduce construction period, early
opening of pavement to traffic, and minimizing the use of expansive
concrete paving plant.

17. Stamped concrete
 Stamped concrete is an architectural concrete which has superior
surface finish.
 After a concrete floor has been laid, floor hardeners (can be
pigmented) are impregnated on the surface and a mold which may be
textured to replicate a stone/brick or even wood is stamped on to
give an attractive textured surface finish.
 After sufficient hardening, the surface is cleaned and generally sealed
to give protection.
 The wear resistance of stamped concrete is generally excellent and
hence found in applications like parking lots, pavements, walkways,
etc.

18. Fibre reinforced
concrete
 Fibre-reinforced concrete (FRC) is
concrete containing fibrous
material which increases its
structural integrity.
 Fibres include steel fibres, glass-
fibres, synthetic-fibres and natural
fibres – each of which lend varying
properties to the concrete.
 The amount of fibres added to a
concrete mix is ranging from 0.1
to 3%.
 Fibre reinforced concrete is
increasingly used on account of
the advantages of increased static
and dynamic tensile strength,
energy absorbing characteristic
and better fatigue strength.

19. Self Compacting
Concrete
 Self-consolidating concrete or self-compacting
concrete(SCC) is characterized by a low yield
stress, high deformability, and moderate viscosity
necessary to ensure uniform suspension of solid
particles during transportation, placement
(without external compaction), and thereafter
until the concrete sets.
 Such concrete can be used for casting heavily
reinforced sections, places where there can be no
access to vibrators for compaction and in complex
shapes of formwork which may otherwise be
impossible to cast, giving a far superior surface
than conventional concrete.
 It has been demonstrated that a total sand
content of about 50% of total aggregate is
favorable in designing for SCC.

20. Dry Lean Concrete
(For Sub-Base)  Dry lean cement concrete (DLC) is
used as a sub- base for concrete
construction.
 It is a plain concrete with a large
ratio of aggregate to cement than
conventional concrete.(i.e. 15:1)
 The work should not proceed if
the temperature rises above 30c
and in that case ice water may be
applied.
 The curing of DLC can be done by
spraying liquid curing compound
or by covering the surface with
wetted jute bags.

21. Conclusion
 Concrete is the material which can stand for longer span without any
structural deterioration or wear and tear of surfaces.
 There are many types of concrete and further more development in
the mix of concrete will improve the quality of pavements surface at
very low cost rather than asphaltic paved roads.
 It provides economical benefits such as low cost, less maintainence,
last long, stand up the seasonal stresses, etc.
 It also provides environmental benefits such as use less energy to
build and maintain, reusable and recyclable, requires less aggregate
for road base, make use of industrial by-products thereby reducing
waste, etc.

22. Thank You
Reference :
• Concrete Technology by M.S.Shetty
• FRC-pdf
• The concrete institute, ―Admixture for Concrete‖,
www.theconcreteinstitute.org.za
• Cement Concrete Pavements, Oxford & IBH Publishing Co. Pvt.
Ltd., 1996.