BUILDING MATERIAL & CONSTRUCTION - CONCRETE STRUCTURES.pdf

 CONCRETE
 Concrete is a composite material composed of fine and coarse aggregate bonded
together with a fluid cement that hardens over time.
 A hard substance made from cement mixed with sand, water, small stones (gravel),
etc., that is used in building.
 Cement and lime are generally used as binding materials, whereas sand cinder is used
as fine aggregates and crushed stones, gravel, broken bricks, gravel are used as coarse
aggregates.
 Freshly prepared concrete till it has not yet set is called wet or green concrete. After it
has thoroughly set and fully hardened it is called set concrete or just concrete.
 TYPESOFCONCRETEANDITSUSES
Concreteareclassifiedintodifferenttypes:
 Accordingtobindingmaterial usedinconcrete.
 Accordingtodesignofconcrete.
 Accordingtopurposeofconcrete.
Cement concrete has High
compressive strength.
COMPILED BY: Syedali Fathima, Asst.Professor
- SRM SEAD 2020-2021

Cement concrete is weak in Tension.
Steel is used in concrete to take up Tensile stress.
Concrete gains strength due to Hydration of cement.
The strength and durability of concrete depends upon Size, grading
and moisture contents of the aggregates.
- SRM SEAD 2020-2021

SPECIFICATIONS FOR CONCRETE
• The specification, production, and delivery of concrete are achieved in different ways.
• ASTM C 94 provides standard specifications for the manufacture and delivery of freshly mixed
concrete.
• Three options for ordering or specifying concrete are described in ASTM.
- Option A is performance based. It requires the purchaser to specify the compressive strength
only, while the concrete producer selects the mixture proportions needed to obtain the required
compressive strength.
- Option B is prescription based. The purchaser specifies mixture proportions, including cement,
water and admixture contents.
- Option C is a mixed option. It requires the concrete producer to select the mix proportions with
the minimum allowable cement content and compressive strength specified by the purchaser.
American Society for Testing and Materials, is
an international standards organization that
develops and publishes voluntary consensus
technical standards for a wide range of
materials, products, systems, and services.
- SRM SEAD 2020-2021

 CLASSIFICATION ACCORDING TO BINDING MATERIAL:
According to binding material used, concrete are classified into two types.
I. Cement concrete
II. Lime concrete.
CEMENT CONCRETE
 The concrete consisting of cement, sand and coarse aggregates mixed in a suitable
proportions in addition to water is called cement concrete.
 In this type of concrete cement is used as a binding material, sand as fine aggregates and
gravel, crushed stones as coarse aggregates.
In cement concrete useful proportions of its ingredients are
1 part cement:1-8 part sand:2-16 parts coarse aggregates.
USES
cement concrete is commonly used in buildings and other important engineering works
where strength and durability is of prime importance.
- SRM SEAD 2020-2021

LIME CONCRETE
 The concrete consisting of lime, fine aggregates, and coarse aggregates mixed in a suitable
proportions with water is called lime concrete.
 In this type of concrete, hydraulic lime is generally used as a binding material, sand and
cinder are used as fine aggregates and broken bricks, gravel can be used as coarse
aggregates.
PLACING OF LIME CONCRETE :
 Placing of concrete shall be completed within three hours of adding water in case of
concrete is prepared with hydraulic lime.
 Concrete should be well cured for a period of atleast 10 days.
USES:
Lime concrete is generally used for the sake of economy in foundation works, under
floors, over roof and where cement is not cheaply and easily available in required
quantity.
In lime concrete, lime is used as Binding material.
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RCC consists of following materials Cement, sand, fine/coarse aggregate & water.
The component added to concrete to improve its qualities is known as Admixture.
The addition of admixture may improve the concrete with respect to Strength,
hardness,Workability and water resisting power
- SRM SEAD 2020-2021

 For different ratio of concrete the amount of water for 50kg of cement is
 Concrete ratio (Cement: Fine Aggregate/Sand: Coarse Aggregate)
Concrete ratio Water quantity
1:3:6 (M10) 34 liter
1:2:4 (M15) 30 liter
1:1.5:3 (M20) 27 liter
1:1:2 (M25) 25 liter
 The following ratios are generally applied for site requirement.
1. Cement concrete 1:8:16
• Where cement concrete 1:8:16 ratio is used it means 1 part of cement 8 parts of fine
aggregate/ sand and 16 parts of coarse aggregate.
• This ratio cement concrete is very low in strength and is recommended for the
following type of building and work:-
-Used in foundation of walls of ordinary and single story building and used as
base coat under floors and pavement.
- SRM SEAD 2020-2021

2. Cement concrete1:6:12
• Where cement concrete 1:6:12 ratio is used it means 1 part of cement 6 parts of sand and 12
parts of coarse aggregate.
• This ratio cement concrete is low in strength and is recommended for the following type of
building and works:-
- Used in foundation of two or three story buildings, used in piers and retaining
walls and used as basecoat under taxi tracks, pavement and cement concrete road.
3. Cement Concrete 1:4:8
• Where cement concrete 1:4:8 ratio is used it means 1 part cement 4 parts of sand/fine
aggregate and 8 parts of coarse aggregate.
• This ratio cement concrete has medium strength and is recommended for the following
type of buildings and works:-
- Used in foundation of multi story buildings, under foundation of RCC
columns, stairs, raft, RCC wall and air strips and taxi tracks base coat.
;
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• Where cement concrete 1:3:6 ratio is used it means 1 part cement 3 parts of fine aggregate or coarse
sand and 6 parts of coarse aggregate.
• This ratio cement concrete has medium strength and is recommended for the following type of
buildings and works:-
• Used in mass concrete, bed plates, concrete blocks, etc.
• Where cement concrete 1:2; 4 ratio is used it means 1 part cement 2 parts of fine aggregate or coarse
sand and 4 parts of coarse aggregate.
• This ratio cement concrete has good strength and is recommended for the following type of
• Used in footings of columns and raft foundation, used in beams, slabs, columns, stairs and walls of
ordinary, single story and temporary buildings and used in retaining walls, pavements, floors and
bedplates etc.
• Where cement concrete 1:1:5:3 ratio is used it means 1 part cement 1.5 parts of fine aggregate or
coarse sand and 3 parts of coarse aggregates.
• This ratio cement concrete has very good strength and is recommended for the following type of
• Important RCC structures, piles, arches, impermeable construction against water heads. This ratio of
cement concrete is safe against earth quake.
;
- SRM SEAD 2020-2021

 The water–cement ratio is the ratio of the weight of water to
the weight of cement used in a concrete mix.
 Lower ratio leads to higher strength and durability, but may
make the mix difficult to work with and form.
 Strength of concrete primarily depends upon the strength of
cement paste.The strength of paste increases with cement
content and decreases with air and water content.

 WATER – CEMENT RATIO:-
§ Example:
W/C = 0.500, and Water = 250 pounds
How much cement is needed?
250 / 0.500 = 500 pounds of cement
§ Example:
W/C = 0.500, and Cement = 600 pounds
How much water is needed?
0.500 X 600 = 300 pounds of water
300 pounds / 8.33 = 36.0 gallons
Water cement ratio is
generally expressed in
volume of water
required per 50 kg.
- SRM SEAD 2020-2021

 For ordinary concrete (sidewalks and driveways), a w/c ratio of 0.6 to 0.7 is considered normal.
 A lower w/c ratio of 0.4 is generally specified if a higher quality concrete is desired.
 The practical range of the w/c ratio is from about 0.3 to over 0.8.
 A ratio of 0.3 is very stiff (unless super plasticizers are used), and a ratio of 0.8 makes a wet and
fairly weak concrete.
 For reference, a 0.4 w/c ratio is generally expected to make a concrete with a compressive
strength (its f’c) of about 5600 psi when it is properly cured.
 On the other hand, a ratio of 0.8 will make a weak concrete of only about 2000 psi.
 The simplest way to think about the w/c ratio is to think that the greater the amount of water in a
concrete mix, the more dilute the cement paste will be.
 This not only affects the compressive strength, it also affects the tensile and flexural strengths,
the porosity, the shrinkage and the color.
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 The more the w/c ratio is increased (that is, the more water that is added for a fixed amount of
cement), the more the strength of the resulting concrete is reduced.
 This is mostly because adding more water creates a diluted paste that is weaker and more
susceptible to cracking and shrinkage.
 Shrinkage leads to micro-cracks, which are zones of weakness.
 Once the fresh concrete is placed, excess water is squeezed out of the paste by the weight of the
aggregate and the cement paste itself.
 When there is a large excess of water, that water bleeds out onto the surface. The micro channels
and passages that were created inside the concrete to allow that water to flow become weak zones
and micro-cracks.
 Using a low w/c ratio is the usual way to achieve a high strength and high quality concrete, but it
does not guarantee that the resulting concrete is always appropriate for countertops.
 Unless the aggregate gradation and proportion are balanced with the correct amount of cement
paste, excessive shrinkage, cracking and curling can result.
 Good concrete results from good mix design, and a low w/c ratio is just one part of a good mix
design.
- SRM SEAD 2020-2021

 SLUMP TEST
• Slump test is a test conducting before concrete to be used for casting.
• The purpose of slump test is to determine the water content in concrete and its workability
EQUIPMENT FOR SLUMP TEST:
1. BASE PLATE.
2. TROWEL TO MIX CONCRETE.
3. STEEL TAMPING ROD.
4. SLUMP CONE.
5. RULER.
STEP 1:
• Fill cone 1/3 full by volume and rod it 25 times with
hemispherical tip steel tamping rod which is 5/8-inch dia,
24-inch-long (This is a specification requirement which will
produce nonstandard results)
• Distribute rodding evenly over the entire cross section
of the sample.
The commonly used
field test to measure the
workability of concrete
is Slump test.
- SRM SEAD 2020-2021

STEP 2:
• Fill cone 2/3 full by volume.
• Again rod it this layer 25 times with rod penetrating
into, but not through first layer.
• Distribute rodding evenly over the entire cross
section of the layer.
STEP 3:
• Remove the excess concrete
from the top of the cone, using tamping rod as a screed.
• Clean overflow from base of cone.
• Immediately lift cone vertically with slow, even motion.
• Do not jar the concrete or
tilt the cone during this process
• Invert the withdrawn cone, and place next to, but not touching the slumped concrete.
(Perform in 5-10 seconds with no lateral or torsional motion.)
- SRM SEAD 2020-2021

STEP 4:
• Lay a straight edge across the top of the slump cone.
• Measure the amount of slump in inches from the bottom of
the straight edge to the top of the slumped concrete at a point
over the original center of the base.
• The slump operation shall be completed in a maximum
elapsed time of 21/2 minutes. Discard concrete.
 SLUMPVALUEFORDIFFERENTCONCRETE
 Mass concrete and road work 2.5 to 5cm
 Ordinary beams and slabs 5 to 10cm
 Columns and retaining walls 7.5 to 12.5cm
Concrete has a tendency to shrink due to loss of water through forms, absorption by
surfaces of forms, etc.
- SRM SEAD 2020-2021

 WORKABILITYOFCONCRETE
 It is the amount of water required to place concrete and to compact it thoroughly.
 Workability of concrete increases with the addition of water but it reduces the strength that’s
why it is not a desirable way of increasing the workability.
 Use of aggregates which are round and have smooth surfaces increases the workability.
 Workability could also be improved by adding air entraining agent such as vinsol resin or
Darex.
 Use of Lisapole liquid at 30 cubic centimeter per bag of cement improves not only the
workability but also the water tightness of concrete.
 Workability of concrete is better determined by compaction factor test.
 PLACINGOFCONCRETE
 After mixing of concrete it should be placed within 30min of adding of water.
 It should be quickly transported to the place of lying by means of iron pans manually,
in wheel barrows, by pumping or by cranes.
 In placing, concrete should be laid in thin layers. Each layer being thoroughly
consolidated, before the next one is laid.
The ease or difficulty with which concrete is handled, transported and placed between the
forms with minimum loss of homogeneity is called Workability.
- SRM SEAD 2020-2021

 Concrete should not be dropped from a height as it would cause segregation of
aggregates.
 In case, concrete has more of water or it has been laid in thick layers then on compaction
water and fine particles of cement comes at the top forming a layer of weak substance
known as laintance
 COMPACTIONOFCONCRETE
 Compaction of concrete is very important in developing qualities like strength, durability,
imperviousness by making the concrete dense and free from voids.
 In case of RCC, compaction is done by pinning with an iron rod or even with trowel
blade.
 Excess temping should be avoided as otherwise water, cement and finer particles would
come to the surface and results in non uniform concreting.
 In case of important and big works, compaction of concrete is done with vibrator.
 Use of vibrator is best and the most efficient way of compacting concrete. It gives very
dense concrete.
 Care should be taken not to make excessive use of vibrators otherwise the concrete
becomes non homogeneous
- SRM SEAD 2020-2021

 CURINGOFCONCRETE
 The process of keeping concrete wet to enable it
to attain full strength is known as curing.
 The objective of curing is to prevent loss of
moisture from concrete due to evaporation or
because of any other reasons.
 Curing should be done for a period of three
weeks but not less then 10 days.
 To do curing, any one of the following
method can be used.
i. The surface of concrete is coated with a
layer of bitumen or similar other
waterproofing compound which gets into
the pores of concrete and prevent loss of
water from concrete.
ii. Concrete surface is covered with
waterproof paper or with a layer of wet
sand. It could also be covered with gunny
bags.
- SRM SEAD 2020-2021

 QUALITIESOFGOODCONCRETE
 STRENGTH: The concrete should be able to withstand the stresses that it is subjected to. It is
quite strong in compression but weak in tension.
 DURABILITY: It should be durable enough to resist the effect of weathering agents.
 DENSITY: the concrete should be well compacted so that there are no voids or hollows left. It
should weigh 3000 kg/cu.m
 WATER TIGHTNESS: when used for construction of water retaining structures such as dams,
elevated tanks and water reservoirs then this property of concrete becomes very important.
Otherwise the moisture inside the RCC would corrode steel and leakage would start resulting in
the ultimate failure of the structure.
 WORKABILITY: It should be easily workable.
 RESISTANCE TO WEAR AND TEAR: when used in floors and in the construction of roads
the concrete should be able to withstand abrasive forces.
- SRM SEAD 2020-2021

SPECIAL CONCRETES
• Special concretes are the concrete prepared for specific purpose. Eg- light weight, high
density, fire protection, radiation shielding etc.
• Concrete is a versatile material possessing good compressive strength. But it suffers from
many drawbacks like low tensile strength, permeability to liquids, corrosion of reinforcement,
susceptibility to chemical attack and low durability.
• Modification have been made from time to time to overcome the deficiencies of cement
concrete.
• The recent developments in the material and construction technology have led to significant
changes resulting in improved performance, wider and more economical use.
• Research work is going on in various concrete research laboratories to get improvement in
the performance of concrete.
• Attempts are being made for improvements in the following areas. Improvement in
mechanical properties like compressive strength, tensile strength, impact resistance.
• Improvement in durability in terms of increased chemical and freezing resistances.
• Improvements in impermeability, thermal insulation, abrasion, skid resistance etc.
- SRM SEAD 2020-2021

Different Types of Special Concrete are:
• Light Weight Concrete
• High Density Concrete
• Plum Concrete
• No Fines Concrete
• Aerated Concrete
• Fiber Reinforced Concrete (FRC)
• Polymer Concrete
• Ferro cement
• High Strength Concrete
• High Performance Concrete
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DIFFERENCE BETWEEN ORDINARY CONCRETE AND SPECIAL CONCRETE
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LIGHT WEIGHT CONCRETE
• Lightweight concrete can be defined as a type of concrete which includes an expanding
agent in that it increases the volume of the mixture while giving additional qualities such as
nailbility and lessened the dead weight. ... The main specialties of lightweight concrete are
its low density and thermal conductivity.
The light-weight concrete is prepared by Using coke-breeze, cinder or slag as
aggregate in the concrete.
- SRM SEAD 2020-2021

THE LIGHT WEIGHT CONCRETE OFFERS THE FOLLOWING ADVANTAGE:
• Reduction of Dead Load.
• Smaller section of structural members can be adopted.
• Lower transportation and handling costs.
• Increase in the progress of work.
• Reduction of foundation costs, particularly in the case of weak soil and tall structures.
• Light weight concrete has a lower thermal conductivity. In case of buildings where air
conditioning is to be installed, the use of light weight concrete will result in better thermal
comforts and lower power consumption.
• The use of light weight concrete gives an outlet for industrial wastes such as fly ash, clinkers,
slag etc. which otherwise create problem for disposal.
• It offers great fire resistance.
• Light weight concrete gives overall economy.
• The lower modulus of elasticity and adequate ductility of light weight concrete may be
advantageous in the seismic design of structures.
THE LIGHT WEIGHT CONCRETE IS ACHIEVED BY THREE DIFFERENT WAYS:
• By replacing the normal mineral aggregate, by cellular porous or light weight aggregate.
• By introducing air bubble in mortar this is known as ‘ aerated concrete’.
• By omitting sand fraction from the aggregate This is known as ‘ no fines concrete’.
- SRM SEAD 2020-2021

AERATED CONCRETE
• The aerated concrete is made by introducing air or gas bubbles
into the plastic cement mortar mix to produce a material with
a cellular structure, somewhat similar to sponge rubber . It is
also known as ‘ Gas Concrete’ or ‘Foam Concrete’ or ‘ Cellular
Concrete’. It is a mixture of water, cement and finely crushed
sand.
• The aerated concrete is different from air entrained concretes,
through in both cases air is introduced into the material. Air
entrained concrete contains a much lower proportion of air
and is in fact a heavy concrete whereas the amount of aeration
is more in cellular concrete and it is weight concrete.
APPLICATION
Different application of aerated concrete are as follows:
• As load bearing masonry walls using cellular concrete blocks.
• As partition walls in residential, institutional and industrial buildings.
• As precast composite wall or floor panels
• As a filler wall in the form of precast reinforced wall panels in high-rise building
• As precast floor and roof panels in all types of buildings.
• As insulation cladding to exterior walls of all types of buildings.
• The cellular concrete may or may not contain coarse aggregates. The densities generally range from
300 kg/ m3 to 1000 kg / m3. lower density grades are used for insulation purposes, medium density
grades are used for the manufacture of prefabricated structural members.
Aerated Concrete is Light weight.
- SRM SEAD 2020-2021

NO FINES CONCRETE
• ‘ No fines concrete’ is obtained by omitting fine
aggregate fraction (below 12 mm) from the
conventional concrete. It consists of cement,
coarse aggregates and water only. Cement
Content is correspondingly increased. Very
often only single sized coarse aggregate, of size
passing through 20 mm and retained on 10 mm
is used. By using single sized aggregate, voids
can be increased.
• No fines concrete is generally made with the
aggregate/ cement ratio 6:1 to 10:1. The water/
cement ratio for satisfactory consistency will
vary between 0.38 to 0.50. The strength of no
fines concrete is dependent on the water/
cement ratio, aggregate/ cement ratio and unit
weight of concrete.
• Though the strength of no fines concrete
is lower than ordinary concrete, the
strength are sufficient for use in structural
members and load bearing wall in normal
buildings up to 3 stories high. Strengths of
the order of 15 N/mm 2 have been
attained with no fines concrete.
- SRM SEAD 2020-2021

POLYMER CONCRETE
• Concrete containing polymers can be classified into three categories, namely:
(a) Polymer- Impregnated Concrete (PIC)
(b) Polymer Portland Cement Concrete (PPCC)
(c) Polymer Concrete (PC)
POLYMER-IMPREGNATED CONCRETE (PIC) •
• Polymer- Impregnated Concrete is produced by impregnating or infiltrating a hardened
Portland cement concrete with a monomer and subsequently polymerizing the monomer in
situ. It is one of the widely used polymer composite.
• The partial or surface impregnation improves durability and chemical resistance while total or
in-depth impregnation improves structural properties of concrete.
• The monomer used for impregnation are: • Methyl methacrylate (MMA) • Styrene •
Acrylonitrile • T-butyl styrene • Epoxy
POLYMER PORTLAND CEMENT CONCRETE (PPCC)
• Polymer Portland cement concrete is a conventional Portland cement concrete which is usually
made by replacing a part of the mixing water with a latex (Polymer emulsion). Earlier latexes
were based on polyvinyl acetate or polyvinylidene chloride, but these are seldom used now
because of the risk of corrosion of steel in concrete in the latter case and low wet strengths in
the former.
• Both elastomeric and glassy polymers have been employed in lattices.
- SRM SEAD 2020-2021

POLYMER CONCRETE (PC) (RESIN CONCRETE)
• Polymer Concrete (PC) is a mixture of aggregates with a polymer as a sole binder. There is
no other bonding material present, i.e. Portland cement is not used.
• It is manufactured in a manner similar to that of cement concrete. Monomers or Pre-
polymers are added to the graded aggregate and the mixture is thoroughly mixed by hand
or machine. The thoroughly mixed polymer concrete material is cast in moulds of woods,
steel or aluminium, etc.
• To minimize the amount of the expensive binder, it is very important to achieve the
maximum possible dry packed density of the aggregates. For Ex, using two different size
fractions of 20 mm maximum coarse aggregate and five different size fractions of sand,
higher densities can be achieved.
• The polymer concrete material cast in the mould is then polymerized either at room
temperature or at an elevated temperature. The polymer phase binds the aggregate to give
a strong composite. The polymer concrete material cast in the mould is then polymerized
either at room temperature or at an elevated temperature. The polymer phase binds the
aggregate to give a strong composite. Polymerization can be achieved by any of the
following methods. • Thermal-catalytic reaction • Catalyst-promoter reaction • Radiation
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 Uses and Application of Special Concrete
• Special concrete is used in extreme weather.
• HPC has been used in large structures such as the Petronas Towers and the Troll
Platform. Petronas Towers was the tallest concrete building in the world built in
Malaysia in the mid-1990s. In 1998, the deepest offshore platform, the Troll platform,
was built in Norway — a structure taller than the Eiffel Tower.
• Good cohesiveness or sticky in mixes with very high binder content
• Some delay in setting times depending on the compatibility of cement, fly ash and
chemical admixture
• Slightly lower but sufficient early strength for most applications
• Comparable flexural strength and elastic modulus
• Better drying shrinkage and significantly lower creep
• Good protection to steel reinforcement in high chloride environment
• Excellent durability in aggressive sulphate environments
• Lower heat characteristics
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 WHAT IS FORMWORK?
• Formwork is a mould including all supporting structures, used to shape and support the
concrete until it attains sufficient strength to carry its own weight.
• It should be capable of carrying all imposed dead and live loads apart from its own
weight.
• Formwork is commonly made of
o Steel
o Timber
 TIMBER FORMWORK
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 STEEL FORMWORK
• Formwork has been in use since the beginning of concrete construction.
• New materials such as steel, plastics and fibreglass are used in formwork.
• Greater attention is being given to the design, fabrication, erection and dismantling of formwork
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 QUALITIES OF FORMWORK
 It should be water tight.
 It should be strong.
 It can be reusable.
 Its contact surface should be uniform.
 It should be according to the size of member.
 IN ORDER TO SUCCESSFULLY CARRY OUT ITS FUNCTION,
FORMWORK MUST ACHIEVE A BALANCE OF FOLLOWING
REQUIREMENTS:
• Containment
• Strength
• Resistance To Leakage
• Accuracy
• Ease Of Handling
• Finish And Reuse Potential
• Access For Concrete
• Economy
- SRM SEAD 2020-2021

Containment:
Formwork must be capable of shaping and supporting the fluid concrete until it cures.
Strength:
Formwork must be capable of safely withstanding without distortion or danger the dead weight of
the fluid concrete is placed on it, labour weight, equipment weight and any environmental loadings.
Ease of Handling:
Form panels and units should be designed so that their maximum size does not exceed that which
can be easily handled by hand or mechanical means.
In addition all formwork must also be designed and constructed to include facilities for
adjustments, levelling, easing and striking without damage to the form work or concrete.
Economy:
All the formwork is very expensive. On average about 35% of the total cost of any finished concrete
unit or element can be attributed to its formwork; of this just over 40% can be taken for material for
formwork and 60% for labour.
- The formwork designer must therefore not only consider the maximum number of times that
any form can be reused, but also produce a design that will minimize the time taken for erection
and striking.
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Major objectives considered in formwork:
 Quality
 Safety
 Economy
 Quality:
Forms must be designed and built with sufficient stiffness and accuracy so that
the size, shape, position, and finish of the cast concrete are maintained.
 Safety:
Forms must be built sufficient strength and factor of safety so that they have
the capable of all supporting loads.
 Economy:
Forms must be built efficiently, minimizing time and cost.
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Requirements of formwork:
 Material should be cheap and re usable,
 It should be practically water proof, so that it should not absorb water from
concrete,
 Swelling and shrinkage should be minimum,
 Strong enough to with stand all external loads,
 Deflection should be minimum,
 Surface should be smooth, and afford easy striping,
 Light in weight, so that easy to transfer,
 Joints should be stiff, so that lateral deformation and leak is minimum .
Three stages in the process :
a) Assembly and erection .
b) Concrete placement.
c) Stripping and dismantling.
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Formwork detail for different structural members
In concrete construction formwork is commonly provided for the following
structural members.
o Wall
o Column
o Slabs & Beams
o Stairs
o Chimneys
o Water tanks
o Cooling Towers
• FORMWORK FOR WALL
It consists of
• Timber sheeting
• Vertical posts
• Horizontal members
• Rackers
• Stakes
• Wedges
After completing one side of formwork
reinforcement is provided at the place then
the second side formwork is provided.
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FORMWORK FOR COLUMN
• It consists of the following
– Side & End Planks
– Yoke
– Nut & Bolts
• Two end & two side planks
are joined by the yokes and
bolts.
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FORMWORK FOR SLABS & BEAMS:
• It consists of
– Sole plates
– Wedges
– Props
– Head tree
– Planks
– Batten
– Ledgers
• Beam formwork rests on head tree
• Slab form work rests on battens and joists
• If prop height are more than 8’ provide horizontal braces.
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LINTEL OR BEAM FORMWORK:
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FORMWORK FOR SLAB:
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FORMWORK FOR STAIRS:
• It consists of
– Vertical & inclined posts
– Inclined members
– -- Wooden Planks or sheeting
– Stringer
– Riser Planks
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REMOVAL OF FORMWORK:
Time of formwork removal depends on the following factors
1. Type of Cement
1. Rapid hardening cements require lesser time as compared to OPC (Ordinary
Portland Cement)
2. Ratio of concrete mix
1. Rich ratio concrete gain strength earlier as compared to weak ratio concrete.
3. Weather condition
1. Hydration process accelerates in hot weather conditions as compared to
cold and humid weather conditions.
- SRM SEAD 2020-2021

Time of Removal of formwork:
Maintenance of formwork:
• Due to continuous use wooden planks & steel plates surfaces become uneven and require
maintenance.
• For wooden formwork use cardboard or plastic fiber board. Bolt hole places must also be repaired.
• For steel formwork plates must be leveled by mallet and loose corners must be welded.
- SRM SEAD 2020-2021

Cost of formwork
 For normal works cost of formwork is about 30%-40% of the concrete cost.
 For special works cost of formwork is about 50%-60% of the concrete cost.
 Formwork cost is controlled by the following factors
• Formwork Material cost , Formwork erecting cost, Formwork removal cost , Formwork
jointing cost (Nails and Cables) & Labor charges.
Advantages of steel form work:
 It can be used for a no. of times.
 It is non absorbent.
 Smooth finish surface obtained.
 No shrinkage of formwork occurs.
 Easy to use.
 Its volume is less
 Its strength is more. COMPILED BY: Syedali Fathima, Asst.Professor
- SRM SEAD 2020-2021

 JOINTS IN CONCRETE - WHEN CASTING
CONCRETE
• IF ON THE SITE NESSESARLY NEEDED
TO STOP CASTING
CONSTRUCTION
JOINT
• IF TOO BIG AREA TO CAST CONCTERE
USE THE EXPANSION JOINT
EXPANSION
JOINT
• TO SEPARATE DIFFERENT ELEMENTS
SHRINKAGE
JOINT
- SRM SEAD 2020-2021

 EXPANSION JOINTS
 Full depth galvanised roll formed steel profile that ensures positive load transfer and eliminates
differential settlement.
 10mm polyethylene closed cell foam – provides compression capabilities.
 Universal Dowel Sleeves (UDS) – quick twist and self supporting.
Hot dipped galvanised dowel bars for load transfer.
 FEATURES AND BENEFITS
 Rigid galvanized steel profile producing straighter joints.
 A full depth straight joint is obtained with 10mm polyethylene closed cell foam, thus providing
for up to 10mm of compression capabilities.
- SRM SEAD 2020-2021

CONSTRUCTION JOINT EXPANSION JOINT
- SRM SEAD 2020-2021

 EXPANSION JOINTS - INSTALLATION
Step 1:
Position expansion joint in specified location and drive in the pegs.
Step 2:
Adjust the expansion joint to the correct height and secure by tapping in the wedges.
Step 3:
Insert dowels into Universal Dowel Sleeves (UDS) and push dowels through the foam, then
twist sleeves 90° to lock in place.
- SRM SEAD 2020-2021

 “Its Simple & Easy”
 Insert Dowels.
 Twist sleeves 90° to fix
in place.
Step 4:
Place reinforcement and pour concrete to both sides of the joint.
Finish concrete surface to the top of the expansion joint (NOT OVER IT).
Ensure concrete is poured evenly to both sides of the joint and recommend vibration.
Features and Benefits
Compression to 10mm ability.
Positive load transfer & deferential settlement .
Rigid galvanised steel profile produces full depth straight joints.
Accommodating a range of dowel sizes.
Quick & Easy Installation
Quick twist & fit sleeves.
Accurate dowel alignment.
Saves time & money. COMPILED BY: Syedali Fathima, Asst.Professor
- SRM SEAD 2020-2021

 REINFORCED CEMENT CONCRETE
 Reinforced cement concrete (RCC) is a composite material in which concrete's relatively low
tensile strength and ductility are counteracted by the inclusion of reinforcement having higher
tensile strength or ductility.
 RCC (Reinforced Cement Concrete) is the combination of using steel and concrete instead of
using only concrete to offset some limitations.
 Concrete is weak in tensile stress with compared to its compressive stress. To offset this
limitation, steel reinforcement is used in the concrete at the place where the section is subjected
to tensile stress.
 Steel is very strong in tensile stress. The reinforcement is usually round in shape with
approximate surface deformation is placed in the form in advance of the concrete.
 When the reinforcement is surrounded by the hardened concrete mass, it form an integral part of
the member. The resultant combination of two materials are known as reinforced concrete.
- SRM SEAD 2020-2021

 The reinforcement is usually, steel reinforcing bars (rebar) and is usually embedded passively in
the concrete before the concrete sets.
 Modern reinforced concrete can contain varied reinforcing materials made of steel, polymers or
alternate composite material in conjunction with rebar or not.
 Rebar (reinforcing bar) is an important component of reinforced concrete.
 It is usually formed from ridged carbon steel; the ridges give frictional adhesion to the concrete.
 Rebar is used because although concrete is very strong in compression it is virtually without
strength in tension.
 To compensate for this, rebar is cast into concrete to carry the tensile loads on a structure.
 REINFORCEMENT
For a strong, ductile and durable construction the reinforcement needs to have the following
properties :
 High relative strength
 High toleration of tensile strain
 Good bond to the concrete, irrespective of pH, moisture, and similar factors
 Thermal compatibility (not causing unacceptable stresses in response to changing temperatures)
 Durability in the concrete environment, irrespective of corrosion or sustained stress
 PROPERTIES
- SRM SEAD 2020-2021

 ADVANTAGES- RCC
• Reinforced Cement Concrete has good compressive stress (because of concrete).
• RCC also has high tensile stress (because of steel).
• It has good resistance to damage by fire and weathering (because of concrete).
• RCC protects steel bars from buckling and twisting at the high temperature.
• Reinforced Concrete is durable.
• The monolithic character of reinforced concrete gives it more rigidity.
• Maintenance cost of RCC is practically nil.
 DISADVANTAGES- RCC
• It needs mixing, casting and curing, all of which affect the final strength of concrete
• The cost of the framework used to cast concrete is relatively high.
• It has low compressive strength as compared to steel (the ratio is about 1:10 depending on
material) which leads to large sections in columns/beams of multi story buildings.
• Cracks develop in concrete due to shrinkage and the application of live loads.
- SRM SEAD 2020-2021

 PRE - STRESSED CONCRETE
• Prestressed concrete is a form of concrete used in construction which is "pre-stressed" by being
placed under compression prior to supporting any loads beyond its own dead weight.
• This compression is produced by the tensioning of high-strength "tendons" located within or
adjacent to the concrete volume, and is done to improve the performance of the concrete in
service.
• Tendons may consist of single wires, multi-wire strands or threaded bars, and are most
commonly made from high tensile steels, carbon fibre or aramid fibre.
• Prestressed concrete is used in a wide range of building and civil structures where its improved
performance can allow longer spans, reduced structural thicknesses, and material savings
compared to simple reinforced concrete.
• Typical applications include high-rise buildings, residential slabs, foundation
systems, bridge and dam structures, tanks, industrial pavements and nuclear containment
structures.
- SRM SEAD 2020-2021

The prestressing of concrete provides many benefits to building structures:
• Longer spans for the same structural depth
Load-balancing results in lower in-service deflections, which allows spans to be
increased (and the number of supports reduced) without adding to structural depth.
• Reduced structural thickness
For a given span, lower in-service deflections allows thinner structural sections to be
used, in turn resulting in lower floor-to-floor heights, or more room for building
services.
• Faster stripping time
Typically, prestressed concrete building elements are fully stressed and self-supporting
within five days. At this point they can have their formwork stripped and re-deployed to
the next section of the building, accelerating construction "cycle-times".
• Reduced material costs
The combination of reduced structural thickness, reduced conventional reinforcement
quantities, and fast construction often results in prestressed concrete showing significant
cost benefits in building structures compared to alternative structural materials.
- SRM SEAD 2020-2021

 PRE - STRESSED CONCRETE
- SRM SEAD 2020-2021

 READY MIX CONCRETE
• Ready-mix concrete is concrete that is
manufactured in a factory or batching plant,
according to a set recipe, and then delivered to
a work site by truck mounted in–transit mixers.
• This results in a precise mixture, allowing
specialty concrete mixtures to be developed
and implemented on construction sites. Ready-
mix concrete is often preferred over on-site
concrete mixing because of the precision of the
mixture and reduced work site confusion.
Advantage of rapid hardening cement is High strength, early removal of formwork
and used in constructing road pavements .
- SRM SEAD 2020-2021

 ADVANTAGES
• Quality assurance.
• Elimination of manual errors.
• Mass production of concrete possible.
• Water cement ratio maintained.
• Reduced material wastage.
• Labour cost saved.
• Design mix as per IS standards resulting in standard deviation and improved
characteristics.
- SRM SEAD 2020-2021

• The materials are batched at a central plant, and the mixing begins at that plant, so the traveling
time from the plant to the site is critical over longer distances. Some sites are just too far away,
however the use of admixtures like retarder can be added.
• Furthermore, access roads and site access have to be able to carry the greater weight of the
ready-mix truck plus load. This problem can be overcome by utilizing so-called 'mini mix'
companies which use smaller 4m³ capacity mixers able to reach more-restricted sites.
• Concrete's limited time span between mixing and curing means that ready-mix should be
placed within 210 minutes of batching at the plant.
• Modern admixtures can modify that time span precisely, however, so the amount and type of
admixture added to the mix is very important.
 DISADVANTAGES
- SRM SEAD 2020-2021

 READY MIX CONCRETE VS SITE MIX CONCRETE
- SRM SEAD 2020-2021

 MAJOR BUILDING PARTS
 The size and depth of a
foundation is determined by
the
- Structure and size of
building it supports
- Bearing capacity of the
ground supporting it.
 The property of a soil which
permits water to percolate
through it, is called
Permeability.
- SRM SEAD 2020-2021

 INTRODUCTION
• ―The foundation of a building is in direct contact with the ground and transmitting loads to
the ground.‖
• Every building needs a foundation of some kind.
 PURPOSEOFFOUNDATION
• To distribute the load of the structure over a large bearing area so as to bring the intensity
of load within the safe bearing capacity of soil.
• To load the bearing surface at a uniform rate to avoid differential settlement.
• To prevent the lateral movement of supporting material.
• To attain a level and firm bed for building operations.
• To increase the stability of the structure as a whole.
The maximum pressure that a soil can bear without shear failure is known as Safe
bearing capacity.
- SRM SEAD 2020-2021

 THE IMPORTANCE OF FOUNDATIONS IN BUILDING CONSTRUCTIONS
• Foundations do not typically contribute to the architectural aesthetics of a building. Yet, without
suitable foundations, a building will not function effectively, will be unsafe and its architectural
merits will rapidly fade.
 REQUIREMENTSOFFOUNDATION
• Structural stability
• Weaken the function of the building
• Durability
• Economy
 FACTORSAFFECTINGDESIGNOFFOUNDATION
• Soil types and ground water table conditions.
• Construction requirements .
• Site condition and environmental factor.
• Economy etc.
- SRM SEAD 2020-2021

SHALLOW FOUNDATION
- SRM SEAD 2020-2021

 TYPES OF FOUNDATION
• There are two basic types of foundations
1. Shallow foundation
2. Deep foundation
 SHALLOW FOUNDATION
– The foundation provided immediately below the lowest part of the structure near the ground
level, transferring load directly to the supporting soil, is known as shallow foundation.
– Shallow foundation is provided when stable soil with adequate bearing capacity occur near to the
ground level.
– Requirements
 Suitable soil bearing capacity
 Undisturbed soil or engineered fill
 TYPESOFSHALLOWFOUNDATION
a) Spread footing or open trench foundation
b) Combined Footing
c) Mat/Raft foundation
- SRM SEAD 2020-2021

 SPREAD FOOTING
• A spread footing foundation, which is typical in residential building, has a wider bottom portion than
the load-bearing foundation walls it supports. This wider part "spreads" the weight of the structure
over more area for greater stability.
 Spread footings are those which spread the super-imposed load of wall or column over larger area.
Spread footing support either column or wall.
It may be following kinds
• Single footing for column:
In which the loaded area of column has been spread to the large size through single spread. The base
is generally made of concrete.
• Stepped footing for column:
This type of footing provided for heavily loaded column which required greater spread with steps. The
base is generally made of concrete.
• Sloped footing for column:
In this type of footing concrete base does not have uniform thickness but is made sloped.
• Wall footing without step:
It consist of concrete base without any steps including masonry wall.
• Stepped footing for wall:
It consist of masonry wall have stepped footing with concrete base .
- SRM SEAD 2020-2021

Spreads the super-imposed load of a wall or a column over a larger area.
Used where the loads are light or there are strong shallow soils.
Spread footing may be of the following types –
1) Single column footing
2) Stepped column footing Pad footing
3) Slopped column footing
4) Simple Wall footing strip footing
5) Stepped wall footing
- SRM SEAD 2020-2021

 SPREAD FOOTING – ISOLATED
PLAN
- SRM SEAD 2020-2021

 SPREAD FOOTING - ISOLATED
SECTION
- SRM SEAD 2020-2021

 SPREAD FOOTING -ECCENTRIC
PLAN
- SRM SEAD 2020-2021

 SPREAD FOOTING - ECCENTRIC
SECTION
- SRM SEAD 2020-2021

• A spread footing which supports two or more columns is termed as combined footing.
The combined footing may be of following kinds.
• Rectangular combined footing:
The combined footings will be provide in rectangular in shape if columns carry equal loads.
The design of rectangular combined footing should be done in such way that centre of gravity
of column coincide with centroid of footing area.
• Trapezoidal combined footing:
If columns carry unequal loads the footing is of trapezoidal shape are provided.
• Combined column-wall footing:
It may be required to provide a combined footing for column and wall.
 SPREAD FOOTING - COMBINED
- SRM SEAD 2020-2021

 COMBINED FOOTING
PLAN
- SRM SEAD 2020-2021

 COMBINED FOOTING
SECTION
A common footing provided for two or more columns is known as Combined footing.
- SRM SEAD 2020-2021

• Raft foundation is a thick concrete slab reinforced with steel which covers the
entire contact area of the structure like a thick floor.
• The reinforcing bars runs normal to each other in both top and bottom layers of
steel reinforcement.
• Sometimes inverted main beams and secondary beams are used to carry column
loads that require thicker foundation slab considering economy of the structure.
• Used generally for higher loads and prevention of excessive settlements.
 RAFTFOOTING
- SRM SEAD 2020-2021

• A raft Foundation is a combined footing that covers the entire area beneath a structure and
support all the wall and column.
• They are used in areas where the soil masses contains compressible lenses or the soil is
sufficiently erratic so that differential settlement would be difficult to control.
• Raft foundation may be divided in to three types based on their design and construction.
• Solid slab system
• Beam slab system
• Cellular system
• All the three types are basically the same, consisting of a large, generally unbroken area of
slab covering the whole or large part of structure.
 RAFTFOOTING
- SRM SEAD 2020-2021

 RAFTFOOTING
 Strip footings are commonly found in load-bearing masonry construction, and act as a long
strip that supports the weight of an entire wall.
 A strip footing is also provided for a row of columns which are so closely spaced that their
spread footings overlap or nearly touch each other. In such a case, it is more economical to
provide a strip footing than to provide a number of spread footings in one line. A strip
footing is also known as continuous footing.
- SRM SEAD 2020-2021

RAFTFOOTING
- SRM SEAD 2020-2021

DEEP FOUNDATION
- SRM SEAD 2020-2021

Deep Foundations - Purpose
transfer building loads deep into the earth
Basic types
– Drilled (& poured)
– Driven
- SRM SEAD 2020-2021

• Deep foundation are those in which the depth of foundation is very large in comparison to
its width.
Deep foundation may be of following types
• Pile foundation
• Pier foundation
• Caissons or Well foundation
 DEEPFOUNDATION
• Pile Foundation is that type of foundation in which the loads are taken to a low level by means of
vertical members which may be timber, concrete or steel.
• Pile foundation may be adopted when no firm bearing strata is available and the loading is uneven.
• Piles may be of following types
• End bearing piles
• Friction Pile
• Compaction pile
 PILEFOUNDATION
- SRM SEAD 2020-2021

• END BEARING PILES:
This types of piles are used to transfer load through water or soft soil to a suitable bearing stratum.
• FRICTION PILE:
Friction piles are used to transfer loads to a depth of friction load carrying material by means of skin
friction along the length of piles.
• COMPACTION PILE:
Compaction piles are used to compact loose granular soils, thus increasing their bearing capacity.
- SRM SEAD 2020-2021

• A Pier foundation consist of cylindrical column of large diameter to support and transfer
large superimposed load to the firm strata below.
• Generally, pier foundation is shallow in depth than the pile foundation.
 PIERFOOTING
Pier foundation is also called Caisson.
- SRM SEAD 2020-2021

• Well Foundation or Caisson are box like structures which are sunk from the surface
of either land or water to the desired depth.
• They are much larger than the pier foundation or drilled caissons.
• Caisson foundations are used for major foundation works like
• Bridge piers
• Docks
• Large water front structure such as pump house.
 WELLFOOTING
- SRM SEAD 2020-2021

 CONSTRUCTION OF FOUNDATION
Construction of foundation consists upon the following activities
– Site preparation
– Site layout
– Excavation
– Pour footing
– Pour slab on grade
– Pour concrete foundation walls
 SITEPREPARATION
• Remove trees and any debris
• Remove top soil (4-6‖ below surface)
- SRM SEAD 2020-2021

 SITELAYOUT
• Define the boundaries by using chalk powder.
• Layout building perimeter, Establish building corners & building perimeter.
• Use surveying instruments
 EXCAVATION
•Excavate foundation along line created.
•If deep foundation, taper edges to prevent collapse
•If soil unstable, or very deep - use shoring
- SRM SEAD 2020-2021

 CONSTRUCTFORMWORK
•Construct formwork (if required)
•Install reinforcement (rebar) for footing.
•Pour concrete footings
•Smooth / finish surface
- SRM SEAD 2020-2021

 PILEFOUNDATION
PLAN
- SRM SEAD 2020-2021

 PILEFOUNDATION
SECTION
- SRM SEAD 2020-2021

BUILDING MATERIAL & CONSTRUCTION - CONCRETE STRUCTURES.pdf

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