Concrete equipments and special concrete

CONCRETE
TECHNOLOGY
[Concrete Equipments and special concretes]
Er. Tushar Harihar Sonawane
( Member : IEI , IAENG )
Civil Engineering Department,
SNJB’s KBJ COE Chandwad
+91 9657688220
tusharhsonawane.wordpress.com
sonawane.thcoe@snjb.org
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Contents
Sr. No. Title Slide No.
1 Concrete 1
2 Concrete Batching Plant 5
3 Concrete Pumps 7
4 Mixers 11
5 RMC Plant 22
6 Roller Compacted Concrete 27
7 Cold Weather and Hot weather concrete 29
8 Special Concrete 37
9 Light weight concrete 39
10 No fine concrete 42
11 Fibre reinforced concrete 50
12 High density concrete 52
13 Self Compacting concrete 53
14 Ferrocement 58
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Concrete
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CONCRETE
Cement
Coarse Aggregate
Fine Aggregate
Water

Concrete is a homogenous mixture of Cement,
Fine aggregate, Coarse aggregate and Water.
Cement is a binding material manufactured by
grinding calcareous and argillaceous materials,
mixing them intimately in certain proportions
depending upon their purity and composition
and burning them in kiln at temp. about 1300-
1500˚c, at which material sinters and forms
clinker. The clinker is cooled and ground to fine
powder with addition of about 3-5% of gypsum.
The product is a Portland Cement
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Concrete Batching Plant
• Concrete batching plants basically used to process
the materials to form concrete.
• It mixes all the materials like sand, gravels,
cement and water to form a better solution that
should be sent to construction site.
• Concrete batching plants divided into types
according to their working capacity from 20 to
120 cum/hr and they are famous for their mobility
as a mobile concrete batcher.
• Batching can be done by Volume or by Weight.
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• Volumetric batching can be done by Gauge boxes [Grid boxes]
or Farmas. Weigh batching is done by weigh batcher, these are
the mixers equipped with weighing balance.
• Volumetric batching is not correct method as like as weigh
batching.
• Cement is always measured by weight and never be measured
by volume.
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Concrete Pumps
• Concrete pumps are one of the fastest
construction machines that get fame in
construction market because of their reliability
and cost-effectiveness.
• Concrete pumps save labor costs, time and
materials with high power electric suction
machine used for pumping the concrete from
mixer and send it direct to construction site.
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• A majority of the concrete pumps are of the direct-acting, horizontal piston-
type with semi-rotary valves. The operation of the direct- acting pump is
simple.
• The concrete is fed into the pump by gravity and partly by suction created due
to the reciprocating motion of the horizontally acting piston, while the semi-
rotary valves open and close alternately.
• Suction pressure of the order of 0.08 N/mm2 is developed in the pumping
cylinder under favorable conditions.
• The concrete moves in a series of impulses, the delivery pipe always
remaining full. Outputs of up to 60 m3/h can be achieved in modern pumps
through 220-mm diameter delivery pipes.
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• Squeeze type pumps are smaller portable peristaltic type pumps.
The concrete from the collecting hopper is fed by rotating blades
into a flexible pipe connected to the pumping chamber, which is
under a vacuum of about 0.08 N/mm2.
• The vacuum ensures that, except when being squeezed by the
rotating rollers, the pipe shape remains cylindrical and thus permits
a continuous flow of concrete.
• The two rotating rollers mounted on planetary drives progressively
squeeze the flexible pipe and thus push the concrete into the
delivery pipe. Outputs of up to 20 m3/h can be obtained with
squeeze pumps using 75-mm diameter pipelines.
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Mixer
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• A device that homogeneously combines cement, aggregate
such as sand or gravel, and water to form concrete
• A typical concrete mixer uses a revolving drum to mix the
components and prepare uniform concrete.
Mixers are of two types
1. Continuous Mixer
These are continuously rotating
mixers without stoppage till the plant
is working.
Generally used in large works like
dam.
2. Batch Mixers
Batch Mixers produces concrete batch
by batch with time interval.
Used in normal concrete works.

Batch Mixers
• The batch mixers are divided in to two types
1. Pan Mixers
2. Drum Mixers
i. Tilting Mixers
ii. Non Tilting Mixers
iii. Reversing Mixers
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• Pan Mixers with revolving
star of blades are more
efficient.
• They are suitable for stiff and
lean mixes, which present
difficulties with most other
type of mixers, mainly due to
sticking of mortar in the
drum.
Pan Mixer

Batch Mixer
1. Non-Tilting Mixer
Single drum rotating about
a horizontal axis. Fixed
blades work the concrete
towards the discharge end
of the mixer, in order to
provide a rapid rate of
discharge.
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2. Tilting Mixer
• They are most suitable
for concrete with large
sized aggregate and,
since they have a rapid
discharge rate, are
suitable for low
workability concrete.
• Internal blades lift and
tumble the ingredients
onto itself.
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3. Reversing Mixer
• Rotate in one direction for mixing and in the reverse direction
for discharge.
• One set of blades exists for each operation.
• Provides efficient mixing with very little build up within the
mixer.
• Are suitable with dry concrete mixes.
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Transit Mixer
• A concrete mixer primarily consists of a revolving drum, a motor,
and a shaft. It is used for uniform mixing of concrete of already
mixed concrete during its transit.
• It has a wide range of application specially for mass concreting
works like Construction of Canals, Bridges, Highways, Dams,
Multi-storeyed & Industrial Buildings, Factories, Airports and for
Ready Mixed Concrete Works (R.M.C.), etc.
A Transit Mixer can perform the following 3 functions :-
1. It can mix coarse aggregates , fine aggregates, cement and water
while it is moving or stationary.
2. It can prevent segregation of already mixed concrete during transit
by agitation, as a result of slow revolution of drum.
3. It can completely mix the ‘shrink mixed’ concrete i.e. the concrete
which is partially mixed in central batching plant and mixing plant
while it is moving or stationary.
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PARTS OF TRANSIT MIXER
DRUM AND BLADES
• The mixing drum is made of high abrasion
resistant steel and blades of high abrasion
resistant alloy
• steel to mix any type of ready mix concrete
and to discharge it smoothly.
Features :-
• Detachable triangle blades for good mixing
performance.
• Option of one or two holes in the drum for
easy cleaning work.
HOPPER
• Wide mouth hopper specially designed to
receive sticky ready mix concrete in large
quantities with ease.
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HOPPER STEPS AND HANDRAIL
• Layout of hopper steps and handrails
are made user friendly for standing at
ease for cleaning purpose ensuring
better safety .Side steps made from
rust proof steel are attached as a
standard equipment with stripes for
anti slip and fender for easy
movement
SCOOP
• Scoop is made from Abrasion
resistant steel for durability and
weight reduction Instead of
traditional MS thick plates with liners
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Chute
Easy to use chute
made of high
abrasion resistant
steel is provided with
two options of
detachable chute
extents on for
smooth flow of
discharged concrete.
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Working of Mixer
• The revolving drum is used to mix all the
components of concrete.
• Inside the mixer, an operator feeds data into
the mixer and several augers feed aggregate
and cement together.
• Water is added to the mix and larger augers
blend the components and the number of
revolutions should be 70-100 rpm.
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RMC Plant
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• Concrete is produced in industrial plants containing
storage facilities and equipment designed for the
purpose of blending the raw materials in desired
proportions. That mixture, which becomes concrete,
is then loaded into mixer trucks. (Agitator Trucks)
• The majority of concrete production facilities are
located nearby areas where concrete is used; taking
into account its setting time, concrete prepared at the
batch plant, must be delivered to its destination within
an hour and a half.
• A concrete factory must be located within a radius of
20 to 30 km from the work site, depending on traffic
conditions.
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• A ready-mix concrete plant consists of silos that contain
cement, sand, gravel and storage tanks of additives such
as plasticizers, as well as a mixer to blend the
components of concrete.
• These components are gravity fed into the preparation
bin. The quality of concrete can be maintained only if
the formulation is carefully administered.
• The water dosage in particular must be very precise and
the mixing itself must remain continuous and
consistent.
• To accommodate all of these constraints, the concrete
plants have been automated to ensure reliability
throughout the manufacturing process.
• Finally, the concrete prepared in a batch plant is loaded
into a mixer truck, also known as a transit mixer, which
delivers it to the construction site.
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Modes of Ready Mixed Concrete
1. Plant Mixed Concrete
1. Mixing is done in central batching plant
2. Transported to site in agitator trucks with speed of 2 to 6
Revolutions Per Minute
2. Transit Mixed Concrete
1. Mixing is done in transit mixers
2. Continuously rotating drum revolves around central axis
3. Shrink Mixed Concrete
1. Water tanks are provided on trucks for preparation of
concrete.
2. Concrete is mixed partly in plant and partly during transit
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• For longer transportation of concrete Transit
mixer gives better results.
• Speed of rotating drum is between 4-16
revolutions per minute. Revolutions are limited
to 300 for mixing and agitation.
• The safe time of transportation of RMC is
lower value of
1. 90 minutes
2. Time taken for 300 revolutions of drum.
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Roller Compacted Concrete
• Roller Compacted Concrete pavement is best described
as a zero slump concrete that is placed with standard or
high-density paving equipment and
consolidated/compacted using steel-drum or rubber-
tired rollers to achieve a durable, wear resistant surface.
• Roller compacted concrete is placed in three layers to
permit complete compaction. THK of layer ranges from
200 to 300 mm.
• 7 Mpa to 30Mpa strength can be obtained using Roller
Compacted concrete.
• Examples – Mumbai Pune Expressway, Delhi Mathura
Expressway
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Benefits of Roller Compacted Concrete
• Speed of Construction
• Durability
• Low Maintenance
• Competitive Cost
• Sustainability
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Cold Weather and Hot Weather Concreting
• Any concreting operation done below 5˚C atmospheric
temperature or below is known as cold weather concreting.
• Cold weather is a period when more than three consecutive
days following situations exist.
1. The average daily air temperature is less than 5˚c (40 ˚F)
2. The air temperature is not greater than 10˚c for more than 12
Hrs of day.
• Problems involved in cold weather concreting
1. Delay in setting time
2. Delay in strength gaining
3. Freezing of concrete at early stage
4. Freezing and Thawing
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Precautions to be taken [IS 7861 (Part II):1981]
1. In no case concrete is allowed to freeze during first 24
hours after concreting
2. Heating the aggregates such that frozen lumps, ice and
snow are eliminated.
3. The average temperature for individual batch is limited to
65˚c
4. Concrete temperature can be increased by passing steam
through pipes embedded in stockpiles.
5. Use of Rapid hardening cement
6. Use of entrained concrete
7. Place concrete in the thermal heat in daylight hours.
8. After final finishing, concrete to be covered with
insulating materials like wood, canvas, polyethylene film
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Hot weather concreting
• Any operation of concrete done at atmospheric
temperature above 40˚c is considered has Hot
weather concreting.
• The climatic factors that affect concreting in
hot weather are
1. High ambient temperature
2. High concrete Temperature
3. Low related humidity
4. High wind speed
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Effect of Hot weather on concrete
1. Rapid rate of hydration, Quick setting and
early stiffening
2. Rapid evaporation of mixing water
3. Greater plastic shrinkage
4. Accelerates slump loss
5. Increases cracks
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Precautions during hot weather concreting
1. Aggregates should be protected fro direct sun rays
by shed or covering, to prevent slump loss.
2. Sprinkling water over aggregates and keeping them
moist
3. Circulating refrigerated air
4. Concrete mixer should be positioned as closed to
point of placement of concrete to reduce length and
time of delivery
5. Use of admixtures
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Special Concrete
• Concrete which meets special performance and uniformly
requirements that can not be achieved by normal concrete process.
• Generally produced by use of special cement, special aggregates and
fibers etc.
• Need of Special Concrete
1. To improve performance of concrete
2. Imparting strength of concrete
3. To make early age strength
4. To reduce durability
5. Improving chemical resistance
6. To Reduce creep
7. To avoid drying shrinkage problems
8. Protection to steel reinforcement in high chloride reinforcement
9. To reduce the heat of hydration
10. To reduce section of structural members.
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Types of Special Concrete
1. Light Weight Concrete
2. High performance concrete
3. Fiber reinforced concrete
4. Mass Concrete
5. No fines concrete
6. Heavy Weight concrete
7. Polymer concrete
8. Self Compacting concrete
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Light weight concrete
• LW concrete has density much lesser than ordinary
concrete
• Density varies from 300 to 1850 kg/m3
• Large quantity of air is added in the aggregate, in
concrete mix or in between particles.
• Maximum slump is limited to 100 mm.
• Types
I. No fine concrete
II. LW aggregate concrete
III. Aerated or foamed concrete
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• Lightweight aggregate may consist of processed shale,
clay, clinker, or other material.
• The production includes a burning process where the
material expands and as a result has less density (weight
per unit volume).
• Due to this expansion, some lightweight aggregate may
be very absorptive.
• Such aggregate may require pre-wetting prior to
concrete batching.
• Because of the high water absorption of lightweight
aggregate, the air content of the mixture is measured
using ASTM C 173 “Standard Test Method for Air
Content of Freshly Mixed Concrete by the Volumetric
Method.”
• This method is necessary since the standard pressure
method will give false readings
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• A Light weight concrete with
no fine aggregates in it.
• The strength of no fines
concrete is less than the
conventional concrete. (up to
15N/mm²)
• Bonding strength is low
• Concrete should be placed
within 20min. of mixing
• Suitable only in situations
where less stress development
is possible.
• Can be suitable for filling and
leveling works.
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No fines Concrete

Ultra light weight concrete
• A light weight concrete added with entrained
air or other gas into the concrete mix known as
cellular or aerated concrete or ultra light
weight concrete
• It can be produced by
i. By adding gas
ii. By adding foam
• When added gas, also known as gas concrete
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Foam Concrete
• Produced by adding foaming agent to the mix
• The foam contains isolated air bubbles, which creates
unconnected voids in concrete mix.
• CLWC ranges with densities 400 kg/m3 to 1800 kg/m3. with
Ec = 1.7 to 3.5 GPa
Autoclave Aerated Concrete
• A light weight concrete produced from mixture of fine grain
siliceous aggregates and inorganic binders and pore forming
agents it decreases its densities.
• High pressure steam curing process used to improve
mechanical strength.
• Density varies from 300-1000 kg/m3
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Advantages of LWC
• Reduction in dead load due to less density
• Less hauling and hoisting charges
• Good drainage property
• Low drying shrinkage
• Better insulating characteristics
• Considered to be a low cost concrete
Limitations
• Cracking may happen under excessive load
• Not suitable for reinforced concrete
• Mixing time is more than conventional
Applications
• Low rise structures
• Drainage layers and floor slab
• Car parking and roof slabs. Prepared for
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• Polymer concrete is composite in which the polymer
replaces cement water matrix in concrete
• Pre polymers are added to the graded aggregate and
mixed thoroughly
• The polymerization can be achieved by thermal
catalytic reaction, radiation etc.
• High strength concrete can be obtained using polymer
concrete (140 MPa)
• Compactness, Minimum voids, Hydrophobic,
resistance to chemical attack are the properties of
polymer concrete.
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Polymer Concrete

Polymers used
• Urethanes
• Acrylics
• Styrene butadiene resins
• Vinyl
• Epoxies
Applications of Polymer Concrete
• Polymer concrete can be used for rapid repair of damaged
airfield pavements and Industrial Structures
• Used for treating the sluice ways and stilling basin of dams.
• Polymer pipes are used for transporting effluents and waste
water.
• Manufacturing of electric pole
• Pressure vessel at nuclear power plant
• Water proofing of structure
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Fiber Reinforced Concrete
• A Composite material consisting of hydraulic
cement, water, fine and coarse aggregate and
discontinuous fibers is known as Fiber reinforced
concrete.
• Fiber is a small piece of reinforcing material
• Fiber can impart properties of concrete
subsequently.
• The closely spaced and dispersed fibers obstructs
the propagation of cracks.
• The fibers may be Natural fiber or artificial fibers
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Natural Fibers Artificial Fibers
Best or stem fiber (Jute, Flax,
kneaf)
Leaf fiber (Sisal, henequen)
Fruit Fiber (Coir)
Wood Fiber (Bamboo, reeds)
Steel,
Carbon,
Glass,
Polypropylene,
Nylon
Polyester
Polyethylene
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Factors affecting properties of Fiber reinforced concrete
• Types of fiber
• Volume of fibers
• Aspect Ratio
• Orientation of fibers in the matrix
• Workability of composite
• Size of coarse aggregate
• Mixing

High Density Concrete
• Concrete produced with heavy weight aggregates like
barites, magnetite, scrap iron is known as heavy
weight concrete.
• The concrete whose density varies from 3500 kg/m3
to 8900 kg/m3 is called as High density concrete
• The density of concrete depends upon the type of
aggregates used.
• Comp. strength of concrete lies between 20 to 21
Mpa
• Aggregate cement ratio is very high.
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Self Compacting Concrete
• SCC developed by Prof. Okamura and his team at University of
Tokyo, Japan in late 1980’s.
• During 1989, Some European Countries recognized the
Importance of SCC they founded EFNARC.
• Japan has developed SCC that does not require vibration to
achieve full compaction.
• “A concrete which is capable of self-consolidating without any
external efforts like vibration, floating, poking etc. under its
own weight. The mix is therefore required to have ability of
passing, ability of filling and ability of being stable.”
SCC Used in India.
• Nuclear Power Corporation of India (NPCIL) intend to use SCC at two
Nuclear Power Plants of India.
• Kaiga in Karnataka
• Tarapur atomic research Plant in 3rd & 4th stages
• Delhi metro project have used SCC in large Scale for dome Construction.
• Used as a backpack concrete in tunnel for Khopoli New Water Conductor
system.
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Benefits Limitations
• Increases speed of construction. • S.C.C. requires higher powder and
admixture contents
• Reduced noise level • Material cost is higher
• Reduction in site manpower. • Greater care with quality control is
required.
• It improves durability of concrete. • For preparation of concrete mix,
number of trails required.
• Placing of concrete becomes easier. • There is no specified procedure for
preparation of SCC mix.
• Better surface finish
• Safe working environment

Essential Properties of Self Compacting Concrete
1. Filling Ability
It is the property of Self Compacting Concrete to flow into and fill all
spaces within the formwork completely under its own weight without any
honeycombing.
If Self Compacting Concrete is satisfying this test, that means one can be
sure about its property to fill the form completely and can believe on ‘Pour
and forget.’
2. Passing Ability
It is the property of the Self Compacting Concrete to pass through congested
reinforcement without blocking.
As one of the distinct advantages of Self Compacting Concrete is that it can
use in the situation of congested reinforcement, it has to satisfy the test of
passing ability.
3. Segregation Resistance (Stability)
It is the ability of Self Compacting Concrete to remain stable in
composition.
SCC being flowing in nature, it must satisfy this property.
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Tests and Desired Results of SCC
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Method Property Unit Typical range of values
Minimum Maximum
1 Slump-flow by
Abrams cone
Filling ability mm 650 800
2 T50cm slump flow Filling ability sec 2 5
3 V-funnel Filling ability sec 6 12
4 V-funnel at T5minutes
Segregation
resistance
sec 0 +3
5 L-box Passing
ability
(H2/H1) 0.8 1.0

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• Ferro cement is a type of thin wall reinforced concrete, commonly
constructed of hydraulic cement mortar, reinforced with closely
spaced layers of continuous and relatively small size wire mesh. The
mesh may be made of metallic or other suitable materials.”
• Mortar provides the mass and wire mesh imparts tensile strength and
ductility. When building Ferro-cement structures the sand/cement
mortar is applied to the reinforcing wire with a trowel, never poured
like common concrete work. Often a form is used to provide the
desired shape.
• Ferro-cement is a super reinforced concrete. It differs from
conventional concrete in that there is a higher ratio of steel to
cement mortar.
• Ferro-cement has many of the properties of steel and yet it will not
rust. Although it looks and feels like concrete it can flex without
cracking.
Ferro cement

Properties of Ferro-cement
• Highly versatile form of reinforced concrete.
• It’s a type of thin reinforced concrete construction, in
which large amount of small diameter wire meshes
uniformly throughout the cross section.
• Mesh may be metal or suitable material.
• Instead of concrete Portland cement mortar is used.
• Strength depends on two factors quality of
sand/cement mortar mix and quantity of reinforcing
materials used.
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Constituent Materials for Ferro-cement
• Cement
• Fine Aggregate
• Water
• Admixture
• Mortar Mix
• Reinforcing mesh
• Skeletal Steel
• Coating
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Process of Ferro-cement Construction
• Fabricating the skeletal framing system.
• Applying rods and meshes.
• Plastering.
• Curing
Applications of Ferro-cements in Construction
• Housing
• Marine
• Agricultural
• Rural Energy
• Anticorrosive Membrane Treatment.
• Miscellaneous.
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TECHNIQUES OF MANUFACTURES
• Hand plastering
• Semi-mechanized process
• Centrifuging and Guniting
MATERIALS USED IN FERRO CEMENT
• Cement mortar mix
• Skeleton steel
• Steel mesh reinforcement or Fibre-reinforced
polymeric meshes
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CEMENT MORTAR MIX
• Ordinary Portland cement and fine aggregate matrix
is used
• The matrix constituantes 95% cement mortar & 5%
wire-mesh of the composite.
• FA (sand), occupies 60 to 75% of the volume of the
mortar
• Plasticizers and other admixtures are used
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MIX PROPORTIONS
• Sand: cement ratio (by mass) 1.5 to 2.5
• Water: cement ratio (by mass) 0.35 to 0.60
SAND
• Confirming to zone-I or Zone-II
• Free from impurities
WATER
• Free from salts and organic impurities
• Minimum to achieve desired workability
• pH equal or greater than 7
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SKELETON STEEL
• It support the steel wire mesh
• 3 to 8 mm steel rods are used
• Thickness varies from 6-20mm according to loading
condition
• Generally mild steel or Fe 415 or Fe 500 bars are
used
• Spacing 7.5cm to 12m
• Used to impart structural strength in case of boats,
barges etc.
• Reinforcement should be free from dust, rust and
other impurities.
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STEEL MESH
REINFORCEMENT
• Consists of galvanized
steel wires of diameter
0.5 to 1.5 mm, spaced
at 6 to 20mm centre to
centre
• Welded wire mesh has
hexagonal or
rectangular openings
• Expanded-metal lath is
also used Made from
carbon, glass etc.
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Advantages
• Basic raw materials are readily available in most countries.
• Fabricated into any desired shape.
• Low labour skill required.
• Ease of construction, low weight and long lifetime.
• Low construction material cost.
• Better resistance against earthquake.
Disadvantages
• Structures made of it can be punctured by collision with pointed objects.
• Corrosion of the reinforcing materials due to the incomplete coverage of
metal by mortar.
• It is difficult to fasten to Ferro-cement with bolts, screws, welding and nail
etc.
• Large no of labors required.
• Cost of semi-skilled and unskilled labors is high.
• Tying rods and mesh together is especially tedious and time consuming.
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