Advanced concrete technology

06CM6151
Advanced Concrete Technology
Faculty
Prof Lathi Karthi

Overview
Course Details
Course Objectives
Syllabus
Course Outcomes
References
Module 1. Concrete Materials/Constituents
Special cements
Testing of cement
Testing of aggregates
Requirements and quality of water for concreting

Syllabus
• Module 1
Concrete materials: Chemical Composition of OPC -- Hydration
process of Portland cement - Structure of hydrated cement paste -
Interfacial transition zone – Significance of interfacial transition zone
–special cements – Testing of cement and aggregates- requirements
and quality of water for concreting. (10 hours)

• Metha, P.K. and Monteiro, P.J.M,2006. Concrete, Microstructure, Properties
and Materials, Fourth Edition, Tata McGraw- Hill Publishing company Limited,
New Delhi.
• Neville, A.M. and Brooks, J.J., 2008. Concrete Technology, 2nd Edition, Pearson
Education India.
• Gambhir, M.L., , 2004. Concrete Technology, Third edition, Tata McGraw-Hill
Education.
• Santhakumar, A.R., 2006. Concrete Technology, First edition, Oxford University
Press India.
• Indian Standard Institution(2009). IS10262-2009, Concrete Mix Proportioning-
Guidelines BIS, New Delhi
References

Special Cements
Special cements are cements that serve some specific function.
• altering the setting or hardening behavior of a concrete
• producing different colors for architectural effects
• imparting superior workability
• imparting water retention and plasticity to mortars
• resisting the penetration of water in walls or containment
vessels
• simply reducing the cost of the cementing agent.
https://www.concreteconstruction.net/how-to/construction/special-cements-for-special-purposes accessed on 30-11-2020
Concrete Materials contd..

https://www.concreteconstruction.net/how-to/construction/special-cements-for-special-purposes accessed on 30-11-2020
Special Cements contd..
Blended hydraulic cements.
• Portland blast-furnace slag
• Portland-pozzolan
• slag
Cements with special setting and hardening
properties.
• Rapid-setting Portland, high alumina/calcium
aluminate/aluminous, magnesia-phosphate
Cements with special colors.
Water Repellent Cements.
Expansive Cements.

1. Acid resistant cement
2. Blast furnace cement
3. Coloured cement
4. Expanding cement
5. High Alumina cement
6. Hydrophobic cement
7. Low heat cement
8. Pozzolana cement
9. Portland Pozzolana Cement
10. Quick setting cement
11. Rapid hardening cement
12. Sulphate resisting cement
13. White cement.
14. Air entraining cement

Acid resistant cement
• Acid-resistance aggregates such as quartz, quartzites, etc.
• Additive such as sodium fluosilicate Na2SiF6
• accelerates the hardening process of soluble glass
• increases the resistance of cement to acid and water.
• Aqueous solution of sodium silicate or soluble glass.
• The binding material
• which is a water solution of sodium silicate, Na2O.nSiO2 or
potassium silicate, K2O.nSiO2( n is the glass modulus).
q used in acid-resistance and heat resistance coatings of installations
of chemical industry
q Not water resistant
q Addition of 0.5% of linseed oil or 2 % of ceresit makes it resistant to
the water it is then known as the acid and water resistant cement.

Blast furnace cement
• composed of the slag as obtained from blast furnace
• Slag is a waste product in the manufacturing process of
pig-iron
• contains the basic elements of cement, namely alumina,
lime and silica
• The clinkers of cement are ground with about 60 to 65 %
of slag
• strength in early days is less, hence it requires longer
curing period
• is durable, but not suitable for use in dry arid zones.
• economical as slag, which is a waste product, is used in its
manufacture

Coloured cement
• desired colour may be obtained by intimately mixing
mineral pigments with ordinary cement
• colouring material may vary from 5 to 10 % and beyond
10% the strength of cement is affected
• The chromium oxide gives green colour
• The cobalt imparts blue colour.
• The iron oxide in different proportions gives brown, red
or yellow colour.
• The manganese dioxide is used to produce black or brown
coloured cement.
• widely used for finishing of floors, external surfaces,
artificial marble, window sill slabs, textured panel faces,
stair treads, etc.

Expansive cement
• this cement expands whereas other cements shrink
• produced by adding an expanding medium like sulpho-
aluminate and a stabilising agent to the ordinary cement
• used for
• construction of water retaining structures
• repairing the damaged concrete surfaces

High Alumina cement
• produced by grinding clinkers formed by calcining bauxite and
lime
• total alumina content should not be less than 32 %
• the ratio by weight of alumina to lime should be between
0.85 to 1.30.
• can withstand high temperatures, hence can be used in
refractories, foundries and other workshops where high
temperatures are involved.
• evolves great heat when setting, hence can be used in colder
temperatures.
• Sets fast and attains high strength in short time (40-50MPa in
3days)
• Evolves high heat, hence not suitable for mass concreting.
• Cost is high

Hydrophobic cement
• considerably increases the water resistance of concrete
• contains admixtures which decreases the wetting ability of
cement grains which forms a thin film layer over the
cement grains
• usual hydrophobic admixtures are acidol, naphthalene
soap, oxidized petrolatum, etc
• when water is added to hydrophobic cement, the
absorption films are torn of the surface and they do not in
any way, prevent the normal setting of cement
• used in construction of dams, spillways, under water
constructions
• very expensive

Low heat cement
• contains lower percentage of tricalcium aluminate C3A of
about 5%
• contains higher percentage of dicalcium silicate C2S of
about 46%.
• possesses less compressive strength and high resistance
against ruptures
• initial setting time is about one hour and final setting time
is about 10 hours
• used for mass concrete work
• compressive strength is lower than that of ordinary
cement.
• Cannot be used in cold weather conditions because it will
retard the setting time less than that in ordinary weather

Pozzolana cement
• is a volcanic powder found in Italy near Vesuvius
• used to prepare mass concrete of lean mix and for marine
structures
• used in sewage works for laying concrete under water.
White cement
• is prepared from such raw materials which are practically
free from colouring oxides of iron, manganese or
chromium
• For burning of this cement, the oil fuel is used instead of
coal.
• white in colour and is used for floor finish, plaster work,
ornament work, etc..

Portland Pozzolana cement
• manufactured by using pozzolanic materials as one of the
main ingredient (10-30%).
• Some of the pozzolanic materials used are volcanic ash,
shales and certain type of clays.
• In India, fly ash is the main constituent used in the
preparation of cement
• gains compressive strength with age
• highly resistant to sulphates and resistant to expansion
• gives better workability during preparation of concrete.
• evolves low heat during setting and gains high tensile
strength
• cheap and affordable
• not resistant to erosion and weathering action

Quick setting cement
• produced by adding a small percentage of aluminium
sulphate and by finely grinding the cement which
accelerates the setting action of cement
• percentage of gypsum or retarder for setting action is also
greatly reduced.
• setting action of cement starts within five minutes after
addition of water and it becomes hard like stone in less
than 30 minutes
• used to lay concrete under static water or running water
• not widely available and expensive also

Rapid hardening Portland cement (RHPC)
• contains high percentage of tricalcium silicate C3S to the extent
of about 56%
• used in concrete to achieve a higher rate of early strength
development, one-day strength of this cement is equal to the
three-day strength of OPC with the same water-cement ratio
• used where formwork has to be removed as early as possible in
order to reuse it.
• used for constructing road pavements, where it is important to
open the road to traffic quickly
• used in industries which manufacture concrete products like
slabs, posts, electric poles, block fence, etc. because moulds
can be released quickly
• used for cold weather concreting because rapid evolution of
heat during hydration protects the concrete against freezing

Sulphate resisting cement
• the percentage of tricalcium aluminate C3A is kept below
5 percent resulting in the increase in resisting power
against sulphates
• used for structures which are likely to be damaged by
severe alkaline conditions such as canal linings, culverts,
siphons, etc.
• widely used in chemical industries and infoundations and
basements where soil contains sulphate .
• used for constructing road pavements, where it is
important to open the road to traffic quickly
• used in pile fabrication which are likely to be buried in
marshy region or sulphate bearing soils

Air entraining cement
• produced by adding indigenous air entraining agents such
as resins, glues, sodium salts of Sulphates etc. during the
grinding of clinker
• suited to improve the workability with smaller water
cement ratio and to improve frost resistance of concrete.
• The bubbles are so small that there may be millions of
them in a cubic foot of concrete. The air bubbles
provide space for freezing water to expand without
damaging the concrete.
• developed to produce concrete that is resistant to
freeze-thaw action, and to scaling caused by chemicals
applied for severe frost and ice removal.

Testing of Cement
• Colour
• Physical properties
• Presence of lumps
• Strength
Field Tests

Colour should be uniform
Typical cement colour (grey colour with light greenish shade)
It gives an indication of excess of lime or clay and the degree
of burning.
Field test : Colour
Testing of Cement contd..
https://www.youtube.com/watch?v=f_YnylDTpo4&feature=youtu.be
accessed on 30-11-2020
https://civildigital.com/field-tests-for-cement-check-the-quality-cement-at-site/ accessed on 30-11-2020

Field test : Physical properties
• Feel smooth when touched or rubbed in between fingers.
– If felt rough, indicates adulteration with sand.(adulteration test)
• If hand is inserted in cement bag, hand feels cool and not
warm indicating that there is no hydration reaction taking
place
• When thrown into water, it should float for sometime before
settling (float test)
• A paste of cement feel sticky
• If it contains clay & silt as adulterant, gives an earthy smell
https://civildigital.com/field-tests-for-cement-check-the-quality-cement-at-site/ accessed on 30-11-2020

Field test : Presence of lumps
• It should be free from hard lumps.
• Lumps indicates the absorption of moisture from atmosphere.
• If the bag of cement contains lumps it should be rejected.
Field test : Shape test
• make a stiff paste with 100g of cement .
• Prepare a cake with sharp edges and put on
the glass plate.
• Immerse this plate in water.
• The shape shouldn’t get disturbed while
settling and should be able to set and attain
strength.
• Cement is capable of setting under water
also and that is why it is called ‘Hydraulic
Cement’.. https://civildigital.com/field-tests-for-cement-check-the-quality-cement-at-site/ accessed on 30-11-2020

Field test : Strength
1. Briquettes with a lean or weak mortar are made (75mm x
25mm x 12mm).
– The proportion of cement & sand is 1:6.
– Immersed in water for 3 days.
If cement is good it will not be broken easily and difficult to
convert to powder form
Strength is tested by three methods:

Field test : Strength contd..
2. A block is prepared (25 x 25 x 200) and immersed in water
for 7 days.
– Then it is placed on supports 150 mm apart and loaded
340N.
– It should not show signs of failure.
3. Thick paste of cement with water is made on thick glass
and kept in water for 24 hours.
It should set and not crack

Laboratory Tests
Sampling
• When cement is loose:
– Sample is taken from at least 12 points from heap.
• When cement is in bags:
– At least from 12 different packages or bags.
Purpose of testing
• To determine physical & chemical properties
• To regulate the various stages in manufacturing
• Behavior of cement
• To ensure the suitability of cement as a construction material

Laboratory Tests : Standard Tests
• Chemical composition
• Fineness/Specific gravity
• Compressive strength
• Tensile strength
• Consistency
• Setting time
• Soundness

Laboratory Tests : Standard Tests contd..
Chemical Composition
• Ratio of alumina to iron oxide < 0.66
• Lime saturation factor (LSF):Ratio of lime to Al2O3, Fe2O3 & SiO2
0.66 > and < 1.22
CaO – 0.7 SO3
2.8 SiO2 + 1.2 Al2O3 + 0.65 Fe2O3
• Total loss on ignition should be < 4% by weight
• Total Sulphur content < 2.75%
• Weight of insoluble residue < 1.5% by weight
• % of free Magnesia < 5%

Fineness : IS:4031-P 1 -1996(2005) & IS:4031-P 2-1996 (2004))
• Sieve Test
• Air permeability Test
• Sieve test is conducted with the standard BIS sieve no. 9(90
Micron)
• 100g is taken and sieved for 15 min
• The residue should < 10%
• In Permeability apparatus test (Blaine Air permeability
apparatus), specific surface area is calculated
– It should not < 225 m2/kg
– It gives the idea of uniformity of fineness
Fineness affects the rate of hydration and rate of gaining strength.
Affects the heat of evolution also

Specific Gravity : IS:2720-PART 3
• Le Chatelier Flask method
• Specific gravity is normally used in mixture proportioning
calculations.
• specific gravity of portland cement is generally around 3.15
• specific gravity of portland-blast-furnace-slag and portland-
pozzolan cements may have specific gravities near 2.90
when specific gravity of cement is greater than 3.15
– cement is not minced finely as per the industry standard
– has more moisture content
– will affect the mix and bonding

Compressive strength : IS:4031-PART 6
• Mortar of cement & sand is prepared, 1:3.
• Water is added, water cement ratio 0.4
• It is placed in moulds & form cubes of sides 70.6 mm.
• The cement required is 185 or 235g
• Compacted in vibrating machine in 2 min.
• Moulds placed in damp cabin for 24 hrs
• Specimens are removed & placed in water for curing.
• It is tested in compressive testing machine after 3 and 7 days.
• Every side is calculated and average is taken
For 53 grade Cement as per IS12269-1987
For 3 days: > 270 kg/cm2 or 27 N/mm2
for 7 days: > 370 kg/cm2 or 37 N/mm2

Tensile strength
• Formerly used to have indirect indication for compressive strength
• At present used for rapid hardening test.
Procedure:
1. Mortar is prepared cement(1) : Sand (3)
2. Water is added 8%
3. Mortar is placed in briquette moulds.
4. Typical briquette is formed.
5. A small heap is formed at its top.
6. It is beaten down by a standard spatula till water appears on the
surface.
7. Same procedure is repeated for other sides of briquettes.
8. 12 standard briquettes are prepared
9. The quantity of cement may be 600g for 12 briquettes

Tensile strength contd..
10. It is kept in damp cabin for 24
hrs.
11. It is carefully removed from
mould and submerged in clean
water for curing.
12. It is tested in testing machine
after 3 and 7 days.
13. The load is applied at the rate
of 35 kg/cm2
14. The cross section of briquettes
at least section is 6.45 cm2
15. Ultimate tensile stress =
failing load/6.45
• After 3 days: > 2.0 N/mm2
• After 7 days: > 2.5 N/mm2

Consistency: IS:4031-PART 4
• The standard consistency of a cement paste
is defined as that consistency which will
permit the vicat plunger to penetrate to a
point 5 to 7mm from the bottom of the vicat
mould.
• It is used to determine the % of water
required for preparing cement pastes for
other tests
Procedure:
1. Take 300g cement, add 30% or 90g of water
2. Mix water and cement on a non-porous
surface. Mixing should be done.
3. Fill the mould of Vicat apparatus.
4. The interval between the addition of water
to the commencement of filling the moulds
is known as the time of gauging.

Setting Time: IS:4031-PART 5
• Initial setting time is that time period between the time water
is added to cement and time at which 1 mm square section
needle fails to penetrate the cement paste, placed in the Vicat’s
mould 5 mm to 7 mm from the bottom of the mould.
• Final setting time is that time period between the time water is
added to cement and the time at which 1 mm needle makes an
impression on the paste in the mould but 5 mm attachment
does not make any impression.

Soundness IS:4031-PART 3
• Soundness means the ability to resist
volume expansion or is the ability of a
hardened paste to retain its volume after
setting.
• In the soundness test a specimen of
hardened cement paste is boiled for a
fixed time so that any tendency to
expand is speeded up and can be
detected.
• A cement is said to be unsound (i.e.
having lack of soundness) if it is
subjected to delayed destructive
expansion.
• Unsoundness of cement is due to
presence of excessive amount of hard-
burned free lime or magnesia
Le Chatelier’s Apparatus

Testing of Aggregates
– Occupy 70-80% of the volume of concrete
– Contribute to weight and strength of concrete
– Normal, light and heavy weight aggregates
Range of Particle Size

Testing of Aggregates contd..
Aggregate
Fine
aggregate
Sand
(Natural and
Manufactured)
Crushed
stone
gravel
Lightweight
CA
12kN/m3
Crushed slag
Pumice
Sintered fly-
ash
Normal
weight CA
15kN/m3
Classification of Aggregates

• Gravel and crushed
stone
• ³ 4.75mm
• typically between
9.5mm and 37.5 mm
Coarse Aggregate
Classification of Aggregates contd..

Expanded
– Shale
– Clay
– Slate
– Slag
Lightweight Aggregate
Source: Pumice, crushed slag, sintered fly ash

Recycled-Concrete Aggregate

• Sand and/or crushed
stone
• < 4.75 mm
• F.A. content usually
35% to 45% by mass
or volume of total
aggregate
Fine Aggregate

Characteristics of Aggregates
(IS383)
1. Strength and
stiffness
2. Toughness
3. Hardness
4. Cleanliness
5. Shape and texture
6. Soundness
• Physical
• chemical
7. Gradation
8. Unit
weight/Specific
Gravity
9. Water absorption
and moisture
effects
Tests on Aggregate contd..

Tests on Aggregates
(IS2386)
1. Crushing strength : Strength and stiffness
2. Impact Test : Toughness
3. Abrasion Test : Hardness
4. Tests for deleterious constituents : Cleanliness
5. Tests for flakiness and elongation index : Shape and texture
6. Tests for alkali aggregate reaction : Soundness
7. Sieve analysis and fineness modulus : Gradation
8. Specific gravity test : Unit weight/Specific Gravity
9. Bulking : Water absorption and moisture effects

IS Codes (IS2386)
Coarse / Fine Aggregate
1 Specification for coarse & fine aggregate IS 383
2 Methods of test for aggregate for concrete particle size and shape IS 2386 (P I)
3 Methods of test for aggregate for concrete estimation of deleterious materials
and organic impurities. IS 2386 (Part II)
4 Methods of test for aggregate for specific gravity, density, voids, absorption &
bulking IS 2386 (Part III)
5 Methods of test for aggregate for Mechanical properties. IS 2386 (Part IV)
6 Methods of test for aggregate Soundness IS 2386 (Part V)
7 Methods of test for aggregate measuring mortar making properties of fine
aggregates. IS 2386 (Part VI)
8 Methods of test for aggregate for alkali aggregate reactivity IS 2386 (Part VII)
9 Methods of test for aggregate for petrographic examination IS 2386 (Part VIII)

Water Absorption

Shape and Texture
Surface
Texture
Angularity
Shape or Form

Fine Aggregate Grading

Moisture Conditions

Bulking of Sand

Alkali-Silica Reaction (ASR)
In most concrete
• aggregates are more or less chemically inert.
• some aggregates react with the alkali hydroxides in
concrete,
• causes expansion and cracking over a period of many
years.
• alkali-aggregate reaction has two forms:
• alkali-silica reaction (ASR)
• alkali-carbonate reaction (ACR)
SiO2 + 2NaOH + H2O Na2SiO32H2O
Silica Alkali Water Alkali-silica gel

• Visual Symptoms
– Network of cracks
– Closed or spalled joints
– Relative displacements

Popouts
Iron Particles in Aggregates

• Visual Symptoms (cont.)
– Fragments breaking out of
the surface (popouts)
n Mechanism
1. Alkali hydroxide + reactive
silica gel Þ reaction
product (alkali-silica gel)
2. Gel reaction product +
moisture Þ expansion

• Influencing Factors
– Reactive forms of silica in
the aggregate,
– High-alkali (pH) pore
solution
– Sufficient moisture
If one of these conditions is
absent ― ASR cannot
occur.

Requirements and quality of water for concreting

Requirements & quality of water contd..
Requirement of water
• To wet the surface of aggregates to develop adhesion because
the cement pastes adheres quickly and satisfactory to the wet
surface of the aggregates than to a dry surface.
• To prepare a plastic mixture of the various ingredients and to
impart workability to concrete to facilitate placing in the desired
position and
• Water is required for hydration of cement and for flow of
concrete in the forms or for pumping.
• Water is also needed for the hydration of the cementing
materials to set and harden during the period of curing.

Quality of water
n Tests required for quality check
• pH
• Acidity
• Alkalinity
• Percentage of solids
• Chlorides
• Sulphates
• Suspended solids
• Inorganic and Organic Solids

Quality Parameters Maximum Limit (ppm)
SO3 1000
Alkali Carbonates
and Bicarbonates
1000
Turbidity 2000
Quality of water contd..
Should have potable quality
• Water shall be clean
• Should not contain
• Sugar, molasses or its derivatives
• Sewage oil or organic substances

Quality of water contd..

• Each source shall be tested
• At the beginning of the work
• Once in three months till the completion
• Once in 6 months for municipal water
• Three tests shall be done for each source
• For ground water, testing shall be done for different points
of draw down
• Water from each source shall be tested before monsoon and
after monsoon
Frequency of testing water

Explain the following in detail aggregate crushing value and Bulking of
aggregates.
Write a note on the Quality of water for concrete preparation
Recommend the tests and explain its procedure for evaluating the toughness
and hardness of coarse aggregate. How these qualities are relevant for
concrete?
Describe the test done to determine aggregate abrasion value
Discuss the various laboratory tests on cement? Explain?
Differentiate between high alumina cement and ordinary portland cement?
Write brief notes on the characteristics and uses of following cements
Acid resistant cement
Blast furnace cement
Coloured cement
Expanding cement
Revision

Advanced concrete technology

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