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Courtesyof Patrick Rimoux(architecte)
Production of extended cements
& the impact on concrete
durability
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AGENDA
1. Introduction
2. About Lafarge
3. The Lafarge Specifier Handbook
4. Cement manufacturing & extenders
5. Soil Stabilization
6. Physical deformations on concrete
7. Chemical deformations on concrete
8. Masonry, Mortars & Plasters
9. Ready-mixed Concrete Products
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ABOUT LAFARGE
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Lafarge is the world leader in building materials
Number 1 in Cement
Number 2 Aggregates and Concrete
Number 3 in Gypsum
15,2 billion Euros in Sales turnover
68 000 employees
Present in 64 countries
Almost 130 million Euros dedicated to research,
product development and industrial process performance
improvement annually. With about 500 dedicated people world wide.
LAFARGE INTERNATIONAL
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LAFARGE IN SOUTH AFRICA
Safety is our number 1 priority
Lafarge South Africa has 2500 employees
All four divisions present in South Africa
Cement
Aggregates Concrete
Gypsum
First in the industry to sign a BBBEE deal in South Africa valued at1.1 billion Rand
Internationally recognized HIV/Aids campaign in place
First cement producer to become a member of the Green BuildingCouncil
5
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LAFARGE CEMENT FACILITIES(SOUTH AFRICA)
Manufacturing facility in Lichtenburg
Biggest in the Southern Africa
Capacity of 3,3 million tons cement
Grinding facility in Richards Bay and Randfontein
Strategic depots in Kaalfontein
Polokwane
Quality Department of Southern Africa
One of the largest and most respected SANAS
accredited Civil Engineering testing facilities in
South Africa
Complies with ISO/IEC 17025
17 year track record of continuous accreditation
Boasting 35 accredited test methods
6
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THE LAFARGE SPECIFIER HANDBOOK
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ABOUT THE MANUAL
The Lafarge Specifier Handbook has been designed to provide our
specifiers & engineers with application specific quick reference cement &readymix guide
In Volume 1 we cover the needs and solutions for each application,
including:
1. Roads & Earthworks2. Civil Construction
3. Concrete Product Manufacturing
4. Masonry Applications
5. Specialised Applications
6. Readymix Concrete
We have also included the SANS 50197-1: Common Cement Table & a
number of case studies for your reference
Dr Reinhold Am tsbchler,
Pr Engineer and Manager
Quali ty Department Southern A fr ica
Lafarge South Afr ica
While maintaining our proud track record of technical excellence, our skills are directly
and indirectly employed to satisfy todays cement market needs and to anticipate the
future needs of our customers.
This handbook is intended to provide a convenient guide for engineers and specifierswhen selecting quality, reliable performance cements for specific applications.
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CEMENT MANUFACTURING
Quintin Wolmarans
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WHAT IS CEMENT?
Portland cement is an extremely fine grey powder manufactured
from some of the earth's most common minerals. It's the glue that
binds sand and gravel together into the rock-like mass we know as
concrete.
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Quarrying
And
Crushing
Preblending
Storage
Raw Milling &
Homogenisation
Burning Cement Milling
Packing &
Despatch
CEMENT MANUFACTURING
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CEMENT CONSTITUENTS
The following materials are milled & blended before entering the kiln:
Limestone -CaCO3
Alumina source -Al2O3 (PozzSand, Bauxite, etc)
Iron oreFe2O3 (Magnetite)
Silica sourceSiO2 (PozzSand)
These materials are heated to temperatures of1450C to produce a
partially molten combination called clinker.
Clinker is then inter-ground with Gypsum to create cement powder.
Other Constituents may be added at the mill (Limestone, Fly Ash, Slag,
etc)
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Quarry Crusher Limestone
Additives
Pozzsand
Bauxite
Magnetite
Raw Mill
Kiln feed Silo
To Raw mix
preperation
Mining of limestone requires the use of drilling and blasting techniques.
The blasting techniques use the latest technology to insure vibration, dust,
and noise emissions are kept at a minimum. Blasting produces materials in a
wide range of sizes from approximately 1.5 meters in diameter to smallparticles less than a few millimeters in diameter.
Material is loaded at the blasting face into trucks for transportation to the
crushing plant. Through a series of crushers and screens, the limestone is
reduced to a size less than 100 mm and stored until required.
Limestone is mined from different faces in the quarry to produce a blendof limestone that complies to chemical requirements set by the plant to
produce quality clinker
The limestone is then transported to site where it is blended and stored
on a stockpile until needed for raw milling
LIMESTONE QUARRY
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Quarry Crusher Limestone
Additives
Pozzsand
Bauxite
Magnetite
Raw Mill
Kiln feed Silo
To pre-heater
Limestone is proportioned with other
corrective materials and then grinded in the
raw mill to a fine powder called kiln feed.
Limestone on its own do not contain all the
elements needed to form good quality clinker.
Limestone provide for CaCO3 the main
component for clinker formation.
Pozzsand and Bauxite is added to introduce
SiO2 & Al2O3 and
Magnetite is added to introduce Fe2O3
When proportioned correctly they will combine in the kiln
to form the following main components in clinker:
C3S (Alite) 3CaO.SiO2 Tricalcium Silicate
C2S (Belite) 2CaO.SiO2 Dicalcium Silicate
C3A 3CaO.Al2O3 Tricalcium Aluminate
C4AF 4CaO.Al2O3.Fe2O3 Tetracalcium Alumino Ferrite
(Give cement is grey colour)
RAW MILLING
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Stack
Filter
Cooler
CLINKER
FuelPreparation
Preheat TowerKiln
To Cement mill about 100C-600C:
free water evaporation
800-1050C:
CaCO3 CaO + CO2
> 800C- iron oxide combines with alumina & lime to form C4AF
- then, the remaining alumina will react with lime to form C3A
- silica and lime start to form C2S
> 1200C
- formation of C3S (C2S reacts with remaining lime)
> 1338C:
C4AF and C3A generate the liquid phase
accelerates solid/solid chemical reactions(silica/ lime)
contributes to burnability
Quenching to set clinker reactions:
prevent C3S reversion to C2S
g + C
Kiln feed
CLINKER FORMATION
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Gypsum
Finish Mill Cement Silos
AdditionsLimestone, slag etc
Fly ashClinker from clinker
storage
Cement Milling
Clinker is grinded in the cement mill to a fine powder to increase the surface area
available for reaction with water. C3S + H2O = HCS +CaOH
This process is called hydration.
The finer the cement is milled the higher the strength of the cement will be.
During the hydration process C3A will also react with water and cause the cement toset immediately. This is called Flash set.
To prevent this from happening Gypsum (CaSO4.2H2O) is added to the cement to
form a layer around the C3A crystals to slow down the reaction with water.
To create cement with different properties for different applications than normal
cement, Fly ash or slag or both can be added to the cement.
Each of these additives or extenders will give the cement enhanced properties that willmake it suitable for a wide range of applications
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THE 5 COMMON TYPES OF CEMENT
SANS 50197
CEM I Portland Cement
CEM II Portland Composite Cement
CEM III Blast furnace Cement
CEM IV Pozzolanic Cement
CEM V Composite Cement
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CEMENT NAMING(SANS 50196 TABLE)
Strength Class Compressive Strength , MPa
Early Strength Standard Strength
2 days 7 days 28 days
32,5 N - > 16,0 > 32,5 < 52,5
32,5 R > 10,0 -
42,5N > 10,0 - > 42,5 < 62,5
42,5R > 20,0 -
52,5 N > 20,0 - 52,5 -
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CEM II / B - M (V-S) 32.5N
Cement family:
CEM I : Portland cement
CEM II : composite Portland cement
CEM III : blast furnace cementCEM IV : pozzolanic cement
CEM V : slag and ash cement
* See French standard for cement NF EN 197-1
CEMENT NAMING(EXAMPLE)
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CEM II / B - M (V-S) 32.5N
Cement family
CEM I : Portland cement
CEM II : composite Portland cement
CEM III : blast furnace cementCEM IV : pozzolanic cement
CEM V : slag and ash cement
Quantity of main constituents
other than
clinker (as a % added)
A: from 6 to 20%
B: from 21 to 35 %
C: from 36 to 65 %
(slag for EM III)
* See French standard for cement NF EN 197-1
CEMENT NAMING(EXAMPLE)
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CEM II / B - M (V-S) 32,5N
Cement family
CEM I : Portland cement
CEM II : composite Portland cement
CEM III : blast furnace cementCEM IV : puzzolanic cement
CEM V : slag and ash cement
Quantity of main constituents
other than
clinker (as a % added)
A: from 6 to 20%
B: from 21 to 35 %
C: from 36 to 65 %
(slag for EM III)
Cement with at least
2 main constituents
other than clinker
* See French standard for cement NF EN 197-1
CEMENT NAMING(EXAMPLE)
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CEM II / B - M (V-S) 32.5N
Cement family
CEM I: Portland cement
CEM II: composite Portland cement
CEM III: blast furnace cementCEM IV: puzzolanic cement
CEM V: slag and ash cement
Quantity of main constituents
other than
clinker (as a % added)
A: from 6 to 20%
B: from 21 to 35 %
C: from 36 to 65 %
(slag for EM III)
Cement with at least
2 main constituents
other than clinker
Names of the main constituents
S: Aggregated slag from blast furnaces
V: silicious fly ash
W: calcic fly ash
L or LL: limestone (depending on the percentageof organic carbon)
D: silica fume
P or Q: pozzolanic materials
T: Pre-fired shale
* See French standard for cement NF EN 197-1
CEMENT NAMING(EXAMPLE)
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CEM II / B - M (V-S) 32.5N
Cement family
CEM I: Portland cement
CEM II: composite Portland cement
CEM III: blast furnace cementCEM IV: puzzolanic cement
CEM V: slag and ash cement
Quantity of main constituents
other than
clinker (as a % added)
A: from 6 to 20%
B: from 21 to 35 %C: from 36 to 65 %
(slag for EM III)
Cement with at least
2 main constituents
other than clinker
Names of the main constituents
S: aggregated slag from blast furnaces
V: silicious fly ash
W: calcic fly ash
L or LL: limestone (depending on the percentageof organic carbon)
D: silica fume
P or Q: puzzolanic materials
T: Pre-fired shale
strength classes (minimum characteristic strength at
28 days, expressed in MPa):
32.5 or 42.5 or 52.5
* See French standard for cement NF EN 197-1
CEMENT NAMING(EXAMPLE)
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CEM II / B - M (V-S) 32,5N
Cement family
CEM I: Portland cement
CEM II: composite Portland cement
CEM III: blast furnace cementCEM IV: puzzolanic cement
CEM V: slag and ash cement
Quantity of main constituents
other than
clinker (as a % added)
A: from 6 to 20%
B: from 21 to 35 %C: from 36 to 65 %
(slag for EM III)
Cement with at least
2 main constituents
other than clinker
Names of the main constituents
S: aggregated slag from blast furnaces
V: silicious fly ash
W: calcic fly ash
L or LL: limestone (depending on the percentageof organic carbon)
D: silica fume
P or Q: puzzolanic materials
T: Pre-fired shale
strength classes (minimum characteristic strength at
28 days, expressed in MPa):
32.5 or 42.5 or 52.5
strength sub-classes (minimum characteristic strength
after 2 days, expressed in MPa).
N: Normal
R: Quick
* See French standard for cement NF EN 197-1
CEMENT NAMING(EXAMPLE)
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CEMENT EXTENDERS
Fresh Concrete
Improves workability and reduces water
requirement for a given slump.
Slightly retards setting.
Hardened Concrete
Slightly reduces rate of strength development.
Increase later strength (eg.90 days).
Reduce rate of chloride diffusion through concrete. Refine pore structure and reduce permeability.
Inhibits ASR reaction.
Improves sulphate resistance.
Reduce rate of heat generation from cementing reactions.
Fly ash / Pulverized fuel ash (PFA)
Spherical particles
0.5-300 m
(D 50
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Fresh Concrete
May improve workability slightly.
Retards setting slightly.
Hardened Concrete
Slows development of strength.
Increase later strength, (e.g.. 90 days)
Refines pore structure and reduce permeability.
Increase rate of carbonation.
Retards alkali-silica reactions.
Binds chlorides and reduce chloride induced corrosion of embedded steel.
Reduce rate of heat generation caused by cementing reactions.
Ground granulated blast furnace slag (GGBS)
Blast-
furnace
slag
floating
Cast-
iron
co
ke
Iron
oreMelting agent
=1450C
CEMENT EXTENDERS
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CEMENT EXTENDERS
Fresh Concrete
Reduces workability.
Increases cohesiveness.
Reduces bleeding significantly.
Hardened Concrete
Increased strength.
Reduces permeability.
Condensed Silica fume (CSF)
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LAFARGE PRODUCT RANGE
2
CEM IV/B-V 32,5R CEM II/A -M (V-L )42,5R CEM II/B-M (V-S) 32,5NCEM II/A-V 52,5N
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SOIL STABILISATION
Mike Fisher
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ROAD CONSTRUCTION
Road construction will continue to be one of the mainstay sectors of the
civil construction market.
The market currently comprises of:
15% - 20% new road building activity
The balance falls into road rehabilitation
SANRAL estimates backlogs in maintenance & rehabilitation on provincial
and municipal roads at R64 billion
31% of total provincial surfaced road network is in a poor and very poor
condition compared to 10% benchmark of the World Bank
Average of only 25km per year was rehabilitated since the year 2000
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SOIL STABILISATION
Stabilization products are designed to reduce the plasticity index (P.I.)
of a wide range of paving materials.
Enhance the strength of various road construction materials.
Composite cements modify moderate soils similar to lime
SOIL STABILISATION PERFORMANCE CHARACTERISTICS
Strength: soil strength and bearing capacity is increased.
Volume stability: controls the swell and shrinkage characteristic caused
by moisture changes
Durability: increases resistance to erosion, weathering or traffic loading
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SOIL STABILIZATION - PRODUCTS
CEM II/ B-M (V-S) 32,5N
Slower strength gain
cementitious binder
Higher ultimate strength
Longer open time
CEM IV/ B-V 32,5R
Slower early rate of strength but
with higher ultimate strengths
Longer open time
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CEMENT USAGE IN ROAD STABILISATION
Based on an analysis of major road projects, cement usage in road
stabilisation is about 1 3% of project value. Examples of consumption
estimates by a large contractor and SANRAL are given below.
Estimated Cement Consumption (Sanral Projects)
Source:Sanral
0
2
4
6
8
10
12
2008/09 2009/10 2010/11 2011/12 2012/13
TotalProjectValue(RBillion)
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
CementConsumption(Tons)
1.5 1.8% of Project Value
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THE STOLTZ SOLUTION
Lafarge offers contractors a unique spreading solution for roadbindercements & alternative stabilising materials with its state-of-the-art Stoltz
Site Spreader.
The first of its type in Africa, the spreader achieves impressive and rapid
application rates.
Radar controlled automated application provides more accurate, even
spreading, resulting in savings in material and time
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BENEFITS
Control your own spreading schedule
Flexible working time
Consistent spreading, reducing risk of failure
Increased productivity based on speed of application
Reduced contingency margins based on efficient spreading rate
Competitive qualitative advantage for pricing tenders
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MOVE FROM THIS....
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...TO THIS
Consistent spread
Dust reclaimer
Reduce labour cost
Silo configuration
34t Capacity
Independent Engine
Digital Rate Controller
with radar
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LABORATORY WORK
Laboratory work based on the Polokwane ring road material.
Material was used to conduct full stabilization evaluations
using Roadcem
Atterburg Limits Stabiliser Type % LL PL PI 1 day
Before Stabilisation Neat 0% 26 20.4 5.6
After Stabilisation Roadcem 2%
4%
6%
24.7
34.1
30.6
24.5
29.3
30.9
0.2
NP
NP
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LABORATORY COMPACTION DATA
EFFORT UCS (Mpa) Average ITS (KPa) Result
2% 10090
3.62.1
320.0254.0
4% 100
90
6.5
4.2
896.0
672.06% 100
90
8.3
7.1
706.0
635.0
LABORATORY WORK
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LAFARGE ROAD PROJECTS:CURRENT AND COMPLETED
4
Client Contractor Project Product Engineers Province
SANRAL Esor Franki N4 Mooinooi Roadcem UWP NWP
TRAC WBHO N4 Middleburg Roadcem Vela VKE
(SMEC)
MPU
SANRAL Steffanutti
Stocks
N12 east
Driefontein
Roadcem Vela VKE
(SMEC)
NWP
SANRAL Roadcrete
Africa
N2 Piet Retief Roadcem Vela VKE
(SMEC)
MPU
SANRAL Roadcrete
Africa
Amersfoort Roadcem Bigen Africa MPU
SANRAL KPMM N14
Carltonville
Roadcem Aurecon NWP
SANRAL Superway R37 Lydenberg Roadcem Goba MPU
SANRAL Concor Simon
Vermooten
Roadcem SSI PTA
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PHYSICAL DEFORMATION OF CONCRETE
Dirk Odendaal
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CONCRETE
Deformation of concrete
Elasticity
Creep
Shrinkage
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PROPERTIES OF CONCRETE
FOR THE DESIGNER
Designers of structures are concerned with:
Safety, Serviceability and Durability
Safety:
Time dependant strains, may not change the load barring capacity of a
member, at failure.
When stability is an issue, creep could play a role in failure load.
This would lead to reduced safety of the structure.
Serviceability:
Deflections and cracking plays the biggest part in serviceability.
This has impact on both short and long term deflections.
Durability:
This has the biggest impact on Economy of the structure
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DEFORMATION OF CONCRETE
Influences on deformation:
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Factors affecting E-Modules
Factors affecting E-modules are strength of the cement paste.
Stiffness of the aggregate.
Aggregate cement paste interface.
The stiffer the individual phases the higher the E-moduli will be, and the
lower the long term movement of the concrete.
Typically the E-moduli will vary from 5 to 25 Gpa dependant on
w/c ratio
Degree of hydration
Air content
ELASTICITY OF CONCRETE
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Structural implications
Importance of E-modules depends on the sensitivity of the structure to
deformations.
Where deflections are critical or secondary cracking is unacceptable E-
Modules predictions becomes important.
In some cases lower E-Modules may be required, where cracking due to
restraint movement are to be avoided.
E-Modules in high strength concrete are dependant on the coarse
aggregate rather than on the compressive strength.
ELASTICITY OF CONCRETE
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ELASTICITY OF CONCRETE
Powercrete Plus 42,5R and Civilcrete 32,5R, are extended with Fly Ash.
The Pozzolanic reaction produces additional Calcium Silicate hydrate
gel, to fill pore spaces leading to a denser matrix, and reducing
permeability of the concrete
Fly ash incorporation leads to increased paste volume, improving the
Aggregate / Cement paste interface.
Lower water demand for given workability, compared to CEM I cements.
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CREEP OF CONCRETE
What is Creep
Defined as the time dependant increase in strain of a solid body under
constant / controlled stress.
Could also manifest as a relaxation stress under constant strain.
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CREEP OF CONCRETE
What is the implications of creep
Creep impacts on the Ductility of the structure.
Could be beneficial
Relieve stress caused by differential structural movements Restraint shrinkage
Mostly detrimental to structures due to
Increased deflections, resulting in cracking
Loss of pre-stress Buckling of columns
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CREEP OF CONCRETE
Creep of concrete is the increased strain under sustained constant
stress.
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CREEP UNDER CONSTANT STRESS
An applied compressive stress ofapprox 40% of compressive
strength, creep would be considered
to be linear proportional to stress
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CREEP UNDER CONSTANT STRESS
Characteristics of creep
Creep occurs at all stress levels, but mechanisms are different at higher
stress levels, above 40% of short term strength.
Concrete is heterogeneous in nature, leading to substantial stress
concentrations in the matrix.
Micro cracks will form in the matrix between aggregate and cement paste.
These micro-cracks will grow with sustained / increased external loading.
This leads to the additional component of creep at high stress levels
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BASIC CREEP VS DRYING CREEP
Creep is simply considered to be
the deformation under load, in
excess of elastic strain and free of
shrinkage strain.
Basic Creep:
Creep that occurs when there is no
moisture movement between
concrete and the environment it is
in.
Drying Creep:
Additional creep that occurs when
concrete is drying while under
stress.
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BASIC CREEP VS DRYING CREEP
Structural effects of creep
Creep will cause redistribution of stresses in concrete, this could lead to
deflections.
Columns could undergo redistribution of stresses, stresses on steel is
increased and may even become very large leading to buckling of thecolumns.
This is where sufficient number of ties and adequate cover to steel plays a
role in creep.
Creep deflections may also lead to instability of arched structures.
Creep at stress levels above 70% of short term compressive strength, the
micro cracks formed at the aggregate cement interface may spread and
propagate to cause complete breakdown.
This would lead to time dependant failure.
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BASIC CREEP VS DRYING CREEP
Creep mechanisms
Recoverable creep
Diffusion of water from areas of hindrance to areas of non hindrance,
reduce the swelling pressure on the pore water, leading to a reduction of
inter partial spacing.
Diffusion of water from high to low pressure areas cause gradual load
transfer from liquid to solid phases in the matrix.
The removal of inter layer to inter layer water, under the action of external
load, leading to reduction of layer thickness.
Irrecoverable creep
Weakening of the interlayer particle bonds, facilitating a relative sliding of
the layers.
Displacement of the gel layers relative to each other (breaking down the
particle bonds).
Formation of new bonds
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THE EFFECTS OF
WATER / BINDER RATIO ON CREEP
Creep, is inversely
proportional to the
strength of concrete at
age of loading
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FACTORS EFFECTING CREEP
The source of creep in concrete is the cement paste.
Aggregate, plays a restraint role in creep.
Water / Binder ratio.
Relative humidity.
Temperature.
Age
Stress.
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CREEP IN CONCRETE
Powercrete Plus 42,5R and Civilcrete 32,5R, are extended with Fly Ash.
The Pozzolanic reaction produces additional Calcium Silicate hydrate
gel, to fill pore spaces leading to a denser matrix.
The R types cements, achieves higher early strength compared to N
types and would therefore allow earlier loading.
Fly Ash also contributes to the cement hydration making the concrete
denser and increasing the late strength ( post 28 day strengthdevelopment)
Lower water demand for given workability, compared to CEM I cements.
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SHRINKAGE
Concrete experience volume changes in both fresh and hardenedstates.
This concerns volume changes due to moisture movement in and out of
concrete during its lifespan.
Conventional concrete generally contain more water than required forthe chemical reaction of cement to take place.
This lead to the consequence that in normal drying conditions moisture
will be lost from the concrete into the environment leading to Shrinkage.
Shrinkage and creep are closely related in that they both are moisture
dependant deformations, and the source of the moisture loss generally
is from the cement paste
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SHRINKAGE
Shrinkage is caused by loss of water by evaporation, hydration ofcement and carbonation.
The loss of water, lead to reduction in volume of the member i.e.
volumetric strain is equal to three times linear contraction.
In practice we express shrinkage as linear strain.
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SHRINKAGE
Shrinkage in concrete is due to the cement paste.
Aggregate plays a role in modifying ways.
1. Dilution
2. Restraint
Shrinkage can be grouped in four different components.
1) Drying Shrinkage
2) Early Age Shrinkage
3) Autogenous shrinkage
4) Carbonation Shrinkage
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EARLY AGE SHRINKAGE
Capillary or Plastic Shrinkage is caused in fresh concrete due to surfacemoisture loss.
Plastic shrinkage is often accompanied by surface cracks.
Plastic shrinkage is the process of moisture loss to the environment by
evaporation.
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DRYING SHRINKAGE
Changes in moisture content in
the cement paste, leads to
volumetric changes.
The decrease in volume due tomoisture loss, is called drying
shrinkage.
The increase in volume on
rewetting, is called swelling.
Shrinkage consist of reversible
and irreversible components
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MECHANISMS OF DRYING SHRINKAGE
Capillary tension
This occurs in the capillary pores, the
loss of moisture causes tensile
stresses in the capillary water.
Swelling pressure
Where gel particles closely approacheach other, absorbed water could
exert swelling presure, if the free film
thickness is greater than the interlayer
distance.
Surface tension
Compressive stresses occurs inside
solid particles due to surface tension.
Drying increase surface tension, with
a increase in compressive stress in
the solids
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FACTORS INFLUENCING DRYING SHRINKAGE
The cement paste is the source of shrinkage, the porosity of concretewill determine the rate of water transport and diffusion.
Irreversible shrinkage is normally linear to the strength of concrete and
therefore a lower water / cement ratio would lead to increase in strength
and increase in hydration.
Paste hold water, the gel pore water is more tightly held than the
capillary water.
During evaporation moisture initially lost from the capillaries, and as theconcrete matures moisture is lost from the gel pores, causing larger
sections of contraction.
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FACTORS INFLUENCING DRYING SHRINKAGE
Paste structure
Hardened cement paste consist of solid & soft gel particles, as well as
two types of pore structures.
Very small gel pores formed by spaces between gel layers.
Larger capillary pores formed by excess water, not required for
hydration of cement
Lower water cement ratio and greater degree of hydration, will
lead to more hydration product being produced. Increasing the
ratio gel pore to capillary pore.
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CARBONATION SHRINKAGE
Carbonation shrinkage is caused
by the reaction between carbon
dioxide from the atmosphere,and the constituents in the
cement paste.
Shrinkage caused by
carbonation is slow, but could in
some severe cases exceeddrying shrinkage in magnitude.
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AUTOGENOUS SHRINKAGE
Autogenous shrinkage is volume reduction as result of internal waterconsumption during hydration.
Concrete with Water / Cement ratio of 0.40 and below, has a much
higher consumption of mix water, leading to higher risk of Autogenous
shrinkage.
Approximately 40% of Autogenous shrinkage occurs within the first 24h,
resulting in early age cracking.
The incorporation of Pfa has been proven to lower Autogenousshrinkage compared to CEM I cement types (Pane & Hansen)
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SHRINKAGE IN CONCRETE
Factors affecting shrinkage
Cement effects
There is evidence that high Alkali cement has greater risk of shrinkage
cracking, Lafarge Lichtenburg Clinker has a very low Alkali cement.
A sodium content of 0,25% compared to 0.6% as recommended by the
ASTM specification.
Aggregates
Aggregates has two effects on shrinkage.
Dilution : shrinkage will decrease with increase in aggregate Restrain : shrinkage will be reduced by increase in aggregate due
to increase in stiffness.
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SHRINKAGE IN CONCRETE
Powercrete Plus 42,5R and Civilcrete 32,5R, are extended with Fly Ash.
The Pozzolanic reaction produces additional Calcium Silicate hydrate
gel, to fill pore spaces leading to a denser matrix, and reducing
permeability of the concrete.
Fly Ash also contributes to the cement hydration making the concrete
denser and increasing the late strength ( post 28 day strengthdevelopment)
Lower water demand for given workability, compared to CEM I cements,
leading to lower moisture movement.
The good early strength achieved when using the R cement types,
gives better resistance to early age cracking.
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RELATIVE SHRINKAGE POTENTIAL
Lower water demand for given workability of Powercrete Plus
42,5R and Civilcrete 32,5R, compared to CEM I cements, could
potentially reduce shrinkage by up to 75%.
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CHEMICAL DEFORMATION OF CONCRETE
Dirk Odendaal
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CONCRETE
Alkali Silica Reaction
Heat of Hydration
Sulphate Attacks
Chloride Attacks
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ALKALI SILICA REACTION
What is ASR?
Reaction between Active Silica constituents of aggregate and the Alkalis
in the cement paste and water.
Reactive forms of silica are Opal (amorphous), Chalcedony (Crypto
Crystalline), Tridymite (crystalline).
Reactive minerals are present in Opaline and Chalcedonic Cherts,
Siliceous lime tones, Rhyolitic tuffs, Dacite tuffs, andersite tuffs and
phyllites.
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ALKALI SILICA REACTION
S C C O
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ALKALI SILICA REACTION
How does the reaction take place.
The reaction starts by attacks on siliceous mineral available in theaggregate, by the alkaline hydroxides from the cement paste.
As a result Alkali Silicate gel is formed, either in the pores in the aggregate,
or on the surface of the aggregate.
This destroy the bond between aggregate and the surrounding hydrated
cement paste.
The gel (of swelling nature) consumes water, increasing in volume.
Because this gel is confined by the surrounding hydrated cement paste,
internal pressures are created.
This internal pressures will eventually lead to expansion, cracking and
disruption of the cement paste.
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ALKALI SILICA REACTION
Typical appearance:
Random crack pattern.
White rim around the aggregate.
Large crack width.
Time:
May take years to develop. Structural Effects:
Loss of strength
Loss of stiffness
Cracking
Deflection
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ALKALI SILICA REACTION
Lichtenburg clinker has a low Alkali content, making Powercrete Plus42,5R and Civilcrete 32,5R low Alkali cements
Sodium equivalent of about 0,25%, well below the 0,6% for a Low Alkali
cement (ASTM definition).
By using a low Alkali cement type, will minimize the risk of ASR
Fly Ash in Civilcrete 32,5R and Powercrete Plus 42,5R, has the ability to
react with Alkali Hydroxides in the paste, making them unavailable to
react with aggregates.
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HEAT OF HYDRATION
Hydration of cement compounds is an exothermic process, with Energy
of up to 500J/g can be achieved.
On the other hand, concrete has a very low thermal conductivity, and
acts as an insulator.
In mass concrete however, the heat created by hydration could lead to
significant rise in internal temp, compared to normal structures.
Rule of thumb is that the gradient between core of the concrete and the
exterior surface should not be more than 20c.
It is therefore advisable to know the heat generating properties of the
cement to be used in this type of concrete.
For practicality, it is not necessarily only the total heat of hydration thatmatters, but also the rate of heat development and the peak temperature
achieved that need to be considered.
Heat generated over longer periods, and with lower peaks can dissipate
to a greater degree.
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HEAT OF HYDRATION
The fineness of the cement also has an impact on rate of heat
development, as the increased surface area will speed up the reaction.
Early age heat development from Hydration of cement/cementitious.
Long term caused by environmental conditions.
Effects are similar to those of drying shrinkage.
Random crack patterns.
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HEAT OF HYDRATION
Reducing temp:
Use a cement with an energy generation of less than 270 J/g of cement at
41, as per EN 197-1, EN 196-9.
Powercrete Plus 42.5R = 227 J/g* at 41hours
Civilcrete 32.5R = 166 J/g* at 41 hours
Typical Heat of Hydration of Concrete
20
30
40
50
60
70
80
010 20 30 40 50 60
Time (days)
Temp.
(oC)
OPC
OPC/30FA
OPC/40FA
+ 64 hours
+ 48 hours
- 12.6 oC
- 7.1 oC
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SULFATE ATTACKS
What is sulfate attack?
Sulfates are regular constituents in ground water, industrial waste water
and sewage water.
Different types of sulfate attacks
Calcium sulfate attack (CaSO4)
Magnesium Sulfate attack (Mg(OH)2
Ammonium sulfate attack (2NH3)
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SULFATE ATTACKS
Sulfates are common in areas where mines are operating.
These are generally calcium, sodium, potassium, and magnesium.
Sulfates, permeates the concrete (in solution with water), and reacts
with:
Portlandite in the cement paste CA(OH)2
Calcium Aluminates C3A
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SULFATE ATTACKS
Calcium Sulfate
When hardened cement paste is in contact with sulfates two principalreactions takes place
Conversion of monosulfate into ettringite
Formation of gypsum
After the Ca(OH)2 has been consumed the sulfate solution will react with
C-S-H paste, yielding more gypsum.
This reduces the C-S ratio in the C-S-H paste reducing mechanical
strength.
Un-reacted C3A will also react with the sulfate yielding ettringite.
Ettringite is very expansive, leading to spalling of the surface, while at the
same time reducing mechanical strength by decomposition of the C-S-H
for the production of ettringite.
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SULFATE ATTACKS
Magnesium Sulfate
Ca(OH)2 is converted into Brucite (magnesium Hydroxide).
C-S-H paste undergoes a decalcification, reducing C-S ratio in the C-S-H
paste.
The low lime C-S-H converts to near amorphous serpentine crystals,
exhibiting no cementing properties, forming additional Gypsum.
The degration of C-S-H in the presence of Mg(SO4) is faster and more
complete than other sulfate attacks.
Eventually a double surface layer is formed, consisting of a layer of Brucite
followed by a layer of gypsum.
Magnesium sulfate attack is characterized by loss of strength and total
disintegration of the concrete under attack
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SULFATE ATTACKS
Ammonium sulfate attack
When hardened concrete is exposed to solution of ammonium sulfate, the
compound will decompose the highly alkaline environment of the
concrete.
Releasing gaseous ammonia.
The Ca(SO4) formed reacts with other constituent within the concrete,
producing Ettringite and causing expansion.
The overall action of ammonium sulfate is a combination of acidic and
sulfate corrosion.
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SULFATE ATTACKS
Attacks of Soduim sulfates Na2SO4
Gypsum has an volume increase of 20% compared to Ca(OH)2
Ettringite formation
Volume increase of 200 600%
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SULFATE ATTACKS
The formation of Gypsum and Ettringite will cause:
Expansion
Cracking
Scaling
Aggregate de-bonding from the cement paste
The severity of the Sulfate attack is dependant on the exposure,concrete type, permeability and available water
SULFATE ATTACKS
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SULFATE ATTACKS
Powercrete Plus 42,5R and Civilcrete 32,5R are blended Fly Ashcements.
The incorporation of Fly Ash in the cement, decreases the amount
available alkalis, thus preventing the formation of Ettringite.
The Pozzolanic reaction produces additional Calcium Silicate hydrate
gel, to fill pore spaces leading to a denser matrix, and reducing
permeability of the concrete.
Lower water demand for given workability, compared to CEM I cements,
leading to lower moisture movement.
Cement with a total Fly Ash content of more than 25%, would be
considered Sulfate Resisting Cements.
SULFATE ATTACKS
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SULFATE ATTACKS
The decrease in water absorption from 28 days to 56 days reflects an
increase in density as result of the refined pore structure
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Sources of chlorides
Available on RAW materials for concrete production
External sources
Penetration through various transport systems
CHLORIDE ATTACKS
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Effect of chloride on durability
Reinforcement corrosion
Steel embedded in concrete is protected by passivation of the steel by
the high alkaline nature of the surrounding pore water.
Carbonation encourages the neutralization of hydration products, until
the passive layer becomes unstable.
Free chloride ions dissolve in the pore water and will destroy the passive
film around the steel, causing anodic iron dissolution.
Chloride induced corrosion of reinforcement may cause the generalcorrosion if the chlorides are spread over the surface of the steel.
With sufficient supply of oxygen, rapid dissolution could occur, creating
deeper pits, leading to considerable reduction in load bearing capacities.
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Chloride ions reacts with cement matrix as they pass through theconcrete matrix.
A large portion of chlorides will be bound by the cement paste, physically
or chemically.
Chloride binding is beneficial to durability as that reduce the amount of
free chlorides in the pore water.
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Types of chlorides in Concrete
Two types of chlorides must be distinguished. Free chlorides in pore solution
Chloride ions bound to hydration products
For corrosion to occur only the free chlorides will have an impact.
Concrete containing Pfa cements is known to bind chlorides
Cement containing a relative high C3A content is desirable, due to the
chemical binding of the chloride ions to create Friedel salts.
Pfa cements also has increased C-S-H which also binds chlorides by
absorption due to surface forces.
On carbonation of the hydration products, will cause extensivedecomposition of the Hydration products, also those that chemically
bound the chlorides.
Friedel salts then decompose into CaCO3 an Al2O, liberating the free
chloride ions and the water. This leads to higher concentration of
chloride ions close to the reinforcement.
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Transport Mechanisms: Fluid is drawn into porous material by the capillary forces.
Amount is dependent on the saturation level of material.
Surfaces most at risk:
Surfaces where chloride concentrations are high.
Surfaces exposed to wetting and drying cycles.
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Transport Mechanisms:
Permeation
This transport mechanism becomes relevant for ingress of chlorides only if
penetrating liquids carries chlorides
During the initial period of penetration, chloride from the salt solution will
combine with the hydration products of the cement paste until anequilibrium is achieved
The concentration of chlorides will then decrease as the depth of
penetration increase
Mostly relevant to extreme exposures, eg. marine structures
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Transport Mechanisms:
Capillary suction
Similar to permeation, the ingress due to capillary action of the pore
system absorbing chlorides containing solution
The driving force is controlled by the pore size and the effective surface
tension.
Absorption of chloride solution must be considered especially in alternating
exposure conditions.
Wetting / drying cycles are most detrimental
Depending on the relative humidity of the environment, the salts will
eventually prevent more and more moisture from evaporation increasing
the moisture concentration With sufficient liquid paths these ions will penetrate deeper and deeper
into the concrete
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Transport Mechanisms:Diffusion
Caused by gradient of chloride concentration
Does not depend on the flow of water to transport chloride ions
If sufficient moisture is available, it will provide a continues liquid path in
the capillary system for transportation of the chloride ions into the matrix.
The diffusion mechanism stops if there is a interruption in the liquid path
Incorporation of cements containing Pfa assist in binding these chloride
ions and limiting the depth of penetration.
CHLORIDE ATTACKS
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CHLORIDE ATTACKS
Powercrete Plus 42,5R and Civilcrete 32,5R are blended Fly Ashcements.
The incorporation of Fly Ash in Powercrete Plus and Civilcrete improve
the permeability, reducing penetration and diffusion of chlorides.
Chlorides are also chemically bound by alumino-silaceous pozzolans.
The Pozzolanic reaction produces additional Calcium Silicate hydrategel, to fill pore spaces leading to a denser matrix, and reducing
permeability of the concrete.
Lower water demand for given workability, compared to CEM I cements,
leading to lower moisture movement.
OPC OPC 30%PFA
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MASONRY, MORTARS & PLASTERS
Quintin Wolmarans
MASONRY APPLICATIONS
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MASONRY APPLICATIONS
Problems & common mistakes
MASONRY APPLICATIONS
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Name Description Cause Solution
Grinning Positions of themortar joints are
clearly visible
through the plaster
Different rate of suction between the
mortar and the bricks
Apply plaster undercoat
or spatterdash coat
before plastering
Crazing Network of closely
spaced, finecracks
Over trowelling a rich mix, or
Sand that contains too many fines.
Use a better plaster sand
Cracking Larger cracksrandomly spaced
Movement of the wall or shrinkage of
the plaster which is caused by
excessive loss of water from the plaster.
Using a badly graded sand that lacks
fine material.
Excessive suction by the bricks orblocks.
Exposure to direct sun or wind.
Do not use very rich
mixes (too much cement).
Use good quality sands.
Limit plaster thickness to
a maximum of 15mm per
coat.
MASONRY APPLICATIONS
Problems & common mistakes
MASONRY APPLICATIONS
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Name Description Cause Solution
Lack of
hardness
Plaster that is easily
chipped away or is
easily scraped off after
hardening
Plastering in full sun and wind.
Not wetting absorbent bricks.
Addition of extra water after first
mixing.Using a very lean mix (too little
cement).
Avoid causes listed
Debonding Plaster not staying onthe wall after
hardening
Dust on the wall when
plastering.
Over-rich mixes.
Very thick layers of plaster (>
15mm)
Prepare surface properly
before plastering.
Limit plaster thickness to a
maximum of 15mm.
Do not use very rich mixes
MASONRY APPLICATIONS
Problems & common mistakes
MASONRY APPLICATIONS
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MASONRY APPLICATIONS
Important Cement properties
Workability
Volume stability
Consistent cohesive mix
Open time
Good strength gain
Formulated for end use by
large building and civil projects,
requiring site custom blending
Versatile products to suite
contractors
Important Sand properties
Free of organic matter
Grading (SABS 1090 and in particular
be well graded from 5 mm particle size
downwards).
Maximum particle size
Particle shape
Clay content
MASONRY APPLICATIONS
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Sand grading properties
MASONRY APPLICATIONS
MASONRY APPLICATIONS
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MASONRY APPLICATIONS
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READYMIX CONCRETE
Herbert Groenewald
READYMIX CONCRETE CONSITUENTS
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READYMIX CONCRETE CONSITUENTS
COARSE AGGREGATE
(granite, dolomite, hornfells, quartzite, recycled..) SANS 1084
9.5mm concrete stone
13.2mm concrete stone
19.0mm concrete stone
22.0mm concrete stone
37.0mm concrete stone
Aggregate size does not have an effect on concrete strength however good
quality aggregate may influence strength and durability.
READYMIX CONCRETE CONSTITUENTS
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READYMIX CONCRETE CONSTITUENTS
FINE AGGREGATE
Natural filler sand
Manufactured crusher sand
Sands have the biggest effect on the water demand of concrete and its
quality could also influence strength and durability..
READYMIX CONCRETE CONSTITUENTS
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READYMIX CONCRETE CONSTITUENTS
CEMENTITIOUS BINDERS
Lafarge Powercrete Plus
Fly Ash
GGBS
Silica Fume
The cement / water ratio of concrete determines its strength. Cement
extenders such as Fly Ash, Slag and Silica fume may reduce / increasewater demands while improving durability by lowering heat of hydration as
well as lowering the risk of ASR, Chloride and Sulphate attack.
READYMIX CONCRETE CONSTITUENTS
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READYMIX CONCRETE CONSTITUENTS
CHEMICAL ADMIXTURES
Water reducing plasticisers
Super-plasticisers
Retarders
Air-entrainers
Accelerators
Water proofing agents
These are used for reasons ranging from; reduced water content, reducedcement contents, workability retention, retarding the hydration process,
improving freeze-thaw resistance, quick setting as well as internal
waterproofing of concrete.
READYMIX CONCRETE CONSTITUENTS
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READYMIX CONCRETE CONSTITUENTS
WATER
Recycled water from internal processes
Fresh water
Fresh water yields marginally better results due to impurities present in some
recycled water sources.
SELF COMPACTING CONCRETE
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SELF COMPACTING CONCRETE
Self Compacting Concreteoriginated in Japan in the late 80s
to combat complex structures and
high labour costs
Lafarges development of Agilia
began in 1995 with Lafarge SouthAfrica launching in Cape Town and
Durban in 2007 and Gauteng in
2008.
Definition: A concrete which flows
under its own weight, and is able to
completely fill all spaces within the
formwork, while remaining
homogeneous
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BENEFITS OF AGILIA
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Reduces placing time
Aesthetically pleasing
Improved compaction in deep level piling
Excellent compaction in areas of heavily congested rebar and difficult
access
No need for power floating or screeding
Thinner walls and columns
Quicker turnaround of shutters
No requirement for finishing crews working into late evening hours
More efficient use of labour means quicker completion of jobs
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116 Peri Wiehan - Midrand
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Le Corbusiers Church of Saint
Pierre, posthumously completed, 40
years after his death, this structure
genuinely breathes true to his
fascination with concrete, his belief in
simplicity, functionality, building on a
human scale, and master plans that
were in harmony with nature sun,
space, and greenery.
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Spinnaker Tower, Portsmouth
by Scott Wilson Advanced
Technology Group, is the UKs
tallest public viewing tower
outside of London. Once again
Agilia supported this innovativedesign giving a perfectly
finished high quality off shutter
aesthetic.
ARTEVIA ADVANTAGES
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Low Maintenance Artevia Polish eliminates the need for
screeds, tiles or carpets.
Aesthetically pleasing
Monolithic slab
Colour throughout
Robust
Can be moulded into different shapes
Can be used in combination with other
products
Polished
Colour
ExposedPolished
ARTEVIA EXPOSED EXAMPLES
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Garden World Johannesburg Durban beach front
Riverside Office Park Oprah Winfrey Leadership
Academy for Girls
ARTEVIA COLOUR EXAMPLES
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Oprah Winfrey Leadership
Academy for Girls
Goo Chi Caf Durban
Private Residence CapeTown
Westville Park Durban
Durban beach front
ARTEVIA POLISHED EXAMPLES
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Oprah Winfrey Leadership
Academy for Girls
Yamaha Johannesburg Private Residence Durban
Stellenbosch UniversitySpier Wine Estate
Stellenbosch
EXTENSIA
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EXTENSIA is a low-shrink design alternative to steel, mesh and fibre
reinforcement concrete.
EXTENSIA
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Ideal for large internal industrial and warehouse
floors. Controlled shrinkage enables saw cuts tobe pushed up to 15m x 15m sections (225 m2
seamless panels) where proper design
principles are followed.
The High flexural strength of 6Nmm, allows
reduced thickness of the floor, high surface
durability and reduced floor maintenance.
Floors can be coloured and polished.
The environmental profile of EXTENSIA is
less than that of conventional steel-meshed
flooring.
Saves the customer money,time and effort by
reducing the need for steel reinforcement
WHAT IS HYDROMEDIA?
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Also known as no-fines concrete or pervious concrete.
Hydromedia is a unique and effective means to address important
environmental issues and support green, sustainable growth.
By capturing storm water and allowing it to seep into the ground,
Hydromedia is instrumental in recharging groundwater and reducingstorm water runoff.
This pavement technology creates more efficient land use by reducing the
need for retention ponds, swales, and other storm water management
devices.
In doing so, Hydromedia has the ability to lower overall project costs on a
first-cost basis.
HYDROMEDIA: BENEFITS
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Manages storm water efficiently andreduces demand on infrastructure,
rapid water removal and safe dry
surfaces.
Can reduce the quantity of first flush
runoff in urban areas.
Sustainable Urban Drainage,minimizes urban impact on natural
water cycle.
Filters particulate including pollutants
(metals and hydrocarbons) from
storm water.
Reduced storm water management
costs and infrastructure. Higher permeability, more consistent
performance, cleaner finish.
HYDROMEDIA: TECHNCIAL DATA
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Compressive strength of 10 20Mpa
Flexural strength of 1.5 3Mpa
Porosity 20 - 30%
Workable up to 90 minutes
Permeability rate 150 litres / m
2
/ min
Children's water fountain in Forever Resorts Bela Bela
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1. Ultra Enviro (Low CO2 concrete)
2. Ultra Fibre (Polypropylene or Steel)
3. Ultra Waterproof (Xypex)
4. Ultra Piling NS, SD, T
5. Ultra Industrial Floor
6. Ultra Lightweight
7. Ultra Pool
8. Ultra Post Tension
9. Ultra Plaster and Mortars
PLACING AND FINISHING
SERVICES
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SERVICES
Product placing and finishing
done by Lafarge
Finished product
No middle man, one point ofcontact
Peace of mind for the
customer
Guaranteed product quality
and workmanship
QUESTIONS?
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