LIMESTONE 071400baalbaki.ppt

© Holcim Group Support Ltd 2008
High Performance Concrete
Moussa Baalbaki
Product Innovation and Development
Course for Cement Applications 2008

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6. HPC.ppt
© Holcim Group Support Ltd 2008 Course for Cement Applications 2008
Learning objectives
 What is High Performance Concrete ?
 How to achieve High performance Concrete
 Selection of materials for HPC
 Mix design
 Field of applications

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6. HPC.ppt
 The concrete that was known as high-strength concrete in
the late 1970’s is now referred to as HPC in terms of:
 high early and late strength
 high E-modulus & low creep
 high workability
 low permeability
 sulfate & chloride resistance
 frost resistant
 chemical resistant
 abrasion resistance
HPC
Concrete
durability Service life / cost ratio
Heavy cost
of repair
- +
+
-
Free-repair concrete
What is High performance concrete?

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6. HPC.ppt
What is High performance concrete?
 Strategic Highway Research Program SHRP-C – 205
definition on High Performance Concrete:
 Very high early strength concrete
- 4-h compressive strength > 17.2 MPa
 High early strength concrete
- 24-h compressive strength > 34.5 Mpa
 Very high strength concrete
- 28-day compressive strength > 68.9 Mpa
 A durability factor greater than 80% after 300 cycles of F&T
 A water – cementitious material ratio < 0.35

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6. HPC.ppt
8 - 16 hours
+/- 20°C
16 - 24 hours
+/- 10°C
24 - 48 hours
+/- 5°C
0
20
40
60
80
100
120
Cube (15 cm) Core (6.5 cm)
Compressive
strength
(%)
High early strength
 Concrete that develops high strength level at early age
according to the temperature condition at the jobsite

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6. HPC.ppt
Advantages
High Early Strength– Precasting Industry
 Element for tunnel at Yverdon
Maximum use of formwork
(more rotation)
Faster handling (enough strength)
Increase productivity and speed of
construction (lighter elements and
more elements per truck load)

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Advantages
Extension at
Jungfraujoch ski station
High Early Strength – Slip form in winter
 Highest construction site in Europe – 3500 m
Concreting in cold weather
Use of slipform in extreme
climate (concrete exposed
after 5 h)
On-site batching plant
(more flexibility)

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Advantages
Reduces size of columns
(more surface for less $)
higher elastic modulus and
less creep
Higher construction speed
New market gained
against steel
300
240
180
120
60
0
Chicago
1959
113 m
Chicago
1968
197 m
Chicago
1975
262 m
Chicago
1989
295 m
Kuala Lumpur
1996
451 m
Paris
1889
300 m
360
420
480 m
Executive
House
Lake Point
Tower
Water Tower
Place
311 South
Wacker Drive
Eiffel
Tower
60
MPa
89
MPa
With SP
Without SP
80
MPa
Petronas Towers
High strength - High-rise buildings

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0
0.2 0.3 0.4 0.5 0.6 0.7 0.8
Water / cement ratio
Rapid
chloride
permeability
(coulomb)
2000
4000
6000
8000
NSC
HPC
RPC
Permeability

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Low porosity
0
10
20
30
40
50
60
1 10 100 1000
Pore diameter (nm)
Cumulative
porosity
(%)
RPC HPC-60MPa NC-30MPa
Micropores Capilarities
SLC demonstrated how HPC can benefit agriculture
by providing protection against acids as well as
reducing bacterial contamination and the spread of
parasites to stock.
HP antibacterial concrete for pig farm

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Thanks to HPC
 Thanks to the features, advantages and
benefices of concrete
 Tallest, deepest and heaviest structures
in 2006 are concrete structures
2004
Taipe 101
+ 509 m
2008
Burj Dubai
+ 800 m
Offshore platform
- 350 m / ~ 1Mio t
1998
Petronas towers
+ 450 m

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How to achieve HPC
 Essentially a concrete with a low W/C or W/B ratio (0.25
to 0.40)
 High amount of fines smaller than 0.125 mm (> 380
kg/m3)
 Minimum 3 days curing

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How to achieve HPC
 Normal strength concrete
 the strength is governed by the water to cement ratio
 Féret law (1896)
- fc = k[c/c+w+a]2
- K = constant
- C, w, a = absolute volume of cement, water and air
 Aggregate properties are not often considered, except for
the usual requirements for cleanliness and grading
 The paste strength is normally < aggregate strength

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6. HPC.ppt
Failure surface of a usual concrete
 Aggregates contribute little to the strength due to the
weakness of the transition zone
Oriented CH
crystals
Gap

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How to achieve HPC
 High performance concrete
 The strength is governed by
- hydrate cement paste (W/C)
- Aggregate strength
- Transition zone paste/aggregate
 De Larrard law: 1992
- fc = kgRc[1+(3.1w/c)/1.4-0.4e-11s/c]2
- Kg is a parameter depending on the type of aggregate (~4.91
for river aggregate)
- Rc is the strength of a standard mortar at 28d
- w, c and s are mass of water, cement and silica fume
 Compressive strength is no longer related only to W/C
like in normal strength concrete

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Failure surface of HPC
 The strength-limiting factor may be the aggregate

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6. HPC.ppt
Normal concrete W/C>0.6 High performance concrete W/C<0.4
Microstructure of normal and HP concrete

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Selection of materials for HPC
 Cement
 Rheology and strength performance are somewhat
conflicting
 Fineness
 Interstitial phase composition (content, morphology)
 Calcium sulfate (content, type)
 Degree of sulfurization
Years 1950 2000
W/C ratio 0.47 0.72
Cement (kg/m3) 380 250
Compressive
strength at 28d
30 MPa

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 Mineral components
 Most modern HPC contain one or more MIC
 Improve fresh properties (less sticky)
 Need less superplasticizers
 Improve significantly the transition zone (less CH)
 Some limitations
- Need for early strength
- Cold weather concreting
- Freeze-thaw durability
- Decrease in maximum temperature

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 Coarse Aggregates
 Grading & particle shape: maximum capacity
 MSA: 10 – 20 mm
 Strength and stiffness: mechanical properties
 Chemical reactivity: affect the bond
 Fine aggregate
 Few investigations
 Fineness modulus (2.7~ 3) - less water demand
 Free of clay and silt
 manufactured sand (partial replacement)

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Mix design
 Important steps to follow according to the Canadian
experience:
 Step 1: Choose the compressive strength to be achieved
 Step 2: select w/c ratio necessary to achieve the strength
 Step 3: select water content
 Step 4: select the amount of coarse aggregate
 Step 5: estimate the amount of superplasticizer (saturation
point)
 Step 6: calculate the mix composition using the absolute
volume method
 Step 7: trial batch

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Compressive strength
Class of resistance I II III IV
Compressive
strength (MPa)
50 - 75 75 - 100 100 - 125 125 - 150

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Water to cement ratio
Compressive
strength (MPa)
50 - 75 75 - 100 100 - 125 125 - 150
W/C ratio 0.35 – 0.40 0.30 – 0.35 0.25 – 0.30 < 0.25

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Water content
 It is recommended to select 3 different water contents
Compressive
strength (MPa)
50 - 75 75 - 100 100 - 125 125 - 150
W/C ratio 0.35 – 0.40 0.30 – 0.35 0.25 – 0.30 < 0.25
Mixing water (L/m3) 150 -160 140 -150 130 -140 < 130

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Coarse aggregate content
Particle shape
Elongated
or flat
Average Cubic Rounded
Coarse aggregate
content (kg/m3)
1000 1050 1100 1150

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Superplasticizer content
Compressive
strength (MPa)
50 - 75 75 - 100 100 - 125 125 - 150
W/C ratio 0.35 – 0.40 0.30 – 0.35 0.25 – 0.30 < 0.25
Mixing water (L/m3) 150 -160 140 -150 130 -140 < 130
Superplasticizer
(L/m3) – without MIC
5 - 10 7.5 - 15 15 - 20 20 – 30
Superplasticizer
(L/m3) – with MIC
5 - 10 5 – 12.5 10 - 20 15 – 21.5
 It is recommended to determine the optimum superplasticizer dosage

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W/B selection Water content SP dosage CA content Air content
Binder content
Sand content
Trial batch
Workability
Strength
Final composition
Adjustments
Change the W/B
Yes
Yes
No
No
(after Lessard, Baalbaki
and Aïtcin, 1995)
Mix design

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6. HPC.ppt
Curing
 HPC must be cured quite differently from usual concrete
 The use of curing compound has no value in inhibiting
autogeneous shrinkage
 The most critical curing period runs from its placement
and finishing up to 2 or 3 days
 Contractors must be specifically paid to cure concrete, it
is a profitable investment

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6. HPC.ppt
Field of applications
 High-rise buildings
 Underground parking & bus station
 Bridges
 Prefabrication
 Residential & non-residential building
 Chemical aggressive environment

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6. HPC.ppt
High-rise buildings
 Scotia Plaza Tower -
Toronto
 68-story & 275m high
 1986 -1987
 70MPa
 First Canadian high-rise
building with slag cement

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6. HPC.ppt
Underground parking & bus station
 Paris – Bercy bus station

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6. HPC.ppt
Bridges
 Vasco de Gama bridge

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6. HPC.ppt
Prefabrication

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6. HPC.ppt
Non-residential building
Civaux
Grande Arche

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6. HPC.ppt
Chemical aggressive environment
Sewage pipe
Manhole
Animal / agricultural farm

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