4.461: Building Technology 1 CONSTRUCTION AND MATERIALS
FALL TERM 2004SCHOOL OF ARCHITECTURE AND PLANNING: MIT
Professor John E. Fernandez Concrete and Composites
Stadelhofen Station
Zurich
Santiago Calatrava Valls
Image courtesy of Per Waahlen, photographer, and Structurae
concrete and composites
1. Introduction
practice
research
2. Concrete Issues
ductility
CO2 generation
durability
3. Improved Structural Materials
substitution
dematerialization
technology transfer
4. Material Selection and Evaluation (CES)
multi-objective optimization
material indices/ CES software
5. New and Emerging Materials
new concretes
composites
6. Architectural Form and Research Priorities
research development: NFRC
design
concrete and composites
1. Introduction
practice
research
2. Concrete Issues
ductility
CO2 generation
durability
3. Improved Structural Materials
substitution
dematerialization
technology transfer
4. Material Selection and Evaluation
multi-objective optimization
material indices/ CES software
5. New and Emerging Materials
new concretes
composites
6. Architectural Form
research development: NFRC
design
concrete and composites ductility
elas
tic z
one
Strain, δ
Str
ess,
σ
Strain, δStrain, δ, ∆L/L
Str
ess,
σ
Str
ess,
σ,
P/A
E = ∆σ/∆δ
∆δ
∆σ
brittle
ductile
plastic flow
extensive cold drawing plastic
partial plasticity reinforced concrete
full plasticity metals
brittle ceramics
Stress - Strain Curves Not To Scale
viscous flow elastomer
Image by MIT OCW.
concrete and composites ductility
Failure strain, Єf
Єf - measure of the deformation of the material at final fracture stress
Ceramics
Fracture and failure is unpredictable
Material εf
concrete, unreinforced(compression)
0
0.02
0
0.02-0.03
0.18-0.25
0.2-0.3
0.45-0.65
0.15-0.25
0-0.18
0.3
0.5
0.55
0.01-0.7
5.0
concrete, reinforced
soda glass
low-alloy steel
mild steel
carbon steel
stainless steel,austenitic
stainless steel,ferritic
cast irons
iron
aluminum
copper
brasses and bronzes
natural rubber
Tensile Ductility, εf (except for certain materials such as concrete, unreinforced)
Figure X
Fracture stress (ceramic)
Probab
ility
funct
ion
Images by MIT OCW.
concrete and composites ductility
Toughness, Gf , and
Fracture toughness, Kc
measures of energy absorption potential through resistance to crack propagation.
Gf ( toughness), Kc (fracture toughness) -
both material properties.
Gf = energy per unit of crack area
Various ways of measuring depending on the material.
Therefore, search for materials that have high resistance to cracks that are formed through loading or other lifecycle stresses.
Sometimes toughness is also referred to as the area under the stress-strain curve.
Price per density1 10 100 1000 10000 100000 1e6
Frac
ture
Tou
ghne
ss (k
si.in
^1/2
)
0.01
0.1
1
10
Carbon Fibre
Alumina Fibre
Ceramic foam (carbon)
Normal Density Concrete
Aerated Concrete
Ice (H2O)
Lightweight Concrete
Granite
Limestone
Aluminium Nitrides (Glass ceramic)
Silicon Nitride (Glass ceramic)
Machineable Glass Ceramic
Low Density Refractory Brick
concrete and composites CO2 generation
Ecological Issues
Concrete production contributes 8% of world’s total CO2emissions.
Research in building materials for the developing world is a moral obligation.
Issues
• Poverty allevation
• Safety
• Health (IAQ, toxicity)
• Resource Management
Cultural Issues
• Form (resonance with place)
• Process (acknowledges local skill set)
• Material (regional resources)
Production Energy (kcal/lb)1 10 100 1000 10000 100000
You
ng's
Mod
ulus
(10^
6 ps
i)
1e-5
1e-4
1e-3
0.01
0.1
1
10
100
Sandstone(2.35)
Marble(2.7)
Granite(2.63)
Concrete (Insulating Lightweight)
Concrete (High Performance)
Common Hard Brick
Low Density Refractory Brick
Plaster of Paris
Cement (Super Sulphate)
Ultra Low Density Wood (Transverse) (0.09-0.22)
Insulation Board, perpendicular to board
Natural Rubber (NR), unfilled
Alumina Tungsten - High Alloy (<89%W)
Medium Density Aluminium Foam (0.24-0.48)
Carbon Steel
Epoxy SMC (Carbon Fibre)
Diamond
Carbon Matrix Composite
concrete and composites durability
Concrete
Need for durable reinforcing and water impermeable concrete matrix
Especially for freeze/thaw climates
concrete and composites
1. Introduction
practice
research
2. Concrete Issues
ductility
CO2 generation
durability
3. Improved Structural Materials
substitution
dematerialization
technology transfer
4. Material Selection and Evaluation
multi-objective optimization
material indices/ CES software
5. New and Emerging Materials
new concretes
composites
6. Architectural Form
research development
design
concrete and composites dematerialization, substitution, technology transfer
02020
2025
Year
Quan
tity
(to
ns)
20
00
1975
1950
1925
1900
1875
1850
1825
1800
1775
1750
109
108
107
106
105
104
103
102
101
C
A
S(r)
S(r)
R
R
B
AB
P
P
C
G
G
S(n)
S(n)
W(r)
W(n)
W(n)
Projection
W(r)
Image by MIT OCW.
concrete and composites dematerialization, substitution, technology transfer
Concrete
Dematerialization: a decrease in the material input per unit service
Is occurring in certain industrial sectors but ‘ecological rucksack’ needs to be accounted for
Substitution: substituting concrete best in situations in which safety is at high risk of compromise
Technology transfer: best employed in situations in which to lengthen lives of existing building stock (such as infrastructure refurbishment using carbon/epoxy reinforcing)
40
20
0
60
80
100
2020
2010
Year
Perc
enta
ge
of Tota
l (w
eight)
20
00
1990
1980
1970
1960
1950
1940
1930
1920
1910
1900
Measurement of Percentage of Renewable Versus NonrenewableMaterials Consumption in the US
Projection
Image by MIT OCW.
concrete and composites
1. Introduction
practice
research
2. Concrete Issues
ductility
CO2 generation
durability
3. Improved Structural Materials
substitution
dematerialization
technology transfer
4. Material Selection and Evaluation (CES)
multi-objective optimization
material indices/ CES software
5. New and Emerging Materials
new concretes
composites
6. Architectural Form
research development
design
concrete and composites multi-objective optimization
concrete and composites multi-objective optimization
Thermal Expansion (µstrain/°F)0.1 1 10 100
You
ng's
Mod
ulus
(10^
6 ps
i)
1e-5
1e-4
1e-3
0.01
0.1
1
10
100
Normal Density Concrete
Carbon Steel
ceramics
• Glass ceramicsMachineable, good fracture
toughness
• Very HPC (Ductal)Ductile concrete
• Ceramic foamsLightweight, structural material
• New laminated glasses
Laminated glass (Dupont SGP interlayer)
concrete and composites new concrete
Ductile concrete
Steel whisker reinforcement
Increased toughess
Increased water impermeability (few micropores)
10
0
20
30
40
50
60
900 12006003000
Displacement, microns
Ben
din
g s
tren
gth
, M
Pa
ductile concrete
normal concrete
Image by MIT OCW.
