NRF-CRP Underwater Infrastructure and Underwater City of the Future
Ultra Durable, High Strength Concrete
and Its Use in Buildings
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 1
Big Thank You to NRF
National Research Foundation provides the funding through Competitive Research
Programme (CRP) on “Underwater Infrastructure and Underwater City of the Future”
Investigators:
Tan Soon Keat (Hydrodynamics) - PI (Principal Investigator)
Chu Jian (Geotechnical Considerations) – Co-PI
Susanto Teng (Structures and Materials) – Co-PI
Current Researchers in Structures and Materials:
- Dr. Liu Yu
- Jimmy Chandra, Darren Lim Tze Yang, Khatthanam Chantabouala,
- Vahid Afroughsabet
- Odd E. Gjorv (Em. Prof. Norway) - Collaborator
GGBS (EnGro Corp); Silica Fume (Elkem); Superplasticizer (BASF); Steel Fibres (Bekaert); Grade
600 steel bars (NatSteel); Concrete mixing (Holcim); Specimen Fabrication & Casting
(Fongsoon).
Partners: JTC, Surbana, HSL
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 2
Ultra Durable Concrete
An Ultra Durable Concrete material is especially suitable
for marine structures that are designed to last 100 years
or more without significant damage.
Poor quality concrete
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 3
A deteriorating concrete bridge
Poor quality concrete
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 4
Life-spans of some concrete structures
The Pyramid, Roman Colosseum, The Parthenon > 1000 years
5
1.
Offshore Concrete Structures – 30 to 60 years
2.
Durable Concrete Bridges, Tunnels – 60 to 100 years?
3.
Guggenheim Museum, Bilboa – 100 years (built on land)
4.
Tjuvholmen Mixed Development, Oslo - 100 to 300 years?
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 5
Titanium for Buildings
The Guggenheim Museum, Bilbao.
The building specification of calls for a 100 year life-span, but many are
convinced that the titanium exterior should be able to last several hundred
years longer.
6
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 6
Mixed Development
(condominium and shops) at Tjuvholmen, Oslo
Courtesy of Skanska
Designed to last 300 Years ?!
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 7
NTU Research on Ultra Durable Concrete
To find a very durable concrete for building a mega-structure which can be partially or
entirely submerged under sea water as an alternative to conventional land reclamation
technique.
The mega marine structure is expected to survive for 300 years or longer in marine
environment.
The concrete has to possess extremely good durability properties but is still economical.
Required Properties:
- Effectively block chloride (from seawater) from entering the concrete.
- Effectively prevents corrosion of reinforcement for a very long time.
- Use normal concrete constituents, possesses high workability, economical, etc.
Additional properties obtained:
- Compressive strength 120 MPa – 150 MPa (typical tall buildings use 60 – 80 MPa).
- The concrete can be made ductile by adding steel fibres.
- Economical (only 50% to 60% more expensive than normal concrete)
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 8
Ultra Durable Concrete – Constituent Materials
Normal Aggregates
Superplasticizer
Normal Sand
Portland Cement
Ground Granulated BlastFurnace Slag (GGBS)
NRF-CRP Underwater City
Water
Silica Fume
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 9
Ultra Durable Concrete – mix design
Mix
A
B
C
D
w/c
Ratio
A/C
Ratio*
E
F
G
H
I
0.25
2.85
UFGGBS (%)
0
0
0
30
45
60
30
0
30
GGBS (%)
0
45
60
0
0
0
15
0
0
USF (%)
0
0
0
0
0
0
0
10
10
TCM (kg/m3)
590
583
579
585
590
579
582
585
580
F/C Ratio
1
Aggregate
Ratio**
0.69
Table 2. Mixture design proportions
*Aggregate/Cement Ratio **Ratio by weight
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 10
Ultra Durable Concrete
(self-compacting – reduces manpower)
A typical Ultra Durable Concrete can have a flow diameter of 650
to 700 mm. Thus, in terms of workability, the Ultra Durable
Concrete is as good as self-compacting concrete.
Flow diameter
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 11
Cost Comparison
Item
Cement
Ultra Fine GGBS
Undensified
Silica Fume
Coarse and Fine
Aggregates
Water
Superplasticizer
Material Cost
Grade 60
(kg)
400
0
0
Unit Price per
kg
0.09
Grade 135
(Ultra Durable)
348
174
58
Unit Price per
kg
0.09
0.115
0.55
1770
0.04
1530
0.04
150
3
0.003
1
145
8.7
0.003
5
110 SGD
NRF-CRP Underwater City
188 SGD
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 12
Service Life Analysis
All the parameters have uncertainties
• Cover Depth, Chloride Permeability, Critical Chloride Content, Curing
Duration and Time of Exposure
• Sea Water Chloride Content and Temperature
Fick’s Second Law of Diffusion
C 𝑥, 𝑡 = Cs [ 1 − erf
Resistance to
withstand the
loads (R)
Environmental
Loads (S)
x
2 D t .t
]
D t =
D0
1−∝
1+
t′
t
k e = exp be
1−∝
−
t′
t
1−∝
t0 ∝
. ke
t
1
1
−
293
T−273
Monte Carlo Simulation
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 13
Probability of Failure
Beyond 150 or 200 years, the analyses are purely theoretical
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 14
Use of High Strength Concrete in Buildings
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 15
CapitaGreen
(Takenaka Corp – Main Contractor)
Some columns (lower floors) are made
of Grade 80 and 100 MPa concrete.
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 16
• Mechanical Property
Flexural Tensile Strength
Compressive Strength &
Modulus of Elasticity
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 17
Long-Term Tests
Shrinkage measurement using
Length Comparator and Strain Gauges
NRF-CRP Underwater City
Typical Creep test
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 18
Creep Properties
The creep coefficient for the Ultra Durable Concrete is about 0.5 for
30 yr period compared to that of normal concrete (about 2.0 in
Singapore)
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 19
Shrinkage Properties
The shrinkage strain is about 240 micro-strain (30 yr value). These
are very low values compared to that of normal concrete (500
micro-strain)
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 20
Advantages of Ultra Durable, High Strength Concrete
•
•
•
•
•
•
Very high durability (delay corrosion of rebars)
Very high workability (self-compacting)
Resistance to aggressive environments.
Longer span lengths and smaller/thinner member sizes.
Reduction in concrete volume and structural weight.
Reduction in maintenance cost and extension of service life.
•
•
•
•
•
High compressive & tensile strengths (fr = 10 MPa versus 4 MPa)
High modulus of elasticity (40 GPa versus 25 GPa)
Very low creep coef & shrinkage strain (0.5 & 240 versus 2 & 500)
“Green” (use of slag 30%, silica fume 10%)
The concrete is recyclable as coarse aggregates
21
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 21
Horizontally Spanning Buildings - The Interlace
Contractor - Woh Hup ; Consultant - T.Y. Lin
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 22
Horizontally Spanning Buildings - The Interlace
Creep & Shrinkage Analysis of Prestressed Transfer Floor
Transfer Floor
fcu = 60 MPa
Columns
fcu = 80 MPa
c
NRF-CRP Underwater City
A/Prof Susanto Teng
c
[email protected]; Tel: 6790 5289
Slide No. 23
Horizontally Spanning Buildings - The Interlace
Transfer Floor fcu
= 60 MPa
Columns fcu = 80 MPa
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 24
Horizontally Spanning Buildings - The Interlace
Initial upward
camber due to
prestressing
= + 9 mm
50 Year deflection
with all loads
= - 25 mm
c
NRF-CRP Underwater City
A/Prof
c Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 25
Vertically Curved & Irregular Building – on Grange Road
LSW Consulting Engineers
Construction Stage Modeling (Stages 4, 18, and 26)
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 26
Vertically Curved & Irregular Building – on Grange Road
Principal tensile stresses (Level 20th)
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 27
Vertically Curved & Irregular Building – on Grange Road
U2, Excl Reinf, w/ PD
U2, Incl Reinf, w/ PD
25
25
56 days
20
Storey Level
224 days
15
10
5
0
-80
-60
-40
-20
0
Column C13: Lateral Deflection (mm
1 yr
2 yrs + sustained
load
5 yrs + sustained
load
50 yrs + sustained
load
Storey Level
20
54 days
224 days
15
1 yr
10
2 yrs + sustained
load
5 yrs + sustained
load
50 yrs + sustained
load
5
0
-80
-60
-40
-20
0
Column C13: Lateral Deflection (mm)
1 yr
224th day
Creep and Shrinkage Analysis &
Construction Stage Modeling
(Stages 4, 18, and 26)
56th day
Deflection (50 yrs)
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 28
Designing Concrete Members (Future Seminars)
Eurocodes cover:
Concrete strengths of up to C90/105 MPa (fck_cyl/fck_cube or old notation f’c/fcu)
Steel yield strengths fyk of up to 600 MPa. But,
there is no design guide for fyk > 500 MPa (equiv. to fy 460 MPa – BS8110)
For shear design (Singapore N.A.), concrete strength is limited to
C50/60 (fcu = 60 MPa) unless proven by experiment.
So, structural design guides are needed for Ultra Durable, High Strength Concrete
(fcu > 105 MPa) and for High Strength steel bars (Grade > 500 MPa).
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 29
Experiments
•
•
•
•
•
Fibre Reinforced Concrete – tensile strength of > 20 MPa.
Beams, Slabs, and Walls (fcu = 120 MPa or higher) with or without fibres
Beam depth (d): 450, 900, 1350, 1800 (mm)
Walls with H/B up to 2 and overall height up to 4 m overall height.
Slabs with low reinforcement ratios
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 30
Thank you
NRF-CRP Underwater City
A/Prof Susanto Teng
[email protected]; Tel: 6790 5289
Slide No. 31