Design and Performance of Cost- Effective Ultra-High ... · UHPC High-performance concrete...
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Weina Meng Department of Civil, Environmental, and Ocean Engineering [email protected] Design and Performance of Cost- Effective Ultra-High-Performance Concrete (UHPC) for Transportation Infrastructure
Transcript of Design and Performance of Cost- Effective Ultra-High ... · UHPC High-performance concrete...
Weina Meng
Department of Civil, Environmental, and Ocean Engineering
Design and Performance of Cost-
Effective Ultra-High-Performance
Concrete (UHPC) for Transportation
Infrastructure
CC
FRC
UHPC
Ten
sile
str
ess
Tensile strain0
➢ High mechanical strengths
✓ Compressive strength (28 days): ≥ 125 Mpa (18 ksi)
✓ Tensile strength (28 days): ≥ 8 Mpa (1.2 ksi)
➢ Strain-hardening behavior
UHPC: ultra-high performance concreteHPC: high-performance concrete
CC
HPC
UHPC
Co
mp
ress
ive
stre
ss
Compressive strain0
Advantages of UHPC
• Resilience
FRC: fiber-reinforced concrete CC: conventional concrete
Advantages of UHPC
• Sustainability➢ Low life-cycle cost
➢ Excellent durability
Ref: https://www.fhwa.dot.gov/hfl/partnerships/uhpc/hif13032/chap01.cfm
Durability properties (the lowest values are desired)
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UHPC High-performance concrete Conventional concrete
➢ Low construction energy (no mechanical vibration for consolidation)
➢ High construction quality
Advantages of UHPC
• Super workability (self-consolidating)
280 mm
• Very high initial cost
➢ Materials cost: 10-20 times of conventional concrete
• High autogenous shrinkage
➢ Autogenous shrinkage (28 days): ≥ 1000 μm/m, risk of cracking
• Special curing conditions
➢ Steam curing: ≥ 90˚C, high energy consumption
• Needs for higher tensile/flexural strength and ductility
➢ Further improvement of resilience
Current challenges
Sand
Binder(cement, fly ash, slag, silica fume)
Admixtures
Water
Steel fibers• Strategies
➢ Use high-volume by-products (e.g. fly ash & slag) to partially replace cement
➢ Use cost-effective sand to replace fine ground silica sand
➢ Reduce fiber content
➢ Reduce silica fume content
➢ Reduce binder-to-sand ratio
Design of cost-effective UHPC
Components of UHPC
Meng W, Valipour M, and Khayat KH. Optimization and Performance of Cost-Effective Ultra-High Performance Concrete, Materials and Structures 2016, 50(1), 29.
Reference UHPC
Cement
Fly ash
Slag
Silica fume
Fine sand
Quartz sand
River sand
Masonry sand
Quartz sand
Cement
Fine sand
Silica fume
UHPC-1 (G50SF5)
Cement
Slag
Masonry sand
River sand
UHPC-2 (G50)
Cement
Slag
Masonry sand
River sand
UHPC-3 (FAC40SF5)
Cement
Fly ash
Masonry sand
River sand
UHPC-4 (FAC60)
Cement
Fly ash
Masonry sand
River sand
Developed UHPC
• Normalized to the properties of the reference UHPC
• The optimized UHPC mixtures demonstrate comparable or better mechanical properties
Mechanical properties of developed UHPC
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UHPC-1 UHPC-2 UHPC-3 UHPC-4
No
rmal
ized
me
chan
ical
p
rop
erti
es
Compressive strength Tensile strength
Flexural strength Young's modulus
Energy dissipation (T150)
99.70
99.75
99.80
99.85
99.90
99.95
100.00
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Fro
st d
ura
bili
ty f
acto
r (%
)
Number of F/T cycles
ReferenceG50SF5G50FAC40SF5FAC60
Frost durability
-800
-700
-600
-500
-400
-300
-200
-100
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0 4 8 12 16 20 24 28
Au
toge
no
us
shri
nka
ge (
μm
/m)
Age (days)
Reference G50SF5G50 FAC40SF5FAC60
Autogenous shrinkage
By 70%
• Compared with the reference UHPC, the optimized UHPC have:
➢ Smaller autogenous shrinkage
➢ Better freezing/thawing durability
Shrinkage and durability of developed UHPC
• Compared with the reference UHPC, the optimized UHPC have:
➢ 40% to 50% lower cost per unit compressive strength
➢ 45% to 65% lower cost per unit energy dissipation (T150)
Cost of developed UHPC
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Reference UHPC-1 UHPC-2 UHPC-3 UHPC-4
Co
st p
er u
nit
dis
sip
ated
en
ergy
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/m3/J
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Co
st p
er u
nit
co
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ress
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stre
ngt
h (
$/m
3/M
Pa)
Normal sand
Pre-saturated lightweight sand
Cured zone
Inte
rnal
cu
rin
g1. Improve UHPC by internal curing
-500
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Au
toge
no
us
shri
nka
ge (
μm
/m)
Age (days)
LWS00 LWS12.5
LWS25 LWS37.5
LWS50 LWS75
130
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158
142140
130
125
135
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155
165
LWS0
0
LWS1
2.5
LWS2
5
LWS3
7.5
LWS5
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LWS7
5
Co
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ress
ive
stre
ngt
h (
MPa
)
Elementary mapping
LWS
• Use of 25% lightweight sand (LWS) can effectively reduce shrinkage and increase compressive strength
Meng W, Khayat KH. Effects of Saturated Lightweight Sand Content on Key Characteristics of Ultra-High-Performance Concrete, Cement and Concrete Research, 2017, 101, 46–54.
2. Improve UHPC by rheology control
• Fibers in UHPC can be controlled with:
1) A uniform fiber dispersion 2) Tension direction fiber orientation
Force ForceUHPC matrix
Fibers
• The rheology of UHPC can be adjusted by adding viscosity modified admixture (VMA). An optimum rheological property results in optimum fiber distribution, and thus, best flexural properties
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Load
(kN
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Deflection (mm)
VMA-0.0 VMA-0.5VMA-1.0 VMA-1.5VMA-2.0
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Dis
sip
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en
ergy
(J)
Flex
ura
l str
engt
h (
MPa
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VMA dosage (%)
Flexural strength
Dissipated energy
Straight (S) Hooked-end (H) PVA (8 mm)
Meng W, Khayat KH. Effect of Hybrid Fibers and Fiber Content on Fresh and Hardened Properties of Ultra-High-Performance Concrete, Journal of Materials in Civil Engineering, 2018, DOI: 10.1061/(ASCE)MT.1943-5533.0002212.
3. Improve UHPC using hybrid fibers
• Bridge cracks at different length scales
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Load
(kN
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Mid-span deflection (mm)
Reference (FAC40SF5)PVA0.5S1.5H0.5S1.5H1S1H1.5S0.5H2S0
-500
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Au
toge
no
us
shri
nka
ge
(μm
/m)
Age (days)
S2 H0.5S1.5H1S1 H1.5S0.5H2 PVA0.5S1.5
GFRP grid CFRP grid
Meng W, Khayat KH, Bao Y. Flexural Behavior of Ultra-High-Performance Concrete Panels Reinforced with Embedded Fiber-Reinforced Polymer Grids, Cement and Concrete Composites 2018 (In press)
4. Improve UHPC using fiber-reinforced polymer (FRP)
• Use glass FRP (GFRP) and carbon FRP (CFRP) grids (40×40 mm)
RollerUHPC panel
FRP
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Load
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Mid-span deflection (mm)
UHPC
One-layer GFRP
Two-layer GFRP
One-layer CFRP
Flexural test setup (unit: mm)
Crack
Application 1: Prefabricated stay-in-place formwork
• Ultra-thin lightweight formwork for accelerated construction
Meng W and Khayat KH, Development of Stay-in-Place Formwork Using GFRP Reinforced UHPC Elements, Proc. 1st Int. Interactive Symposium on UHPC, Des Moines, Iowa, 2016.
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Design of formwork (Unit: mm)
• Large-scale (3 m 1.5 m 0.1 m) panel specimens
➢ Ultra-thin UHPC overlay (25 mm) on a concrete substrate (75 mm)
Application 2：UHPC bonded overlay
Bao Y, Valipour M, Meng W, Khayat KH, Chen G. Distributed Fiber Optic Sensor-Enhanced Detection and Prediction of Shrinkage-induced Delamination of Ultra-High-Performance Concrete Bonded over an Existing Concrete Substrate, Smart Materials and Structures, 2017, 26, p8.
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Lo
ad (
kN
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Mid-span deflection (mm)
CC
UHPC
UHPC-CC
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Peak load
(kN)
Stiffness
(kN/mm)
Energy
(J)
Val
ues
CC
UHPC-CC
UHPC
Functionally-graded slab demonstrates less yet close flexural properties, compared with the monolithic UHPC slab.
• Functionally-graded (UHPC-CC) vs. monolithic (CC, UHPC) slabs
Application 3: Functionally graded concrete slab
Meng W and Khayat KH, Flexural Performance of Ultra-High Performance Concrete Ballastless Track Slab, Proc. 2016 Joint Rail Conference, Columbia, SC, 2016.
