Materials and Structures: Recent Research and Innovations - - PowerPoint PPT Presentation

Materials and Structures: Recent Research and Innovations

P.N.Balaguru National Science Foundation Rutgers University

Hotel Caesar Park, Rio de Janeiro, Brazil August 2-6, 2004

Historical Time Line

• Stone (Caves); Cut

Stones without and with mortar

• Bricks; Lime; Portland

Cement

• Timber
• Cast-Iron…….Steel

( ductility )

• High Strength

Composites

Requirements

• Strength
• Stiffness
• Constructability
• Durability
• Cost

New Construction; Rehabilitation

• Earthquakes
• Blast resistance
• Repair: compatibility, specific strength
• Structures less than 75 years old
• Historical structures

Lessons Learned

• Clay bricks are more durable; some structure

are 800 years old

• Concrete is the most versatile construction

material

• Structural Components should be in

compression

• Steel corrodes

Research at NSF

• Infrastructure materials
• Division of Materials

Research

• Division of

manufacturing

Active Research

• Understanding and mitigation of

corrosion

• Improving the durability of concrete
• Enhancing the properties of concrete
• Self healing concrete
• Cement particles as sensors
• High strength composites

Emerging Materials

• High strength

composites

• Alloys
• Titanium
• Highbred

combinations

High Strength Composites Fiber Reinforced Polymers(FRP)

• Fibers: carbon, glass
• Matrix: organic polymers
• Applications: aerospace, ship building,

automobiles, rail cars, infrastructures

FRP

• High Strength
• Low unit weight
• High specific strength
• Corrosion resistance
• Used for more than 40

years

Major Disadvantage

• Resistance to high temperature (fire)
• Loss of life in crash landing
• Vehicle fire
• Fire hazard in transportation structures,

31% as compared to 37% flooding and 8% earthquake

• Restricted use in buildings
• Tunnels

Features of the Inorganic Matrix

• Polysialate (“Geopolymer”)
• Aluminosilicate
• Water-based, non-toxic, durable
• Curing temperature: 20, 80, 150°C
• Resists temperatures up to 1000°C
• Protects carbon from oxidation

Variables

• Fibers; aramid, basalt, carbon, AR glass, E glass,

S glass, high modulus carbon, silicon carbide, steel

• Micro and short fibers, rovings, fabrics, hybrids

Common Tow Reinforcements

Common Fabric Reinforcements

Carbon Fabric with Glass Mat

Main Thrust Areas

• Mechanical properties of composites
• Comparison with other inorganic matrix

composites

• Durability
• Protective and graffiti resistant coatings
• Strengthening; bricks, concrete, reinforced

concrete

• Sandwich panels

Composite Plates

• Hand impregnation
• Room temperature (20°C) or 150 C curing
• Vacuum Bagging under 3 MPa pressure
• Post curing for 3 days
• Room temp. curing reduces degradation of

glass under alkali environment

Typical Hybrid Samples

50 100 150 200 250 300 350 400 450 500 0.2 0.4 0.6 0.8 1 1.2

Strain (%) Flexural Stress (MPa)

3 Layers 2 Layers 1 Layer Glass 3k Unidirectional Carbon

3k Unidirectional Carbon

Matrix (Resin) Hybrid

• Organic resins – high strength,

commercially available products

• Inorganic (Geopolymer) – high temperature

resistance, non-toxic

Hybrid Configurations

• Organic core
• Glass and carbon
• Vinyl ester and epoxy
• Skin
• Glass or carbon
• Inorganic matrix

Core: Strength Skin: Fire protection

Typical Resin Hybrid Samples

Comparison of Polysialate and Other Inorganic Composites

• Carbon/Carbon composites
• Ceramic matrix composites
• Carbon/Polysialate

composites

Stress vs. Strain Relationships of Bi- directional Composites in Tension

Tensile Strength of Bi-directional Composites

Durability Tests: As Coating Material

• WET-DRY EXPOSURE

(0, 50, and 100 cycles)

• SCALING EXPOSURE

(50cycles) Samples Reinforced with:

• 2 and 4% discrete carbon fibers
• 1, 2, and 3 carbon tows
• 1 and 2 layers of carbon fabric

Peak Load of Samples after Wet-dry Exposure

1 2 3 4 5 6 CON 2%FIB 4%FIB 1TOW 2TOW 3TOW 1LAY

Peak Load (kN)

0 cycles 50cycles 100 cycles

Peak Load of Samples after Scaling Exposure

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

CON00 2FIB00 4FIB00 1TOW00 2TOW00 3TOW00 1LAY00 2LAY00 Peak Load (kN) 0 cycles 50cycles

Sandwich Panels

• Balsa wood core
• Lightweight organic
• Lightweight Inorganic
• Cement based

Typical Sample Prior to Test

• Balsa wood core with

inorganic carbon fiber facings

• Smooth & glossy
• Sample dimensions:

– 4 inches wide – 4 inches long – ¼” inch thick

Sample After Fire Testing

• Facings visibly

charred from intense heat

• Rough surface with

minor cracking

• Sample dimensions

change, including weight

Comparison of Strengths

Test vs analytical results

Lightweight Sandwich Panels

• Core features:
• Inorganic matrix + ceramic spheres
• Density: 0.6 to 0.7 g/cm3
• Compressive strength: 5.12 MPa
• Carbon fabric laminated onto facings

Typical Section of Sandwich Slab (Panel)

Lightweight ceramic core Carbon facings on both tension and compression sides

500 1000 1500 2000 2500

P/P PM/P PM/PM 1C/P 2C/P 1C/PM 3T/PM 2C/PM 4T/PM 3T/3T 1C/1C 2C/1C 2C/2C

Load (N)

X/Y: Tension/Compression Side P: Plain PM: Primer C: Carbon Fabric T: Carbon Tows

Flexural Strength of Slabs With Different Reinforcement

Beam Test Setup Beam Test Setup

1600 mm 240 mm 240 mm 560 mm 560 mm

P/2 P/2

26mm 2#3 bars 2#2 bars 160mm 108mm 110mm 57mm

Load Load-

• Deflection Curve

Deflection Curve

10 20 30 40 50 60 70 80 5 10 15 20 25

Deflection (mm)

4O-1 3O-2 2O-1 5IO-2 4IO-2 3IO-2 2IO-1 PC

Crack Patterns: All Specimens

PC 2IO-1 3IO-1

4IO-2 5IO-2

2O-1 3O-2 4O-1

Challenges: Material Science

• Particle dispersion
• Pot life
• Reduction of shrinkage
• Increase of strain capacity

Collaboration

• University of Alabama
• University of Rhode

Island

• University of South

Florida

• Curtin University
• National University of

Singapore

• University of British

Columbia

• Dan-Kook University

Further Research and Applications

• Restoration of historical

buildings

• Earthquake resistant

structures

• Blast and Fire

Resistance, incorporation of Sensors, Special coatings

Emerging Areas

• Self healing Concrete
• Concrete structural

components with no cracks

• Smart Concrete
• Cement particles as

sensors

• Low carbon dioxide

emission

• Concrete with more

strain capacity

Functionally Graded Materials

• Strength and

stiffness

• Durability
• Thermal and noise

insulation

• Blast protection
• Act as sensors
• Healing materials

High strength Composites

• Strengthening of

buildings and bridges

• Chimneys and

storage containers

• Plain and reinforced

concrete

• Masonry structures
• Timber
• Steel

High Strength Composites

• New fibers: carbon

with 640 GPa modulus,

• Basalt, high

strength steel,

• rganic
• New matrices: fire

resistance

• Hybrids: titanium+

carbon+ fire resistant matrix

Feedback

• Questions ?
• Comments ?