durability of gfrp reinforcement in the seacon...

CDCC 2017Fifth International Conference on Durability of FRP Composites for

Construction and Rehabilitation of Structures

Durability of GFRP Reinforcement in the SEACON Project

July 19-21, 2017

Morteza Khatibmasjedi and Antonio NanniUniversity of Miami

Outline

• Introduction• Background• Work Packages (WPs)• WP2 Tasks and Objectives• Durability of SEACON (Concrete)• Durability of Embedded GFRP Bars in SEACON• Conclusions (Past Accomplishments)• Future Activities

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Introduction (critical issues)

• Cement production contributes 5% of annual anthropogenic global CO2

• Concrete industry uses more than 500 million gallon of fresh water annually

• Aggregate is mined from the earth, either dug out of pits or blasted out of quarries. Mining has many significant environmental impacts

• In many countries, sand is being extracted at a rate far greater than its renewal and having a major impact on rivers, coastal and marine ecosystems

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Introduction (challenges)

• Potential alternatives to concrete constituents:– Seawater– High chloride content cement (CKD)– Recycled Concrete Aggregate (RCA) and Recycled

Asphalt Pavement (RAP)• Using seawater in concrete is prohibited by standards

and codes due to associated risks of steel reinforcement corrosion. But seawater concrete could be combined with noncorrosive reinforcement.

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Background

• On October 1, 2015, a consortium of six partners and three collaborators led by the University of Miami started a 2.5-year research project

• This project titled “Sustainable concrete using seawater, salt-contaminated aggregates, and non-corrosive reinforcement” or SEACON was funded under the aegis of the European research program called Infravation (www.infravation.net)

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http://www.infravation.net/

Consortium Membership

Partners• University of Miami (UM)• ATP srl (ATP)• Politecnico di Milano (POLIMI)• Owens Corning (OC)• Buzzi Unicem (BUZZI)• Acciaierie Valbruna (AV)

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Collaborators• Florida DOT (FDOT)• Pavimental (PV)• Titan America (TT)

Work Packages (WPs)

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WP2 Tasks and Objectives

• Production and characterization at lab scale of chloride contaminated concrete (SEACON) developed in WP1 containing GFRP bars (made of E-CR glass fibers in vinyl ester resin)

• Output: evaluation of expected life of SEACON and embedded GFRP bars and recommendation for demo project (Halls River Bridge)

• Tasks:– Properties of GFRP bars– GFRP bars under accelerated conditioning– Recommendations for demos

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Durability of SEACONSpecimens cast from two different concrete mixes:

i. Mix A: benchmark conventional concrete mixii. Mix B: proportions identical to Mix A, but tap-water

replaced with seawater from Key Biscayne Bay

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Materials (lb./yd3) Mix A Mix BCement (type I – II) 560 560Fly ash (class F) 140 140Fresh water 283 -Sea water - 283Coarse aggregate (#57 stone) 1750 1750Fine aggregate (silica sand) 1032 1032

Fresh PropertiesSlump (in.) 4 4Density (lb./ft3) 146.8 147.2Air Content (%) 1.3 1

Durability of SEACON (Phase I)

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0 200 400 600 800

Com

pres

sive

Stre

ngth

(ksi)

Age (days)

Mix A

Mix B

:Conventional Concrete

:Seawater ConcreteTropical EnvironmentTidal Zone

Cylinder Compressive Strength

Subtropical Environment of Miami, FL

Tidal Zone at Key Biscayne, FL

Durability of SEACON (Phase II)

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:Conventional Concrete

:Seawater Concrete

Cylinder Compressive Strength

Seawater Immersion at 60°C

Moisture room0

2

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0 60 120 180 240 300 360 420

Com

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sive

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(ksi)

Age (days)

Mix A

Mix BMoisture roomSeawater at 60°C

Durability of Embedded GFRP Bars

Phase I : GFRP bars extracted from 1 year old concrete cylinders to study residual mechanical properties

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0

1

2

3

4

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6

Mix A Mix B Mix A Mix B

Tropical Environment Tidal Zone

Horizontal Shear Strength (ksi)


SEM imaging to evaluate potential degradation of GFRP microstructure and GFRP-concrete interface. Images were taken from the edges of extracted GFRP bars prone to degradation.

Mix A (Conventional Concrete)

Pristine Bar

Mix B (Seawater Concrete)

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Phase II : GFRP bars embedded in concrete beams with cross section replicating test blocks from bulkhead cap of Halls River Bridge (WP4). Beams exposed to accelerated conditioning (seawater at 60°C) for a year and GFRP bars extracted every 6 months and tested for:

I. Tensile properties including tensile chord modulus II. Horizontal and transverse shear strengths

GFRP microstructure and its interface with concrete also examined using SEM imaging

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0123456789


Pristine 6 months 1 year

Tensile Chord Modulus (Msi)

020406080

100120140160180200



Tensile Strength (ksi)


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Transverse Shear Strength (ksi)

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Horizontal Shear Strength (ksi)


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• The relative bond between the GFRP rebar and concrete was experimentally determined by pullout testing (ACI440.3R).

0

0.5

1

1.5

2

2.5


Lab Environment Seawater Immersion at 60°C

Concrete-GFRP Bond Strength (ksi)


SEM is being used to evaluate potential degradation at GFRP microstructure and GFRP-concrete interface. The edge of extracted GFRP bars which is prone to degradation was imaged.

Mix A (Conventional Concrete)

Pristine

Mix B (Seawater Concrete)

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Conclusions

• Fresh and hardened properties of SEACON evaluated • Mechanical behavior of SEACON after exposure to different

aging conditions comparable to conventional concrete• Residual mechanical and physical properties of embedded

GFRP bars aged in different environments show no degradation

• Microstructure of embedded GFRP bars shown unaltered using SEM imaging

• Recommendation for the demo project (Halls River Bridge) using WP2 outputs

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Future Activities

• Durability of SEACON using micro and macro structural analysis• Mechanical behavior of concrete exposed to different aging

conditions • Residual mechanical and physical properties of embedded GFRP bars

aged under different conditioning regimes• Microstructure of embedded GFRP bars using SEM imaging• Bond between the GFRP rebar and concrete by pullout testing

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Acknowledgements

21

Infravation under grant 31109806.005-SEACON

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Thank

Questions?seacon.um-sml.com

www.youtube.com/seaconinfravation

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!

http://www.youtube.com/seaconinfravation

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