The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of GFRP Reinforcement in Seawater

ConcreteMorteza Khatibmasjedi and Antonio Nanni

University of Miami

FRPRCS – 13 The 13th International Symposium on Fiber-Reinforced Polymer Reinforcement

for Concrete StructuresAmerican Concrete Institute Fall 2017 Convention

October 14 – 15, 2017

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

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

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Introduction (critical issues)Currently, the concrete industry uses about 180 billion gallons of freshwater annually. that water could be going to people who are suffering from water shortages.

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Introduction (critical issues)Aggregate is mined from the earth, either dug out of pits or blasted out of quarries. Mining has many significant environmental impacts

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Introduction (critical issues)Sand is being extracted at a rate far greater than its renewal and having a major impact on rivers, coastal and marine ecosystems

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Introduction (critical issues)Cement production contributes 5% of annual anthropogenic global CO2

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Introduction (challenges)• Potential alternatives for concrete constituents:

– Seawater– Recycled Concrete Aggregate (RCA) and Recycled Asphalt

Pavement (RAP)– High chloride content cement (CKD)

• Using seawater in concrete is prohibited by codes due to steel reinforcement corrosion. But seawater concrete could be combined with noncorrosive reinforcement

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

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)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

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

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

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Work Packages (WPs)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

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

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of SEACONSpecimens cast from two different concrete mixes:

– Mix A: benchmark conventional concrete mix– Mix B: proportions identical to Mix A, but tap-water

replaced with seawater from Key Biscayne Bay

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

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of SEACON (Phase I)

0

2

4

6

8

10

12

0 200 400 600 800 1000 1200

Com

pres

sive

Stre

ngth

(ks

i)

Age (days)

Cylinder Compressive Strength

Mix A

Mix B

:Conventional Concrete

:Seawater Concrete

Subtropical Environment of Miami, FL

Tidal Zone at Key Biscayne, FL

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of SEACON (Phase II)

0

2

4

6

8

10

12

0 60 120 180 240 300 360 420

Com

pres

sive

Stre

ngth

(ksi)

Age (days)

Cylinder Compressive Strength

Mix A

Mix B

:Conventional Concrete

:Seawater Concrete

Seawater Immersion at 140°F

Moisture room

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of Embedded GFRP BarsPhase I : GFRP bars extracted from concrete cylinders exposed to tidal zone for 2 years to study residual mechanical properties

0

1

2

3

4

5

6

Mix A Mix B Mix A Mix B

Pristine 1 year 2 years

Horizontal Shear Strength (ksi)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of Embedded GFRP BarsSEM 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)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of Embedded GFRP BarsPhase II : GFRP bars embedded in concrete beams and exposed to accelerated conditioning (seawater at 140°C) for a year. They were extracted every 6 months and tested for:

– Tensile properties including chord modulus – Horizontal and transverse shear strengths – GFRP microstructure and its interface with concrete

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of Embedded GFRP Bars

0

50

100

150

200

Mix AMix B Mix AMix B

Pristine 6 months 1 year

Tensile Strength (ksi)

0

2

4

6

8

10

Mix AMix B Mix AMix B

Pristine 6 months 1 year

Tensile Chord Modulus (Msi)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of Embedded GFRP Bars

01234567

Mix A Mix B Mix A Mix B

Pristine 6 months 1 year

Horizontal Shear Strength (ksi)

05

1015202530

Mix A Mix B Mix A Mix B

Pristine 6 months 1 year

Transverse Shear Strength (ksi)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of Embedded GFRP BarsBond between GFRP rebar and concrete was experimentally determined by pullout test (ACI440.3R). Concrete cubes reinforced with GFRP bars were exposed to accelerated aging in seawater at 140°C.

0

1

2

3

4

5

6

Mix AMix B Mix AMix B Mix AMix B

Benchmark 6 months 1 year

Concrete-GFRP Bond Strength (ksi)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Durability of Embedded GFRP BarsSEM 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)

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Conclusions• Seawater concrete has shown comparable and even

better performance in terms of compressive strength compared to conventional concrete after exposure to different aging regimes

• Tensile properties of GFRP bars embedded in both conventional and seawater concretes are comparable after one-year exposure to accelerated conditioning.

• Seawater concrete appears to have a positive impact on the horizontal and transverse shear strengths of the embedded GFRP bars.

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Conclusions• The same trend of comparable performance

between seawater and conventional concrete was observed in bond strength of the GFRP bars.

• The bond failure occurred at the interface of the sand coating and helically wrapped fibers and bar’s core. This is due to the lower shear strength in these interfaces compared to concrete shear strength.

• Microstructure of embedded GFRP bars shown unaltered using SEM imaging

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Conclusions• Based on one-year data, introducing seawater into

concrete as the mixing water has no significant effect on the durability of GFRP bars.

• Additional research is planned to confirm these results with the aim of predicting the long-term durability of the GFRP reinforcement in both conventional and seawater concretes.

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Future Activities• Durability of SEACON using micro and macro

structural analysis• 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

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Acknowledgements• Infravation under grant 31109806.005-

SEACON

• ACI Foundation’s Concrete Research Council for seed funding

The Concrete Convention

and Exposition

The Concrete Convention

and Exposition

Thank !

Questions? seacon.um-sml.com

http://www.youtube.com/seaconinfravation