The Concrete Convention and Exposition The Concrete Convention and Exposition Durability of GFRP Reinforcement in Seawater Concrete Morteza Khatibmasjedi and Antonio Nanni University of Miami FRPRCS – 13 The 13th International Symposium on Fiber-Reinforced Polymer Reinforcement for Concrete Structures American Concrete Institute Fall 2017 Convention October 14 – 15, 2017
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Durability of GFRP Reinforcement in Seawater Concrete
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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
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