Durability of GFRP Reinforcement in Seawater Concrete. Morteza Khatibmasjedi and Antonio Nanni University of Miami

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2 Durability of GFRP Reinforcement in Seawater Concrete Morteza Khatibmasjedi and Antonio Nanni University of Miami

3 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 Orange County Convention Center Orlando, Florida, USA

4 Introduction (critical issues) Concrete industry uses more than 180 billion gallons of fresh water annually Cement production contributes 5% of annual anthropogenic global CO 2 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 from coastal areas and then washed with fresh water

5 Introduction (challenges) Potential alternatives for concrete constituents: Seawater High chloride content cement (CKD) Recycled Concrete Aggregate (RCA) and Recycled Asphalt Pavement (RAP) Using seawater in concrete is prohibited by codes due to steel reinforcement corrosion. But seawater concrete could be combined with noncorrosive reinforcement

6 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, saltcontaminated aggregates, and non-corrosive reinforcement or SEACON was funded under the aegis of the European research program called Infravation (

7 Consortium Membership Partners 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)

8 Work Packages (WPs)

9 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

10 Durability of SEACON Specimens cast from two different concrete mixes: I. Mix A: benchmark conventional concrete mix II. Mix B: proportions identical to Mix A, but tap-water replaced with seawater from Key Biscayne Bay, FL Materials (lb./yd 3 ) Mix A Mix B Cement (type I II) Fly ash (class F) Fresh water Sea water Coarse aggregate (#57 stone) Fine aggregate (silica sand) Fresh Properties Slump (in.) 4 4 Density (lb./ft 3 ) Air Content (%) 1.3 1

11 Durability of SEACON (Phase I) Compressive Strength (ksi) Cylinder Compressive Strength Tropical Environment Tidal Zone Age (days) Mix A :Conventional Concrete Mix B :Seawater Concrete Subtropical Environment of Miami, FL Tidal Zone at Key Biscayne, FL

12 Durability of Embedded GFRP Bars Phase I : GFRP bars extracted from concrete cylinders exposed to tidal zone for 2 years to study residual mechanical properties Horizontal Shear Strength (ksi) Mix A Mix B Mix A Mix B Pristine 1 year 2 years

13 Durability of Embedded GFRP Bars 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) Mix B (Seawater Concrete) Pristine Bar

14 Durability of SEACON (Phase II) Compressive Strength (ksi) Cylinder Compressive Strength Moisture room Seawater at 140 F Age (days) Mix A Mix B :Conventional Concrete :Seawater Concrete Seawater Immersion at 140 F Moisture room

15 Durability of Embedded GFRP Bars Phase II : GFRP bars embedded in concrete beams and exposed to accelerated conditioning (seawater at 140 F) for a year. They were extracted every 6 months and tested for: I. Tensile properties including tensile chord modulus II. Horizontal and transverse shear strengths III.GFRP microstructure and its interface with concrete

16 Durability of Embedded GFRP Bars Tensile Strength (ksi) Tensile Chord Modulus (Msi) Mix A Mix B Mix A Mix B 0 Mix AMix B Mix AMix B Pristine 6 months 1 year Pristine 6 months 1 year

17 Durability of Embedded GFRP Bars 8 Horizontal Shear Strength (ksi) Mix AMix B Mix AMix B Pristine 6 months 1 year Transverse Shear Strength (ksi) Mix AMix B Mix AMix B Pristine 6 months 1 year

18 Durability of Embedded GFRP Bars Bond 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 F Concrete-GFRP Bond Strength (ksi) Mix AMix B Mix AMix B Mix AMix B Benchmark 6 months 1 year

19 Durability of Embedded GFRP Bars 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) Mix B (Seawater Concrete) Pristine

20 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 same trend of comparable performance between seawater and conventional concrete was observed in bond strength of the GFRP bars.

21 Conclusions 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 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.

22 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

23 Acknowledgements Infravation under grant SEACON ACI Foundation s Concrete Research Council for seed funding

24 Thank! Questions? seacon.um-sml.com