The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

TESTS FOR THE EVALUATION OFBOND PROPERTIES OF FRP

BARS IN CONCRETEMaurizio Guadagnini, Kypros Pilakoutas, Peter Waldron

Centre for Cement and ConcreteUniversity of Sheffield, Sheffield, S1 3JD, UK

Zenon AchillidesPublic Works Department, Cyprus

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Outline

•Introduction

•Testing Programme

•Pull-out tests and results

•Splitting tests and results

•Conclusions

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

•Bond between concrete and reinforcement is a fundamental aspect of the composite action of reinforced concrete

•Reliable test methods are needed for the characterization of the wide range of FRP reinforcing bars available in the global market

Introduction

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

i-RRT International Round Robin Test for the Evaluation of Bond of FRP Bars in Concrete

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ISIS Canada

6 manufacturers10 FRP bars13 laboratories

CEB-FIPCEB-FIPfib

•To assist international committees to assess test methods for bond

•To provide a comparison of results between different laboratories

•To compare the bond properties of the different bar tested

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Testing Programme: sample specimens

Ribbed20646012SteelS-12

Ribbed41-55517-120710GlassRe-Bars Chile S.A.ReB-G

Peel Ply459008x8GlassEurocrete LtdEUR-G

Ribbed (smooth)417589.8GlassMarshall IndustriesCBAR-G

Ribbed (smooth)114172410.3CarbonMarshall IndustriesCBAR-C

Sand Coated426899.5GlassPultrall IncPUL-G

Sand Coated Helical Wrap40.862015.8GlassHughes BrothersHB-G5

Sand Coated Helical Wrap40.86909.53GlassHughes BrothersHB-G3

Sand Coated Helical Wrap40.87606.35GlassHughes BrothersHB-G2

Sand Coated130280010CarbonSireg SpaSIR-C

Peel ply60135010AramidSireg SpaSIR-A

Surface finishE(GPa)

fu(MPa)

φ(mm)

TypeManufacturerBar

Parameters investigated:- Type of composite- Diameter- Surface treatment

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Testing Programme: sample specimens

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Testing Programme: overview

Pull-out test: to simulate the bond strength of bars in confined conditions

Splitting test (eccentric pull-out): to simulate the bond strength of bars near the surface

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Pull-out Test: specimen set-up and data collection

Pull-out force Average bond stress Average slip End slip

Positioning of the bar in the concrete cube and test set-up

Data collection

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

15.15±1.311.23±0.2834.27±2.95S-12

10.53±0.952.29±1.4632.13±1.50ReB-G

9.24±0.660.70±0.1128.21±4.22EUR-G

21.30±0.871.19±0.0733.52±1.31CBAR-G

16.93±0.671.17±0.2416.53±01.12CBAR-C

9.24±0.660.84±1.0959.16±1.37PUL-G

14.04±1.823.29±0.9655.74±7.23HB-G5

16.44±0.710.87±0.1023.45±1.01HB-G3

16.03±2.451.13±0.1310.15±1.55HB-G2

13.70±0.480.30±0.0521.23±0.75SIR-C

10.01±1.540.64±0.0415.73±2.42SIR-A

τpull-out max(MPa)

δLpeak(mm)

Pu(kN)

Bar

Pull-out Test: results

Specimen PUL-G after pull-out Specimen ReB-G after pull-out

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Pull-out test of specimen SIR-C

Pull-out Test: results

Typical average bond stress vs. slip relationships

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Pull-out Test: results

Pull-out test of HB specimens

Variation in the post peak behaviour withina group of similar bars

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Energy approach:

Energy required to generate a given displacement of the

loaded-end (ω-α)

Energy dissipated during the progression of failure (δ)

Pull-out Test: results

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Splitting Test: specimen set-up and data collection

Pull-out Average bond Average slip End slip crack inducedforce stress displacement

Positioning of the bar in the concrete cube and test set-up

Data collection

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

PCF4.17±1.169.40±2.70S-12

TCF5.15±0.078.05±0.07ReB-G

TCCD3.30±0.664.20±0.82EUR-G

PCF4.30±1.916.47±2.81CBAR-G

PCF3.50±0.955.80±161CBAR-C

TCF5.10±0.957.23±1.40PUL-G

TCF4.40±0.5017.37±2.00HB-G5

TCF4.47±1.866.37±2.58HB-G3

TCF3.27±0.812.07±0.55HB-G2

TCCD5.50±0.878.63±1.42SIR-C

TCCD4.87±1.127.67±1.72SIR-A

Failure mode

τsplitting max(MPa)

Pu(kN)

Bar

Splitting Test: results

The crack pattern observed varied considerably within the whole set of tested specimens as well as within each group

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Instant crack

Sliding crack

Typical crack patterns

Multiple crack

Splitting Test: results

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Conclusions: Reliability of testing methodology

•Pull-out tests seem to yield consistent results (averageCV=8%; maxCV=15%)

•Splitting tests data were highly variable (averageCV=23%; maxCV=40%)

•The natural variability of concrete highly affects splitting behaviour

•Improved instrumentation set-up to reduce error

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Conclusions: Bond behaviour

•Pull through type of failure always occurs in well confined situations

•Bars with smaller diameter develop higher average maximum bond strength

•Sand coated bars seem to perform best

The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004

Splitting to pull-out bond ratio

Conclusions: Bond behaviour (continued)

•Maximum average bond stress in unconfined conditions can be up to 80% lower than in confined conditions