Develop Epoxy Grout Pourback Guidance and Test Method to Eliminate Thermal/Shrinkage Cracking at Post- Tensioning Anchorages Project Manager Rick Vallier Investigators: Irtishad Ahmad, Florida International University Nakin Suksawang, Florida Institute of Technology Khaled Sobhan, Florida Atlantic University John A. Corven, Corven Engineering Inc.

Outline Full-Scale Testing Finite Element Analysis Preliminary Conclusion

Full-Scale Testing 2 sets of pourback with different geometry were tested. – Set 1 consists of irregular shaped pourbacks found on the Le Roy Selmon Expressway – Set 2 consists of rectangular shaped pourbacks. Three v/s ratios (0.26, 0.32, 0.37) were selected based on possible ratios of actual pourbacks. It is highly unlikely that actual pourbacks would exceed these ranges.

Experimental Plan (Set 1) 4 EquationS2S2.5S3 Specimens S2S2.5S3 Number of grout caps n 366 Type ECI grout caps ECI 6-7ECI 6-12ECI 6-19 Grout caps diameter (in) D Grout caps height (in) h Volume of caps (ft 3 ) Pourback height (in) H Pourback width (in) B Clear cover (in) c Area of face surface(ft 2 ) A Length of free edges (ft) L Thickness (in) t Exposed surface (ft 2 ) S=A+(L. t) Volume (ft 3 ) V=(A.t) - V c Volume/surface ratio V/S

Full Scale Pourbacks

Experimental Plan (Set 2) 6 EquationR2R2.5R3 Specimens R2R2.5R3 Number of grout caps n 366 Type ECI grout caps ECI 6-7ECI 6-12ECI 6-19 Grout caps diameter (in) D Grout caps height (in) h Volume of caps (ft 3 ) Pourback height (in) H Pourback width (in) B Clear cover (in) c Area of face surface(ft 2 ) A Length of free edges (ft) L Thickness (in) t Exposed surface (ft 2 ) S=A+(L. t) Volume (ft 3 ) V=(A.t) - V c Volume/surface ratio V/S

Instrumentation Plan (Typical) S2S2.5S3 Number of Thermocouples 12 Number of Vibrating gauges 222 Time48 hours (Record at 10 minutes time interval continuously for 48 hours period after the casting) 7

Formwork Preparation

Mixing Epoxy Grout

Casting Full-Scale Pourbacks

Temperature History Note: Peak Exothermic Temperature based on ASTM D2471 is only 60C (Specimen size is 12 by 12 by 3 in)

Cracked Pourbacks S3 Model R3 ModelS2.5 Model

Actual Pourback Cracked Location 13

Finite Element Analysis (FEA) FEA was performed using ANSYS by first performing thermal analysis followed by thermal stress analysis.

Flow Chart showing Thermal and Stress Analysis Start 1.PRE-PROCESSING A.EXECUTION PARAMETERS  Analysis Type (Transient thermal)  Element Type A.EXECUTION PARAMETERS  Analysis Type (Transient thermal)  Element Type B. MATERIAL PROPERTIES  Conductivity (k)  Specific Heat (Cp)  Density (ρ) B. MATERIAL PROPERTIES  Conductivity (k)  Specific Heat (Cp)  Density (ρ) C. MODEL GEOMETRY  Meshing C. MODEL GEOMETRY  Meshing D. APPLICATION OF LOADS  Heat Generation  Heat Convection (wood)  Ambient Temperature D. APPLICATION OF LOADS  Heat Generation  Heat Convection (wood)  Ambient Temperature E. BOUNDARY CONDITION  Placing Temperature E. BOUNDARY CONDITION  Placing Temperature 2. SOLUTION  Input total time and time step for the solution of temperature 2. SOLUTION  Input total time and time step for the solution of temperature 3. POST-PROCESSING  Obtain and examine results (Time- Temperature Curve) 3. POST-PROCESSING  Obtain and examine results (Time- Temperature Curve) End Start PRE-PROCESSING EXECUTION PARAMETERS  Analysis Type (Transient thermal)  Element Type EXECUTION PARAMETERS  Analysis Type (Transient thermal)  Element Type B. MATERIAL PROPERTIES  Thermal Expansion (α)  Elastic Modulus (E)  Poisson’s ratio (υ)  Density (ρ) B. MATERIAL PROPERTIES  Thermal Expansion (α)  Elastic Modulus (E)  Poisson’s ratio (υ)  Density (ρ) C. MODEL GEOMETRY  Meshing C. MODEL GEOMETRY  Meshing D. APPLICATION OF LOADS  Thermal distribution from thermal analysis D. APPLICATION OF LOADS  Thermal distribution from thermal analysis E. BOUNDARY CONDITION  Constraints at Top, Bottom, Back and Formwork E. BOUNDARY CONDITION  Constraints at Top, Bottom, Back and Formwork 2. SOLUTION  Define Analysis option and Run 2. SOLUTION  Define Analysis option and Run 3. POST-PROCESSING  Obtain and examine Stress results 3. POST-PROCESSING  Obtain and examine Stress results End

ANSYS Models

Material Properties

Results from Thermal Analysis ANSYS Experiment

Results: Contour with Maximum Stress S3 ModelR3 Model

Von Mises Stress at Different Locations

Comparison of Actual Crack Location and ANSYS Model S2.5 Model

R3 Model Comparison of Actual Crack Location and ANSYS Model

Stress Analysis Results Pourback S3 (V/S=0.37)

Preliminary Conclusions The time-temperature curves predicted by the ANSYS finite element model closely matched the data obtained from field experiments. Thermal stresses predicted by FEM around the vicinity of the actual physical crack observed in the field showed close agreement with the limiting tensile strength Both the peak exothermic temperature and the maximum thermal stress increased as V/S ratio increased. For the S-type, the maximum thermal stress reached or exceeded the tensile strength of 24 MPa at V/S ratio between 0.32 and For the R-type, this limit was reached at V/S ratio of about 0.37.