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Task Group on Mechanical Behavior of Cement

Task Group on Mechanical Behavior of Cement. 26 th of J une, 201 3 Washington DC. CHARGE. Develop a technical report on the characterization of mechanical behavior of cement and test methods to measure the mechanical parameters of cement in the laboratory . . New Orleans Winter Minutes.

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Task Group on Mechanical Behavior of Cement

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  1. Task Group on Mechanical Behavior of Cement 26thof June, 2013 Washington DC

  2. CHARGE Develop a technical report on the characterization of mechanical behavior of cement and test methods to measure the mechanical parameters of cement in the laboratory.

  3. New Orleans Winter Minutes The meeting was called to order at 11:15 AM. A presentation highlighting the current status of the Task Group was reviewed. Discussion centered on the following: • There is no need to prescribe number of samples and analysis range for a technical report. • Using different control mechanisms for monotonic and cyclic tests is not required • Units of Measure should follow API guidelines • Dimensions of splitting tensile test specimen The next steps are: • Clean up draft procedures • Email to TG volunteers • Receive feedback by Summer meeting The meeting was adjourned around 11:45 AM.

  4. Status of Working Document • Version 6 • Formatted like other Technical Reports • All comments incorporated • Changed units to match API guidelines • Quality control • Acoustic technique • Other improvements

  5. Next Steps • Review and comment period • Comments due by Sept 1st. • Discuss around ATCE meeting? Sept 30th – Oct 4th • Finalize document • Publications Committee • Other needs?

  6. Thank you

  7. Cooperative Series #1 • Plastic Standard • Load Frames: 6 • Consistent E • Avg: 0.565 Mpsi • COV: 4.6% • Consistent ν • Avg: 0.35 • COV: 5.5% • One outlier • Acoustic: 3 • 2 matched • E = 0.68 Mpsi • ν = 0.38

  8. Cooperative Series #1 • Neat H Cement • Load Frames: 4 • Consistent E • Avg: 2.06 Mpsi • COV: 5.3% • One outlier • Consistent ν • Avg: 0.19 • COV: 9.7% • One outlier • Inconsistent Strength

  9. Cooperative Series #1 • Neat H Cement • Splitting Tensile Strength: 4 • Avg: 677 psi • COV: 12.5% • Acoustic • 2 Labs • 0.55 Mpsi and 3.20 Mpsi

  10. Cooperative Series #1 • 40 % Slag Blend • 3 Labs • One outlier • Consistent E • Consistent ν • Inconsistent Strength • No Acoustic Data

  11. Cooperative Series #1 • Summary • Load frames are consistent • Need more data for acoustic • Instrumentation differences can influence stress-strain curve • Different loading applied

  12. Cooperative Series #2

  13. Slurry preparation • Large scale blender • Lab 1, Lab 2, Lab 7 • Regular blender and low-shear mixer • Lab 3, Lab 5 • Regular blender and spatula mixing • Lab 4 • No information • Lab 6 Slurry density measured by Lab 3 using a Helium pycnometer is 13.99 lb/gal.

  14. Specimen density (lb/gal) test results *: Samples prepared by coring from a big specimen **: Sample position is not applicable here since a single mold is used for each sample (samples not cut).

  15. Monotonic compression test(Lab 1-I) Stress-strain curves of three different tests indicate excellent repeatability. Note: Strain is measured by attached extensometers. 0.0001 in./sec displacement control, 2’’ by 4’’ samples

  16. Strain measurement by extensometers vs. by piston displacement (Lab 1-I) Specimen deformation measured by piston displacement in the test frame tends to significantly overestimate the axial strain due to the fact that the test frame and the piston also deform during the test. Both test methods can be used to check repeatability of test results. Measured by Extensometers Measured by piston displacement

  17. Monotonic compression test(Lab 2) Variability in ultimate compressive strength. Note: strain is measured by attached extensometers. Outliers ? 0.0001 in./sec displacement control, 2’’ by 4’’ samples

  18. Monotonic compression test(Lab 3) Loading rate seems to have some effect on test results. Note: Strain is measured by piston displacement. Displacement control, 1.6’’ by 3.2’’ samples

  19. Monotonic compression test(Lab 4-I) Loading rate seems to have some effect on test results. Note: strain is measured by measuring platen to platen displacement during compression. Load control, 1’’ by 2’’ samples

  20. Monotonic compression test(Lab 4-II) Loading rate seems to have some effect on test results. Note: strain is measured by measuring platen to platen displacement during compression. Load control, 1’’ by 2’’ samples

  21. Monotonic compression test(Lab 6: representative test plot) Note: Strain is measured by attached extensometers. Control mode and loading rate not reported, 1.5’’ by 3’’ sample

  22. Cyclic compression test(Lab 1) • Cyclic • 50% of estimated strength (Avg of 3 monotonic test) • Minimum load during unloading was 100 lbf (32 psi). • Lab 1-I • Load control during the entire loading process. • Test data are only partially obtained due to instrumentation errors. • Lab 1-II • Load control during the first cycle • Displacement control during the second half-cycle to failure.

  23. Effective loading rate of a typical displacement-controlled test (Lab 1-I) 0.0001 in./sec displacement control, 2’’ by 4’’ samples

  24. Effect of control mode on stress-strain curve (linear-elastic portion, Lab 1) Control mode (and loading rate) seem to have very little effect on the stress-strain curve of the specimen in the linear-elastic range.

  25. Effect of control mode on measured mechanical properties (Lab 1) *: Standard Deviation **: Coefficient of Variation ***: Only one valid test result was obtained

  26. Cyclic compression test(Lab 1-II: representative test plot) Note: Strain is measured by attached extensometers. Loading rate and sample size are shown in the next two slides.

  27. Cyclic compression test(Lab 1-II: first cycle of three samples) Repeatability of the stress-strain curve of three different tests are acceptable. 31 lbf/sec (10 psi/sec) load control, 2’’ by 4’’ samples

  28. Cyclic compression test(Lab 1-II: second half-cycle of three samples) Repeatability of the stress-strain curve of three different tests are acceptable. 0.0001 in./sec displacement control, 2’’ by 4’’ samples

  29. Variations of measured elastic properties during cyclic loading (Lab 1) *: Young’s Modulus **: Poisson’s Ratio

  30. Cyclic compression test(Lab 4-I: representative test plot of first 3 cycles) Note: strain is measured by measuring platen to platen displacement. Young’s modulus and Poisson's ratio were calculated from test data of the 2nd and 3rd cycles. 0.05 mm/min (3.3 x 10-5 in./sec) displacement control, 1’’ by 2’’ samples

  31. Cyclic compression test(Lab 7: representative test plot) Note: strain is measured by LVDT. Young’s modulus and Poisson's ratio were calculated from test data of the 2nd half-cycle. 0.01 mm/min (6.6 x 10-6 in./sec) displacement control, 1.4’’ by 2.8’’ samples

  32. Comparisons of measured mechanical properties (uniaxial compression tests) *: Samples tested with load control were not included in calculation. **: Previously identified potential outliers were not included in calculation. ***: Uniaxial Compressive Strength, including samples tested cyclically.

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