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Modulus of Elasticity and Poisson Ratio of Concrete

Learn how to find the Modulus of Elasticity & Poisson's Ratio of concrete through standardized tests & calculations. Analyze stress & strain data to determine properties accurately. Study by Benjie Cho & Mulugojam Alemu, Undergraduate Civil Engineering students at the University of Southern California.

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Modulus of Elasticity and Poisson Ratio of Concrete

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  1. Modulus of Elasticity and Poisson Ratio of Concrete Benjie Cho and Mulugojam Alemu Undergraduate Civil Engineering Univ.. of Southern California

  2. Objective • Find the Modulus of Elasticity of Concrete • Find Poisson’s Ratio of Concrete

  3. Introduction • Compressive Strength of Concrete • Standardardized test of concrete • American Society for Testing and Materials (ASTM) • Specifications include • Correct mix • Properly affixing strain gauges • Properly capping the cylinder with sulfur

  4. Procedure • Select (5) 4in diameter by 12in length concrete with 28-day age with 4 ksi design strength. • Cap all the bearing surfaces with sulfur to make the end flat. • Mark area where strain gauges will be attached. • Clean area with chemical cleaners and sand paper.

  5. Procedure • Affix strain gauges on their designated area, one vertical and one horizontal, using glue. • Attach wire to strain gauges by soldering. • Test voltage of the strain gauges. • Place and center samples on the Satec Universal Testing Machine. • Connect the wires to the P3500 strain indicator, which in turn is connected to a computer for recording.

  6. Procedure • Set gauge factor to 2.055 +/- .5% and zero the strain readings. • Begin loading the specimens and record values of strain for given loads. • Continue testing until failure of the specimen.

  7. Organizing the data • Compute the stress by dividing the load by the cross-sectional area. • Graph the strength against the vertical and horizontal strains of each specimen. • Find values for the Young’s Modulus and Poisson’s ratio from the data. • Calculate the theoretical values the Young’s Modulus and Poisson’s ratio.

  8. Calculation procedures • Young’s Modulus • E=(s1-s2)/(e2-.000005) • s1=The stress corresponding to the longitudinal strain of 50 micro strain. • s2=The stress corresponding to .4f ‘c. • E2=The longitudinal strain corresponding to s2. • Based on ASTM C 469 • Poisson’s Ratio • n=(Lateral Strain)/(Longitudinal Strain)

  9. Example

  10. Cylinder #2

  11. Cylinder #3

  12. Cylinder #4

  13. Cylinder #5

  14. Selected Values of Stress and Strain

  15. Selected Values of Stress and Strain

  16. Data

  17. Conclusion • All specimens performed under the theorectical values of E. • Average E= 2.60E6 psi • Average Poisson Ratio= .119691

  18. Conclusion • Concrete performed to design specifications. • E= 1.5 - 5 ksi • n= .1 • Xiao, Yan. Experimental Analysis of Engineering Materials. University of Southern California lecture notes 2002.

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