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Quality Control Testing

Quality Control Testing. Mississippi Concrete Industries Association Robert Varner, P.E. Testing Freshly Mixed Concrete. Sampling - ASTM C172 Slump - ASTM C143 Temperature - ASTM C1064 Density - ASTM C138 Air Content - ASTM C231/C173 Strength Specimens - ASTM C31. Sampling - ASTM C 172.

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Quality Control Testing

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  1. Quality Control Testing Mississippi Concrete Industries Association Robert Varner, P.E.

  2. Testing Freshly Mixed Concrete • Sampling - ASTM C172 • Slump - ASTM C143 • Temperature - ASTM C1064 • Density - ASTM C138 • Air Content - ASTM C231/C173 • Strength Specimens - ASTM C31

  3. Sampling - ASTM C 172 • 1 ft3 • Composite sample • Middle of truck • Protect sample

  4. Slump - ASTM C143 • Consistency: The ability of freshly mixed concrete to flow as measured in the slump test. (expressed in inches of slump)

  5. Temperature ASTM C1064 • Affects concrete behavior • May be important in trouble-shooting problems • May be a specification issue

  6. Density - ASTM C138 • Density (Unit Weight) • Weight of concrete divided by a known volume. • Conventional concrete has a unit weight in the range of 137 to 150 pcf • Lightweight: 15 pcf • Heavyweight: 375 pcf • Measured primarily to compute yield

  7. Yield Yield is the volume of concrete produced in a batch (typically expressed in yd 3) yield = Batch weights (Cement,FA,CA,H2O) Unit Weight

  8. Air Content ASTM C 173 - ASTM C231 • Measures entrained (tiny) and entrapped (larger) air voids, expressed as a percentage of the total volume of concrete • Entrained: generally 0.0004” to 0.04” Ø • Entrapped: 0.04” Ø and up • Somewhat a function of aggregate characteristics • Non-air-entrained concrete w/ 1” coarse aggregate has about 1-1/2% entrapped air

  9. Volumetric Method ASTM C173

  10. Pressure Method ASTM C231

  11. Strength Specimens • Cylinders • 6 X 12 • 4 X 8 • Beams • 6 X 6 X 20 • Curing Specimens • Standard curing • Field curing

  12. Making & Curing Concrete Test Specimens ASTM C31 Field ASTM C192 Lab Compressive Strength of Cylindrical Specimens ASTM C39

  13. Making & Curing Concrete Test Specimens ASTM C31 Field ASTM C192 Lab ASTM C 78 Flexural Strength - Third Point Loading

  14. Standard Curing • Curing procedures required by ASTM C 31 for strength specimens that are made for: • Acceptance testing • Checking adequacy of mix proportions • Quality control • Includes 2 curing stages: • Initial curing • Final curing

  15. Initial Curing • Temperature • < 6000 psi – 60 to 80 ° F • ≥ 6000 psi – 68 to 78 ° F • Moisture • Prevent moisture loss • Time • Up to 48 hours

  16. Transportation of Cylinders To Laboratory • Wait 8 hours after final set • Protect with suitable cushioning material • Protect from freezing • Prevent moisture loss • Transportation time not to exceed 4 hours

  17. Final Curing • Temperature • 73° ± 3° F • Moisture • Free moisture on surface at all times • Time • Within 30 minutes after removing the molds until testing

  18. Field Curing Temperature and moisture conditions as close as possible to those of the in-place concrete for curing specimens that are made for: • Strength verification prior to putting the structure or pavement into service • Comparison with test results of standard cured specimens or various in-place test methods • Adequacy of curing and protection of concrete in the structure • Strength check for form or shoring removal

  19. Questions? Mississippi Concrete Industries Association Phone: (601) 957-5274 email: rvarner@mississippiconcrete.com website: mississippiconcrete.com

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