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Concrete Testing: It is costing millions

Concrete Testing: It is costing millions A view of where the results are used….by Jacques Smith Pr Eng. In Disputes…. Somebody measures Somebody disagrees Somebody accuses Somebody defends Somebody pays….. What is on paper is what counts He who claims, must prove….

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Concrete Testing: It is costing millions

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  1. Concrete Testing: It is costing millions A view of where the results are used….by Jacques Smith Pr Eng

  2. In Disputes… • Somebody measures • Somebody disagrees • Somebody accuses • Somebody defends • Somebody pays….. • What is on paper is what counts • He who claims, must prove…

  3. Strength Investigation? Low Results vs No Results Concrete is underperforming The test is underperforming

  4. Cube test • Sampling • Compacting • Curing • Crushing • Interpreting the results • It is a simple test… even the teaboy can do it… • And frequently does…

  5. Cube mould • 100 mm or 150 mm?

  6. Uhm…

  7. Ok, you noticed…

  8. Centre in the machine is key

  9. Curing

  10. Cubes must be submerged

  11. Crushing Cubes

  12. Cubes centre in machine

  13. Incorrect failures

  14. Horizontal crack in cube

  15. See it?

  16. Check the crushed cubes…

  17. So the lab is accredited… • Sampling on site • Make cubes and leave them… no heating device on site • Two days later transported to an accredited lab • Result is done under accreditation

  18. Did the cubes fail? • Sampling • Curing: • Marking and storing, always submerged • Curing tank stirred? Hmm? • Temperature control (always plugged in) • Crushing machine: • Calibrated • Centre in machine with formed faces against platens • Ball seat loose • Loading rate set • Any horizontal cracks in crushed cubes • Recordkeeping

  19. Core Testing

  20. How do we test this???

  21. Cores from an accredited Laboratory

  22. Interpretation of the results • Unless you cook them or crook them ..... • Any mistake will give you a lower result and that costs money! • So now… two accredited labs… one gets 8 MPa on average less than the other… • The engineer is scared… he chooses the lower result • Which one would you choose?

  23. This is what I tell the clients... • Don’t act like an idiot... Learn from others’ mistakes..... • You have the right to know and check • Go and take a look

  24. An Accredited Lab said 0% air and 0.5% in one core only...

  25. Thank You!

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