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IPWEA NZ Wellington/Taranaki Branch Meeting

IPWEA NZ Wellington/Taranaki Branch Meeting . Civil Engineering Testing Frequently Asked Questions. A presentation by Bob Smith, Principal Engineer, and Rhys Jones, L aboratory Manager, Opus Wanganui. Scratching the surface. Fundamental question to be answered.

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IPWEA NZ Wellington/Taranaki Branch Meeting

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  1. IPWEA NZ Wellington/Taranaki Branch Meeting Civil Engineering Testing Frequently Asked Questions

  2. A presentation by Bob Smith, Principal Engineer, and Rhys Jones, Laboratory Manager, Opus Wanganui.

  3. Scratching the surface

  4. Fundamental question to be answered When you specify a test, do you understand how you will use the result?

  5. Sampling “The test result is only as good as your sample.”

  6. Frequently Asked Questions • What is the target density for this material? • Is there a quick and easy way to test (especially compaction of small lots)? • How can compaction be over 100%? Can you over-compact soil/aggregate? • What is the difference between Standard, Heavy, and Vibrating Hammer compaction? Which one should we use? • What can we do when we can not achieve the compaction requirements in the specification?

  7. Frequently Asked Questions • Is this compaction curve okay – shouldn’t it be a regular parabolic curve? • How many tests are required – one or one lot? • What are Density Index (ID) and Relative Density (RD)? Are they the same? • What should we do if two labs give different results? • Can you find these test methods for me – Sand Equivalent NZS4402 Part 1:1980 Test 7, Wet Sieving NZS4401:1986 Test 2.8.1?

  8. Frequently Asked Questions • What is the best method to compact sand? • How much sample do you need for testing? • Can you explain what this report is telling me? • What does IANZ accreditation cover? • Why do a wet grading when a dry grading is quicker? • Why do we have to do Insitu CBR tests on the subgrade? • What testing does the specification require me to get carried out? • Why does M/4 require CBR to be tested without a surcharge? Is it done? Does it make a difference?

  9. Typical Compaction Curves SILT material compaction curve Note: Flat dry side, drops off steeply on wet side. Vibrating compaction curve Note: Sometimes flicks up on dry side of optimum

  10. Cohesive Soils • Max Dry Density (MDD) is 1.60 t/m3, therefore 98% of MDD is 1.57 t/m3. • Water content range for 98% of MDD is approx. 21% to 24%. • Should be able to achieve >98% compaction between these water content ranges.

  11. But … beware

  12. Compaction Curves

  13. Which one should we use? • Standard Compaction - General earthworks • Heavy Compaction - Building foundations - Civil structures foundations e.g bridge abutments • Vibrating Compaction - Highways/roads (B/2) - Carparks/driveways

  14. Achieving Compaction

  15. What does the equipment measure? • Each test method measures something specific. - Scala Penetrometer - Clegg Impact Value - Nuclear Density Meter - Benkelman Beam - CBR

  16. Where to from here? • “Specifiers should talk to the laboratory before writing the specification if they want anything other than normal quality tests. Find out the appropriate test method …”

  17. Where to from here? • “… the best time to talk to the laboratory is BEFORE taking the sample, rather than after.”

  18. Where to from here? • “Communication between Contractor, Client, Contractor’s Laboratory, and Consultant’s Laboratory can result in great benefits for all parties. … Working towards the same end.”

  19. Contact details Bob Smith Principal Engineer PO Box 654 Wanganui 4540 Ph 06 349 6616 Email: Bob.Smith@opus.co.nz Rhys Jones Laboratory Manager PO Box 654 Wanganui 4540 Ph 06 349 6640 Email: Rhys.Jones@opus.co.nz

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