Assessment of Compaction Quality Control Methods – NACOE Best Practice Research

Jun 12, 2020 | Compaction Control, Rail Formation & Ballast Condition Assessment

Plate Load Test Pacific Complete W2B

The acceptance of earthwork and unbound pavement construction in Australia currently relies mostly on density testing and CBRs for Quality Assurance (QA).

Though its National Asset Centre of Excellence (NACoE) research program, Queensland’s Department of Transport & Main Roads sponsored a vital ARRB research project to update test methods acceptable for use for QA of pavement and subgrade materials. This state-of-the-industry study assessed test methods that have the potential to:

(a) reliably provide a direct measure of the strength or in-situ modulus value; and
(b) offer significant time savings in turnaround time of test results.

Methods evaluated included Light Weight Deflectometer’s (LWD’s), PANDA® Instrumented DCP, Clegg Hammer, DCP and Plate Load Testing (PLT). Specifically, the devices evaluated included the Zorn Light Weight Deflectometer, the Anix Instrumented Plate Load Test and PANDA® Instrumented DCP.

Alternative Testing Methods for Quality Assurance NACoE Light Weight Deflectometer PANDA DCP Clegg

Plate Load Test PANDA DCP
In earthworks testing, using density ratios is applied widely in quality control. There are currently many different measuring devices which can provide a more accurate measurement of design parameters (strength or stiffness) and can provide a more direct route for parameter assessment (i.e. limit need for any inclusion of generic relationships). 

Comparisons of density with alternative in-situ testing show the latter provides significant benefits to the industry. Accuracy is not the same as precision, and industry’s reliance on density places an emphasis on precision rather than accuracy, data usability or timeliness of results.

This research has found density measurements are, although precise, not very accurate due to poor correlation with the results of other modulus or strength-based tests.

Presenters:

Part 1: June 2018

Part 1 introduced alternative methods to assess compaction in the field. The advantages, limitations, and fundamentals of the measurement methods are discussed.

Best Practice in Compaction QA for Pavement and Subgrade Materials Year 1 Report Jeffrey Lee, David Lacey & Burk Look NACOE P60 QLD DTMR, Australia Aug 2017
NACOE Advanced Methods for Compaction Quality Control – June 2018 Webinar – Part 1 (Webinar Slides)

Part 2: February 2020

Part 2 compared the limitations, benefits and issues associated with traditional density testing and other types of testing with research data various sites.

You can download the presentation slides and view a recording of the webinar. The presenters were kind enough to answer your questions.

Part 3: March 2020

Part 3 focused on the applications and procedures associated with alternative testing to a density-based approach.

You can download the presentation slides and view a recording of the webinar.

The ZFG 3000 is an excellent tool and should be included in any professional contractors equipment list of assets. This tool should have a similar impact on the construction industry as the laser level. The ability to accurately and reliably measure this aspect of ground condition will improve the quality of the work and remove doubt as to the progress of the project.

I bought my ZFG 3000 and on the same day less than two hours later, it had paid for itself. Using this instrument, I was able to demonstrate scientifically, repeatably and independently the quality of the work that we had completed for our client. Ending the disagreement and creating an improved working relationship. Most jobs are not as confrontational as this was however, most jobs are built to a standard. The contractor can now measure as required, to know on site, at the time of testing if this standard is being achieved.

I strongly recommend the ZFG 3000 Deflectometer to any earthmoving, civil construction contractor. Good luck with your projects.

Jim Bassett

Managing Director, Bassearth Pty Ltd

The Light Weight Deflectometer (LWD) was first used in 1998 by the Minnesota Department of Transportation (Mn/DOT) at the Minnesota Road Research Project. Starting in 2005 the LWD has been used by Mn/DOT as an acceptance tool for the compaction of roadbed and miscellaneous embankment and trench construction, culvert treatments and other tapered construction.

Minnesota Department of Transportation (Mn/DOT)

FH is now routinely using the LWD with very good feedback and useful engineering data. The equipment is an easy to use Zorn LWD.

Laszlo Petho

Pavements Manager, Fulton Hogan

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