Nuclear Vs. Non Nuclear Density Testing of Asphalt

[BootLegPit]

Presently using core samples and nukes for Quality Assurance in asphalt paving. Contractors want to start using non nuclear devices....such as the Trans Tech PQI 301 or Pavetracker Plus 2701-b. Costs driving factor.

Question.......any links to good test data or comparitive results out there. Looking for side by side testing results with both pros and cons of each method. We are a Gov. Agency looking to phase out nuclear density gear.

 

[Ron]

With any nondestructive method of testing asphalt, I would correlate to cores. Once a correlation is established for the particular asphalt being tested, the method of test is then somewhat irrelevant.

 

[Drumchaser]

Bootleg

Within the last year or so I have been hearing that the non-nuclear gauges are not as accurate as the nuclear. I thought the reasoning (besides cost) was that sometimes the nuke gives bogey readings if not allowed to cool off between successive shots, and the process of dealing with the source material.

If you are having good luck with correlation between cores and nuke.....I would do some research (googleage), and present the results of what the industry (asphalt and or feds) recommends.

I am familiar with the anal retentive characteristics/rules of regulatory agencies in maintaining storage and use on the nuke.

hope this helps

 

[BootLegPit]

Thanks guys, the problem with correlating a nuke or non nuke to cored sample density tests is the results cannot be obtained quickly enough for the contractors. Our consultants turnaround time is 24 hr or greater, by that time the contractors got 3000 tonne on the road.

We'll typically do a test strip at the beginning of the paving job, and do a battery of tests. We then wait for the sample results to get back before allowing the contractor to pave away full bore.

Looks like i will be doing field tests in the spring.

 

[Ron]

BLP....if the contractor wants to change test methods then do another test strip, otherwise continue with nukes since you already have test strip correlation.

Just because the contractor wants to change things doesn't make it happen.

 

[Grouser]

The contractor should be responsible for the quality of the completed construction. Let him do the quality control testing to prevent production delays. You do the QA testing to verify his results. Florida DOT has been doing this now for about 10 years and it works quite well, especially for HMA. It is called Contractor Quality Control and is required for all major roadway materials; conrete, asphalt and earthwork.

The contractor can work through the state or regional road builders association to get the state DOT to allow alternate testing procedures.

Cheers

 

[Hoaokapohaku]

I don't know where to find the comparative data you seek. However, any method alternative to cores would have to be correlated to cores. I have no experience with non-nuclear alternatives, but I would think if one evaluated the variability of non-nuc test results in comparison to the variability of nuclear test results and increased or decreased the number of required tests as needed to compensate for a higher or lower standard deviation, the non-nuc results should be as accurate as the nuclear results.

In the case where a contractor wants to change methods in an ongoing project where the test strip is already completed and approved, both the nuc and non-nuc methods could be employed on prodution paving and the results compared. If the adjusted sample size non-nuc method repeatedly produces averages reasonably equal to the nuclear method, there would be no reason not to allow the change.