Monday, November 28, 2011

CT 202 Changes-November 2011

You may have already noticed but Caltrans has posted a new version of CT 202-Method of Tests for Sieve Analysis of Fine and Coarse Aggregates as of November.  Luckily there isn't much change this time.  In fact, the main test method has not changed at all except for some very minor formatting updates.  The noticeable changes to the test method are in Appendix A: Sieve Analysis of Aggregate from Extracted Bituminous Mixtures and are as follows:

  • You no longer need to use a washing solution containing denatured alcohol.  The test method now only requires distilled, deionized, or good-quality tap water as the washing solution.
  • The notes about “sudsing” previously in the materials section of the test method are moved from the materials section to the procedure section.
  • For samples extracted using CT 382, washing of the entire sample is no longer required.  You can now grade the material as if it was a normal sieve analysis (ex. base rock) and only wash the fine aggregate portion.
  • When you add the sample to the wash vessel, you no longer need to add exactly 1000mL of washing solution.  Now you will add “enough water to cover sample”.
  • The test procedure now adds the wetting agent to the wash vessel before shaking.  Previously, although the wetting agent was mentioned in the materials section, the wetting agent was not actually mentioned in the test procedure and as a result was not used.

   That's all! The new test method can be found on the Caltrans website and here.

Friday, November 11, 2011

AMRL and Caltrans together at last?

The last thing from the CalAPA meeting that I thought was worth mentioning to our quality control readers is that Caltrans is currently moving towards using AASHTO test methods in the future.  They plan to require each lab that tests materials for Caltrans jobs to be AASHTO/AMRL certified in the future.  This includes the Caltrans laboratories, and will probably make quite a few independent laboratories happy because there has always been grumblings about how it can't be effective for Caltrans to certify its own laboratories.  With AMRL, the Caltrans laboratories will be certified by a third party, making the entire process more fair.  This will hopefully reduce some of the issues between Caltrans lab results and independent lab results not matching up.

Joe Peterson is not sure at this time whether or not Caltrans will still keep the Caltrans Independent Assurance (IA) program but believes that they probably will because several of the tests that Caltrans requires (CV for example) are not AASHTO test methods and therefore can not be AMRL qualified.

Although this will take the independent lab certifications from being free through Caltrans to having a fee from a AMRL certification company, this is a great move on Caltrans' part.  Like I mentioned before, it should cut down on some of the inaccuracies and trust issues between Caltrans' labs and our labs but it will also save the taxpayers a great deal of money since the IA program will likely be greatly reduced in size and man hours.

The AASHTO/AMRL accreditation information can be found here.  Their system of accreditation is very similar to the Caltrans IA program but is slightly more strict.  You will probably need to update your Quality Control Manual with additional information about your lab, personnel, and procedures and you may also have to implement a few additional lab and calibration procedures into your work.  Your Quality Management System will need to meet the requirement of AASHTO R-18: "Standard Practice for Establishing and Implementing a Quality Management System for Construction Materials Testing Laboratories"  which is for sale for $55 at the online AASHTO Bookstore here.

Good Luck!

Caltrans and Superpave

At the CalAPA meeting on 10/27/11 there was also discussion about Caltrans' movement towards Superpave specifications.  Caltrans plans to have 6 pilot projects with Superpave specifications across the state in 2012 and even more in 2013.  As of right now Joe Peterson (Caltrans Chief of Roadway Materials Testing) is 99% sure that all new Caltrans specifications will be Superpave starting in 2014.

The Superpave specifications are very similar to the specifications that recently came out that we lovingly refer to as new Section 39.  The major difference is that in Superpave specifications, mix designs are creating using a gyratory compactor instead of a kneading compactor.  Here is a video that shows the gyratory compactor in action.

Caltrans has announced the purchase of 12 Pine Instruments Corp. gyratory compactors; one for each of their district labs.  The Pine Instruments website is here.  Although Caltrans will be using the Pine Instruments Corp. compactors there are several companies who make a gyratory compactor that can be used for Superpave mix designs.  The cost per unit is roughly $50-60k.

In other terms of the specifications, most of what we will be doing in Superpave overlaps with the new Section 39 requirements.  The Superpave mix designs are based on the same metrics as new Section 39 where attention will be paid to, not only gradation and oil content, but VMA, VFA, and Air Voids.  The construction and testing specifications for method, standard, and qc/qa jobs will also be the same, though a few of the test value specifications may change slightly due to the new compaction method.

Superpave has been around for quite a long time and has been used in Europe as well as most of the rest of the country for decades.  Although I acknowledge that is is frustrating that we are switching to yet another set of specifications so soon after adapting the new Section 39 specifications, the Superpave mix designs do seem to have good performance records.  It should also be recognized that, despite being behind the times or even in our own world in terms of test methods for quite a few years, Caltrans is finally making an effort to join the rest of the country, something I'm extremely happy about.  The difficult part for suppliers will be that many of the other entities like cities and counties may not switch over to Superpave leaving the suppliers having to produce Medium, Coarse, HMA, and new Superpave designs.  But if we didn't have these types of changes, the job wouldn't be so fun right?

Friday, November 4, 2011

Caltrans' progress with Warm Mix and Hamburg Test

I was able to attend the California Asphalt Pavement Conference last Thursday in Sacramento and it was filled with useful and productive presentations for the quality control community.

The 3rd speaker of the day, Joe Peterson, Caltrans' Chief of Roadway Materials Testing spoke about the implementation of Warm Mix Paving Specifications.  Caltrans has already completed 26 projects with warm mix asphalt and there are 14 projects currently in construction now.  What was impressive to hear was not only the amount of jobs that warm mix asphalt is being used on, but that they have already laid down 1,310,000 tons of it.

As we speak, Caltrans specifications are being drafted in two forms: permissive and required.  The "permissive" specifications will give contractors the option to use warm mix at the contractor's expense.  Caltrans is planning on releasing this specification in January of 2012 so keep your eyes open.  The "required" specifications will require contractors to use warm mix on the job and the contractor will be compensated for the additional cost of warm mix which is pretty much the cost of the additive.  They did not mention an exact date for the release of this specification but they are shooting for next year sometime.  Both specifications will have the same quality standards as the new section 39 hot mix asphalt products for the standard and qc/qa jobs.  Even the method specification is remaining the same, including temperatures.  This is a little bit of a disappointment because one of the perks for the producers is the fuel savings from producing the mix at lower temperatures.

As of July 7, 2011 there are currently only four warm mix technologies that have been approved by Caltrans: Advera, Rediset WMX, Evotherm DAT, and Sasobit.  These processes all use a chemical additive of some sort and can be used on any Caltrans warm mix job with either a permissive spec or required spec.  I'm sure you're wondering, but what about the water injection system?  At this time the water injection system has not been unconditionally approved by Caltrans because they are still doing a few studies on it.  Peterson believed that a decision will be made in the next year about whether to add certain water injection systems to the approved warm mix technologies list.  The list of Caltrans approved products can be found at: Approved Products.  I encourage you to visit it frequently over the next year because I have a feeling that at least three or four new technologies could be added to this list soon. In the mean time, you still have the chance to use the water injection systems and any other warm mix technology not currently on the approved list by submitting your choice of warm mix technology to the Caltrans approval process.  The full approval process can be found at the same link that I mentioned before.  Basically you will submit a brief summary of the technology, results of laboratory and field testing, and evidence that the WMA can perform equal or better than conventional HMA.  You must also specify how the warm mix additive is added to the hot mix in production and provide the Caltrans laboratory with samples in order for them to recreate the process in the lab and run their own tests.

One of the tests that will need to be run on warm mix asphalt is the Hamburg Wheel -Track Test (AASHTO T 324).  This test is being written into the specifications as a requirement at production start-up and once every 10,000 tons.  I'm still examining the test method but will hopefully be posting on the test soon.  On non-warm mix jobs, Caltrans is also looking at the Hamburg test as a replacement for the TSR test.  The machine costs from $40-60k.  The concerning part of the day was when we were told that Caltrans is not planning on putting the machine in each district laboratory.  Although they are 98% sure that this test will be used to measure stability, resistance to raveling, and potentially some moisture sensitivity, they are still not 100% and they don't want to spend the money to put them in all of the laboratories just to find out that there is a new improved test that might be better.  They have one machine in the north part of the state and one in the south part of the state currently.  This is concerning for the producers and private laboratories who may be considering buying this machine.  Up until this point Caltrans seemed very gung-ho about taking this test on permanently but personally I'll be wanting to hold off on buying this very expensive machine until Caltrans can commit to it among their own labs.