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Twining’s team of experts are unparalleled in their knowledge and experience in the fields of concrete, welding, asphalt concrete, materials testing and inspection, and geotechnical engineering. Our experts are frequently called upon to provide support on issues such as thermal monitoring of massive concrete placements, inadequacies of concrete mix designs, unique field and laboratory testing requirements for concrete and structural steel elements, performance and interpretation of non-destructive testing of welds (including phased array evaluations), and value engineering of foundation and pavement designs that are suspected to be overdesigned.

We invite you to challenge our team of registered geotechnical and civil engineers, PhD’s, ASNT Level III professionals, and specialty testing experts with your specific questions on your current or future projects. We are confident that our team, with a combined 255 years serving as experts in their respective fields, will provide useful answers to your technical questions.

Twining Consulting

I am consulting engineer in the amusement industry. I may have a need to have some mountaineering dynamic rope tested. There are a series of tests defined in the standard BS EN892:2012. However, my question right now is; if you were to do just a pull test on the rope for breaking strength, how much rope would be necessary?
Ed Pribonic

Asked by: Ed Pribonic

Hi Eric,

We would suggest you carry out the tests in accordance with BS EN Standard 5.6 on three unused test samples with a minimum length of 5 m for single and half ropes, and 10 m for twin ropes, cut out of the available test sample.

Thanks for using Ask an Expert!

Twining Consulting

What are some ways to improve an asphalt mixture’s moisture damage resistance (higher tensile strength ratio per Lottman test) after it is already treated (1% lime DWA) while keeping aggregate source the same?

Asked by: Ed

Unfortunately, there aren’t many other options to improve the moisture susceptibility other than lime treatment. However, if the dry strength of the samples is good, increasing the asphalt film thickness and using coarser aggregate gradation will reduce the damage during the moisture treatment and will relatively improve the moisture damage resistance.

Please feel free to contact us, to discuss this matter further.

Twining Consulting

Hi, are you providing training for personnel in highway and geotechnical engineering? If yes, please message me back through thanks

Asked by: Mr. Sunday Onadiran


Hello Mr. Onadiran, Twining does provide some training in these fields.  Typically, we provide this as a service to clients and agencies for a specific topic or project.  Please email, so we can understand what you are specifically looking to accomplish with your training and we can more directly address your needs.

Twining Consulting

What are the steps to be able to join your crew into becoming an inspector myself?

Asked by: Michael

Hi Michael,

Assuming you are already an inspector, the first order of business would be to verify your certifications currently held to determine if we have a need for someone with your qualifications.  Secondly, membership in IUOE Local 12 is mandatory, so we would need to know if you are currently in Local 12, or would be willing to join Local 12.  Assuming you are a member or are willing to join, we would then speak with our Dispatch who would provide you with contact information for Local 12 so that you can get on the out of work list which would allow us the opportunity to request an inspector with the qualifications that we need.

Hope this helps, and thank you for asking!

Twining Consulting

Hi, does your lab run oil extractions using a solvent? And what type?

Asked by: Mario

Hi Mario,

Yes, if you are referring to asphalt binder chemical extraction, we use Trichloroethylene. Twining is capable of running chemical asphalt binder extractions following ASTIM D 2172, Method A and B.

Twining Consulting

Is there a Standard (Test Method) for using a thermal imaging camera to confirm grout and resteel installation in a CMU wall?

Asked by: Michael

We are not aware of any Standard test method utilizing thermal imaging cameras to confirm grout and reinforcing steel installation in a CMU wall.  However, Ground Penetrating Radar (GPR), is a non-destructive method that can be used to verify that cells are grouted and also to verify placement of reinforcing steel.

Twining Consulting

Sir, I am having BE,Diploma,Post Diploma in Mechanical engg. I have 9years of experience in material testing lab at INDIAN INSTITUTE OF TECHNOLOGY. So will I be elligible for your company? Thank you.

Asked by: Rabindra Nath Biswal (INDIA)

Hi Rabindra,

Please submit your resume on our website and someone will be in contact with you.

Twining Consulting

Caltrans will begin implementing a range for dry tensile strength for the Lottman Test (AASHTO T283) to 100-300 psi instead of just specifying a minimum dry strength of 100 psi.

Aside from the aggregate source and binder viscosity, what are some ways to reduce the dry tensile strength of a particular HMA mix? For instance, if we have an approved design already but the dry IDT is over 300 psi, what are some ways to adjust the design to reduce the dry strength but still use the same rock source and PG grade for the binder?

Asked by: Ed

Hi Ed,

To better respond to to your question, I would need more information, and to review the Mix Design and Aggregate properties.  This could be a very a project specific answer. By reviewing these, I may be able to come up with a more complete answer. However, here is a list of parameters that can affect the Dry Strength of your mix:

  • Aggregate Gradation: mixes with finer aggregates (higher passing sieve #4) show lower strength
  • Asphalt Binder Content: higher asphalt content lowers the strength
  • Coarse Aggregate Crushed Particles: more crushed surface aggregates will increase the strength
  • Fine Aggregate Crushed Particles: more crushed surface aggregates will increase the strength
  • Use of Natural Sand: usually use of natural sand will reduce the dry strength.

Please note that many other parameters are involved in determining the properties of each mix, and above mentioned factors may not necessarily change the mix properties as expected. Some try and error would be required to come of with the correct resolution. Please feel free to contact me to discuss this matter further.

Amir Ghavibazoon, PhD
Pavement Engineer 

Twining Consulting

Does Twining have the capability to test and quantify a product’s ability to reduce or eliminate ‘thermal bridging’ through a structural steel member and if so is there also a code for this performance which can be listed with the ICC-ES?

Asked by: Tommy Sharp

We would like to discuss this in more detail with you in order to provide a helpful response.

Please contact Esmeralda Martinez at 562.272.7231 ext 144 or

Twining Consulting

My project has a structural steel component to it. Am I required to have shop inspection?

As with almost all questions related to materials testing and inspection, the answer to this question will depend on the authority having jurisdiction over the project.  Per 1704.2.5 of the 2013 California Building Code (CBC) special inspection of structural load-bearing members and assemblies at the fabricator is required.  However, per the exception in 1704.2.5.1 if the fabricator is approved by the building official this requirement is waived.  Each jurisdiction has their own procedure/policy for approval of fabricators so you should verify with the jurisdiction and with your contractor if the fabricators that will be utilized for your project are approved.  In addition, should complete joint penetration welds be performed at the fabricator these will still need to be independently ultrasonically tested as the exception is only for inspection and does not also apply to any testing required.  Please also note that this exception is not present in Chapter 17A which governs DSA and OSHPD projects.