BATT Lab Forensic Analysis: We get to the bottom of pavement failures.

When a pavement fails prematurely, the owner wants to know who to blame, what is the fix, and who will pay. The consultant and contractor are on the receiving end of the problem. Costly remediations, a complete remove and replacement, or expensive litigation are a few of the reasons why a forensic analysis can be your best strategy for addressing the problem.

Project failures usually stem from out-of-spec materials, subgrade issues, or construction deficiencies. Generally, three parties are involved in a failure dispute — the owner/agency, a consulting engineering firm, and the contractor. Our most recent forensic investigations were requested by engineering firms and contractors.

In our approach to investigation, we first recognize that every project is different, and we respect local knowledge of materials and conditions. BATT begins by gathering all available project data and photos, and then we dig in. A detailed discussion with the client also gives us the groundwork on where to start and focus. Most investigations start by taking core samples of the pavement.

Depending on the problem, we follow a dynamic testing plan that adapts quickly as results from various stages of testing develop. If premature cracking or signs of damage are the problem, the most obvious place to start is an examination of thickness and density of the cores.

Sometimes we find that density was not achieved. For example, we have seen projects that were expected to reach 8% of maximum density, yet measures show 15% or more. That is enough to tell us something is wrong, and we move on to the next stage of testing. It is not uncommon to also see that thickness requirements were not met.

Performance level tests like the Hamburg Wheel Tracker (HWT) or IDEAL-CT can further identify the problem, but more often we focus on the construction specification document. We want to fully understand what the contractor was paid to do, and the contract specification is the guiding document.

An owner may have high expectations for a project, but if limits — density for example — are not specified, then how can a contractor be held accountable if they were unaware that density was part of the inspection?

Contracts usually specify the quantity of material to be placed, followed by the quality of items like asphalt content (%AC) and aggregate gradation. BATT can thoroughly dissect them and chemically remove the asphalt binder (bitumen), capture the aggregate for a gradation, and recover the asphalt binder if needed for further testing. At this point, we have usually discovered the problem. If not, we have other technologies that allow us to examine further.

The forensics process includes a thorough evaluation of your sample, whether core or loose mix. From the time your samples are received at the lab, we begin time-tested procedures to deconstruct and determine what caused the pavement to fail prematurely.

The range of testing available through the BATT Lab can pinpoint how the failure occurred, whether it was in the construction process, a property density or thickness problem, an issue with the binder or aggregate, or a mix design error. Upon completion of our analysis and testing, you’ll have a solid game plan for providing a remedy to the problem.

For more information on our forensic evaluation services, contact info@blankenshipasphalttech.com