Materials testing is important when building a road

Hamburg Wheel Tracker

This is the Hamburg Wheel Tracker. The Pavement Materials Testing group uses it to evaluate asphalt mixes and determine whether or not the mix is prone to rutting. The machine rolls a wheel several times over a slab of asphalt concrete to test the mix.

Yesterday we told you about ADOT’s Pavement Materials Testing group and how it is responsible for testing aggregate and creating asphalt friction course mix designs.

Today, we’ll fill you in on everything else they do … starting with preliminary engineering evaluations.

These evaluations start long before construction begins on a project. A good, solid foundation is important when you’re building a road so soil samples get tested by ADOT for a number of things…

In the PI lab material is tested for clay (not a great foundation to build upon).

Then there’s the soil mechanics lab. Here they measure the strength of the soil by putting a vertical load on a sample and measuring the displacement.

There’s also the proctor test, which basically beats the soil with a kind of hammer to test how much construction crews will need to compact the soil for maximum strength.

Binder lab

Finally, there’s the binder lab. This is where asphalt is tested.

Samples come in from projects and the lab makes sure the asphalt will work the way it’s supposed to.

Temperature is very important when it comes to asphalt – this lab tests the asphalt properties at a range of different temperatures. They’ll also test for stress and strain and try to determine how the asphalt will stand up over the years.

More testing

This isn’t all the testing that ADOT does …

Under the umbrella of ADOT’s Materials Group there are several teams responsible for structural materials testing, quality assurance, pavement design and management, and geotechnical design and operations. There are also several regional and area labs that do different types of tests.

We’ll be blogging about these groups soon … so stay tuned!