“The service life of a road increases if segregation is kept to a minimum” -Paul Angerhofer, MOBA PAVE-IR Specialist-

This blog post covers the most common asked questions in regards to PAVE-IR and thermal segregation.

1. When does asphalt segregation occur?

Segregation occurs if there are high temperature differences during asphalt paving. This shows up as cold spots in asphalt that cannot get compacted properly. This, in turn, means that maintenance and resurfacing costs drop dramatically if the asphalt is paved at the correct, uniform temperature. Signs of wear then do not occur until later, and the road needs to be repaved less frequently.

2. How does a PAVE-IR Scanner work?

The PAVE-IR Scanner measures the surface temperature of the paved material at 61 different measurement points. This is done over the entire mat and in real-time. Besides temperature, additional information such as weather data, wind, and paver speed can also be displayed and documented.

See the video for further details:

3. What are the differences to other methods measuring asphalt temperature?

Other methods of measuring asphalt temperatures are infrared cameras and infrared thermometers. The differences of these tools compared to a scanner are that they only take spot measurements and not measure the complete mat. This means less coverage, no distance data, data savings and reports.

4. How easy is the Scanner to install?

The scanner is mounted on the back of the paver as seen in the picture below. The install itself takes about 2 hours. As stated by one of the PAVE-IR users, “The scanners considerably simplify the recording of temperatures. It is compact and mounted outside of the work area”.

5. How hard is a PAVE-IR System to run?

The system is fairly easy to run after it is set up. Training takes between one and two days in average, depending on the requirements and expertise of the paving crew. The video below is a snapshot of a paving job done with the use of PAVE-IR. There is no immediate work to be done during paving besides monitoring the system and adjusting accordingly.

6. How do you monitor the paving process in real-time?

The PAVE-Project Manager Software displays the data in an easy-to-understand way. The profile in the picture below shows the number of sections (profiles) paved and gives an overview how many sections showed moderate to severe segregation. It also displays the quality of the overall work done that can be seen in the status column. In this case, the majority of the paved sections were done well (green section) and the current test results below show that the asphalt differentials are within set limits.

7. What other data will be collected and why?

Weather data like outside temperature, wind speed, paver stops, and paver speed can also be displayed and monitored.

The temperature map displays at first sight how uniform the asphalt temperature of the laid asphalt is. Cold spots in form of high temperature differentials would be seen as color variations on the screen. The speed diagram shows how continuously the paving process is taking place. This is valuable information considering that continuous paving at a steady pace is an important indicator for a quality-paved road.

8. What is a good versus a bad section? Minimal versus severe segregation?

As described in the paragraph before, there are different levels of segregation. These are minimal, moderate, and severe segregation. The definition of these classifications may slightly vary from state to state or country to country depending on the local or federal road agencies.

In our example, "minimal" segregation class is defined as a zero to twenty-five degrees Fahrenheit variation within the sample area of 150 feet of continuous paving.

"Moderate" segregation is defined as variation between twenty-five to fifty degrees Fahrenheit.

"Severe" segregation is defined above fifty degrees Fahrenheit variation.

9. How much can a contractor influence segregation?

These are several variables relevant that can determine which category is prevalent throughout a project. A good starting point is Paving Practices. This refers to Best Practices from the plant, into trucking and through paving.

These are, for example, the do(s) & don't(s) in hot mix asphalt paving ranging from multiple staggered loads in the trucks to not folding in the wings on the paver hopper.

When using the Best Practices established by the industry and fine-tuning any part of the process to obtain uniformity, contractors can greatly reduce the variation in numbers to achieve the (0-25) degree minimal segregation classification.

Fine-tuning paving machine settings, such as auger height or flow gate adjustments, can already eliminate various types of mechanical segregation.

However, there are uncontrollable variables such as poor environmental conditions, long haul distances, and poor traffic conditions that can throw a wrench into the best of practices making numbers below 25 degrees hard to obtain. Measuring asphalt temperatures, beginning with prep at the plant and continuing all the way through, until the completion of the newly paved road, can keep these variables under control. For further details, please refer to the blog post “A New Era in Paving Quality has begun, starting NOW!”

10. What steps can be taken when the asphalt temperature is getting too low?

The paving crew can use the real-time data to tell the first roller to speed up if they see low temperatures on the screen. Or they can fine-tune their overall paving process by speeding up paving if they suspect low asphalt temperatures for the asphalt that is about to get laid down.

What’s the take-away? “What’s getting measured….is what’s getting done”. One can only react when they see these temperatures in real-time.

Are there some questions that are not covered? Let us know and we will try our best to also answer these!