Jun 10, 2019
Use Density Gauges to Assess Mat Quality
BY AsphaltPro Staff
When it comes to quality control/quality assurance, many workers in the field think of the rolling pattern and the density gauges that “double check” the rolling pattern. That’s fair. For this week’s tip, let’s look at what it takes to get the gauge reading.
There are two types of gauges available for getting density measurements of your asphalt mat: nuclear and non-nuclear. A portable nuclear density gauge sounds high-tech and a little “James Bond,” doesn’t it? In the United States—and provinces like Puerto Rico, the Virgin Islands, etc.—you must have formal radiation safety training to be certified as a portable nuclear gauge operator. You also need to meet the U.S. DOT training requirements for 49 CFR 172 Subpart H. If you check with your nuclear gauge OEM, it will likely have a one-day training course that you can take online or in a classroom to achieve your operator’s certificate.
Portable non-nuclear density gauges don’t have radioactive material, thus do not require the same safety training.
Both help you get readings of the densification of the asphalt mat. In other words, when you know that you’re at 97 percent density behind the breakdown roller, you know you’ve got a good mat. If you set the gauge down and discover you have 88 percent density behind the intermediate roller, you know it’s time to make some changes in the rolling pattern. Check out the rolling practices article linked below for some ideas.
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