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Asphalt Paving and Pavement Maintenance Essentials
By AsphaltPro Staff
W
ith summer paving well under way, AsphaltPro continues a unique-to-us method for examining the equipment, products and services available in the asphalt professional’s marketplace. Of course we still focus on the items relevant to an asphalt business, but we have a new approach to make the focus more useful to you each month. Notice this month that all equipment and services listed in the product gallery relate to the paving side of the industry. From the information we receive and solicit from OEMs and consultants, we’ve selected just the bits that pertain to laying, compacting and testing a gorgeous asphalt mat, or maintaining and preserving any pavement surface, or profiling and testing the road for perfect quality assurance. When you see the Asphalt Paving and Pavement Maintenance Essentials headline for our product gallery, you’ll know you have the latest and greatest in 50 August 2015
the paving/preservation/testing side of the asphalt game. To that end, the team at TransTech has provided the following material for this month’s introduction to the gallery:
Using Electromagnetic Density Gauges to Measure In-Place Density of Asphalt Since the early 1960s, the asphalt paving industry has used nuclear gauges to determine the in-place density of hot mix asphalt (HMA) by a nondestructive manner. Nuclear gauges are classified as containing hazardous materials and can present a concern for both the operator and the general public. A little more than a decade ago, an alternative nondestructive electromagnetic gauge joined the industry and was documented by ASTM in an inter-laboratory study in 2006, ILS 95 and Research Report RR:D04-1033. Let’s take
a look at what this means for contractors using electromagnetic gauges by first describing density testing. While density gauges are routinely used for quality control, a destructive sample is also taken for quality assurance requirements. Essentially, the state or owner needs to independently verify the results of the density gauges, accept the pavement and pay the contractor. A cylindrical sample is sawed or cored from the new pavement and is tested for density and percentage of air voids in the sample by using Archimedes Principle. This procedure involves determining the air dry weight, submerged weight and the saturated surface dry weight of the sample. Using these three values, the in-place density, specific gravity and the percentage of air voids in the sample can be calculated. Nuclear gauges use Cesium 137 as a gamma radiation source and a Geiger