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Status: Implemented 

Using Ground Penetrating Radar (GPR) to Evaluate Air Voids Content in Hot Mix Asphalt (HMA). 

Air voids content is crucial for durability of the HMA as improper content can cause pavement issues like; fatigue cracking, rutting, raveling, bleeding, moisture damage, and accelerate aging. Destructive convectional test, such as coring and measuring the air voids in the laboratory, is localized and doesn’t provide continuous measurement. In addition, core holes provide weak spots within the pavement structure and can aesthetically damage the pavement. Other methods like nuclear density gauges have safety, and environmental concerns. 

The GPR is a non-destructive alternative technique to estimate the air voids content in the HMA. It measures dielectric changes to continuously monitor air voids, providing faster and more reliable QA/QC data and expedite pavement construction. The technique has already been calibrated against the conventional method (Coring) and demonstrated good repeatability and correlation with cores’ measured air voids content (refer to graph below). The technique was used in Al Khor Expressway where it supported  the Client to achieve a Guinness World Record for 25 Km of non-stop Wearing Course paving.

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