Pavements and Materials Research

Feasibility Study for the Global Evaluation of Segregation in Flexible Pavements with Ultrasound (RP 06-14)

The purpose of the proposed research is to determine the feasibility of using ultrasonic/seismic waves as a global, rapid, reliable and non-biased technique for detecting aggregate segregation beneath the pavement surface for in-place asphalt mixtures. Ultrasound-based methods have been used successfully to identify flaws and to quantify their size and distribution in a range of materials, including composites, metals, and portland cement concrete. A global methodology that is free of the need for operator interpretation could be developed for field inspection of flexible pavements to detect segregation rapidly and accurately by ultrasound.

This proof-of-principle research will take a physics-based approach to determine the feasibility of using ultrasound to detect and quantify segregation in flexible pavements. The research will first examine a spot technique with contact transducers, and then determine the feasibility of using air-coupled ultrasound for a global technique capable of mat wide characterization. Full-scale test slabs will be produced for both spot and global testing in a laboratory environment, and complementary data will be collected by standard methods to benchmark the performance of the proposed global ultrasound-based procedure. These results will be assessed and recommendations as to the potential for field measurements will be made.

For further information, please contact David Jared at 404-363-7569.  

Effectiveness of Anti-Strip Agents in HMA Mixtures (RP 06-23)

There are two objectives of this research study. One purpose of the project will be to evaluate the past field performance of Georgia’s mixes designed with hydrated lime to the performance of Georgia’s mixes designed using liquid anti-strip agents. The second purpose of this research will be to evaluate the long-term effectiveness of anti-strip agents based on laboratory aging procedures and determine which product is best suited for Georgia.

Since 1982, only “off-system” projects (county and city roads not on the state route system) have been allowed to use liquid anti-strip agents. Therefore, the first part of the study will be to identify off-system projects with similar traffic volume, age, aggregate source, and aggregate type as on-system projects. The comparisons will be used to determine the in-place strength and performance of mixtures with liquid anti-strip with similar projects that used hydrated lime in the mixtures. The second part of the project will be to conduct a series of laboratory comparisons using different aging periods to make long-term comparisons of the effectiveness of hydrated lime versus liquid anti-strip.

For further information, please contact David Jared at 404-363-7569.

Assessing Techniques and Performance of Thin PEM Overlay on Micromilled Surface (RP 07-07)

In conjunction with a rehabilitation project on I-75 near Perry, the objectives of this project are to (1) evaluate the quality of paving operations including micromilling and porous European mix (PEM) placement; (2) assess the long-term performance of the PEM overlay; and (3) offer suggestions for revisions to GDOT Specification Section 432, “Mill Asphalt Concrete Pavement” that would include the micromilling operation.

For further information, please contact David Jared at 404-363-7569.  

Categorization of Erosion Control Matting  (RP 07-25)

Development of methodology for designers to 1) assess erosion protection level required for a given ditch; and 2) develop a standardized test protocol that will allow categorization of turf reinforcement mats for erosion protection level required.

For further information, please contact Binh Bui at 404-675-1435.

Inverted Base: Field Evaluation (SRS 07-28)

Gathering of detailed information before, during, and after the construction of an inverted base to gain critically needed understanding of the internal behavior and macro-scale performance of these pavement systems.

For further information, please contact David Jared at 404-363-7569.