2013 Session: 517

• Prediction of Asphalt Pavement Surface Characteristics Using Torque Measurements
  Abstract: Continuous increase in traffic volume in the recent years has resulted in greater surface friction loss of asphalt pavements. While the literature presents several ways of aggregate and asphalt mix screening to ensure that surface characteristics are at an acceptable level of friction to control skid-related accidents, the recommended polishing tests using different accelerated polishing devices are time consuming and labor intensive. Therefore, it is imperative that existing polishing devices be improved to significantly shorten the test duration to a level desired by the industry as well as state and federal agencies. This paper aims at addressing this improvement that uses power unit (or motor) to generate energy enough to rotate the polishing disk at constant rotational speed while being pressed against the specimen surface then read the power needed from the display screen for the following steps.Multiple verification techniques including comparison studies and statistical analyses were used to examine the validity of this improvement. It was found that data collected by the power unit was repeatable and able to precisely detect surface deterioration history for different asphalt mixes with different polish susceptibility in a manner similar to conventional friction and texture measuring devices. Hence, aggregates and mixes were classified based on their surface frictional properties. Additionally, results from this study correlated well with results from other studies using conventional methods. Most importantly, it was found to be possible to cut the polishing test time dramatically by using torque values in lieu of conventional surface quantification methods.
  Authors: Khasawneh, Mohammad Ali; Liang, Robert
  Authors: Khasawneh, Mohammad Ali; Liang, Robert
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 517
  Paper Number: 13-0473
• Laboratory Test Methods for Polishing Asphalt Surfaces and Predicting Their Skid Resistance
  Abstract: In this paper, laboratory test methods reproducing phenomena affecting pavement skid resistance evolution are presented. Polishing tests are performed by Wehner/Schulze machine to simulate the polishing induced by traffic and the binder removal phase (typical for bituminous asphalt concrete). Accelerated ageing tests are performed by a weatherometer, operating conditions being adjusted according to local weather conditions, to simulate the binder ageing responsible for friction increase at early age. With respect to seasonal variations, a new test was developed to evaluate the effect of pollutants deposited on the road and the washing effect of rainfalls. Description of specimens and test procedures is given. Simulations are compared to observations to check their relevance.A model is developed to combine, in a physical way, laboratory test results and give place to a prediction of the friction-polishing duration curve. Conversions are done to predict actual skid resistance variation from laboratory polishing curve. Predictions are compared to road data and results are discussed.
  Authors: Do, Minh-Tan; Kane, Malal; Cerezo, Veronique
  Authors: Do, Minh-Tan; Kane, Malal; Cerezo, Veronique
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 517
  Paper Number: 13-2444
• 4.75-mm SMA on Thin Durable Asphalt Overlays
  Abstract: This paper presents the development of stone matrix asphalt (SMA) with 4.75-mm nominal maximum aggregate size (NMAS) and alternative surfacing cross-section for an asphalt wearing course that may improve pavement performances while controlling costs by using locally available aggregates. The 4.75-mm NMAS dense-graded mix was previously used in a few states in order to reduce layer thickness and for its cost-effective application. However, due to its poor friction and limited performance, it was generally used as leveling binder and placed on low-volume roads. To improve surface texture and its performance, the 4.75-mm SMA is proposed for thinner asphalt overlays in this study. The ultimate goal of this study is to develop the 4.75-mm SMA and evaluate its performance as a wearing course under laboratory and field conditions. Test pavement sections were constructed in October and November 2010 in northern Illinois to evaluate its performance under actual traffic loading. On-site performance tests were conducted, and the results suggest its proper application as an efficient and cost effective wearing course that improves pavement performance.
  Authors: Son, Songsu; Al-Qadi, Imad L.; Zehr, Thomas G.
  Authors: Son, Songsu; Al-Qadi, Imad L.; Zehr, Thomas G.
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 517
  Paper Number: 13-4378
• Development of Predictive Model for Skid Loss of Asphalt Pavements
  Abstract: Pavement friction is one of the primary factors that affect highway safety. Pavements with adequate surface friction reduce the number of wet skidding crashes. The objective of this study is to develop a predictive model for friction loss of pavement surface. The model incorporates parameters that describe aggregate shape characteristics, aggregate resistance to abrasion and polishing, aggregate gradation, and polishing cycles. This model was developed based on the results of a comprehensive experimental program. Square-shape slabs of different asphalt mixtures were prepared in the laboratory using a linear kneading compactor and polished using a wheel-polishing device. The frictional characteristics of the surface of the test slabs were measured after different intervals of polishing and statistical analysis was performed to relate friction to mixture characteristics.
  Authors: Kassem, Emad; Awed, Ahmed; Masad, Eyad A.; Little, Dallas N.
  Authors: Kassem, Emad; Awed, Ahmed; Masad, Eyad A.; Little, Dallas N.
  Year: 2013
  Document Type: Paper
  Subject: Materials; Pavements
  Session: 517
  Paper Number: 13-5229
• Laboratory Test Methods for Polishing Asphalt Surfaces and Predicting Their Skid Resistance
  Authors: Do, Minh-Tan
  Authors: Do, Minh-Tan
  Year: 2013
  Document Type: Presentation
  Subject: Materials; Pavements
  Session: 517
  Paper Number: 13-2444
• 4.75-mm SMA on Thin Durable Asphalt Overlays
  Authors: Son, Songsu
  Authors: Son, Songsu
  Year: 2013
  Document Type: Presentation
  Subject: Materials; Pavements
  Session: 517
  Paper Number: 13-4378