High-speed texture measurement of pavements.
This study was conducted to validate high-speed texture measuring equipment for use in highway applications. The evaluation included two high-speed systems and a new static referencing device. Tests were conducted on 22 runway and taxiway test sections from the National Aeronautics and Space Administration's Wallops Flight Facility and 7 surfaces from Virginia's Smart Road. Texture estimates recorded with the high-speed (dynamic) equipment correlated extremely well with estimates made with static referencing methods. The system developed by International Cybernetics Corporation was very functional for most conventional highway surfaces. However, a better correlation may be achieved with the referencing methods by using a system (such as the MGPS surface system developed by the Federal Highway Administration) that produces the American Society for Testing and Materials' standard mean profile depth. Finally, an analysis conducted using the CTMeter (circular track meter, a laser-based but static system) demonstrated an important advantage of combining indices produced from high-definition surface profiles. By comparing the mean profile depth with the root mean square data for a particular surface, it is possible to characterize more fully the shapes that contribute to a pavement's macrotexture.
SEGREGATION IN HOT-MIX ASPHALT PAVEMENTS
This report presents recommended methods and specifications to detect and measure segregation of hot-mix asphalt (HMA) using infrared thermography or ROSANv laser surface texture measurements. It will be of particular interest to materials and construction engineers in state highway agencies, as well as contractor personnel responsible for construction of HMA paving projects. Further, the report contains criteria for classifying the severity of segregation with these measurement techniques and for correlating segregation to rutting potential, loss of fatigue life, permeability, and several other performance-related HMA properties.
DETECTION OF CHANGES OF PAVEMENT TEXTURE MATERIAL RECOGNITION
In order to keep the road network in optimal condition, the pavement manager needs adequate information on the functional and structural condition of the pavements. For this reason the network is periodically monitored by means of visual condition surveys and measurements of evenness and skid resistance. Hardly any monitoring is carried out to gather information on texture although texture is a major factor in noise emission, skid resistance and water spray. KAOC/WMD is developing a method to collect and process texture data to inform the road manager about the functional properties of pavements. As quality of life becomes more and more important, since the late eighties more attention has been paid to safety and environmental issues like noise emission, vibrations and pollution caused by traffic. Most of these aspects are being influenced by surface characteristics and studied by the CROW-workgroup on Surface characteristics. The aim of this workshop is, amongst others, to create the appropriate tools for the design of road surfaces as pavement design not only involves the choice and dimensions of materials in a layered construction but also the optimal choice of surface characteristics. When it comes to design of surfaces, not only initial properties are worth knowing but also behavior in terms of changes of surface texture. The first step in development is detection of the type of surface. The second step will be to relate texture variations to loss of aggregate, post compaction or instability.