Identifying Segregation in Hot Mix Asphalt Pavements Using Rolling Nuclear Gage Measurements and Infrared Imaging

Identifying Segregation in Hot Mix Asphalt Pavements Using Rolling Nuclear Gage Measurements and Infrared Imaging
Author: M. Stroup-Gardiner
Publisher:
Total Pages: 10
Release: 2000
Genre: HMA segregation
ISBN:

Previous research indicated that density, gradation, and asphalt content change due to segregation. A rolling nuclear gage capable of measuring both density and hydrogen count was evaluated for its ability to detect and measure both density and asphalt content. Eight projects (four recently constructed pavements and four during construction) were used to evaluate this instrument. Longitudinal density profiles were obtained for each project at transverse quarter points across the lane. Additional testing included infrared thermography and traditional destructive testing of cores.

Evaluation of Nonnuclear Density Tests on Hot Mix Asphalt Segregation

Evaluation of Nonnuclear Density Tests on Hot Mix Asphalt Segregation
Author: Chieh-Min Chang
Publisher:
Total Pages: 8
Release: 2007
Genre: Asphalt
ISBN:

Since the identification of segregation on asphalt pavements has been based on visual observations around the world, it is essential to develop a quantitative method to detect the presence and severity of segregation.The nonnuclear density device was selected for the field measurements at nine test sites, and cores were taken for laboratory testing.The nonnuclear density difference between segregated and control areas was found to increase with increasing the segregation severity.For medium or heavy segregated areas, the nonnuclear density difference was more than 90 kg/m3.In medium or heavy segregated areas, the air voids increased by 20 % and the indirect tensile strength decreased by 8 % as compared to the control areas.The criterion to detect segregation was based on the statistical differences in nonnuclear measured density values with a p-value 0.05.If a statistical difference in nonnuclear density between segregated and control areas existed, the chance of aggregate gradation difference in percent passing the 3/8 in., No.4 and No.8 sieves for medium and heavy segregation was 78 and 64 %, respectively.In addition to the field nonnuclear density readings, the material properties of asphalt mixtures obtained from 108 cores, including texture depth and percent air voids were selected as independent variables to develop a model to predict the calibrated nonnuclear density difference between the segregated and control areas.This quantitative model holds a great promise as a tool to identify potential areas of segregation using both lab data and field nonnuclear density measurements for quality assurance purposes.

Measurement of Aggregate Texture and Its Influence on Hot Mix Asphalt (HMA) Permanent Deformation

Measurement of Aggregate Texture and Its Influence on Hot Mix Asphalt (HMA) Permanent Deformation
Author: T. Fletcher
Publisher:
Total Pages: 8
Release: 2002
Genre: Aggregate
ISBN:

Aggregate shape has a significant effect on the performance of asphalt mixes. Designing well-performing asphalt pavements requires developing methods to quantify rapidly and accurately the different aggregate shape properties, and most importantly, relate these properties to performance. Aggregate texture has been identified in several studies to be the shape property that has the most significant influence on asphalt mix performance. This study presents a new procedure for measuring aggregate texture using image analysis techniques. The main advantages of this new procedure are the ability to capture the different sizes of texture elements, to separate the true texture from the color variations on the aggregate surface, and to characterize both fine and coarse aggregates. The procedure is used to measure texture for a wide range of fine and coarse aggregates, and the results are compared with the laboratory performance of asphalt mixes. The analysis shows that the procedure yields detailed information on aggregate texture in a short time. The texture measurements have very good correlation with the resistance of asphalt mixes to permanent deformation measured in the laboratory using different wheel tracking devices.

Estimation of Surface Macrotexture in Hot Mix Asphalt Concrete Pavements Using Laser Texture Data

Estimation of Surface Macrotexture in Hot Mix Asphalt Concrete Pavements Using Laser Texture Data
Author: JN. Meegoda
Publisher:
Total Pages: 11
Release: 2005
Genre: Air voids
ISBN:

This paper describes development of an automated technology to quantify surface segregation seen during construction of hot mix asphalt concrete pavements. Segregation manifested on the surface produces nonuniform surface macrotecture. A laser-based system was used for detection of nonuniform surface macrotexture caused by segregation. Two segregated test sections and a control test section were tested to evaluate the laser texture method. Laser texture data were gathered from three sites, and sand patch and nuclear density tests were performed at 25 ft (7.62 m) intervals along three sections. In addition to the above, visual surveys were performed to confirm the measurements. Based on the test results, it was found that the nuclear density test could not be used to detect surface segregation but it could be used as a confirmation test. Test results from the control section were used to establish a correlation between the sand patch tests and the laser texture data.