Application of Imaging Techniques to Evaluate Polishing Characteristics of Aggregates

Previous research conducted at the University of Florida (UF) to investigate the use of the Aggregate Image Measurement System (AIMS) and Micro-Deval (MD) to evaluate frictional performance of aggregates concluded that the current AIMS system cannot be reliably used because color variation in aggregate surfaces have an overwhelming effect on texture as measured by AIMS. In response, a new technique called Photometric Stereo-Independent Component Analysis (PS-ICA) was developed at UF that was able to effectively separate texture from color variation in images obtained by AIMS. The use of AIMS with the PS-ICA method and the MD polishing system was further evaluated in this study to determine its suitability for pre-evaluation purposes to reliably identify aggregates with acceptable frictional performance. Extensive evaluation of texture index (TI) values obtained using the PS-ICA method indicated that the system appeared to effectively mitigate the color variation effect. However, evaluation also revealed that specularity strongly influenced TI values for granite and siliceous wackestone aggregate. An approach developed using the PS-ICA method with modified light intensity was determined to result in the most consistent and reliable TI results for all aggregates evaluated, but the system could not completely mitigate effects of specularity, which causes erroneous results in texture analysis. The best approach to interpret TI values to neutralize effects other than reduction in surface roughness on TI (e.g., specularity) was identified for two types of aggregate: (1) those that exhibit specularity and (2) those that do not exhibit specularity. Thresholds were established for these two aggregate types based on the approaches identified. Independent analysis conducted to evaluate MD performance indicated that MD polishing resulted in polishing levels comparable to those observed in aggregates from in-service pavements. In conclusion, TI obtained from the PS-ICA method with modified light intensity developed for use with AIMS image processing system, along with MD-accelerated polishing technique, can be used for pre-evaluation purposes to effectively screen aggregates with acceptable frictional performance.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 106p

Subject/Index Terms

Filing Info

  • Accession Number: 01630045
  • Record Type: Publication
  • Report/Paper Numbers: 00115827
  • Contract Numbers: BDV31-977-28
  • Files: NTL, TRIS, ATRI, STATEDOT
  • Created Date: Feb 22 2017 12:12PM