Microstructural characteristics of bituminous mix using X-ray CT
- 1 Downloads
The study of internal structure of bituminous paving mixes is very essential to understand its air void (AV) characteristics, which ultimately influences the structural and functional performances of bituminous mixture. The present study is an attempt to investigate the AV properties and their distribution in a profound and precise manner using an effective and quick three dimensional (3-D) high resolution technology such as X-ray micro computed tomography (X-ray CT) combined with the digital image processing tools. Using 3-D images obtained from imaging technique, the internal structure of bituminous mix was visualized and then image analysis was done to determine various AV parameters such as AV content, number of AV, AV size and shape of AV of the compacted bituminous specimen. Two compaction methods, namely Marshall method and Superpave gyratory compaction (SGC) methods were used to prepare dense graded bituminous concrete (BC) specimens. With the help of continuous spatial data obtained from volumetric X-ray CT images, the variation of AV parameters were assessed along the vertical, horizontal and radial directions of the specimens. The results show that the distribution of various AV parameters is quite uniform in radial direction as compared with vertical and horizontal directions. For both compaction methods, higher percent AVs are present in top and bottom parts of the specimens as compared with the middle part of the specimens. Besides, Marshall specimens exhibit more heterogeneity in the distribution of AV parameters in the horizontal direction as compared with SGC specimens.
KeywordsX-ray CT AV parameters sphericity AV distribution
Unable to display preview. Download preview PDF.
The authors gratefully acknowledge the support of Indian Institute of Technology, Kharagpur, West Bengal, India in utilising the X-ray CT facility for image acquisition. The writers also express their thanks to the technical and nontechnical staff of the Highway Laboratory of National Institute of Technology Rourkela, Odisha, India, for their assistance during the material collection and specimen preparation.
- N. Shashidhar, X. Zhong, A. V. Shenoy, E. Bastian, Investigating the role of aggregate structure in asphalt pavements, In Proceedings of the 8th Annual Symposium on Aggregates, Asphalt Concrete, Bases and Fines. International Center for Aggregates Research, Denver, CO, USA, 2000 (CD-ROM).Google Scholar
- L. Tashman, E. Masad, B. Peterson, H. Saleh, Internal structure analysis of asphalt mixes to improve the simulation of Superpave gyratory compaction to field conditions, Assoc. Asphalt Paving Technol. 70 (2001) 605–645.Google Scholar
- K. Eriksen, V. Wegan, Optical Methods for Evaluation of Asphalt Concrete and Polymer-Modified Bituminous Binders, Danish Road Institute, Copenhagen, Denmark, (1993).Google Scholar
- J. Desrues, Tracking strain localization in geomaterials using computerized tomography, X-ray CT for Geomater. (2004) 15–41.Google Scholar
- E. Landis, D. Keane, X-ray micro-tomography for fracture studies in cement-based materials, Inter. Soci. Optical Eng. 3772 (1999) 105–113.Google Scholar
- Ministry of Road Transport and Highways (MoRTH), Specifications for road and bridge works, Indian Roads Congress, New Delhi, India, 2013.Google Scholar
- A. E. Alvarez, A. E. Martin, C. Estakhri, Connected air voids content in permeable friction course mixtures, J. Test. Eval. 37 (3) (2009) 254–263.Google Scholar