Abstract
This study investigated the viability of quantifying the affinity between aggregate and bitumen by means of different imaging techniques. Experiments were arranged in accordance with the rolling-bottle test, as indicated in UNI EN 12697-11, “Test methods for hot bituminous conglomerates—Part 11”. Digital image processing (DIP) techniques have only recently been used for such quantification. The data gathered with a multi-sensor optical platform equipped with VIS–NIR and SWIR spectrometers were compared with DIP outcomes. Data were processed using the unsupervised ISODATA and the supervised parallelepiped algorithms. The exposed aggregate index (EAI) and the bitumen index (BIT) were calculated to retrieve the bitumen percentage coverage of different mixtures. The comparison with the results obtained employing the traditional 6, 24, 48 and 72 testing hours reveals the possibility to implement a standardized analysis methodology combining digital and hyperspectral imagery to highlight potential inaccuracies deriving from the visual interpretation.
Highlights
Hot mix asphalts (HMAs) of road pavements are composed of different combinations of aggregates and bituminous binders
By comparing the different techniques, this study demonstrated that, by means of both VIS–NIR and short-wave infrared (SWIR) spectrometers and a digital camera, an objective quantification of the bitumen loss caused by the stripping process can be obtained and inaccuracies related to visual inspection overcome
The results show no evident decrease of bitumen coverage at 48 and 72 h, while the VIS spectrometer provides similar results (63% and 48%), and a decreasing trend can be observed
Summary
Hot mix asphalts (HMAs) of road pavements are composed of different combinations of aggregates and bituminous binders. The bituminous coverage of the stones using two different methods of digital image analysis is evaluated in [24] This method works for stones of any color because bitumen reflects light much better than rough stones. Different approaches were investigated to extrapolate the degree of bitumen coverage in the rolling-bottle test at 6, 24, 48 and 72 h To achieve this goal, samples of trachytic and limestone mixtures were tested at different temporal steps with supervised (parallelepiped) and unsupervised (iterative self-organizing data analysis technique (ISODATA)) algorithms and compared with several operators’. By comparing the different techniques, this study demonstrated that, by means of both VIS–NIR and SWIR spectrometers and a digital camera, an objective quantification of the bitumen loss caused by the stripping process can be obtained and inaccuracies related to visual inspection overcome
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call