Digital image analysis applied in asphalt mixtures for sieve size curve reconstruction and aggregate distribution homogeneity

Digital tools have been applied to study the mechanical and dynamic behavior of asphalt samples, allowing a rapid, simple, and economic analysis process. This work presents the results obtained from the application of digital image processing in asphalt mixtures. First, an algorithm for the digital reconstruction of the sieve size curve for different types of mixtures is developed. Then, with the sample image, the mixture segregation index (homogeneity in the distribution of the aggregates) is determined and this distribution is correlated with the maximum resistance and the work of fracture obtained with the Semicircular bend test (SCB). With images taken with a conventional camera of 18MP, an error of less than 4% is obtained in the reconstruction of the sieve size curve up sieve No.80. It is also evidenced that there is a correlation between the mixture segregation index within the image and the results of th e SCB test, presenting a higher incidence in asphalt mixtures with coarse aggregates. To corroborate the functionality of the m odel, the algorithm was applied for four types of hot mix asphalt (HMA) of different characteristics, such as an open-graded HMA, a dense-graded HMA, one with recycled pavement and the other made with natural asphalt.