Volume 39, Issue 5 (September 2011)
CT Image Entropy Analysis Technique for the Determination of Damage to Indirect Tensile Test of Asphalt Mixtures
This study identifies how the microstructure system of asphalt mixture is influenced by moisture and the Indirect Tensile Test (IDT) using digital image analysis methods. Concepts such as digital image segmentation technology, CT (Computer Tomography) value, grey scale of the image, edge detection, and entropy are introduced and incorporated to describe the image characteristics. The impact of moisture and the IDT test on the mixture is analyzed on 24 scanning sections of two specimens. Two moisture conditions are designed to treat the specimens separately before the indirect tension test according to the specification. The original internal structures of the specimens and the corresponding internal structures after the IDT test are obtained through CT scanning. An edge detection process is conducted to find the micro point contact between the binder and the aggregate using a Laplacian arithmetic operator. Differences in the destruction degree of different moisture conditions in IDT are shown through image entropy calculation. A statistical hypothesis test method, the Student t-test, is introduced to examine the significance of the calculation results. From the viewpoint of statistics, the test and calculation results of the 24 sections of the two specimens are of representative significance.