Abstract
The warm mix asphalt was fabricated with different moisture contents (0%, 1%, 2%, and 3%) of limestone aggregates using the Superpave gyratory compactor. The moisture susceptibility of asphalt mixtures with an organic wax additive RH was studied. The samples were compacted and tested using the modified Lottman test AASHTO T283, and the X-ray computed tomography technology was used to capture the internal structure images before and after the freeze-thaw cycles. The test results show that the air voids were distributed in the size range of 0–5 mm3 and 5–10 mm3. The number of air voids decreased with the increase of air void size and increased after freeze-thaw cycles. The air void content can be influenced by the residual moisture in aggregates. The higher the moisture content of aggregates is, the larger the air void content is. So, the air void content is likely to be sensitive to moisture damage. The increase ratio of the air void and moisture content of aggregates had good correlation with the indirect tensile strength and tensile strength ratio of the samples. The indirect tensile strength and tensile strength ratio of the samples decreased linearly, and the samples were sensitive to the moisture damage with the increases of increase ratio of the air void/moisture content in aggregates.
Highlights
Moisture susceptibility of warm mix asphalt (WMA) with an organic wax additive based on X-ray computed tomography (CT) technology
Studies from the National Center for Asphalt Technology (NCAT) indicate that mixtures showed a tendency to have problems with rutting and moisture susceptibility if the mixing temperatures are reduced in WMA [4,5,6]. e addition of organic wax additive in mixtures affects the viscosity of asphalt binders
An imaging processing technique is a process of converting an image into a digital form and applying various mathematical procedures to extract signi cant information from the image
Summary
E OAC (optimal asphalt content) of the RHWMA (WMA with RH additive) is determined in accordance to the Marshall Mix design procedures and American Society for Testing and Materials (ASTM) D1559 (2006), and it is 4.8%. E same parameters in the mixture design and tests were selected for all RH-WMA with dried/moist aggregates. E bucket mixer heating method was used to condition the moist aggregates; the following procedures are seen as below:. (iv) e extra distilled water (1.0%, 2.0%, and 3.0% by mass of aggregates) was added to the bucket mixer and mixed with aggregates (the 90 s) to condition the different moist aggregates. RH-WMA samples with dried/moist aggregates were compacted using the Superpave gyratory compactor (SGC). E tomography images of materials without overlapping are obtained by reconstruction algorithms or the distributions of linear attenuation coefficients of X-ray on cross-sections of the materials. E linear attenuation coefficient of a material is not constant and varies as a function of its density. e attenuation of X-ray penetrates the materials with different penetrating energies. e tomography images of materials without overlapping are obtained by reconstruction algorithms or the distributions of linear attenuation coefficients of X-ray on cross-sections of the materials. e CT image is a map of the spatial distribution of the linear attenuation coefficient, where bright regions correspond to high values of the coefficient, vice versa. e differences in densities of two-dimensional slices were used for identification
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