Abstract
Morphological characteristics of aggregates have direct impacts on performances of asphalt mixes. This paper aims to investigate the effects of the morphological characteristics of fine and coarse aggregates on the high-temperature viscoelastic properties of asphalt mortars and mixtures. For this purpose, an experimental proportion scheme was designed for asphalt mixes prepared with three different types of aggregates (basalt, andesite and pebble/river sand) based on the simplex lattice design (SLD) method. Three morphological parameters were chosen to characterize shape, angularity and texture of aggregates. Afterwards, the uniaxial compression creep test was conducted for asphalt mixes and the high-temperature viscoelastic properties were obtained based on Burgers model. The effects of fine and coarse aggregates on the viscoelastic properties are analyzed through asphalt mortars and mixtures, respectively. The results showed that aggregate morphological characteristics correlate with the high-temperature viscoelastic properties of asphalt mixes, especially for fine aggregates. Aggregates with complex morphological characteristics are conducive to improving the deformation recovery and anti-deformation of asphalt mixes. Furthermore, coarse aggregates can enhance the anti-deformation of asphalt mixture effectively due to its skeleton effect.
Highlights
Asphalt as a kind of composite material has been widely used in pavement and building constructions
Composite index for fine where Composite index includes composite roundness, composite perimeter index, and erosiondilation area ratio for fine and coarse aggregates abbreviated as fine aggregate (FR), CR, FPI, CPI, FEDR, CEDR, respectively. ai is the gradation percentage of the ith aggregate. indexi is morphological characteristics index (R, PI and EDR) of the ith aggregate
Where Composite index includes composite roundness, composite perimeter index, and erosion-dilation area ratio for fine and coarse aggregates abbreviated as FR, CR, FPI, CPI, FEDR, CEDR, respectively. ai is the gradation percentage of the ith aggregate. indexi is morphological characteristics index
Summary
Asphalt as a kind of composite material has been widely used in pavement and building constructions. Aggregates in asphalt mixtures account for approximately over 90% of mixtures by weight, which play a major role in its stability, durability and mechanical properties. Researchers in many countries have been trying to focus on the influence of aggregate morphological characteristics on performances of asphalt mixture [1,2,3]. A great number of laboratory tests have been developed in previous research to evaluate the morphological characteristics of aggregates. Wilson and Klotz [4] presented a method of measuring angularity using Hough transform for quantitative analysis of aggregate angularity. Kuo et al [5] used a digital image-analysis method to investigate the morphologies of coarse aggregates and effectively quantified the morphological characteristics. The morphological characteristics were found to be correlated well with indirect characterization test results by regression analysis. Wang et al [6]
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