Characterization of Air Void in Porous Asphalt Mixture Using Image Techniques and Permeability Test

Zhongping Tang,Fanglin Huang,José António Fonseca De Oliveira Correia

doi:10.1155/2021/4560727

Zhongping Tang, Fanglin Huang + Show 1 more

Open Access

https://doi.org/10.1155/2021/4560727

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Abstract

In this study, air void contents and distributions of porous asphalt mixtures along the vertical and horizontal directions were quantitatively measured on planar images. Air void contents were determined using some image techniques; while the permeability was measured by the falling head test. Two aggregate gradations (G1 and G2) and three blow numbers (30, 40, and 50) were chosen to explore the effects of gradation and compaction effort on the porosity and permeability. Results showed that porosities and permeabilities are symmetrically distributed along the middle of the specimens; the porosities and permeabilities got the minimum values around the middle zone. A finer gradation or a significant compaction effort generally led to a lower porosity and permeability coefficient. In the horizontal direction, the air void content showed an increasing trend from the outside layer to the inner layer, indicating the nonuniformity of porosity distribution.

Highlights

Porous asphalt mixture (PAM) is featured by its large drainage capacity, which is generated by the large porosity produced by the gap-graded or open-graded aggregate structure [1, 2]
Objective and Scope e objective of this study is to investigate the content and distribution of air voids in PAMs with different gradations under different compaction efforts
Relationship between porosity and permeability was set. e uniformity of air void content distribution was measured by checking the porosities from the outside to the inner layer

Summary

Introduction

Porous asphalt mixture (PAM) is featured by its large drainage capacity, which is generated by the large porosity produced by the gap-graded or open-graded aggregate structure [1, 2]. Noise reduction effectiveness is another feature that distinguishes PAM with other types of asphalt mixtures [4, 5]. The interconnected porosity of PAM leads to a low-albedo value, which results in a reduction of nighttime urban heat island effect [6]. All these benefits make PAM a sustainable pavement material, which attracts extensive attentions these years

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