rutting of hot mix asphalt pavements due to increased number of heavy vehicles, especially in tropical regions, causes several performance problems. large stone asphalt mixtures have more stiffness and shear resistance and so more rutting resistance compared to conventional mixtures. hence, using these mixtures in thick layers of hot mix asphalt pavements at tropical regions could be an appropr...

Indoor air pollution studies have became the focus of increasing regulatory public and research concerns due to the negative impact of their components on the human health and the environment. In the field of road construction, laboratory personnel are exposed to different types of air pollutants; Foremost of which are the asphalt vapours, fumes and dust that have a negative effect on their hea...

• Simulating the micromechanical behavior of asphalt mixes during compaction using DEM. Representing interactions a viscoelastic contact model. The influence temperature on process and compactability. Analyzing internal structure air-void distribution compaction. paper aims to simulate mixtures Discrete Element Method (DEM). between components Porous Asphalt (PA) mixture were represented an Ela...

Putting Research Into Practice Page 10 The National Center for Asphalt Technology (NCAT) has just completed a National Cooperative Highway Research Program (NCHRP) Project: NCHRP 9-11, “Segregation in Hot Mix Asphalt Pavements.” Dr. Mary Stroup-Gardiner was the principal investigator on this project. Segregation has historically been defined to mean localized areas of coarse materials in some a...

This paper aims to characterize the three-dimensional (3D) internal structure evolution of asphalt mixtures under freeze–thaw cycles. Asphalt with three levels design void content (3%, 5%, and 7%) were prepared in laboratory. Subsequently, X-ray computed tomography (CT) tests conducted capture two-dimensional (2D) images samples before after testing. A set image processing techniques for recons...

A review of several past studies clearly shows the effect of reduced air voids on improved fatigue and rutting performance of asphalt mixtures, both in the laboratory and field. Depending on mix type and experiment (which included constant-stress bending beam fatigue testing and field results from WesTrack), fatigue performance improved between 8.2 and 43.8% with a 1% decrease in air voids. Lik...

The road performance decay law of EACRM under freeze-thaw cycles was studied using laboratory tests on the macroscopic scale in order to comprehensively analyze serious damage mechanism emulsified asphalt cold recycled mixture (EACRM) regions during service period. surface cracking behavior, internal void evolution characteristics, and mortar morphology were by means digital speckle, industrial...

The pressure variations associated with a filling undulating pipeline containing an entrapped air pocket are investigated both experimentally and numerically. The influence of entrapped air on abnormal transient pressures is often ambiguous because the compressibility of the air pocket permits the liquid flow to accelerate but also partly cushions the system, with the balance of these tendencie...

This study presents micromechanical finite-element FE and discrete-element DE models for the prediction of viscoelastic creep stiffness of asphalt mixture. Asphalt mixture is composed of graded aggregates bound with mastic asphalt mixed with fines and fine aggregates and air voids. The two-dimensional 2D microstructure of asphalt mixture was obtained by optically scanning the smoothly sawn surf...