Evaluating the Potential for Hot Mix Asphalt Rutting Performance Using Laboratory and Digital Imaging Technique

ABSTRACT The objective of this study is to evaluate the non-structural rutting resistance of six typical Superpave™ mixes used in Ontario for surface course using conventional and advanced methods. Hamburg Wheel Rut Tester (HWRT), Dynamic modulus test, and Digital Imaging Processing (DIP) technique were used in the evaluation. These mixes include two Superpave SP12.5 and four SP12.5 FC2 mixes. Six Superpave Performance Grading (PG) binders and three traffic levels were used in the design of these mixes. The effect of aggregate type and binder type in improving the rutting resistance was investigated. Manual method was used to quantify the shear upheave for all mixes. The common devices in measuring Hot Mix Asphalt (HMA) rutting ignore the effect of shear flow and only measure the effect of densification which might affect the ranking of mixes according to rutting susceptibility. DIP was used for further analysis of aggregate effect on HMA rutting resistance. This included estimating aggregate contacts, segregation and orientation of two dimensional cross section images after loading. This method provides internal structural analysis of HMA in order to understand the failure mechanism in rutting and its relationship with each individual component characteristics. Dynamic modulus test was also conducted to investigate the correlation between the HMA stiffness and rutting. It was found that Dynamic modulus |E*| is very effective for evaluating the resistance of HMA mixtures against rutting due to the strong correlation. The results of this study also showed that DIP provides an indication of HMA rutting potential. Aggregate contacts showed a good correlation with mixture rutting resistance measured manually and by using HWRT. Overall, imaging analysis would assist in the design of long lasting pavement

Targeted nanoparticle binding & detection in petroleum hydrocarbon impacted porous media

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.chemosphere.2018.10.046 © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Targeted nanoparticle binding has become a core feature of experimental pharmaceutical product design which enables more efficient payload delivery and enhances medical imaging by accumulating nanoparticles in specific tissues. Environmental remediation and geophysical monitoring encounter similar challenges which may be addressed in part by the adoption of targeted nanoparticle binding strategies. This study illustrates that engineered nanoparticles can bind to crude oil-impacted silica sand, a selective adsorption driven by active targeting based on an amphiphilic polymer coating. This coating strategy resulted in 2 mg/kg attachment to clean silica sand compared to 8 mg/kg attachment to oil-impacted silica sand. It was also shown that modifying the surface coating influenced the binding behaviour of the engineered nanoparticles – more hydrophobic polymers resulted in increased binding. Successful targeting of Pluronic-coated iron oxide nanoparticles to a crude oil and silica sand mixture was demonstrated through a combined quantitative Orbital Emission Spectroscopy mass analysis supported by Vibrating Scanning Magnetometer magnetometry, and a qualitative X-ray micro-computed tomography (CT) visualization approach. These non-destructive characterization techniques facilitated efficient analysis of nanoparticles in porous medium samples with minimal sample preparation, and in the case of X-Ray CT, illustrated how targeted nanoparticle binding may be used to produce 3-D images of contaminated porous media. This work demonstrated successful implementation of nanoparticle targeted binding toward viscous LNAPL such as crude oil in the presence of a porous medium, a step which opens the door to successful application of targeted delivery technology in environmental remediation and monitoring.Natural Sciences and Engineering Research Council of Canad

Mechanical characterization of PVA hydrogels' rate-dependent response using multi-axial loading.

The time-dependent properties of rubber-like synthesized and biological materials are crucial for their applications. Currently, this behavior is mainly measured using axial tensile test, compression test, or indentation. Limited studies performed on using multi-axial loading measurements of time-dependent material behavior exist in the literature. Therefore, the aim of this study is to investigate the viscoelastic response of rubber-like materials under multi-axial loading using cavity expansion and relaxation tests. The tests were performed on PVA hydrogel specimens. Three hyperelasitc models and one term Prony series were used to characterize the viscoelastic response of the hydrogels. Finite element (FE) simulations were performed to verify the validity of the calibrated material coefficients by reproducing the experimental results. The excellent agreement between the experimental, analytical and numerical data proves the capability of the cavity expansion technique to measure the time-dependent behavior of viscoelastic materials

4D evolutions of cracks, voids, and corrosion products in reinforced concrete materials

Abstract This research paper presents a comprehensive investigation into the corrosion process in reinforced concrete structures using advanced analytical techniques, namely non-destructive X-ray computed tomography (CT) imaging, scanning electron microscopy (SEM) images, energy dispersive x-ray spectrometry (EDS), and Raman spectroscopy. The CT image analysis allowed for the identification and quantification of pore structures, crack propagation, and corrosion progression at different stages of corrosion. CT scanning and data analysis offer valuable 4D (3D spatial + time) insights into corrosion in reinforced concrete, revealing changes in pore sizes, with smaller pores increasing and larger pores decreasing as corrosion progresses. Our investigation reveals dynamic changes in reinforced concrete pores during the accelerated corrosion test leading to new pore formation and cracking. The research identifies two distinct types of cracks: one filled with corrosion products and the other, zipper-like cracks, resulting from the connection of deformed pores without corrosion products. The SEM images and EDS analysis confirmed the absence of corrosion products within these unique zipper cracks, suggesting a different mechanism of crack formation compared to the first type of cracks. The results revealed two distinct categories of corrosion products: iron oxides and iron hydroxides, with their distribution correlated to the duration of accelerated corrosion testing. The integration and verification of results from X-ray CT imaging and Raman spectroscopy established a comprehensive understanding of corrosion-induced damage in the reinforced concrete specimen, shedding light on complex interactions among different corrosion products during the corrosion process. These findings offer crucial insights for better understanding of the corrosion process in reinforced concrete paving the way for future development of effective treatments and strategies to mitigate corrosion impact

Deformable image registration of heterogeneous human lung incorporating the bronchial tree

Purpose: To investigate the effect of the bronchial tree on the accuracy of biomechanical-based deformable image registration of human lungs