Correlating Laboratory Conditioning with Field Aging for Asphalt using Rheological Parameters

2020 ◽  
Vol 2674 (5) ◽  
pp. 393-404 ◽  
Author(s):  
Runhua Zhang ◽  
Jo E. Sias ◽  
Eshan V. Dave
Keyword(s):  
Asphalt Binder ◽  
Life Time ◽  
Rheological Parameters ◽  
Performance Grade ◽  
Wide Range ◽  
Binder Aging ◽  
Long Term Performance ◽  
Term Performance

Aging has a significant effect on performance of asphalt materials. Reliable characterization of asphalt binder properties with aging is crucial to improving asphalt binder specifications as well as modification and formulation methods. The objective of this study is to correlate the laboratory conditioning methods with field aging using evolution of binder rheological parameters with time and pavement depth. Loose mixtures are aged in the lab (5 and 12 days aging at 95°C, and 24 h at 135°C) and recovered binder rheological properties are compared with those from different layers of field cores. The virgin binder results with 20 h pressure aging vessel (PAV) aging are also included. Binder testing is conducted using a dynamic shear rheometer with a 4 mm plate over a wide range of frequencies and temperatures. Rheological parameters calculated from the master curves, performance grade system, and binder Christensen–Anderson–Marasteanu model are used to evaluate changes with aging. The field aging gradient is evaluated, and the laboratory conditioning durations corresponding with the field aging durations at different pavement depths are calculated. The results show that 5 days of aging can simulate around 8 years of field aging (in New Hampshire) for the top 12.5 mm pavement, and 12 days’ aging can simulate approximately 20 years; 20 h PAV binder aging is not adequate to capture the long-term performance of the pavement. This study provides a way to optimize the laboratory conditioning durations and evaluate the performance of asphalt material with respect to pavement life (time) and depth (location) within the pavement structure.

Long Term Performance of PE4710 Materials in Disinfectant Treated Nuclear Raw Water Systems

2013 ◽  
Author(s):  
Alexander M. Summe ◽  
Douglas P. Munson ◽  
Kenneth Oliphant ◽  
Sarah Chung
Keyword(s):  
Power Plants ◽  
Slow Crack Growth ◽  
Life Time ◽  
Water Systems ◽  
Superior Performance ◽  
Mechanical Degradation ◽  
Service Water ◽  
Long Term Performance ◽  
Term Performance

Degradation of service water systems is a major issue facing nuclear power plants and many plants will require repair or replacement of existing carbon steel piping components. High-density polyethylene (HDPE) has been used in non-safety service water systems for over ten years and has demonstrated superior performance. However, there still exist knowledge gaps around material properties, inspectability, and long-term performance. Specifically, there is a lack of insight on the aging of HDPE piping in disinfectant treated service water systems. This paper summarizes the methodology and results of predicting the expected life time of HDPE piping exposed to oxidizing biocides in numerous end-use scenarios. The aging mechanism of concern is Stage III Chemical-Mechanical degradation, where the polymer is oxidized by biocides and then experiences slow crack growth (SCG). An Aging Model is used to provide general predictions of pipe service life. The results were analyzed for trends and limiting or sensitive operating parameters were identified. For most applications, the specific resin used in the model demonstrated good performance for lifetimes of well over 40 years.

Quantification of the Effect of Binder Source on Flexibility of Long-Term Aged Asphalt Concrete

2020 ◽  
Vol 2674 (9) ◽  
pp. 605-616
Author(s):  
Zehui Zhu ◽  
Punit Singhvi ◽  
Uthman Mohamed Ali ◽  
Hasan Ozer ◽  
Imad L. Al-Qadi
Keyword(s):  
Asphalt Concrete ◽  
Asphalt Binder ◽  
Rheological Parameters ◽  
Index Test ◽  
Performance Grade ◽  
Aged Asphalt ◽  
Aging Conditions ◽  
Aged Binder ◽  
Flexibility Index

Asphalt concrete (AC) aging reduces the resistance of flexible pavements to fatigue, thermal, and block cracking. Therefore, it is critical to understand the effects of AC aging on flexible pavement serviceability. Binder source has a significant effect on AC long-term aging. Therefore, it is necessary to develop a reliable, practical, and systematic method to quantify the effect of binder source on AC cracking resistance. Seven laboratory mixes were designed and produced at three asphalt binder replacement (ABR) levels using various binders, but same binder performance grade (PG). The AC mixes were tested using the Illinois Flexibility Index Test (I-FIT) under unaged and long-term aged conditions. Standard Superpave tests and temperature-frequency sweep tests, were conducted on virgin binders under various aging conditions. By comparing the binder rheological parameters and flexibility index (FI) of long-term aged AC specimens, the [Formula: see text] and m-value after 40-h of aging using a pressure aging vessel (PAV) were identified as valid indicators to reflect the effects of the binder source on AC long-term flexibility. A minimum [Formula: see text] of -8°C and m-value of 0.280 were proposed as the preliminary thresholds. A new parameter, [Formula: see text], which is defined as the m-value of 20-h PAV-aged binder minus the m-value of a 40-h PAV-aged binder, correlates well with the aging rate of AC. A binder with a high [Formula: see text] may induce an excessive drop in flexibility after long-term aging.

Characterization of the Charging and Long Term Performance of Cytop Electret Layers for MEMS Applications

2008 ◽  
Vol 1134 ◽  
Author(s):  
Ulrich Bartsch ◽  
Joao Gaspar ◽  
Oliver Paul
Keyword(s):  
Corona Discharge ◽  
Silicon Substrates ◽  
Charging Station ◽  
Corona Charging ◽  
Initial Charge ◽  
Charge Stability ◽  
Long Term Performance ◽  
Term Performance

AbstractThis paper reports on the characterization of the charge stability of an amorphous fluoropolymer electret called Cytop. Cytop is a dissolved polymer material, compatible with standard micromachining fabrication technologies. In this study, Cytop layers are deposited and patterned on Pyrex and silicon substrates, followed by the electrical poling of the material by corona discharge using a customized charging station. The long-term performance of Cytop as an electret material is evaluated as a function of several relevant charging parameters. The results reveal highly stable layers, able to keep at least 92% of the initial charge 143 days after the corona charging stored at 23°C.

Comprehensive Performance Evaluation of Multiscale Transportation Strategies: Large Metropolitan Planning Organization Methodology

2003 ◽  
Vol 1858 (1) ◽  
pp. 124-132 ◽  
Author(s):  
Brian J. Fineman ◽  
Anthony J. DeJohn ◽  
Keith E. Miller ◽  
Lois M. Goldman
Keyword(s):  
Long Range ◽  
Time Frame ◽  
Decision Makers ◽  
The North ◽  
Metropolitan Planning ◽  
Wide Range ◽  
Long Term Performance ◽  
Term Performance ◽  
Transportation Plan

Innovative structuring of the decision-making process has allowed a large metropolitan planning organization, the North Jersey Transportation Planning Authority (NJTPA), to face the challenge of cooperatively developing a long-range transportation investment agenda in a complex and diverse region. The wide range of applicable geographic scales is a problem when exploring alternative strategies in such a region, so a single, multiscaled, technically based planning analysis was designed and conducted to unify decision makers around a comprehensive set of performance goals and the estimated potential effects of all reasonable actions. The analysis, built within an accelerated 10-month time frame under federal scrutiny, relied on participation by elected officials, planners, engineers, and regional stakeholders. It produced a full regionwide identification of long-term performance needs and an exhaustive assessment and prioritization of location-specific strategies. NJTPA applied this prioritization to select strategies to update its long-range transportation plan and to develop specific immediate guidance for implementation agencies.

Review of the performance of full-scale MBR plants: design, operation and on-site experimental data

2010 ◽  
Vol 5 (2) ◽  
Author(s):  
S.K. Pattanayak ◽  
S. Chang ◽  
M. Theodoulou ◽  
V. Mahendraker
Keyword(s):  
Full Scale ◽  
Design Parameters ◽  
Plant Design ◽  
Treatment Technology ◽  
Wide Range ◽  
Pre Treatment ◽  
Long Term Performance ◽  
Term Performance ◽  
Removal System

The membrane bioreactor (MBR) process has become an effective alternative wastewater treatment technology that produces effluent with excellent quality. Globally, a wide range of municipal and industrial MBR plants are in operation, varying both in size and complexity. The objective of this investigation was to develop a better understanding of the long term performance of MBR plants. To achieve this objective, eight full-scale municipal MBR plants were examined. The methodology included a review of plant design parameters, pre-treatment system, biological operation, membrane operation, disinfection system and nutrient removal system. In addition, on-site tests were done on permeate, final effluent and mixed liquor to understand MBR performance.

scholarly journals Characterization of selective laser-sintered hydroxyapatite-based biocomposite structures for bone replacement

2007 ◽  
Vol 463 (2084) ◽  
pp. 1857-1869 ◽  
Author(s):  
L Hao ◽  
M.M Savalani ◽  
Y Zhang ◽  
K.E Tanner ◽  
R.J Heath ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Porous Structure ◽  
Cell Attachment ◽  
Selective Laser Sintering ◽  
Bone Implant ◽  
Powder Particles ◽  
Long Term Performance ◽  
Term Performance

Integration of the bone into the implant is highly desirable for the long-term performance of the implant. The development of a bone–implant interface is influenced by the surface morphology and roughness, surface wettability and porosity of the implants. This study characterizes these important properties of a hydroxyapatite-based biocomposite structure fabricated by selective laser sintering (SLS) with a comparison to a moulded specimen. The sintered specimens exhibited a rougher surface with open surface pores and a highly interconnected internal porous structure. It was shown that the characteristics of the powder particles used in the SLS provided a more influential means to modify the surface morphology and the features of the internal pores than laser parameter variation. The correlation of wettability and porous structure shows that although surface open pores could help cell ingrowth and bone regeneration, they resulted in a poorer wettability of the materials, which may not encourage initial cell attachment and adhesion. The potential solution to improve the wettability and cell anchorage is discussed.

scholarly journals Characterization of Turbulent Flow Behind a Transcatheter Aortic Valve in Different Implantation Positions

2022 ◽  
Vol 8 ◽  
Author(s):  
Leonardo Pietrasanta ◽  
Shaokai Zheng ◽  
Dario De Marinis ◽  
David Hasler ◽  
Dominik Obrist
Keyword(s):  
Aortic Valve ◽  
Flow Field ◽  
Turbulent Flow ◽  
Aortic Root ◽  
Flow Topology ◽  
Transcatheter Aortic Valve ◽  
Long Term Performance ◽  
Term Performance

The development of turbulence after transcatheter aortic valve (TAV) implantation may have detrimental effects on the long-term performance and durability of the valves. The characterization of turbulent flow generated after TAV implantation can provide fundamental insights to enhance implantation techniques. A self-expandable TAV was tested in a pulse replicator and the three-dimensional flow field was extracted by means of tomographic particle image velocimetry. The valve was fixed inside a silicone phantom mimicking the aortic root and the flow field was studied for two different supra-annular axial positions at peak systole. Fluctuating velocities and turbulent kinetic energy were compared between the two implantations. Velocity spectra were derived at different spatial positions in the turbulent wakes to characterize the turbulent flow. The valve presented similar overall flow topology but approximately 8% higher turbulent intensity in the lower implantation. In this configuration, axial views of the valve revealed smaller opening area and more corrugated leaflets during systole, as well as more accentuated pinwheeling during diastole. The difference arose from a lower degree of expansion of the TAV's stent inside the aortic lumen. These results suggest that the degree of expansion of the TAV in-situ is related to the onset of turbulence and that a smaller and less regular opening area might introduce flow instabilities that could be detrimental for the long-term performance of the valve. The present study highlights how implantation mismatches may affect the structure and intensity of the turbulent flow in the aortic root.

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