Modelling and Laboratory Studies on the Adhesion Fatigue Performance for Thin-Film Asphalt and Aggregate System

Adhesion between asphalt and aggregate plays an important role in the performance of asphalt mixtures. A low-frequency adhesion fatigue test was proposed in this paper to study the effect of environment on the asphalt-aggregate adhesion system. The stress-based fatigue model had been utilized to describe the fatigue behavior of thin-film asphalt and aggregate system. The factors influencing the adhesion fatigue performance were also investigated. Experiment results show that asphalt has more important effect on the adhesion performance comparing with aggregate. Basalt, which is regarded as hydrophobic aggregates with low silica content, has better adhesion performance to asphalt binder when compared with granite. The effects of aging on the adhesion fatigue performance are different for PG64-22 and rubber asphalt. Long-term aging is found to reduce the adhesion fatigue lives for rubber asphalt and aggregate system, while the effect of long-term aging for aggregate and PG64-22 binder system is positive. Generally the increased stress amplitude and test temperature could induce greater damage and lead to less fatigue lives for adhesion test system.

Download Full-text

Properties of Pavement Bitumens Assessed Using European and American Approach

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.737.554 ◽

2017 ◽

Vol 737 ◽

pp. 554-559

Author(s):

Pavel Coufalik ◽

Ondrej Dasek ◽

Petr Hyzl ◽

Iva Krcmova

Keyword(s):

United States Of America ◽

Fatigue Behavior ◽

Asphalt Binder ◽

The United States ◽

Asphalt Binders ◽

Short Term ◽

European Standards ◽

Unites States ◽

Key Parameter

This paper compares the different approaches to assessing asphalt binders used in Europe and the Unites States. A series of pavement bitumens is assessed using European standards and also by the Performance Graded Asphalt Binder Specification based on AASHTO MP 1, which was developed as part of the Strategic Highway Research Program (SHRP) in the United States of America. The results show that the European approach places high requirements on the pavement bitumens in relation to their behavior at low-temperatures, while in case of the American approach, the key parameter is fatigue behavior after short-term and long-term aging. It is evident that it is necessary to evaluate properties of pavement bitumens after long-term aging in Europe, too.

Download Full-text

Aging Influence on Fatigue Characteristics of RAC Mixtures Containing Warm Asphalt Additives

Advances in Civil Engineering ◽

10.1155/2010/329084 ◽

2010 ◽

Vol 2010 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Feipeng Xiao ◽

Wenbin Zhao ◽

Serji N. Amirkhanian

Keyword(s):

Fatigue Life ◽

Aging Process ◽

Fatigue Behavior ◽

Asphalt Binder ◽

Crumb Rubber ◽

Dissipated Energy ◽

Negative Effect ◽

Rubberized Asphalt Concrete ◽

Term Performance

Aging is an important factor to affect the long-term performance of asphalt pavement. The fatigue life of a typical warm mix asphalt (WMA) is generally related to various factors of rheological and mechanical properties of the mixture. The study of the fatigue behavior of the specific rubberized WMA is helpful in recycling the scrap tires and saving energy in terms of the conventional laboratory aging process. This study explores the utilization of the conventional fatigue analysis approach in investigating the cumulative dissipated, stiffness, and fatigue life of rubberized asphalt concrete mixtures containing the WMA additive after a long-term aging process. The aged beams were made with one rubber type (−40 mesh ambient crumb rubber), two aggregate sources, two WMA additives (Asphamin and Sasobit), and tested at 5 and20ºC. A total of 55 aged fatigue beams were tested in this study. The test results indicated that the addition of crumb rubber extends the fatigue resistance of asphalt binder while WMA additive exhibits a negative effect. The study indicated that the WMA additive generally has an important influence on fatigue life. In addition, test temperature and aggregate source play an important role in determining the cumulative dissipated energy, stiffness, and fatigue life of an aged mixture.

Download Full-text

Performance of Noise Reduction and Skid Resistance of Durable Granular Ultra-Thin Layer Asphalt Pavement

Materials ◽

10.3390/ma13194260 ◽

2020 ◽

Vol 13 (19) ◽

pp. 4260

Author(s):

Wei Li ◽

Sen Han ◽

Qibo Huang

Keyword(s):

Thin Layer ◽

Asphalt Binder ◽

Resistance Index ◽

Test System ◽

Maximum Aggregate Size ◽

Skid Resistance ◽

Fine Aggregate ◽

Asphalt Rubber ◽

Pavement Thickness

In this paper, the ultra-thin layer (UTL) is defined as the dense framework structure mixture made of asphalt binder, fine aggregate with nominal maximum aggregate size (NMAS) not greater than 13.2 mm and possible additives (mineral or organic), thickness of 2–4 cm. The study aims to investigate comprehensive performance of UTL asphalt mixture. The method of impact freeze thaw split test and the index of impact freeze–thawing damage degree (IFTDD) are proposed to reflect the durability. The indoor tire-rolling-down test system and accelerated abrasion machine are used to simulate the tire-pavement interaction and test road noise and skid resistance, respectively. Though evaluating the influencing factors (pavement thickness, gradation, asphalt binder type, and the content of KS additive) on durability, the optimum parameters with excellent durability are recommended. Combined with the test of noise and skid resistance, the factors affecting the surface function are analyzed. Moreover, the prediction mathematical model of skid resistance and the long-term safety benefit value Eeff are put forward. Results indicate that pavement thickness is the most significant factor effecting on durability, and gradation is the most significant factor affecting noise. Compared with KS additive, gradation has a greater influence on skid resistance index of Texture Depth (TD), whereas, KS additive is the most significant factor affecting British Pendulum Number (BPN). Furthermore, with the addition of asphalt rubber (AR), IFTDD and noise are reduced by 29.17% and 1.6 dB, and BPN and TD increase by 0.7 and 0.03 mm, remarkably. Compared with different asphalt types, the noise of UTL asphalt rubber mixture with 13.2 mm NMAS (UTL13 AR) is the lowest. Additionally, when KS content increases by 0.6%, the noise increases by 3 dB. Furthermore, on the basis of the calculation results of Eeff, UTL13 AR mixture with 0.5% KS has the best long-term benefit of pavement safety and is recommended for field project.

Download Full-text

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

American Journal of Audiology ◽

10.1044/1059-0889.0104.52 ◽

1992 ◽

Vol 1 (4) ◽

pp. 52-55 ◽

Cited By ~ 4

Author(s):

Gail L. MacLean ◽

Andrew Stuart ◽

Robert Stenstrom

Keyword(s):

High Frequency ◽

Sound Pressure ◽

Low Frequency ◽

Test System ◽

Output Frequency ◽

Frequency Effects ◽

Adult Men ◽

Frequency Responses ◽

Significant Difference ◽

Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

Download Full-text

Long Term Effects of Low Frequency (10 Hz) Vagus Nerve Stimulation on EEG and Heart Rate Variability in Crohn's Disease: A Case Report

Brain Stimulation ◽

10.1016/j.brs.2014.08.001 ◽

2014 ◽

Vol 7 (6) ◽

pp. 914-916 ◽

Cited By ~ 26

Author(s):

Didier Clarençon ◽

Sonia Pellissier ◽

Valérie Sinniger ◽

Astrid Kibleur ◽

Dominique Hoffman ◽

...

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Crohn’S Disease ◽

Case Report ◽

Vagus Nerve ◽

Nerve Stimulation ◽

Vagus Nerve Stimulation ◽

Low Frequency ◽

Long Term Effects

Download Full-text

Achieving over 4% efficiency for SnS/CdS thin-film solar cells by improving the heterojunction interface quality

Journal of Materials Chemistry A ◽

10.1039/d0ta06937j ◽

2020 ◽

Vol 8 (39) ◽

pp. 20658-20665 ◽

Cited By ~ 2

Author(s):

Jae Yu Cho ◽

SeongYeon Kim ◽

Raju Nandi ◽

Junsung Jang ◽

Hee-Sun Yun ◽

...

Keyword(s):

Thin Film ◽

Solar Cells ◽

Vapor Transport ◽

Thin Film Solar Cells ◽

Interface Quality ◽

Heterojunction Solar Cells ◽

Term Stability ◽

Long Term Stability ◽

Cds Thin Film

The highest efficiency of 4.225% for vapor-transport-deposited SnS absorber/CdS heterojunction solar cells with good long-term stability over two years is achieved.

Download Full-text

Induction of long-term potentiation without participation of N-methyl-D-aspartate receptors in kitten visual cortex

Journal of Neurophysiology ◽

10.1152/jn.1991.65.1.20 ◽

1991 ◽

Vol 65 (1) ◽

pp. 20-32 ◽

Cited By ~ 47

Author(s):

Y. Komatsu ◽

S. Nakajima ◽

K. Toyama

Keyword(s):

Nmda Receptors ◽

Stimulus Frequency ◽

Low Frequency ◽

Nmda Antagonist ◽

Long Term Potentiation ◽

Conditioning Stimulation ◽

Postsynaptic Potential ◽

Term Potentiation ◽

Stimulation Of

1. Intracellular recording was made from layer II-III cells in slice preparations of kitten (30-40 days old) visual cortex. Low-frequency (0.1 Hz) stimulation of white matter (WM) usually evoked an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP). The postsynaptic potentials (PSPs) showed strong dependence on stimulus frequency. Early component of EPSP and IPSP evoked by weak stimulation both decreased monotonically at frequencies greater than 0.5-1 Hz. Strong stimulation similarly depressed the early EPSP at higher frequencies (greater than 2 Hz) and replaced the IPSP with a late EPSP, which had a maximum amplitude in the stimulus frequency range of 2-5 Hz. 2. Very weak WM stimulation sometimes evoked EPSPs in isolation from IPSPs. The falling phase of the EPSP revealed voltage dependence characteristic to the responses mediated by N-methyl-D-aspartate (NMDA) receptors and was depressed by application of an NMDA antagonist DL-2-amino-5-phosphonovalerate (APV), whereas the rising phase of the EPSP was insensitive to APV. 3. The early EPSPs followed by IPSPs were insensitive to APV but were replaced with a slow depolarizing potential by application of a non-NMDA antagonist 6,7-dinitro-quinoxaline-2,3-dione (DNQX), indicating that the early EPSP is mediated by non-NMDA receptors. The slow depolarization was mediated by NMDA receptors because it was depressed by membrane hyperpolarization or addition of APV. 4. The late EPSP evoked by higher-frequency stimulation was abolished by APV, indicating that it is mediated by NMDA receptors, which are located either on the recorded cell or on presynaptic cells to the recorded cells. 5. Long-term potentiation (LTP) of EPSPs was examined in cells perfused with solutions containing 1 microM bicuculline methiodide (BIM), a gamma-aminobutyric acid (GABA) antagonist. WM was stimulated at 2 Hz for 15 min as a conditioning stimulus to induce LTP, and the resultant changes were tested by low-frequency (0.1 Hz) stimulation of WM. 6. LTP of early EPSPs occurred in more than one-half of the cells (8/13) after strong conditioning stimulation. The rising slope of the EPSP was increased 1.6 times on average. 7. To test involvement of NMDA receptors in the induction of LTP in the early EPSP, the effect of conditioning stimulation was studied in a solution containing 100 microM APV, which was sufficient to block completely synaptic transmission mediated by NMDA receptors. LTP occurred in the same frequency and magnitude as in control solution.

Download Full-text

A Chronology of El Niño Events from Primary Documentary Sources in Northern Peru*

Journal of Climate ◽

10.1175/2007jcli1830.1 ◽

2008 ◽

Vol 21 (9) ◽

pp. 1948-1962 ◽

Cited By ~ 53

Author(s):

R. Garcia-Herrera ◽

D. Barriopedro ◽

E. Hernández ◽

H. F. Diaz ◽

R. R. Garcia ◽

...

Keyword(s):

El Niño ◽

El Nino ◽

Southern Oscillation ◽

Low Frequency ◽

Primary Sources ◽

Proxy Data ◽

Documentary Sources ◽

Low Frequency Variability ◽

Northern Peru

Abstract The authors present a chronology of El Niño (EN) events based on documentary records from northern Peru. The chronology, which covers the period 1550–1900, is constructed mainly from primary sources from the city of Trujillo (Peru), the Archivo General de Indias in Seville (Spain), and the Archivo General de la Nación in Lima (Peru), supplemented by a reassessment of documentary evidence included in previously published literature. The archive in Trujillo has never been systematically evaluated for information related to the occurrence of El Niño–Southern Oscillation (ENSO). Abundant rainfall and river discharge correlate well with EN events in the area around Trujillo, which is very dry during most other years. Thus, rain and flooding descriptors, together with reports of failure of the local fishery, are the main indicators of EN occurrence that the authors have searched for in the documents. A total of 59 EN years are identified in this work. This chronology is compared with the two main previous documentary EN chronologies and with ENSO indicators derived from proxy data other than documentary sources. Overall, the seventeenth century appears to be the least active EN period, while the 1620s, 1720s, 1810s, and 1870s are the most active decades. The results herein reveal long-term fluctuations in warm ENSO activity that compare reasonably well with low-frequency variability deduced from other proxy data.

Download Full-text