Laboratory Aging and Annealing of Asphalt Binders by Microwave Radiation

1996 ◽  
Vol 1535 (1) ◽  
pp. 98-107 ◽  
Author(s):  
S. W. Bishara ◽  
R. L. McReynolds
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Molecular Size ◽  
Petri Dish ◽  
Microwave Treatment ◽  
Intermediate Temperature ◽  
Size Exclusion ◽  
Asphalt Binders ◽  
Average Difference

A household microwave oven with a frequency of 2.45 × 103 ±13 MHz and an output power of 1000 W is used to simulate short- and long-term aging of asphalt, and for annealing, prior to sampling, to remove steric (isothermal) hardening. A quartz petri dish holds the asphalt during microwave treatment, at atmospheric pressure. To simulate thin film oven (TFO) aging, a 10-g sample is microwaved for a total of 33 min. For 11 asphalts, the average difference in G*/sin δ, at limiting high temperature, between TFO and microwave aging is ±0.68 kPa. Simulating rolling thin-film oven (RTFO) aging is possible by microwaving for a total of 63 min. For 18 asphalts, the average difference in G*/sin δ, at limiting high temperature, between RTFO and microwave aging is ± 1.19 kPa. Aging by RTFO + pressure aging vessel (PAV) and TFO + PAV is simulated by microwaving for a total of 158 min. Microwave aging marginally underestimates long-term aging. For 18 asphalts, the average difference in intermediate temperature obtained after RTFO + PAV versus microwave aging is −2.8°C; for TFO + PAV versus microwave aging, the average difference is −2.7°C. Annealing for 2 hr at 150°C in a convection oven (conductive heating) is simulated by microwaving for a total of 27 min. The average difference in G*/sin δ between the two methods is ±0.24 kPa. Molecular size index (MSI, the ratio of first to second fraction from size exclusion chromatography) correlates with stiffness at low temperature. At intermediate temperature, tan δ remains practically unchanged until MSI reaches a minimum, then increases sharply. At limiting high temperature, G* does not correlate with MSI.

Long-Term Field Aging of Warm-Mix and Hot-Mix Asphalt Binders

2017 ◽  
Vol 2632 (1) ◽  
pp. 140-149 ◽  
Author(s):  
Weiguang Zhang ◽  
Shihui Shen ◽  
Shenghua Wu ◽  
Louay N. Mohammad
Keyword(s):  
High Temperature ◽  
Prediction Model ◽  
Hot Mix Asphalt ◽  
Field Studies ◽  
Asphalt Binders ◽  
Climate Effect ◽  
Air Voids ◽  
Multiple Parameters ◽  
Term Field

Limited field studies have considered the aging of warm-mix asphalt (WMA) binders, especially from the perspective of long-term aging. This paper quantifies the long-term (10 to 82 months) field aging properties of WMA binders and the control hot-mix asphalt (HMA) binders and identifies the key factors associated with long-term field aging of asphalt. Asphalt binders from 23 field projects consisting of 65 HMA and WMA pavements were recovered, and high-temperature performance grade (PG) was tested. The effects of climate, month of aging, WMA technologies, and original binder high-temperature PG on field asphalt aging were analyzed. A prediction model that included multiple parameters was developed and validated. Results indicated that Evotherm WMA binder had a lower high-temperature PG than HMA binder shortly after construction, but this difference reduced with time. No statistical difference of field aging between HMA and WMA binders was observed. The climate effect on asphalt field aging was apparent within dry areas or freeze areas, whereas the aging difference between dry and freeze areas was inconclusive and requires further research. Other conclusions were that ( a) the field asphalt aging affects more of top-down longitudinal wheelpath crack than transverse crack, ( b) foaming WMA binder ages slowest of all binders considered, ( c) PG 64-XX and PG 70-XX binders aged more than PG 58-XX and PG 76-XX binders, and ( d) the prediction model had good agreement with test results and was well validated. The identified factors that affected field asphalt aging were overlay thickness, in-place air voids, effective binder content, complex shear modulus, and solar radiation.

scholarly journals Effects of Short-Term Ageing Temperature on Conventional and High-Temperature Properties of Paving-Grade Bitumen with Anti-Stripping and WMA Additives

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6229
Author(s):  
Krzysztof Maciejewski ◽  
Piotr Ramiączek ◽  
Eva Remisova
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Critical Temperature ◽  
Production Process ◽  
Dynamic Viscosity ◽  
Softening Point ◽  
Creep Compliance ◽  
Asphalt Binders ◽  
Short Term ◽  
Bituminous Binders

The presented study explores the effects of decreased temperatures utilized in rolling thin-film oven (RTFOT) laboratory short-term ageing of asphalt binders based on 35/50- and 50/70-penetration paving-grade bitumen. Additionally, the effects of three additives used with these binders at different concentrations are evaluated: liquid anti-stripping agent, liquid warm-mix additive, and solid warm-mix additive. The resulting asphalt binders were subjected to basic (penetration at 25 °C, softening point, dynamic viscosity) and functional high-temperature characterization (G*/sin(δ), high critical temperature, non-recoverable creep compliance). It was found that the decreased short-term ageing temperatures may detrimentally impact the high-temperature grade of bituminous binders, but this effect can be mitigated by the use of appropriate additives. What is more, it was found that bituminous binders may respond differently to the aforementioned factors. Based on the results, it is advised that asphalt binders intended for use in warm-mix asphalts should be thoroughly tested to appropriately simulate the mixture production process and its effects.

scholarly journals Aging of Rejuvenated Asphalt Binders

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Mojtaba Mohammadafzali ◽  
Hesham Ali ◽  
James A. Musselman ◽  
Gregory A. Sholar ◽  
Wayne A. Rilko
Keyword(s):  
High Temperature ◽  
Great Influence ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Accelerate Aging ◽  
Aging Rate ◽  
Important Concern ◽  
Different Types ◽  
Aged Binder

An important concern that limits the RAP content in asphalt mixtures is the fact that the aged binder that is present in the RAP can cause premature cracking. Rejuvenators are frequently added to high RAP mixtures to enhance the properties of the binder. There is no existing method to predict the longevity of a rejuvenated asphalt. This study investigated the aging of rejuvenated binders and compared their durability with that of virgin asphalt. Various samples with different types and proportions of RAP, virgin binder, and rejuvenator were aged by RTFO and three cycles of PAV. DSR and BBR tests were conducted to examine the high-temperature and low-temperature rheological properties of binders. Results indicated that the type and dosage of the rejuvenator have a great influence on the aging rate and durability of the binder. Some rejuvenators make the binder age slower, while others accelerate aging. These observations confirm the importance of evaluating the long-term aging of recycled binders. For this purpose, critical PAV time was proposed as a measure of binder’s longevity.

Packaging of Optical MEMS Devices

2003 ◽  
Vol 125 (3) ◽  
pp. 325-328 ◽  
Author(s):  
Yee L. Low ◽  
Ronald E. Scotti ◽  
David A. Ramsey ◽  
Cristian A. Bolle ◽  
Steven P. O’Neill ◽  
...  
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Telecommunications Industry ◽  
Optical Networking ◽  
Mems Devices ◽  
Optical Mems ◽  
Packaging Industry ◽  
Micro Systems ◽  
Package Materials

Recently, optical MEMS devices have gained considerable attention in the telecommunications industry—particularly in the optical networking and switching arenas. Since optical MEMS are micro-systems which rely on high precision optics, electronics and mechanics working in close concert, these emerging devices pose some unique packaging challenges yet to be addressed by the general packaging industry. Optical MEMS packages often are required to provide both optical and electrical access, hermeticity, mechanical strength, dimensional stability, and long-term reliability. Hermetic optical access necessitates the use of metallized and anti-reflection coated windows, and ever-increasing electrical I/O count has prompted the use of higher density substrate/package technologies. Taking these requirements into consideration, we explore three ceramic packaging technologies, namely high-temperature co-fired ceramic (HTCC), low-temperature co-fired ceramic (LTCC), and thin-film ceramic technologies. In this paper, we describe some optical MEMS packages designed using these three technologies and discuss their substrate designs, package materials, ease of integration and assembly.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

KUBOTA KNC-03

Alloy Digest ◽  
2010 ◽  
Vol 59 (1) ◽  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Temperature Performance ◽  
Resistance To Oxidation

Abstract Kubota KNC-03 is a grade with a combination of high strength and excellent resistance to oxidation. These properties make this alloy suitable for long-term service at temperature up to 1250 deg C (2282 deg F). This datasheet provides information on physical properties, hardness, elasticity, tensile properties, and compressive strength as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: Ni-676. Producer or source: Kubota Metal Corporation, Fahramet Division. See also Alloy Digest Ni-662, April 2008.

ATI 6-2-4-2

Alloy Digest ◽  
2020 ◽  
Vol 69 (8) ◽  
Keyword(s):  
Tensile Strength ◽  
Titanium Alloy ◽  
High Temperature ◽  
Creep Strength ◽  
High Strength ◽  
Heat Treating ◽  
Good Combination ◽  
Long Term Stability ◽  
Temperature Performance

Abstract ATI 6-2-4-2 is a near-alpha, high strength, titanium alloy that exhibits a good combination of tensile strength, creep strength, toughness, and long-term stability at temperatures up to 425 °C (800 °F). Silicon up to 0.1% frequently is added to improve the creep resistance of the alloy. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ti-169. Producer or Source: ATI.

scholarly journals CO Detection Investigation at High Temperature by SiC MISFET Metal/Oxide Gas Sensors

Proceedings ◽  
2021 ◽  
Vol 56 (1) ◽  
pp. 41
Author(s):  
Lida Khajavizadeh ◽  
Anita Lloyd Spetz ◽  
Mike Andersson
Keyword(s):  
High Temperature ◽  
Gas Sensors ◽  
Elevated Temperatures ◽  
Long Term Stability ◽  
Stability Performance ◽  
Catalytic Metal ◽  
Co Detection ◽  
Effect Transistor ◽  
Metal Oxide Gas Sensors

In order to investigate the necessary device improvements for high-temperature CO sensing with SiC metal insulator semiconductor field effect transistor (MISFET)-based chemical gas sensors, devices employing, as the gas-sensitive gate contact, a film of co-deposited Pt/Al2O3 instead of the commonly used catalytic metal-based contacts were fabricated and characterized for CO detection at elevated temperatures and different CO and O2 levels. It can be concluded that the sensing mechanism at elevated temperatures correlates with oxygen removal from the sensor surface rather than the surface CO coverage as observed at lower temperatures. The long-term stability performance was also shown to be improved compared to that of previously studied devices.

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