scholarly journals Effect of Short Term Aging on Unmodified and Local Crumb Rubber (LCR) Modified Bitumen

2020 ◽  
Vol 18 (02) ◽  
pp. 63-70
Author(s):  
Muhammad Saad Waheed ◽  
Manzoor Elahi
Keyword(s):  
Thin Film ◽  
Phase Angle ◽  
Complex Modulus ◽  
Crumb Rubber ◽  
Dynamic Shear ◽  
Short Term ◽  
Modified Bitumen ◽  
Before And After ◽  
The Difference ◽  
Effects Of Aging

Two grades of bitumen, (60/70 and 80/100), were modified by addition of Local Crumb Rubber (LCR) by weight of base bitumen. To investigate the effects of short-term aging on modified and LCR modified bitumen, Rolling Thin Film Oven (RTFO) test was used to simulate the short term aging. Dynamic shear rheometer (DSR) was used to assess the rheological properties of bitumen, both before and after aging. It was observed that at 65 degree Celcius on aging, the phase angle (sigma) of unmodified bitumen decreased by 3 and 4% for 60/70 and 80/100 bitumen respectively; whereas, for 60/70 LCR modified bitumen, the phase angle (sigma) on RTFO aging decreased by 7% for all LCR content (10, 15 and 20%) by weight of base bitumen. However, on RTFO aging (sigma), values for LCR modified 80/100 bitumen varied across different LCR content and could not be generalized. The complex modulus |G*| of LCR modified 60/70 bitumen increased on aging for both modified and unmodified bitumen at 65C, but with the increase in LCR content, the difference between bitumen aged and un-aged values of |G*| was considerably lowered. An interesting finding was for 80/100 bitumen modified with 20% LCR content by weight, which showed a reduction in |G*| values and an increase in (sigma) values on aging. This shows that to some extent, LCR compensates for the stiffening effects of aging.

Effects of Aging on the Physical and Rheological Properties of Asphalt Binder Incorporating Rediset®

2014 ◽  
Vol 70 (7) ◽  
Author(s):  
Mohamad Yusri Aman ◽  
Zulkurnain Shahadan ◽  
Munzilah Md. Ruhani ◽  
Rosnawati Buhari
Keyword(s):  
Statistical Analysis ◽  
Rheological Properties ◽  
Asphalt Binder ◽  
Dynamic Shear ◽  
Short Term ◽  
Rotational Viscometer ◽  
Aging Index ◽  
Modified Binders ◽  
Before And After ◽  
Effects Of Aging

This paper focuses on physical and rheological properties of virgin asphalt binder blended with different percentage of Rediset® content. The rheological properties of the Rediset® modified binders were characterized before and after being subjected to short-term aging using rotational viscometer (RV) and dynamic shear rheometer (DSR) according to SuperpaveTM test protocols. The results indicated that the penetration and softening point were consistently decreased and increased, respectively for unaged and short-term aged samples. The penetration index (PI) and viscosity aging index (VAI) were increased as the Rediset® modified binders aged and showed a high significance correlation. The addition of Rediset® in asphalt binder exhibited change in binder rheology after subjected to short-term aged which influenced the rutting parameter. A statistical analysis showed that Rediset® used as warm asphalt additive had significantly increased the G*/Sin δ parameter which indicated greater resistance to rutting.

Evaluation of Effects of Extended Short-Term Aging on the Rheological Properties of Asphalt Binders at Intermediate Temperatures Using Respond Surface Method

2015 ◽  
Vol 73 (4) ◽  
Author(s):  
Meor Othman Hamzah ◽  
Seyed Reza Omranian ◽  
Babak Golchin ◽  
Mohd Rosli Hainin
Keyword(s):  
Rheological Properties ◽  
Phase Angle ◽  
Test Temperature ◽  
Complex Modulus ◽  
Asphalt Binders ◽  
Short Term ◽  
Surface Method ◽  
Binder Type ◽  
Aging Conditions ◽  
Effects Of Aging

Predicting the effects of short term aging on asphalt binders’ rheological properties can be a complicated task.  This is due to the exposure of different binders to different conditions. Hence, the utilization of a Respond Surface Method (RSM) is a practical way to predict these effects. An experimental matrix was planned to predict asphalt binders behavior at intermediate temperatures based on the central composite design for aging duration and test temperature. The test results showed that prolonging aging increased the binder complex modulus, but decreased the phase angle, while increasing the test temperature decreased the complex modulus but increased the phase angle. However, the trends in aging differ and depend on the binder type, test temperature and aging conditions. It was also found that the RSM method is a fast, effective and reliable tool to predict the effects of aging on binders’ rheological behavior.

scholarly journals Experimental Investigation of Rubber Swelling in Bitumen

2020 ◽  
Vol 2674 (2) ◽  
pp. 203-212 ◽  
Author(s):  
Haopeng Wang ◽  
Xueyan Liu ◽  
Panos Apostolidis ◽  
Sandra Erkens ◽  
Athanasios Skarpas
Keyword(s):  
Volume Expansion ◽  
Dominant Role ◽  
Gravimetric Method ◽  
Crumb Rubber ◽  
Mechanical Tests ◽  
Modified Bitumen ◽  
Truck Tire ◽  
Before And After ◽  
Swelling Characteristics ◽  
X Ray Computed

Rubber swelling in bitumen, which is a diffusion-induced volume expansion process, plays a dominant role in the design of crumb rubber modified bitumen binders and their properties development. This study aims to investigate the kinetics of bitumen diffusion into truck tire rubber, the equilibrium swelling characteristics of rubber, and the mechanical properties of rubber before and after swelling at different high temperatures. Fourier transform infrared spectroscopy results indicate that no rubber dissolution happens during the interaction in the temperature range from 160°C to 200°C. Aliphatic compounds from bitumen preferentially diffused into rubber during the swelling process. The diffusion coefficients of bitumen into rubber were determined by the sorption test using the gravimetric method. The diffusion coefficient increases with the increase of temperature in an Arrhenius form. The volume expansion of rubber during swelling was captured by the X-ray computed tomography scan images. Rubber swells faster at the earlier stages, then the expansion rate slows down. The swelling ratio of rubber increased from 1.97 at 160°C to 3.03 at 200°C after 36 h interaction. Mechanical tests by dynamic shear rheometer reveal that swollen rubber becomes softer compared with the dry rubber and exhibits obvious viscoelastic behaviors. With the increase of temperature, the softening and viscous effect are more significant. The obtained parameters can be implemented to swelling and micromechanical models to better predict the binder properties.

Phase II breast cancer chemoprevention study with celecoxib in women at increased risk for breast cancer

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 1010-1010
Author(s):  
B. Arun ◽  
V. Valero ◽  
G. Yin ◽  
G. Babiera ◽  
J. L. Murray ◽  
...  
Keyword(s):  
Breast Cancer ◽  
High Risk ◽  
Atypical Hyperplasia ◽  
Post Treatment ◽  
Short Term ◽  
Ki 67 ◽  
High Risk Women ◽  
Before And After ◽  
The Difference ◽  
Er Expression

1010 Background: Short-term chemoprevention trials offer a convenient model to screen chemopreventive agents and identify endpoint biomarkers. One of the potential agents is celecoxib (C), which has antiproliferative and apoptosis inducing properties. In this prospective study, our primary aim was to evaluate changes in proliferation induced by C in breast tissue of high risk women. Here, we report changes in estrogen receptor (ER) proliferation index. Methods: 42 eligible high risk women were enrolled into the study, underwent fine needle aspiration (FNA) and started celecoxib treatment at 400 mg BID. Median age: 51.9 years. Risk factors: Gail risk > 1.67% (n=13), lobular carcinoma insitu (n=13), atypical hyperplasia (n=11), previous history of breast cancer (n=5). For ER and Ki-67 testing, thin preparations slides were incubated with primary mouse monoclonal antibody 6F11 against the ER and clone MIB-1, respectively. Appropriate negative and positive controls were included. At least 100 epithelial cells were evaluated per slide. Immunoreactivity for each marker was scored as the percentage of positive nuclei. We assessed the difference in ER and Ki-67 levels before and after treatment using a Wilcoxon signed rank test. Results: The average pre-treatment ER expression in FNA samples was 35.9% and Ki-67 was 2.4%. 19 (45%) showed hyperplasia or atypical hyperplasia. 39 patients underwent also post-treatment FNAs. The pre-and post treatment ER expression in this group was 35.7% (range 0–100%) and 27.4% (range: 0–100%), respectively. The difference in ER levels was statistically significant (p = 0.04). Twenty-six patients had Ki-67 levels measured both before and after treatment. The median difference in Ki-67 levels was 0 (range 0- 5). This change was not statistically significant (p = 0.63). Conclusions: We have completed accrual to a prospective short-term chemoprevention trial with celecoxib. We have found a significant downregulation of ER expression with 6 months celecoxib. Since ER expression is a marker of proliferation, this finding confirms celecoxibs antiproliferative properties. Currently, we have not observed a change in Ki-67; this could be partly due to the small number of samples and the fact that Ki-67 is low in normal epithelium. [Table: see text]

scholarly journals Evaluation of Petroleum Resin in Rubberized Asphalt Binder

2021 ◽  
Vol 13 (16) ◽  
pp. 9319
Author(s):  
Hyun Hwan Kim ◽  
Mithil Mazumder ◽  
Moon-Sup Lee ◽  
Soon-Jae Lee
Keyword(s):  
Thin Film ◽  
Low Temperatures ◽  
Asphalt Binder ◽  
Crumb Rubber ◽  
Creep Recovery ◽  
Dynamic Shear ◽  
Bending Beam Rheometer ◽  
Rotational Viscometer ◽  
Multiple Stress ◽  
Multiple Stress Creep Recovery

The crumb rubber modified (CRM) binder was evaluated considering the general operating temperatures of high, intermediate, and low temperatures. CRM binders were produced with four different contents (0, 5, 10, and 15%) using the base asphalt binder (PG64-22). Then, they were artificially aged by a rolling thin-film oven (RTFO) and pressure aging vessel (PAV). Superpave binder tests using a rotational viscometer (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR) was applied to characterize the performance of the original and aged binders. Multiple stress creep recovery (MSCR) tests were also performed for deeper rutting characterization. The results of this study are as follows: (1) the presence of PR increases the binder viscosity, (2) the integration of CRM greatly improved the rutting resistance of the binder, and it was found that PR also improved the rutting characteristics, and (3) it is observed that PR is detrimental to the cracking properties of CRM binders.

scholarly journals Aging and Rheological Properties of Latex and Crumb Rubber Modified Bitumen Using Dynamic Shear Rheometer

2020 ◽  
Vol 52 (3) ◽  
pp. 385 ◽  
Author(s):  
Abdulnaser M Al-Sabaeei ◽  
Bayu Agus Mustofa ◽  
Muslich Hartadi Sutanto ◽  
Sri Sunarjono ◽  
Nura Bala
Keyword(s):  
Rheological Properties ◽  
Crumb Rubber ◽  
Dynamic Shear ◽  
Modified Bitumen ◽  
Dynamic Shear Rheometer

scholarly journals Influence of Short-Term Aging on Mechanical Properties and Morphology of Polymer-Modified Bitumen with Recycled Plastics from Waste Materials

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1985
Author(s):  
Clara Celauro ◽  
Edwina Saroufim ◽  
Maria Chiara Mistretta ◽  
Francesco Paolo La Mantia
Keyword(s):  
Morphological Changes ◽  
Fluorescent Microscopy ◽  
Aging Effect ◽  
Waste Materials ◽  
Processing Temperature ◽  
Polymer Modification ◽  
Short Term ◽  
Modified Bitumen ◽  
Before And After ◽  
Polymer Modified Bitumen

Polymer-modified bitumen (PMB) is bitumen that has been specifically engineered with polymer for providing enhanced performance in service. The aging of bitumen is a main aspect that is able to affect its final performance: during the production phase in a hot mix plant, all the binders experience short-term aging due to the high processing temperature. The same is true during the production of the modified binder, when the polymer is dispersed at high temperature in the bitumen mass. This paper aims at studying the effect of short-term aging when using different types of modifiers such as recycled polymers obtained from waste materials. A 50/70 penetration-grade bitumen has been modified, and bitumen characterization has been carried out before and after short-term aging; conventional tests, viscosity measurements, and dynamical mechanical analysis have been used to investigate the properties. Different aging indices have been determined for predicting the effect of short-term aging based on the type of modifier. Furthermore, the morphology of the modified bitumen has been investigated via fluorescent microscopy, before and after aging, in order to highlight morphological changes due to aging. The results confirm that aging affects all the modified binders, due to the thermal stress imposed during PMBs production. Nevertheless, polymer modification is proved to reduce the aging effect in terms of an increase in the elastic modulus as experienced by the original binder.

UV Aging Performance of Asphalt Containing LDHs

2014 ◽  
Vol 599 ◽  
pp. 265-270 ◽  
Author(s):  
Pan Fei Liu ◽  
Jun Zheng ◽  
Shao Peng Wu
Keyword(s):  
Aging Process ◽  
Complex Modulus ◽  
Short Term ◽  
Uv Aging ◽  
Oven Test ◽  
Aging Properties ◽  
Aging Resistance ◽  
Before And After ◽  
Double Hydroxides

In this paper the effect of Layered double hydroxides (LDHs) on aging properties of asphalts was studied. The thin film oven test TFOT tests and ultraviolet (UV) aging process were used to simulate short-term and long-term aging of asphalts, respectively. After aging, the physical properties and dynamic shear rheological behaviors of LDHs modified asphalts were investigated. The viscosity of LDHs modified asphalts was measured by Brookfield viscometer before and after UV aging. After UV aging, with an increase of LDHs, softening point and viscosity value of modified asphalts decreased, while both of ductility and penetration increased, compared to base asphalts. Temperature sweep tests showed that the complex modulus of LDHs modified asphalts was lower than that of base asphalt, while phase angle was higher. The results showed that LDHs improved the UV aging resistance of the asphalt, and it could prevent asphalt from UV aging.

scholarly journals Meditation Practice Improves Short-Term Changes in Heart Rate Variability

2020 ◽  
Vol 17 (6) ◽  
pp. 2128 ◽  
Author(s):  
Kang-Ming Chang ◽  
Miao-Tien Wu Chueh ◽  
Yi-Jung Lai
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Physiological Parameters ◽  
The Other ◽  
Meditation Practice ◽  
Short Term ◽  
Face To Face ◽  
Before And After ◽  
The Difference

Background: It is well known that meditation improves the physical and psychological condition of its practitioners. This study investigated the heart rate variability response of meditation practitioners in two Chan master teaching environments, namely face-to-face and video classes. Methods: Experimental sessions were conducted, one featuring face-to-face classes and the other featuring video classes. The difference in participants’ physiological parameters (blood pressure and heart rate variability) between the two experimental sessions was determined. In the first session, physiological parameters were recorded twice, before and after one teaching course, and the second session took place one month after the first. The first and second sessions had 45 and 27 participants, respectively. Those involved in the first experiment had no experience with meditation, whereas participants in the second experiment had practiced meditation for an average of 9 years (range = 1 to 27 years). Both experiments were conducted once a week, with each session lasting 1.5 h. Results: For both experiments, both heart rate and heart rate variability by age significantly decreased after one teaching course. Conclusions: Chan meditation practitioners benefit from receiving both face-to-face and video class teaching from a Chan master.

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