Laboratory Investigation of Rubberized Asphalt Using High-Content Rubber Powder

Rubberized asphalt (RA) has been successfully applied in road engineering due to its excellent performance; however, the most widely used rubber content is about 20%.To improve the content of waste rubber and ensure its performance, seven rubberized asphalts with different powder content were prepared by high-speed shearing. Firstly, penetration, softening point, and ductility tests were carried out to investigate the conventional physical features of high-content rubberized asphalt (HCRA). Then, the dynamic shear rheometer test (DSR) was conducted to estimate the high-temperature rheological properties. The bending beam rheometer test (BBR) was carried out to evaluate the low-temperature rheological performance. Finally, combined with the macroscopic performance test, the modification mechanism was revealed by the Fourier transform infrared reflection (FTIR) test, and scanning electron microscope (SEM) analysis was used to observe the microscopic appearance before and after aging. The results show that rubberized asphalt has excellent properties in high- and low-temperature conditions, and fatigue resistance is also outstanding compared with neat asphalt. As the crumb rubber content increases, it is evident that the 40% RA performance is the best. The low-temperature properties of HCRA are better than the traditional 20% rubberized asphalt. This study provides a full test foundation for the efficient utilization of HCRA in road engineering.

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Research on Performance Test System of Space Harmonic Reducer in High Vacuum and Low Temperature Environment

Machines ◽

10.3390/machines9010001 ◽

2020 ◽

Vol 9 (1) ◽

pp. 1

Author(s):

Jing Wang ◽

Zhihua Wan ◽

Zhurong Dong ◽

Zhengguo Li

Keyword(s):

Low Temperature ◽

High Speed ◽

Performance Test ◽

High Reliability ◽

High Vacuum ◽

Test System ◽

Low Noise ◽

Speed Ratio ◽

Space Harmonic ◽

Temperature Environment

The harmonic reducer, with its advantages of high precision, low noise, light weight, and high speed ratio, has been widely used in aerospace solar wing deployment mechanisms, antenna pointing mechanisms, robot joints, and other precision transmission fields. Accurately predicting the performance of the harmonic reducer under various application conditions is of great significance to the high reliability and long life of the harmonic reducer. In this paper, a set of automatic harmonic reducer performance test systems is designed. By using the CANOpen bus interface to control the servo motor as the drive motor, through accurately controlling the motor speed and rotation angle, collecting the angle, torque, and current in real time, the life cycle test of space harmonic reducer was carried out in high vacuum and low temperature environment on the ground. Then, the collected data were automatically analyzed and calculated. The test data of the transmission accuracy, backlash, and transmission efficiency of the space harmonic reducer were obtained. It is proven by experiments that the performance data of the harmonic reducer in space work can be more accurately obtained by using the test system mentioned in this paper, which is convenient for further research on related lubricating materials.

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Low-Temperature Rheological Properties and Microscopic Characterization of Asphalt Rubbers Containing Heterogeneous Crumb Rubbers

Materials ◽

10.3390/ma13184120 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4120 ◽

Cited By ~ 1

Author(s):

Mingfeng Chang ◽

Yixing Zhang ◽

Jianzhong Pei ◽

Jiupeng Zhang ◽

Min Wang ◽

...

Keyword(s):

Low Temperature ◽

Rheological Properties ◽

Fine Particles ◽

Physicochemical Characteristics ◽

Crumb Rubber ◽

Rubber Content ◽

Evaluation Indexes ◽

Asphalt Rubber ◽

Linear Viscoelastic Material ◽

Microscopic Morphology

Asphalt rubbers mixed with untreated and plasticized crumb rubbers and a compounding coupling agent were investigated in this study. The low-temperature rheological properties of asphalt rubbers at different aging levels were tested using a dynamic shear rheometer (DSR). An interconversion between linear viscoelastic material functions was used to obtain converted evaluation indexes for the asphalt rubbers at low temperatures. Lastly, the physicochemical characteristics and the microscopic morphology of the asphalt rubbers were evaluated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. In conclusion, the storage moduli of the asphalt rubbers containing heterogeneous crumb rubbers increased with the plasticized crumb rubber content and the aging level. The converted relaxation moduli were consistent with the change trend of the storage moduli, and the relaxation rate decreased as the plasticized crumb rubber content and the aging level increased. The process of mixing the base asphalt with crumb and plasticized crumb rubbers was physical blending, and the effect of aging on the absorption peak change of asphalt rubber with plasticized crumb rubbers was less than that of asphalt rubber with ordinary crumb rubbers. Aging deteriorated the blending between the crumb rubber and the base asphalt, and a distinct interface appeared between the crumb rubber and the base asphalt. The particle cores of the plasticized crumb rubber in the asphalt rubber were difficult to maintain. Furthermore, as the plasticized crumb rubber content increased, more fine particles stripped off the plasticized crumb rubber after aging.

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Evolution of Rheological Behaviors of Styrene-Butadiene-Styrene/Crumb Rubber Composite Modified Bitumen after Different Long-Term Aging Processes

Materials ◽

10.3390/ma12152345 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2345 ◽

Cited By ~ 2

Author(s):

Yangsheng Ye ◽

Gang Xu ◽

Liangwei Lou ◽

Xianhua Chen ◽

Degou Cai ◽

...

Keyword(s):

Low Temperature ◽

High Speed ◽

Crumb Rubber ◽

Modified Bitumen ◽

High Speed Railway ◽

Modified Asphalt ◽

Styrene Butadiene Styrene ◽

Styrene Butadiene ◽

Butadiene Styrene

In this study, a new type of composite modified bitumen was developed by blending styrene-butadiene-styrene (SBS) and crumb rubber (CR) with a chemical method to satisfy the durability requirements of waterproofing material in the waterproofing layer of high-speed railway subgrade. A pressure-aging-vessel test for 20, 40 and 80 h were conducted to obtain bitumen samples in different long-term aging conditions. Multiple stress creep recovery (MSCR) tests, linear amplitude scanning tests and bending beam rheometer tests were conducted on three kinds of asphalt binders (SBS modified asphalt, CR modified asphalt and SBS/CR composite modified asphalt) after different long-term aging processes, including high temperature permanent deformation performance, resistance to low temperature thermal and fatigue crack. Meanwhile, aging sensitivities were compared by different rheological indices. Results showed that SBS/CR composite modified asphalt possessed the best properties before and after aging. The elastic property of CR in SBS/CR composite modified asphalt improved the ability to resist low temperature thermal and fatigue cracks at a range of low and middle temperatures. Simultaneously, the copolymer network of SBS and CR significantly improved the elastic response of the asphalt SBS/CR modified asphalt at a range of high temperatures. Furthermore, all test results indicated that the SBS/CR modified asphalt possesses the outstanding ability to anti-aging. SBS/CR is an ideal kind of asphalt to satisfy the demand of 60 years of service life in the subgrade of high speed railway.

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Temperature Sensitivity Characteristics of SBS/CRP-Modified Bitumen after Different Aging Processes

Materials ◽

10.3390/ma11112136 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2136 ◽

Cited By ~ 8

Author(s):

Rui He ◽

Shuhua Wu ◽

Xiaofeng Wang ◽

Zhenjun Wang ◽

Huaxin Chen

Keyword(s):

Low Temperature ◽

Temperature Sensitivity ◽

Aging Process ◽

Performance Test ◽

Good Condition ◽

Natural Aging ◽

Crumb Rubber ◽

Modified Bitumen ◽

Rubber Powder ◽

Sensitivity Performance

Temperature sensitivity characteristics of bitumen can be evidently influenced by modifier types and natural aging processes. Many types of modifiers have been used to improve the temperature sensitivity performance of bitumen, but their effects are different. Therefore, different bitumen specimens as well as SBS/CRP (Styrene-butadiene-styrene polymer/crumb rubber powder)-modified bitumen were prepared and the temperature sensitivity characteristics of bitumen after different aging processes were analyzed in this study. A dynamic rheological property test and performance test at low temperature were carried out to analyze temperature sensitivity and low temperature rheological properties of bitumen. An infrared spectrum test was adopted to study the effect of functional groups under different aging process on the properties of bitumen. The relationship between macroscopic properties and microstructures of bitumen was analyzed. The results show that SBS/CRP-modified bitumen has a strong anti-aging ability in that its flexibility and structure remain in a good condition after long-term aging. The aging process has no significant effect on SBS/CRP-modified bitumen. SBS/CRP-modified bitumen has an excellent low-temperature relaxation ability and low-temperature crack resistance. In contrast to original bitumen and SBS-modified bitumen, the temperature sensitivity performance of SBS/CRP-modified bitumen is evidently enhanced. The physical blending effect is dominant in the bitumen modified process and there is no evident chemical reaction between bitumen and crumb rubber powder. SBS/CRP-modified bitumen is recommended for wide use in plateau areas with ultraviolet and cold surroundings.

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Evaluation of rubber influence on cracking resistance of crumb rubber modified binders with wax additives

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2014-0510 ◽

2016 ◽

Vol 43 (4) ◽

pp. 326-333 ◽

Cited By ~ 10

Author(s):

Hyun Hwan Kim ◽

Soon-Jae Lee

Keyword(s):

Crumb Rubber ◽

Asphalt Binders ◽

Rubber Content ◽

Short Term ◽

Cracking Resistance ◽

Bending Beam Rheometer ◽

Modified Binders ◽

Lower Temperature ◽

Rheometer Test

Cracking properties of crumb rubber modified (CRM) asphalt binders containing wax additive were evaluated through the dynamic shear rheometer test at 25 °C and the bending beam rheometer test at −12 °C. The CRM binders were produced using three rubber contents of 5%, 10%, and 15% by the binder weight, and then mixed with two commercial wax additives of LEADCAP and Sasobit. Three states of original, short-term and long-term aging were applied to evaluate the cracking properties using rolling thin film oven and pressure aging vessel. From the results, it is concluded that (1) the increase of rubber content significantly decreases the binder stiffness at lower temperature, (2) the higher the rubber content, the lower the G*sinδ of CRM binders with wax additives at intermediate temperature, and (3) the rubber can be used to improve the cracking resistance of asphalt binders modified with wax.

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Low-temperature f.e.t. for low-power high-speed logic

Electronics Letters ◽

10.1049/el:19770111 ◽

1977 ◽

Vol 13 (6) ◽

pp. 156 ◽

Cited By ~ 15

Author(s):

H. Rees ◽

G.S. Sanghera ◽

R.A. Warriner

Keyword(s):

Low Temperature ◽

Low Power ◽

High Speed

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Material Properties and Environmental Benefits of Hot-Mix Asphalt Mixes Including Local Crumb Rubber Obtained from Scrap Tires

Environments ◽

10.3390/environments8060047 ◽

2021 ◽

Vol 8 (6) ◽

pp. 47

Author(s):

Lim Min Khiong ◽

Md. Safiuddin ◽

Mohammad Abdul Mannan ◽

Resdiansyah

Keyword(s):

Asphalt Binder ◽

Crumb Rubber ◽

Environmental Benefits ◽

Asphalt Binders ◽

Rubber Content ◽

Scrap Tires ◽

Asphalt Mixes ◽

Temperature Resistance ◽

Modified Asphalt ◽

Marshall Stability

This paper presents the results of a laboratory-based experimental investigation on the properties of asphalt binder and hot-mix asphalt (HMA) mixes modified by locally available crumb rubber, which was used as a partial replacement of asphalt by weight. In this study, fine crumb rubber with a particle size in the range of 0.3–0.6 mm, obtained from scrap tires, was added to the asphalt binder through the wet process. Crumb rubber contents of 5%, 10%, 15%, and 19% by weight of asphalt were added to the virgin binder in order to prepare the modified asphalt binder samples, while the unmodified asphalt binder was used as the control sample. The crumb rubber modified binder samples were examined for measuring viscosity indirectly using the penetration test, and temperature resistance using the softening point test. Later, both the modified and unmodified asphalt binders were used to produce HMA mixes. Two categories of HMA mix commonly used in Malaysia—namely, AC 14 (dense-graded) and SMA 14 (gap-graded)—were produced using the modified asphalt binders containing 5%, 10%, 15%, and 19% crumb rubber. Two AC 14 and SMA 14 control mixes were also produced, incorporating the unmodified asphalt binder (0% crumb rubber). All of the AC 14 and SMA 14 asphalt mixes were examined in order to determine their volumetric properties, such as bulk density, voids in total mix (VTM), voids in mineral aggregate (VMA), and voids filled with asphalt (VFA). In addition, the Marshall stability, Marshall flow, and stiffness of all of the AC 14 and SMA 14 mixes were determined. Test results indicated that the modified asphalt binders possessed higher viscosity and temperature resistance than the unmodified asphalt binder. The viscosity and temperature resistance of the asphalt binders increased with the increase in their crumb rubber content. The increased crumb rubber content also led to improvements in the volumetric properties (bulk density, VTM, VMA, and VFA) of the AC 14 and SMA 14 mixes. In addition, the performance characteristics of the AC 14 and SMA 14 mixes—such as Marshall stability, Marshall flow, and stiffness—increased with the increase in crumb rubber content. However, the AC 14 mixes performed much better than the SMA 14 mixes. The overall research findings suggest that crumb rubber can be used to produce durable and sustainable HMA mixes, with manifold environmental benefits, for use in flexible pavements carrying the heavy traffic load of highways.

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Evaluation of Micro-Mechanism and High- and Low-Temperature Rheological Properties of Disintegrated High Volume Crumb Rubber Asphalt (DHVRA)

Materials ◽

10.3390/ma14051145 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1145

Author(s):

Wei Li ◽

Sen Han ◽

Xiaokang Fu ◽

Ke Huang

Keyword(s):

High Temperature ◽

Low Temperature ◽

Rheological Properties ◽

Particle Diameter ◽

Gel Permeation Chromatography ◽

High Volume ◽

Crumb Rubber ◽

Test Method ◽

Polar Component ◽

Temperature Performance

The aims of this paper are to prepare disintegrated high volume crumb rubber asphalt (DHVRA) with low viscosity, good workability and low-temperature performance by adding disintegrating agent (DA) in the preparation process, and to further analyze the disintegrating mechanism and evaluated high-temperature and low-temperature rheological properties. To obtain DHVRA with excellent comprehensive performance, the optimum DA dosage was determined. Based on long-term disintegrating tests and the Fluorescence Microscopy (FM) method, the correlations between key indexes and crumb rubber (CR) particle diameter was analyzed, and the evaluation indicator and disintegrating stage division standard were put forward. Furthermore, Fourier transform infrared spectroscopy (FT-IR) and Gel Permeation Chromatography (GPC) was used to reveal the reaction mechanism, and the contact angle test method was adopted to evaluate the surface free energy (SFE). In addition, the high-temperature and low-temperature rheological properties were measured, and the optimum CR content was proposed. Results indicated that the optimum DA dosage was 7.5‰, and the addition of DA promoted the melt decomposition of CR, reduced the viscosity and improved the storage stability. The 135 °C rotational viscosity (RV) of DHVRA from mixing for 3 h could be reduced to 1.475 Pa·s, and the softening point difference was even less than 2 °C. The linear correlation between 135 °C RV and the diameter of CR particle in rubber asphalt system was as high as 0.968, and the viscosity decay rate (VDR) was used as the standard to divide the disintegrating process into a fast disintegrating stage, stable disintegrating stage and slight disintegrating stage. Compared to common rubber asphalt (CRA), DHVRA has an absorption peak at 960 cm−1 caused by trans olefin = C-H, and higher molecular weight and polar component of surface energy. Compared with CRA, although the high-temperature performance of DHVRA decreases slightly, the low-temperature relaxation ability can be greatly improved.

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Evaluation of Properties and Micro-Characteristics of Waste Polyurethane/Styrene-Butadiene-Styrene Composite Modified Asphalt

Polymers ◽

10.3390/polym13142249 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2249

Author(s):

Bei Chen ◽

Fuqiang Dong ◽

Xin Yu ◽

Changjiang Zheng

Keyword(s):

Low Temperature ◽

Performance Test ◽

Permanent Deformation ◽

Modified Asphalt ◽

Basic Performance ◽

Styrene Butadiene Styrene ◽

Styrene Butadiene ◽

Sbs Modified Asphalt ◽

And Storage ◽

Butadiene Styrene

In order to solve the problems caused by asphalt diseases and prolong the life cycle of asphalt pavement, many studies on the properties of modified asphalt have been conducted, especially polyurethane (PU) modified asphalt. This study is to replace part of the styrene-butadiene-styrene (SBS) modifier with waste polyurethane (WP), for preparing WP/SBS composite modified asphalt, as well as exploring its properties and microstructure. On this basis, this paper studied the basic performance of WP/SBS composite modified asphalt with a conventional performance test, to analyze the high- and low-temperature rheological properties, permanent deformation resistance and storage stability of WP/SBS composite modified asphalt by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The microstructure of WP/SBS composite modified asphalt was also observed by fluorescence microscope (FM) and Fourier transform infrared spectroscopy (FTIR), as well as the reaction between WP and asphalt. According to the results of this study, WP can replace SBS as a modifier to prepare WP/SBS composite modified asphalt with good low-temperature resistance, whose high-temperature performance will be lower than that of SBS modified asphalt. After comprehensive consideration, 4% SBS content and 15% WPU content (4 S/15 W) are determined as the suitable types of WPU/SBS composite modified asphalt.

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Experimental Study on Deformation Behavior and Compressive Strength of Concrete Cast in Steel Tube Arches under Low-Temperature Conditions

Advances in Materials Science and Engineering ◽

10.1155/2020/8016282 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Tuo Shi ◽

Nianchun Deng ◽

Xiao Guo ◽

Wen Xu ◽

Shi Wang

Keyword(s):

Compressive Strength ◽

Low Temperature ◽

Performance Test ◽

Large Diameter ◽

Test Site ◽

Steel Tube ◽

Design Strength ◽

Curing Conditions ◽

Expansive Agent ◽

Arch Bridges

Taking the construction of a concrete-filled steel tube (CFST) arch bridge (part of the Sichuan-Tibet Railway) in low temperatures as the test site, firstly the deformation performance test of concrete was carried out. Following this initial testing, measurement of compressive strength and shrinkage performance was conducted in large-diameter CFSTs under a variety of curing conditions. Experimental results showed that the expansion effect of Ca-Mg composite expansive agent in concrete was better than that of other expansive agents at any stage. Under low-temperature curing (0°C), the sampling strength of the large-diameter CFSTs reached 73.5% of the design strength at 28 d in the presence of a nonthermal curing system. The design strength itself was reached, when a curing system involving a thermal insulation film was applied, and use of this film also led to improvements in concrete shrinkage. The results suggested that a Ca-Mg composite expansive agent, combined with an insulation film curing system, should be the technique selected for concrete pumping construction of CFST arch bridges in Tibet.

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