Effect of Crumb Rubber Modifier Dissolution on Storage Stability of Crumb Rubber–Modified Asphalt

Poor storage stability is a key problem restricting the rapid development and wide application of rubber-modified asphalt binder, and activation of rubber has shown good prospects to solve this problem. In this study, two activation methods, coating by polyamide 6 and grafting by acrylamide, were introduced to treat crumb rubber. Then the activated rubber was added to base asphalt binder to prepare modified asphalt binder. The chemical structure and morphology of rubber powder before and after activation and of asphalt binder before and after modification were characterized by Fourier transformation infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The conventional and rheological properties and storage stability were analyzed to reveal the influence of activation method on the performance of asphalt binder. The results showed that after being activated, the surface of the rubber is loose and rough. A chemical reaction did not occur during activation by polyamide but occurred during activation by acrylamide. The activation of the rubber effectively improved the high- and low-temperature performance, and the softening difference decreased by 79.8%. This is because the interaction between rubber and asphalt binder was enhanced through activation of rubber, and grafting activation had better effect due to the chemical reaction between the basic amide groups of acrylamide and acid groups of asphalt binder.

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Enhanced Storage Stability of Different Polymer Modified Asphalt Binders through Nano-Montmorillonite Modification

Nanomaterials ◽

10.3390/nano10040641 ◽

2020 ◽

Vol 10 (4) ◽

pp. 641 ◽

Cited By ~ 7

Author(s):

Zhibin Ren ◽

Yongqiang Zhu ◽

Qi Wu ◽

Minye Zhu ◽

Feng Guo ◽

...

Keyword(s):

Storage Stability ◽

Crumb Rubber ◽

Styrene Butadiene Rubber ◽

Butadiene Rubber ◽

Widespread Application ◽

Remarkable Effect ◽

Modified Asphalt ◽

Positive Effects ◽

Polymer Modified Asphalt ◽

Styrene Butadiene

The storage stability concern, caused by phase separation for the density difference between polymers and asphalt fractions, has limited the widespread application of polymer modified asphalt (PMA). Therefore, this study aims to improve the storage concern of PMA by incorporating nano-montmorillonite. To this end, different nano-montmorillonites were incorporated to three PMAs modified with three typical asphalt modifiers, i.e., crumb rubber (CRM), styrene–butadiene-rubber (SBR) and styrene–butadiene-styrene (SBS). A series of laboratory tests were performed to evaluate the storage stability and rheological properties of PMA binders with nano-montmorillonite. As a consequence, the incorporation of nano-montmorillonite exhibited a remarkable effect on enhancing the storage stability of the CRM modified binder, but limited positive effects for the SBR and SBS modified binders. The layered nano-montmorillonite transformed to intercalated or exfoliated structures after interaction with asphalt fractions, providing superior storage stability. Among selected nano-montmorillonites, the pure montmorillonite with Hydroxyl organic ammonium performed the best on enhancing storage stability of PMA. This paper suggests that nano-montmorillonite is a promising modifier to alleviate the storage stability concern for asphalt with polymer modifiers.

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Investigation on Rheological Properties and Storage Stability of Modified Asphalt Based on the Grafting Activation of Crumb Rubber

Polymers ◽

10.3390/polym11101563 ◽

2019 ◽

Vol 11 (10) ◽

pp. 1563 ◽

Cited By ~ 6

Author(s):

Xie ◽

Yang ◽

Lv ◽

Zhang ◽

Zhu ◽

...

Keyword(s):

Rheological Properties ◽

Storage Stability ◽

Crumb Rubber ◽

Modified Asphalt ◽

Rubber Particles ◽

Polymer Separation ◽

Low Temperature Creep ◽

Rheological Test ◽

And Storage ◽

Separation Test

Acrylamide with a double bond and amide group can not only copolymerize with macromolecules of crumb rubber but also react with acidic groups in asphalt, so it was selected as a modifier to activate crumb rubber through chemical graft action. The purpose is to improve the compatibility between crumb rubber and asphalt and thus improve the rheological properties and storage stability of rubber asphalt. Infrared spectroscopy (IR) and scanning electron microscopy (SEM) were used to characterize the crumb rubbers and their modified asphalt. It was found that the crumb rubber of grafting acrylamide had better compatibility in asphalt due to its larger specific surface area and chemical reaction with asphalt. In addition, the high temperature rheological test, low temperature creep test, and polymer separation test were carried out to study the effect of grafted activated crumb rubber on the properties of modified asphalt. The results showed that compared with modified asphalt with common crumb rubber (CRMA), the rheological properties and storage stability of modified asphalt with grafting activated crumb rubber (A–G–R) were improved significantly. The results of microscopic and macroscopic tests show that the activated rubber particles have a larger contact area with asphalt due to a rougher surface and the chemical cross-linking between rubber particles and asphalt further strengthens their interaction. Therefore, there is a relatively stable blend system formed in modified asphalt, and its performance of modified asphalt has been improved.

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Enhanced Storage Stability and Rheological Properties of Asphalt Modified by Activated Waste Rubber Powder

Materials ◽

10.3390/ma14102693 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2693

Author(s):

Weihong Liu ◽

Yishen Xu ◽

Hongjun Wang ◽

Benan Shu ◽

Diego Maria Barbieri ◽

...

Keyword(s):

Rheological Properties ◽

Large Scale ◽

Storage Stability ◽

Chemical Activation ◽

Crumb Rubber ◽

Rubber Powder ◽

Modified Asphalt ◽

Waste Rubber ◽

Waste Rubber Powder ◽

Physical And Chemical

Segregation of waste crumb rubber powder (WR) modified asphalt binders the large-scale application of WR in asphalt. The method of microwave activation combined with chemical activation (KMWR) was proposed to improve storage stability and rheological properties of WR modified asphalt in this work. Storage stability and rheological properties of virgin asphalt, MWR modified asphalt, and KMWR modified asphalt were comparatively studied by the standard segregation test, bending beam rheometer (BBR) test, and dynamic shear rheometer (DSR) test. The effect of composite activation on waste rubber powder particles was studied by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET) tests. The main results showed that after the physical and chemical composite activation, the storage stability of waste rubber powder modified asphalt was significantly improved, WR modified asphalt had better crack resistance, better rutting resistance, and better fatigue performance. After physical and chemical activation, WR was desulfurized, and a large number of active groups was grafted on the WR particles.

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Treatment on Crumb Rubber Modifier towards Enhanced Storage Stability of Asphalt Rubber

智能城市应用 ◽

10.33142/sca.v2i5.815 ◽

2019 ◽

Vol 2 (5) ◽

Author(s):

Guocheng Su ◽

Jiangmiao Yu ◽

Mijash Vaidya

Keyword(s):

Low Temperature ◽

Surface Structure ◽

Interfacial Adhesion ◽

Storage Stability ◽

Research Direction ◽

Crumb Rubber ◽

Modified Asphalt ◽

Waste Tire ◽

Asphalt Rubber ◽

Temperature Performance

Breaking waste tires into crumb and adding it to asphalt as modifier to prepare asphalt rubber (AR) is an effective method to solve the waste tire problem and improve the performance of matrix asphalt. The modified asphalt has better high and low temperature performance. However, the segregation of the crumb rubber modifier (CRM) causes storage instability of the AR. At present, studies have been conducted that improving the solubility of the CRM or adding some macromolecular polymer can improve the storage stability of the AR. However, the structure and polarity of the CRM surface are rarely explored for its correlation with the storage stability of AR. In this paper, the surface structure and polarity of the CRMs was changed by four different reagents, and the properties of the ARs prepared by the CRM were measured to analyze the adhesion between the CRM and the asphalt. It is concluded that the CRM with rough porous and non-polar surface has higher storage stability due to the better interfacial adhesion, which provides a research direction for improving the storage stability of rubber asphalt.

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Performance of SBS modifier-crumb rubber composite modified asphalt used as an anti-wear layer of perpetual pavement

International Journal of Pavement Engineering ◽

10.1080/10298436.2021.1932882 ◽

2021 ◽

pp. 1-15

Author(s):

Zhihao Yang ◽

Linbing Wang ◽

Xu Bin ◽

Dongwei Cao ◽

Jianfeng Li ◽

...

Keyword(s):

Crumb Rubber ◽

Modified Asphalt ◽

Rubber Composite ◽

Perpetual Pavement

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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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Greener Solution to Waste Corn Stalks and Shortage of Asphalt Resource: Hydrochar Produced by Hydrothermal Carbonization as a Novel Performance Enhancer for Asphalt Binder

Materials ◽

10.3390/ma14061427 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1427

Author(s):

Xiaoming Wu ◽

Chichun Hu

Keyword(s):

High Temperature ◽

Reaction Temperature ◽

Storage Stability ◽

Asphalt Binder ◽

Aging Effect ◽

Experimental Tests ◽

Hydrothermal Carbonization ◽

Modified Asphalt ◽

Direct Combustion ◽

Aging Property

Utilization of waste corn stalks (CS) has seized extensive attention due to high annual output and hazardous impact of piling aside or direct combustion on environment. However, previously there has been a lot of emphasis on improvement of its energy efficiency as solid fuel while limited investigations are available which explore the possibility of applying corn stalks as performance enhancer in asphalt binder. The purpose of this study is to examine the potential of employing hydrochar as modifiers in asphalt binder by a series of experimental tests. In this study, two hydrochar were produced from corn stalks by a novel process called hydrothermal carbonization at a different reaction temperature. The two hydrochar and their responding hydrochar-modified asphalt (HCMA) were tested by chemical and rheological tests. Chemical analysis detected the interaction between hydrochar and binder factions, resulting in poor compatibility but satisfying anti-aging property. Even though hydrochar increased the viscosity of bitumen, implying worse workability, and caused poor storage stability, ameliorated performance of asphalt binder at high temperature by incorporating hydrochar was verified by various criteria such as higher performance grade (PG) failure temperature and lower non-recoverable creep compliance (Jnr). Moreover, higher reaction temperature makes hydrochar’s particles smaller and more homogeneous, which results in slightly lower enhanced high temperature performance, more satisfying workability, better storage stability, and greater anti-aging effect of hydrochar-modified asphalt. Eventually, this study provided a promising win-win solution to environment problems concerning corn stalk treatment and shortage of asphalt binder. Further exploration of methods to improve HCMA’s storage stability, real-scale corroboration on trial section and life cycle assessment of asphalt pavement containing hydrochar modifiers will be followed in the future.

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