Crumb Rubber Modified Binders Research Articles

Optimization of Fracture and Moisture Damage Resistance of Stone Matrix Asphalt Mixtures Containing Crumb Rubber-Modified Binder with the Fracture Mechanics Approach

Optimization of Fracture and Moisture Damage Resistance of Stone Matrix Asphalt Mixtures Containing Crumb Rubber-Modified Binder with the Fracture Mechanics Approach

Perpetual pavement utilizing crumb rubber modified bitumen: A case study of the trial section on the S-19 expressway

To minimize the environmental impact of road construction and reduce the carbon footprint, it is essential to design pavements with sustainability in mind, considering their entire life cycle. On the S19 expressway between Kraśnik and Janów Lubelski, a 400-meter-long trial section was designed and constructed in full alignment with this strategy. The pavement structure was developed following the American concept of perpetual pavement, incorporating a stiff and rut-resistant binder course along with a flexible and fatigue-resistant base course. This layer arrangement significantly extended the service life of the pavement without increasing the structure’s thickness. Additionally, recycled crumb rubber-modified bitumen from used vehicle tires was used for all asphalt layers. Beyond its ecological value, recycling waste tires also positively impacts material parameters. The constructed pavement structure enables the reduction of natural resource consumption, elongation of the periods between maintenance, and the utilization of fully valuable waste, like used car tires. Moreover, this type of structure is entirely recyclable, allowing for its use in the construction of new roads after its designated service life. The paper describes a method for designing perpetual pavement structures, presents a comparison of properties between crumb rubber-modified binders and standard binders, and provides test results for asphalt mixtures. The deflection measurements obtained by the falling weight deflectometer are also discussed.

Exploring potential of Marshall-RT as simple performance test to evaluate rutting resistance of asphalt mixtures

ABSTRACT This study explored a new simple monotonic Marshall rutting test (Marshall-RT) to evaluate the rutting resistance of asphalt mixtures. The Marshall-RT test setup combines the Marshall fixture (at the bottom) and the IDT fixture (at the top). The rutting resistance of asphalt mixtures was evaluated using peak load (Pmax) and work done for the deformation damage obtained from the load-displacement curve. Nine plant-produced asphalt mixtures having different types of binders (unmodified, crumb rubber modified binder (CRMB)), and polymer modified binder (PMB)) and gradations having different nominal maximum aggregate sizes (NMAS) were evaluated. The Marshall-RT test parameters (i.e. Pmax and W P m a x ) have shown a strong correlation with fundamental (i.e. Flow Number (FN)), simulative (i.e. Hamburg wheel tracking test (HWTT)), and simple monotonic (i.e. Ideal rutting test (IDEAL-RT)) rutting tests. Moreover, the Marshall-RT test has shown good repeatability, the highest differentiation potential, and consistent ranking with other rutting tests. Furthermore, for high traffic levels (i.e. 100 MSA (Million Standard Axle)), at 50°C preliminary minimum threshold criteria were proposed for Marshall-RT (Pmax and W P m a x ), and IDEAL-RT (RTIndex) as 5 kN, 14 kN-mm, and 90, respectively, to avoid premature rutting failure. Thus, the newly developed monotonic Marshall-RT test can also be used as a surrogate simple performance test to estimate the rutting potential of asphalt mixtures during the mix design and plant production phases as quality control (QC)/quality assurance (QA).

Optimization of Crumb Rubber Modified Binder Formulation through Compatibility Analysis.

The research is devoted to developing the production of crumb rubber-modified bitumen with improved stability. It has been established that the most suitable semi-empirical coefficient for determining the compatible plasticizer to crumb rubber is based on the ratio of paraffin-naphthenic compounds to resinous-asphaltene compounds. With the help of differential scanning calorimetry, temperature regimes of crumb rubber destruction and preparation of rubber-containing components (210 °C) were studied and determined. It was established that determining the dynamic viscosity of hydrocarbon concentrates with crumb rubber on a rotary viscometer is not applicable due to elastic components, making it difficult to measure and obtain reliable data. The most suitable method is the shear viscosity method. Using fluorescent microscopy, it was established that the formation of a branched structure of crumb rubber is achieved in the waste industrial oil, indicating devulcanization processes. It was found that hydrocarbon plasticizer with high naphthenic oil content is the most compatible with crumb rubber. Synthetic wax was found to be of greater interest as a devulcanizing/stabilizing agent, and its application in an amount of 3% allows the formation of a stable CRMB structure and stabilizes the devulcanization process.

Investigating bonding mechanism of rubberized RAP asphalt mastic from rheological and physiochemical perspectives

Considering the enormous amounts of virgin materials consumed in road construction and rehabilitation, recycling reclaimed asphalt pavement has aroused great interest recently. Among different modifiers, crumb rubber is a waste material that significantly enhances different characteristics of the asphalt binder. This study investigates the bonding strength of asphalt mastic of reclaimed asphalt binder modified by crumb rubber-modified binder. The study also attempts to model the mastic bonding strength and understand its mechanism. Thirty binders with different percentages of crumb rubber and reclaimed asphalt were mixed with two filler types to produce the asphalt mastics. Moreover, the two phases of the binder colloid, gel and liquid phases, created by crumb rubber modification, were separated to evaluate the crumb rubber interaction and its impact on mastic bonding. The pull-off test was used to evaluate the bonding strength of asphalt mastics and binders, while dynamic shear rheometer and Fourier-transformed infrared spectroscopy were used to evaluate the physiochemical and rheological characteristics of the asphalt binders. The results show that crumb rubber and reclaimed asphalt modifications greatly strengthen the mastic bonding. The accretion of carbonyl groups due to the reclaimed asphalt addition and withdrawal of light components due to the crumb rubber interaction improves the stiffness of the liquid phase binder, which is strongly correlated to the mastic bonding strength. Furthermore, despite its role in strengthening the binder stiffness, the crumb rubber particles as fillers no longer affect the mastic bonding, where this role is undermined by the mineral fillers.

Laboratory Assessment of Modified Asphalt Binders Using Crumb Rubber Modifier (CRM) and Processed Oil

The study examines the effects of modifying PG 64-22 asphalt binder with Crumb Rubber Modifier (CRM) and processed oil on its properties. The binder was tested at different temperatures, and different amounts of CRM and processed oil were added to the binder. The modified binders were also aged using different procedures. The study found that adding processed oil to CRM-modified binders reduces viscosity and improves workability, while CRM improves the rutting resistance. However, the addition of processed oil reduces the binder’s rutting performance. The study also found that CRM and processed oil improve the low temperature cracking resistance. The study’s results indicate that co-modifying CRM binders with processed oil resulted in a significant reduction in viscosity values, resulting in improved workability. The results also showed that increasing the processed oil concentration from 6% to 12% caused a viscosity reduction of 27%, 34%, 33%, and 31% for modified binders containing 0, 5%, 10%, and 15% CRM, respectively. Even though the addition of processed oil results in a reduction in the rutting performance of asphalt binder, the addition of CRM significantly improved the rutting resistance of asphalt binders. The CRM binder containing processed oil decreased the G*sin δ values, and the content of 6% processed oil containing 5%, 10%, and 15% CRM decreased by 28%, 17%, and 11%, respectively, while the 12% processed oil-modified asphalt binder showed a reduction in G*sin δ by 5%, 13%, and 22%, respectively. The BBR results for modified asphalt binders showed that the incorporation of CRM and processed oil improved the low temperature cracking resistance significantly. The stiffness values with 6% processed oil containing 5%, 10%, and 15% CRM were observed to be 118, 97, and 80 MPa, respectively, while at the same temperature for the same CRM contents with 12% processed oil, the stiffness values were found to be 89, 72, and 56 MPa, respectively.

Optimization of asphalt mixture design using response surface method for stone matrix warm mix asphalt incorporating crumb rubber modified binder

The use of crumb rubber as an asphalt bitumen performance improver has received special attention. The high viscosity of crumb rubber modified binder (CRMB) and the need for high production temperatures in mixtures containing this type of bitumen necessitate the use of warm mix asphalt (WMA) technology. One of the important applications of CRMB is in special-use mixtures such as stone matrix asphalt (SMA). This study aimed to determine the optimal design of stone matrix warm mix asphalt containing CRMB. Therefore, the response surface method (RSM) was used to develop the response prediction models. Production temperature and the content of polyethylene wax and CRMB were considered independent variables of the study. Moisture sensitivity, flow number, resilient modulus, and critical stress intensity factor were used as response (dependent) variables to determine the optimal design of the mixture. The results showed that the prediction models of response variables can predict the performance results with acceptable accuracy. Production temperature and polyethylene wax content are the most important factors in prediction models. To achieve the optimal design of the mixture, minimizing the production temperature and resilient modulus and maximizing the flow number, resistance to moisture susceptibility, and critical stress intensity factor led to the achievement of desirable solutions. The optimal design of stone matrix warm mix asphalt containing CRMB at 135 °C, 7.02 % CRMB, and 2.1 % polyethylene wax using predictive models with 0.765 desirability were obtained.

Effect of Blending and Curing Conditions on the Storage Stability of Rubberized Asphalt Binders.

Crumb rubber modifier (CRM) binders easily suffer from instability at high temperatures, with many suggestions being developed to evaluate their storage stability. However, much uncertainty around CRM binders still exists regarding the relationship between mixing methods and experiments in order to calculate the separation index. In this study, a laboratory investigation into how CRM binders behave regarding storage stability using different mixing methods and experiments was conducted. The CRM asphalt binder in this study was prepared through a wet mixing process with the addition of 5% and 10% crumb rubber modifier (by weight) at 200 °C. The three main modification methods were method A: high-shear mixing (8000 rpm) for 2 h, method B: low mixing (300 rpm) for 8 h, and method C: high-shear mixing (8000 rpm) for 2 h + low mixing (300 rpm) for 6 h. In addition, the effect of separation index (SI) on storage stability was assessed, measuring viscosity, G*/sin δ, and percentage recovery. In general, the results of this study revealed that method C appeared to have the most prominent effect on decreasing the difference between the values of the top and bottom parts; the results for 5% CRM using method C showed that there were no differences among the values for the top, middle, and bottom parts; from the MSCR test, method C was effective in decreasing the difference between the values of the top and bottom parts. It was observed that method C improved storage stability. However, the results for percentage recovery were relatively higher than the separation index when using rotational viscosity and G*/sin δ.

Aging Potential and its Impact on the Bonding Strength of Rubberized RAP Asphalt Binder

Rejuvenating the reclaimed asphalt binder using crumb rubber-modified binder is a sustainable paving technology that has the advantage of using waste to recycle another waste material. As binder durability is crucial in evaluating the recyclability of reclaimed asphalt using crumb rubber-modified binder, this study investigates the binder potential for aging and the impact of aging on binder bond strength. Thirty binders with different crumb rubber and reclaimed asphalt dosages were aged by rolling thin oven and pressure aging vessel and tested by Fourier-transformed infrared spectroscopy and pull-off tests. The results reveal that binder aging and reclaimed binder addition strengthen the bonding strength and elevate the carbonyl intensity, which is the keen factor responsible for bonding enhancement. However, incorporating reclaimed binders attenuates the binder aging potential and limits the bonding enhancement after aging. Crumb rubber interacts with the asphalt binder and improves the bonding strength accordingly. However, the crumb rubber interaction with the binder significantly affects the aging potential of the binder, which increases with crumb rubber disintegration and decreases with rubber swelling. As rubber swelling is the dominating interaction mechanism, the crumb rubber modification mostly undermines the bonding enhancement after aging.

Modeling the Viscosity Behavior of Crumb Rubber–Modified Binder Using Response Surface Methodology

Modeling the Viscosity Behavior of Crumb Rubber–Modified Binder Using Response Surface Methodology

Bond Strength in Dry Condition of Reclaimed Asphalt Modified by Crumb Rubber Modified Binder

ABSTRACT Reclaimed asphalt modified by crumb rubber-modified binder aroused great interest due to its advantage of using two waste materials without compromising the mechanical performance. Apart from the economic and environmental benefits, many studies revealed that excellent mechanical characteristics could be obtained at some particular rubber and reclaimed asphalt percents. In this study, a binder bond test was performed to evaluate the binder bond strength of reclaimed asphalt modified by rubber modified binder in dry condition. Twenty-four binders with various rubber and reclaimed asphalt contents were prepared and tested. The 24 binders can be divided into four binder categories: virgin binder, reclaimed asphalt modified by a virgin binder, rubber modified binder, and reclaimed asphalt modified by rubber modified binder. Three aggregate types, limestone, basalt, and granite, were fostered. The results showed a fair correlation between binder viscosity and bond strength, indicating that higher bond strength can be achieved by increasing the reclaimed asphalt content in the reclaimed asphalt modified by rubberized binder. Even more, for binder # 70, reclaimed asphalt modified by rubberized binder with 40% reclaimed asphalt content has bond strength similar to the virgin binder, irrespective of the aggregate type.

Evaluation of an Asphalt Mixture Containing a High Content of Reclaimed Asphalt and Different Crumb Rubber Modified Binders

Abstract Recently, environmental concerns have become a primary driving force in most countries and industries dealing with natural resources. As a part of this category, asphalt pavement industry is trying to implement more green and sustainable features in its products, while maintaining the mechanical and performance-based properties of the resulting asphalt mixtures. Among potential recycled materials, vehicle tires and aged asphalt pavement have been demonstrated to show economic, ecological, and behavioral improvements in the mixtures. However, mixtures with a high content of reclaimed asphalt (RA) and crumb rubber present some limitations. Therefore, using another group of additives, i.e., a warm mix asphalt (WMA) additive, has been considered. The presented paper investigates the use of an elevated content of RA with different crumb rubber modified binders and (in some mixtures) a warm mix additive in an asphalt concrete (AC) binder mix. Regular empirical tests have been conducted and more advanced performance or functional characteristics, i.e., stiffness, thermal induced cracking, resistance to permanent deformation, complex modulus have been determined and evaluated. Selected results are presented in the paper.

Characterizing Compatibility of Crumb Rubber Modified Asphalt by Customized Drainage Method

Abstract The poor compatibility between crumb rubber (CR) and asphalt matrix always brought difficulties to the engineering application of CR modified (CRM) asphalt. The compatibility in CRM asphalt was universally characterized by storage stability test at a macroscale. Actually, the term “compatibility” was introduced to describe the “level of interaction” between the asphalt and polymers in polymer modified asphalt. Therefore, in this study, the compatibility in CRM asphalt (i.e., the level of asphalt-rubber interaction) was newly characterized by removing the CR particles in the CRM binder through a customized drainage process and quantifying the difference between drained asphalt and base asphalt. In practical terms, the changes in the rheological properties and chemical composition of binder relative to base asphalt were measured by dynamic shear rheometer and gel permeation chromatography, respectively. Based on this novel characterization, it was found that smaller CR particles tended to possess greater compatibility with asphalt, and the asphalt with a higher percentage of light fractions was expected to be more compatible with CR particles. On the other hand, the result of the conventional hot tube test found the storage stability mainly depended on the size and content of CR particles. Furthermore, a strong statistical correlation between the novel characterizations (i.e., changes in rheology and chemistry of binder) and the common characterization (i.e., storage stability) was found, and its essential cause was discussed. Therefore, this novel characterization could provide another reliable and simple way to evaluate the compatibility in CRM asphalt.

Evaluation of Petroleum Resin in Rubberized Asphalt Binder

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.

Effect of Recycled Asphalt Pavement Binder on Rheology of Crumb Rubber–Modified Binder—An Experimental, Analytical, and Analogical Study

Abstract The popularity of recycled asphalt pavement (RAP) is on the rise because of the benefits of sustainability. In an unavoidable scenario wherein crumb rubber–modified binder (CRMB) is adopted as a base binder in RAP mixes, the binder from RAP will blend with CRMB, thereby influencing its rheology and performance at high, intermediate, and low temperature. Hence, in this study, binder extracted from two RAP sources (RAP X and RAP Y) was blended with CRMB at varying proportions of 15, 25, and 40 % by weight. Isochronal temperature sweeps, isothermal frequency sweeps, and bending beam rheometer tests were conducted on the prepared blends. Thereafter, analytical and analogical studies were performed using master curve construction, 2S2P1D, and Huet modelling. The results indicated that RAP from different sources affects the high-, intermediate-, and low-temperature performance of CRMB. Different RAPs were observed to have contrasting effects on high-temperature performance grading. Intermediate-temperature performance based on cross-over temperature (TCROSS-OVER) indicated a compromise because of the inclusion of RAPs. An evaluation of the differences among critical temperatures at low temperature (ΔTc) indicated the degradation of low-temperature performance. Such changes in high-, intermediate-, and low-temperature performances were validated by complex modulus (G*), stiffness (S(t)), and stress relaxation (E(t)) master curves. Finally, the 2S2P1D and Huet model were observed to depict reasonably good fits for the prepared blends. This study concludes that RAPs from different sources have contrasting impact on CRMB and may adversely impact the intermediate- and low-temperature performance.

A new rheological approach to evaluating the aged performance of Crumb Rubber Modified binders

ABSTRACT Crumb Rubber Modified (CRM) binder specifications has historically relied on empirical testing with limited relationships to pavement performance. Several fundamental rheological tests have been developed in the Dynamic Shear Rheometer (DSR) with demonstrated correlation to field performance. However, these tests are conducted on aged materials to simulate in service performance through laboratory aging protocols that are not suitable for CRM binders. With the growing need for reliable performance-based characterisation of asphalt binders, a new approach to evaluating CRM binder performance is needed. This study utilises an experimental approach to introduce a new analysis methodology for evaluating performance characteristics of CRM binders. A new rheological parameter ‘Crossover Temperature’ is introduced and defined as the temperature at which the stiffnesses of CRM and residual (rubber filtered out after interaction) binders coincide. Crossover Temperature provided strong correlations to CRM binder fatigue and rutting characteristics, without the need for binder aging or micromechanical modelling. A wide range of base asphalt binders and CR sizes were utilised in this study. This parameter is recommended for Quality Control screening of CRM binders.

Performance Evaluation of Crumb Rubber Asphalt Modified with Silicone-Based Warm Mix Additives

This research was conducted to elucidate better understanding of the performance of crumb rubber asphalt modified with silicone-based warm mix additives. Two different silicone-based warm mix asphalt (WMA) additives (herein Tego XP and Addibit) were used to prepare crumb rubber modified (CRM) warm mix asphalt binders. The viscosity of these CRM binders was measured at different temperatures and shearing rates. Furthermore, softening point and penetration tests, Multiple Stress Creep Recovery (MSCR), Time Sweep (TS), Atomic Force Microscopy (AFM), Frequency sweep (FS), and Fourier Transform Infrared (FTIR) tests were also conducted on prepared samples. Based on these robust and rigorous laboratory experiments, it was established that viscosity of CRM binders was reduced by addition of Tego XP and Addibit WMA additives. However, WMA additives had different influence on rheological properties of the binder. CRM binder with Tego XP improved resistance to rutting of the binders but would degrade the fatigue performance. On the contrary, viscoelastic continuum damage (VECD) model results and those of phase angle approach revealed that the binder with Addibit improved resistance to fatigue cracking of the binders but had no adverse effects on high temperature rutting performance. FTIR test results established a presence of polydimethylsiloxane (PDMS) in CRM binders with Tego XP and Addibit. PDMS is a well-known hydrophobic organic and inorganic polymer that is water repellent; therefore, binders containing these silicone-based warm mix additives could be beneficial in resisting moisture damage in asphalt binders and mixtures. Morphology of CRM binders with and without WMA revealed good distribution of the rubber particles in asphalt binder matrix. Further addition of WMA increased surface roughness of the binder, which can be correlated to changes in microstructure properties of the binder. Therefore, the study concluded that addition of Tego XP and Addibit reduces viscosity and improves mechanical properties of the asphalt binder.

An Investigation on Bituminous Concrete Mix Design by using Crumb Rubber Modified Binder (CRMB)

An Investigation on Bituminous Concrete Mix Design by using Crumb Rubber Modified Binder (CRMB)

Influence of binder type on performance of dense bituminous mixture prepared with coarse recycled concrete aggregate

Conventional stone aggregates are becoming scare and costly because of huge infrastructure activities going on since last three decades in India. On the other hand, wastes such as that resulting from old concrete constructions are abundantly available. Many attempts have already been made to utilise these wastes referred to as recycled concrete aggregate (RCA) in various constructions including in bituminous paving layers. All types of bituminous binders commonly used in paving mixes in India may not be compatible with RCA. This experimental study aims to study the influence of binder type on the performance of dense graded bituminous mixtures containing RCA replacing the coarse fraction of conventional stone aggregates. In order to achieve this main objective, dense bituminous macadam (DBM) mixtures as per the relevant Indian specifications were prepared using three different types of bituminous binders commonly used in India, namely conventional VG 30 and VG 40 bitumens, and crumb rubber modified binder (CRMB). Separate Marshall samples were prepared using RCA and natural aggregate (NA) and either of the above three binders. As per the main scope of this study, the mixtures thus prepared were evaluated in terms of their engineering properties such as Marshall characteristics, indirect tensile strength, moisture susceptibility characteristics, resilient modulus and rutting resistance. It is observed that all mixtures considered in this study, in general satisfy the requirements in terms of Marshall and moisture susceptibility characteristics. Considering all engineering properties studied, the CRMB/VG40 bitumen offer superior and satisfactory results for mixtures containing either NA or RCA, with NA showing slightly better result as compared with RCA in the mixtures.

High-Temperature Performance and Workability of Crumb Rubber–Modified Warm-Mix Asphalt

Abstract Crumb rubber produced from scrap tires has been widely applied in asphalt mixtures to improve the pavement performance. Warm-mix technology has also been employed to lower the production temperature of asphalt mixtures. The objective of this article is to investigate the effects of warm-mix additive types and crumb rubber concentration on the resistance to deformation of crumb rubber–modified (CRM) binders through the repeated creep and recovery test (RCRT), dynamic shear rheometer (DSR), and rotational viscosity test. The CRM binders with crumb rubber concentrations of 10 %, 15 %, 20 %, and 25 % were prepared first as the control binders. Then, three types of warm-mix additives, Sasobit, RH, and Advera, were added into the CRM asphalt to produce CRM warm-mix asphalt (WMA) binder. Generally, the workability of CRM asphalt can be improved with the addition of warm-mix additives. The effect of warm-mix additive on the high-temperature performance is highly dependent on the crumb rubber dosage. The RCRT results overall showed that the warm-mix additives can improve the high-temperature performance of asphalt when the crumb rubber concentration is low. However, according to the DSR test, Sasobit improved the rutting resistance of CRM asphalt, while the RH and Advera sacrificed the rutting resistance. The inconsistency between the RCRT and DSR results suggests that it may be necessary to conduct both the tests when investigating the high-temperature performance of CRM asphalt with warm-mix additives.