Crumb Rubber Modified Bitumen Research Articles

Experimental Investigations of Bituminous Concrete Using Dissimilar Trash Which Improve the Results

Abstract: Bituminous mixture is an admixture of coarse aggregate, fine aggregate and fill. CRMB is based on a unique technology that permits homogeneity. CRMB is suited for use in heavy load traffic lanes, air fields. In this study, Crumb Rubber Modified Bitumen (CRMB-60) blended with normal asphalt binder VG-30 with various different percentages of crumb rubber in different proportions with constant optimum binder content i.e. 5% which shows improved characteristics when compared with regular bitumen. The cost for Bituminous course for CRMB-60 came out to be Rs 68.23 Lacs per Km which was 20.81% economical than the bituminous work done by normal VG- 30 bitumen. The Marshall Mix design using CRMB 55 with 0.04 % Zycosoil chemical, reflects the significant rise in stability, unit weight and flow values for better compaction and enhancing the workability conditions.

Incorporting Tire Dust in Roadworks

Abstract: In this study the changes that are incurred in the properties of bitumen upon adding scrap tire dust in it are investigated. The basic properties of bitumen are Ductility, Softening Point and Penetration Value. These values change depending on the grade of bitumen. The objective of this study is to determine the rate of change of basic bituminous properties and other key properties such as Marshall Stability and Flow Rate of Dense Bituminous Macadam due to addition of scrap tire dust in bitumen. Crumb Rubber Modified Bitumen is acquired by adding certain amount of tire dust in bitumen, in this study 10% and 30% of bitumen is replaced with scrap tire dust and their properties are compared with the properties of pure bitumen. Modifying bitumen with scrap tire dust increases the stability, flow rate, penetration value and softening point which makes it more resistant to loading and temperature. Incorporating scrap tire dust in roadworks also helps in reducing the overall volume of waste tires. Scrap tires are often a breeding place for mosquitoes as tires contain huge concentration of carbon. Burning of tires leads to even greater hazards. So, through modifying bitumen with tire dust we can prevent harm to environment and enhance the properties of Bitumen

Performance of Stone Matrix Asphalt Modified with Crumb Rubber and Fibres

This article investigates the impact of Crumb Rubber Modified Bitumen (CRMB) and fibre additives (aramid fibre and basalt fibre) on the performance properties of Stone Matrix Asphalt (SMA) mixtures. Tests were conducted to evaluate mix design, draindown, cantabro loss, moisture sensitivity, rutting resistance and fatigue behavior. The Marshall method, the draindown parameters (ASTM D6390-11) and the cantabro loss characteristics (ASTM D 7064) were used to examine the mix design qualities. The modified Lottman test was used to assess the moisture sensitivity of SMA mixes. The roller compactor cum rut analyzer was used to assess rutting resistance. Findings showed that CRMB and fibre additives effectively controlled binder draindown and minimized abrasion loss in SMA mixtures. SMA-CRMB mixtures had higher draindown, but comparable cantabro loss than SMA-AF and SMA-BF mixtures. Incorporating CRMB and fibre additives enhanced moisture sensitivity, rutting resistance and fatigue behavior. SMA mixtures with 0.3% fibre addition displayed similar performance properties to SMA with CRMB. Further, substituting fibre additions for CRMB in SMA combinations may yield similar performance. KEYWORDS: Stone matrix asphalt, Crumb rubber-modified bitumen, Fibre additives, Draindown, Cantabro loss, Moisture sensitivity, Rutting resistance, Fatigue behaviour.

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.

Effect of ozone aging on the rheological and chemical properties of crumb rubber-modified bitumen

Crumb rubber can not only solve the environmental pressure but also improve the properties of bituminous pavement. To study the characteristics and mechanism of ozone aging on CRMB, the effects of ozone aging on the rheological properties and chemical composition of crumb rubber-modified bitumen (CRMB) were explored. It was also compared with thermal oxygen. The results show that the macromolecules such as aromatic rings and polar functional group were formed after ozone aging, and the average molecular weight of CRMB increased. Ozone reacted rapidly with the CRMB surface at the beginning of the reaction and leaded to an increase in surface roughness. The risk of fatigue cracking increased. The effect of ozone aging (3 days, 60°C, 1000 ppb) on CRMB was similar to that of long-term aging. The effect of ozone on CRMB was mainly due to the ozone sensitivity of the crumb rubber modifier.

Optimisation of the preparation procedure of crumb rubber modified bitumen with wax-based additives

Wax-based additives can be added to crumb rubber modified bitumen (CRMB) at different stages to enhance the workability. This study aims to optimize the preparation procedure by investigating the effects of the preparation procedure on the rheological properties of CRMB containing wax-based additives and the interaction mechanism. Rubber swelling tests under various conditions were conducted to examine the effects of temperature and additives on the interaction process. Rheological and thermal characterizations were performed on the CRMB binder and its liquid phase. Results show that reducing the bitumen viscosity by adding wax-based additives can promote the bitumen-rubber interaction and achieve similar swelling results at a lower temperature. However, a significant proportion of wax-based additives were found to penetrate rubber particles for the warm-produced CRMB. Although warm-produced CRMB may save energies compared to hot-produced CRMB, it is not recommended to replace the traditional hot-produced CRMB procedure.

Emission of Volatile Organic Compounds in Crumb Rubber Modified Bitumen and Its Inhibition by Using Montmorillonite Nanoclay

Bitumen emits a large amount of volatile organic compounds (VOCs) during the production and construction of asphalt mixture, which can cause both environmental hazards and health risks. In this study, a setup was designed to collect the VOCs released by base and crumb rubber-modified bitumen (CRMB) binders and their composition was characterized by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Next, organic montmorillonite (Mt) nanoclay was added into CRMB binder and its inhibiting effect on the VOCs emission of the binder was investigated. Finally, the VOCs emission models for the CRMB and Mt-modified CRMB (Mt-CRMB) binders were established according to reasonable assumptions. The results indicated that the VOCs emission of CRMB binder was 3.2 times larger than that of the base binder. Due to its intercalated structure, the nanoclay can reduce the VOCs emission of CRMB binder by 30.6%. Especially, its inhibition effects on alkanes, olefins, and aromatic hydrocarbons were more significant. After finite element verification, the established model based on the Fick's second law can describe the emission behavior of CRMB and Mt-CRMB binders well. Overall, the Mt nanoclay can be used as an effective modifier to inhibit the VOCs emission of CRMB binder.

Performance of crumb rubber bitumen and asphalt modified in the wet process alone and in combination with SBS polymer

Crumb rubber can be used as a bitumen or asphalt mixture modifier. Many investigations showed promising properties of crumb rubber-modified bitumen. However, the performance of crumb rubber-modified bitumen depends on crumb rubber properties, modification conditions and neat bitumen properties. The goal of this study is to determine the effect of the amount of crumb rubber and crumb rubber and SBS polymer combination on modified bitumen properties and also to evaluate the resistance to rutting of the asphalt mixture with crumb rubber-modified bitumen. The experimental research results showed that 2% crumb rubber can reduce the required amount of SBS polymer by half and ensure the main properties are equal to those of polymer-modified bitumen. It was also found that crumb rubber-modified bitumen (4% of the crumb rubber) and crumb rubber and SBS polymer-modified bitumen (2% of crumb rubber and 2% of SBS polymer) are equal in rutting resistance.

Features of structure formation in crumb rubber modified bitumen

The research is devoted to developing the science-based technological solution for obtaining crumb rubber modified bitumen (CRMB) with improved stability. The technological solution provides a preliminary process of devulcanization of crumb rubber in hydrocarbon plasticizer in the presence of stabilizing agent and subsequent preparation of CRMB. 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 the most compatible with crumb rubber is a hydrocarbon plasticizer with a high content of naphthenic oil. Synthetic wax was found to be of greater interest as a stabilizing agent, and its application in an amount of 3% allows the formation of a stable CRMB structure and stabilizes the devulcanization process. The test results of obtained CRMB showed that their viscosity corresponds to the requirements for PG bitumen

Swelled Mechanism of Crumb Rubber and Technical Properties of Crumb Rubber Modified Bitumen.

Crumb rubber modified bitumen (CRMB) has excellent high-temperature performance and fatigue resistance, and is widely used in asphalt pavement to cope with increasing traffic axle load and changing climate. Under conventional preparation conditions, the swelling degree of CR can directly impact the comprehensive properties of CRMB; however, physical and chemical properties research on swelling crumb rubber (SCR) and crumb rubber recycled bitumen (CRRB) in CRMB is relatively lacking. In this paper, the working performance of CRMB and CRRB in high-temperature and low-temperature conditions were studied through physical and working performance testing of bitumen. The CR and SCR were tested by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), gel permeation chromatography (GPC), and particle size distribution (PSD) tests to study the physicochemical behavior and microscopic effects before and after CR swelling. The results showed that CR dosage was in the range of 10%, 15%, and 20%, as well as that CR dosages have a positive effect on the high- and low-temperature performance, storage stability, and elastic recovery of bitumen. The high-temperature PG grades of bitumen were directly improved by four grades, and the elastic recovery rate increased by 339.9%. CR improved the ultra-low temperature crack resistance of bitumen. Due to the absorption of lighter components by CR, the relative content of the heavy component of bitumen increased; however, its low-temperature performance decreased significantly. After swelling, the CR particle size increased and the range became wider, the surface complexity of CR became higher, and the specific surface area was larger. At the same time, CR carried out the transformation process from large and medium molecules to small molecules. During the swelling process, a new benzene ring structure appeared in the CR, and the C-C bond and C-S bond of CR broke, forming part of the C=C bond.

Enhancing the asphalt binder's performance against oxidative ageing and solar radiations by incorporating rubber from waste tyres

• Comparisons were made between PAV and UV ageing of neat and rubber modified bitumen. • 1× PAV ageing cycle is compared with 1-year of Melbourne’s UV ageing. • Compared to neat bitumen, crumb rubber reduced the PAV ageing by 2.35 times. • Compared to neat bitumen, crumb rubber reduced the UV ageing by 1.30 times. This study investigates the ageing of neat and crumb rubber modified bitumen (CRMB) under various conditions. Bitumen was modified with a high content of crumb rubber (CR) (22.5% by weight of base bitumen) and subjected to the equivalent amount of UV radiation occurring in one year in Melbourne, Australia. Long-term ageing via pressure ageing vessel was also used to age CRMB. Fourier transform infrared spectroscopy (FTIR) was used to capture the mechanism and evaluate the ageing effect that UV radiation and PAV ageing had on both types of binders. It was found that PAV ageing, due to its high temperature and pressure, mainly involves the evaporation of volatiles, oxidation of bitumen, and the conversion of aromatics to asphaltenes, while UV radiations, on the other hand, destroy the molecular structure of bitumen in addition to providing oxidation. The effect of ageing on rheological performance parameters such as crossover modulus, J nr , and %R was also found in line with the findings from the FTIR spectroscopy. The ageing index developed from the crossover modulus showed that applying a 1-year equivalent of UV radiations in Melbourne (Australia) provides 1.51 times increase in ageing to the neat bitumen while ageing is up to 2.64 times after 20-hour PAV. When the same neat bitumen was modified with CR, the ageing resistance against both PAV and UV radiations was enhanced by limiting the level of ageing to 1.16 and 1.12 times, respectively. Kruskal-Wallis test showed that there is no significant difference between the unaged and aged samples of CRMB in terms of I com . That showed 20-h PAV ageing and 1-year UV ageing did not significantly affect the CRMB, which is evidence of the ageing resistance of CRMBs.

Influence of Evotherm on the thermal equilibrium time of unmodified and modified bituminous binders

ABSTRACT The rheological properties of bitumen largely influence the performance of the pavement. Determination of rheological properties of bitumen depends on thermal equilibrium time. The main objective of this study is to evaluate the effect of Evotherm, a chemical warm mix additive on the thermal equilibrium time of bituminous binders. The bituminous binders used for this study included two unmodified binders, a polymer-modified bitumen (PMB) and a crumb rubber-modified bitumen (CRMB). The thermal equilibrium times for bituminous binders with and without Evotherm were measured using a dynamic shear rheometer. The results indicate that the thermal equilibrium time primarily depends on the type of binder, wherein the asphaltene content, presence of polymer and rubber influence thermal equilibrium time. The higher thermal equilibrium times observed for the Evotherm-modified PMB40 binder and Evotherm-modified CRMB60 binder in unaged condition can be attributed to a change in morphology and chemical interaction respectively upon the addition of Evotherm. Lesser thermal equilibrium time exhibited by short-term aged Evotherm binders can be because of the reduced formation of ageing compounds due to reduced short-term ageing temperature and presence of Evotherm. The linear regression model well predicted the thermal equilibrium time based on test temperature and softening point of binders.

Experimental investigation of impact of crumb rubber on modified bitumen

ABSTRACT Population growth and industrialisation have led to the accretion of rubber waste which increased public concern about environmental pollution. The use of crumb rubber (CR) as a bitumen modifier is an effective way to protect the environment from pollution. The study of different properties of crumb rubber modified bitumen (CRMB) is the substance area of today’s research. Base bitumen having penetration grade 60/70 and crumb rubber proportions from 4% to 12% by weight of bitumen content following wet process was used. Physical properties, rheological properties, chemical properties and binding properties of unaged CRMB and aged CRMB were evaluated by using conventional tests, dynamic shear rheometer (DSR), Fourier transform infrared spectroscopy (FTIR) and bitumen bond strength (BBS) test, respectively. Modification index of complex shear modulus (G*) of bitumen increased with an increase in CR content. FTIR spectra of aged CRMB illustrated that rate of change in indices decreased with an increase in CR content which shows ageing resistance of CRMB. Crumb rubber influenced the adhesion phenomenon of bitumen and aged CRMB tends to achieve better adhesion effects. BBS results revealed that in dry conditions, POTS values of samples after peaking tended to decrease with an increase in the concentration of crumb rubber above 8%.

Micromechanics-Based Viscoelasticity Predictions of Crumb Rubber Modified Bitumen Considering Polymer Network Effects

Crumb rubber modified bitumen (CRMB) can be regarded as a binary composite system in which swollen rubber particles are embedded in the bitumen matrix. Previous study has successfully implemented the micromechanics models in predicting the complex moduli of CRMB binders using more representative constituent parameters. In the regime of master curves, while the micromechanics models used predicted well in the high-frequency range, they underestimated the complex modulus in the low-frequency range. The current study aims to further improve the prediction accuracy of micromechanics models for CRMB by considering the interparticle interactions. To accomplish this goal, a new reinforcement mechanism called chain entanglement effect was introduced to account for the interparticle interaction effect. Results show that the polymer chain entanglement effect accounts for the underestimation of complex modulus and lack of elasticity (overestimation of phase angle) for CRMB at high temperatures/low frequencies. The mechanical properties of bitumen matrix and entangled polymer network can be determined based on the rubber content. The introduction of the entangled polymer network to the generalized self-consistent model significantly improved the prediction accuracy for both complex modulus and phase angle in the whole frequency range. In summary, by incorporating the physio-chemical interaction mechanism into the currently available models, a new dedicated micromechanics model for predicting the mechanical properties of CRMB has been developed. The predicted viscoelastic behaviors can thereafter be used as inputs for an improved mix design.

Performance Evaluation of Flexible Pavements with Modified Bitumen Binders

Abstract: In India majority of roads are being constructed by flexible pavements. But the performance of the pavement largely depends on quality and type of materials used, Construction methodology adopted, temperature, climatic conditions etc. Because of these variations in the mentioned parameters, pavements undergo distress/ failure. The different types of failure in flexible pavement are Rutting, Shovelling, Edge breaks, Cracks, Slippage etc. Rutting is a common phenomenon which occurs in flexible pavement surface due to overloading of vehicles and repeated application of wheel load. Rutting is defined as channelized depression in the pavement surface along wheel path due to heavy repetitive traffic load. Design of bituminous paving mixes greatly effects the performance of pavements. In the present laboratory research work, conventional bitumen is used in wearing/ surface course and Modified Bitumen is used in binder course of the layer. Pavement layers are constructed/casted in an Indigenously designed, developed and fabricated equipment called Roller Compactor cum Rut Analyzer (RCRA) and Rutting test was performed. The overall objective is to compare the Marshall properties of the conventional and Modified Bituminous mix and to study the rutting performance of these bituminous mixes. Results shows that bituminous mixes prepared with Modified Bitumen/Binders has a very high Marshall Strength and offers greater resistance to rutting Keywords: Modified Bitumen, Bituminous Concrete (BC), Dense Bituminous Macadam (DBM), Marshall Stability, Roller Compactor cum Rut Analyzer (RCRA), Crumb Rubber Modified Bitumen (CRMB)

Influence of swelling-degradation degree on rheological properties, thermal pyrolysis kinetics, and emission components of waste crumb rubber modified bitumen

This study investigated the effects of swelling-degradation degree on the rheological properties and thermal pyrolysis behaviors of crumb rubber modified bitumen (CRMB). The equilibrium viscosity of CRMB in 160 °C-swelling process is 10.5 Pa·s at 8 h. During the 200℃-degradation procedure, the viscosity increased to a maximum value of 20.58 Pa·s at 7.5 h and gradually reduced to a stable value of 11.09 Pa·s after 35 h. The swelling and degradation processes exhibit the opposite influence on the rheological properties of CRMB. Moreover, the degradation process accelerated the pyrolysis rate of CRMB but hindered the release of toxic gas CO and hydrocarbons.

Impact of Crumb Rubber Concentration and Plastic Coated Aggregates on the Rheological Performance of Modified Bitumen Asphalt

The diminution of natural resource exploration, the retrieval of waste, and the structural modification of polymers by additives are the main contributions to sustainable development. The properties of bitumen are enhanced by the crumb rubber through effective bitumen modification techniques, which have environmental and economic advantages. In this study, plastic waste, plastic-coated aggregate (PCA), and bitumen were blended in order to enhance the engineering properties of the flexible pavement. In order to compute the composition of crumb rubber modified bitumen (CRMB), the adopted materials were subjected to the relevant experiments. PCA was a very effective material when compared to the standard bitumen road pavement. The recycling of waste crumb rubber and plastic was tested by adding them into the hot mix asphalt. The Marshall properties of standard (virgin) bituminous mix, CRMB grade 55, and plastic mix asphalt were studied in detail to explore the solutions for a sustainable environment. The comparison was performed between these two materials with the standard bitumen, which resulted in the CRMB and plastics being found as the most effective additions with robust properties such as low-cost material, high strength, long life usage, and un-harmful to nature. The optimal bitumen content was found to be 6.166%, 6.1%, and 5.833% for standard bitumen, crumb rubber modified bitumen, and plastic-coated aggregate, respectively.

Vocs Emission Characteristics of Crumb Rubber Modified Bitumen and its Inhibition by Using Montmorillonite Nanoclay

Vocs Emission Characteristics of Crumb Rubber Modified Bitumen and its Inhibition by Using Montmorillonite Nanoclay

Investigating the High- and Low-Temperature Performance of Warm Crumb Rubber–Modified Bituminous Binders Using Rheological Tests

Rubberized asphaltic materials have been frequently combined with warm-mix asphalt technologies to tackle the issues of high energy consumptions and emissions during construction. Effective and accurate characterization of binder properties is conducive to the improvement of long-term pavement performance. The current study aims to quantify the effects of rubber content and warm-mix additives on rutting and thermal cracking performance of crumb rubber-modified bitumen (CRMB), and explore the rubber and additives modification mechanisms and their impacts on the binder performance. CRMBs containing different rubber contents and warm-mix additives after long-term aging were subject to multiple stress creep and recovery (MSCR) tests and low-temperature frequency sweep tests using a dynamic shear rheometer (DSR) with 4-mm loading plate to investigate the high- and low-temperature performance, respectively. Rheological tests were also conducted on the bitumen and rubber phases of CRMB to understand the rubber modification mechanism. Results show that CRMB binders have superior rutting and thermal cracking resistance due to rubber modification. The improvement of high- or low-temperature performance is more prominent at higher rubber concentrations. The effects of warm-mix additives on the rutting and thermal cracking performance are different. Generally, the wax-based additive improves the rutting resistance but negatively affects the low-temperature performance. In contrast, the chemical-based additive has an opposite effect except for the high-temperature performance of neat bitumen. The stiffening of the bitumen phase and the contribution of swollen rubber particles in the bitumen matrix together contribute to the peculiar viscoelastic response of CRMB, i.e., stiffer/softer and more elastic at high/low temperatures. This modification mechanism explains the superior rutting and thermal cracking performance of CRMB.

The continuous swelling-degradation behaviors and chemo-rheological properties of waste crumb rubber modified bitumen considering the effect of rubber size

The chemo-rheological properties of crumb rubber modified bitumen are always unstable due to the mutable and uncontrollable swelling-degradation degree of crumb rubber in bitumen matrix. The study aimed at exploring the continuous swelling and degradation behaviors of crumb rubber modified bitumen (CRMB) considering the influence of rubber size through monitoring the dynamic viscosity changes of CRMB binders. Moreover, the synergistic effects of swelling-degradation degree and rubber size on the chemical and rheological properties of CRMB were investigated. The results revealed that the rubber size significantly influenced the swelling and degradation behaviors of CRMB. The reduction of rubber size shortened the equilibrium swelling and degradation time, while increased the related viscosity dramatically. Moreover, during the degradation process, the decrease of rubber size could accelerate the continuous swelling rate, increase the maximum viscosity and reduce the continuous swelling time of CRMB. Meanwhile, the high swelling degree and large rubber size were beneficial to enhance the high temperature properties, while the CRMB binder with high degradation degree showed the better low-temperature property, workability and wider Newtonian flow region. Furthermore, the degradation degree promoted the formation of free hydroxide groups, aldehydes, carboxylic acids and esters, while the swelling process increased the average molecular weight of whole liquid phase in CRMB binder. The outputs from this fundamental study are beneficial to provide the guidance to preparation conditions optimization of CRMB binders with different viscous property standards.