Rubber Bitumen Research Articles

Effect of nano silica on the performance of modified crumb rubber bitumen and asphalt mixtures

Effect of nano silica on the performance of modified crumb rubber bitumen and asphalt mixtures

Experimental Investigation of Sand–Rubber–Bitumen Mixtures as a Geotechnical Seismic Isolation Material

Experimental Investigation of Sand–Rubber–Bitumen Mixtures as a Geotechnical Seismic Isolation Material

Improving anti-aging performance of terminal blend rubberized bitumen by using graft activated crumb rubber

Abstract The appearance of terminal blend rubberized bitumen (TB) has improved a series of defects of traditional rubber bitumen, such as high viscosity, poor storage stability. Therefore, its wide application prospect is self-evident. However, different degrees of thermal-oxidative aging problem still exist in the process from production to use of TB, which seriously affects the service life of pavement. To improve the anti-aging performance of TB, grafting activated crumb rubber (GACR) was obtained by using acrylamide, and then compounded with TB. Firstly, TB was prepared in the self-developed nitrogen protection device. Secondly, GACR modified bitumen (GACR-MB), TB/CR composite modified bitumen (TB/CR) and TB/GACR composite modified bitumen (TB/GACR) were developed in the atmospheric environment. Finally, the performance of four kinds of crumb rubber modified bitumens before and after aging was compared and analyzed by testing high and low temperature rheological properties. The results show that GACR slowed down the formation rate and aggregation degree of asphaltenes and other macromolecular substances, and TB/GACR showed excellent aging resistance.

Performance analysis of non-conventional Stone Mastic asphalt (SMA) elaborated with crumb rubber bitumen or by mean of glass macrofibers addition

Stone Mastic Asphalt (SMA) are high performance mixes that are widely used throughout the world. Originally designed in Germany, they are identified as mixtures with high percentages of coarse aggregates, lower quantities of fine materials, high filler content and higher bitumen contents than a conventional asphalt. To achieve these higher bitumen percentages, it is necessary to incorporate fibres, generally cellulose fibres, to prevent binder draindown during mixing, transport and compaction. There are currently studies, at research level, to eliminate or reduce the dosage of fibres using high-viscosity bitumen’s. One way to achieve this kind of bitumen is through high rates of Crumb rubber (CR) from end-of-life tyres. This allows the use of high bitumen percentages without draindown and dispense with the use of fibres. Another alternative is to replace cellulose fibres with synthetic or glass macrofibre’s, these latter being considered structural. The macrofibre acts improving rutting and cracking resistance, providing performance improvements, especially in extreme weather conditions. This work focuses on the study of a 19 mm maximum size SMA analysing its performance to rutting, cracking, dynamic modulus, and moisture damage. Alternatives to the traditional SMA with cellulose fibres were studied here; one through the addition of glass macrofibres maintaining the commercial polymer modified asphalt and other alternative was a fibreless SMA elaborated with a high-viscosity modified asphalt with Crumb rubber (CR) from end-of-life tyres. It was found it is possible to produce SMA with high viscosity crumb rubber bitumen binder without fibres (SMA CR) and met all the volumetric characteristics specified for SMAs, specifically the draindown. The SMA CR and Glass addition in SMA showed improvements in dynamic modulus behaviour. The addition of glass macrofibres provide improvements with higher cracking resistance at low temperatures.

Performance characterization of crumb rubber modified bitumen using pyrolyzed waste tyre treated bitumen

Exponential deterioration in pavement caused by heavy loads, temperature variations, and heavy rainfall had led to pavement failure. To overcome those failures, bitumen properties needed to be enhanced in an economical and sustainable way. Researchers have used various modifiers to enhance the properties of virgin bitumen, but the end product still does not seem to be accepted by the asphalt industry at the required level. On the other hand, the construction cost has also increased due to the addition of modifiers, which have varying performance characteristics. To address such issues, waste materials such as crumb rubber obtained from waste tyres are used to enhance the properties of bitumen. The incorporation of crumb rubber has enhanced the properties of bitumen and has been well proven for decades. However, the product is still not widely accepted due to limitations such as consistency and uniformity during and after the production stages. In this research, crumb rubber was converted into pyrolyzed oil using a pyrolysis protocol and it was observed through the values of penetration and softening point test shows that optimum 2% pyrolyzed oil can be treated with bitumen to increase workability and flowability at low temperatures, such that additional crumb rubber in crumb form can be added homogenously. The results showed that an optimum quantity of 20% crumb rubber by mass of bitumen can be blended with pyrolyzed modified bitumen that is 5% crumb rubber more compared to untreated modified crumb rubber bitumen, which simultaneously increases the physical and mechanical properties of the mix. It enhances the softening point, viscosity, and storage stability while decreasing the penetration value.

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.

Soft Computing Approach for Predicting the Effects of Waste Rubber–Bitumen Interaction Phenomena on the Viscosity of Rubberized Bitumen

The ability to anticipate the effects of the interaction between waste rubber particles from end-of-life tires and bitumen can encourage the use of rubberized bitumen, a material with proven environmental benefits, in civil engineering applications. In this study, a predictive model of rubberized bitumen viscosity is presented for this purpose. A machine learning-based approach (Multi-Gene Genetic Programming—MGGP) and a more traditional multi-variable least square regression (MLSR) method are compared. The statistical analysis indicates that the robustness and the capability of the MGGP algorithm led to a better estimation of the rubberized bitumen’s viscosity. Additionally, the MGGP analysis returned an actual equation that could be easily implemented in any spreadsheet for an initial tuning of the production protocol based on the desired level of interaction between the rubber and bitumen.

Aging Process Effects on the Characteristics of Vacuum Residue Oxidation Products with the Addition of Crumb Rubber.

This paper considers the effect of aging processes on viscoelastic characteristics of vacuum residue oxidation products modified with crumb rubber. Viscoelastic properties were compared to original bitumen raw material-vacuum residue and vacuum residue oxidation products during short-term and long-term aging. The complex shear modulus of the vacuum residue and its oxidation products decreased with an increase in temperature. Short-term aging resulted in increased shear modulus for all samples.The vacuum residue oxidation product modified with crumb rubber had the maximum values of the rutting parameter and fatigue parameter. There was an expansion of the temperature range of plasticity: for the vacuum residue oxidation product with crumb rubber, its value was 67.2 °C. The curves of the black diagram of the modified vacuum residue oxidation product are shifted towards smaller phase angles with the increase in the shear modulus, which indicates the increase in the stiffness and elasticity of the rubber bitumen binders. The vacuum residue oxidation product modified with crumb rubber corresponded to the rubber bitumen binder of the grade RBB 60/90, according to its physical and mechanical indicators.

Rubber–Bitumen Interaction of Plant-Blended Rubberized Bitumen Prepared under Various Blending Conditions

Abstract Rubberized bitumen produced from waste tire rubber has been widely used as a sustainable paving material worldwide. However, different production conditions may lead to rubberized bitumens with different performances. This study aims to understand the mechanism of the physicochemical interaction between rubber particles and virgin bitumen of the rubberized bitumens prepared in the plant under various blending conditions. To achieve this objective, samples of the rubberized bitumens prepared in the plant under four conditions were first collected and then characterized through various laboratory tests. The infrared spectra and gel permeation chromatograph test results demonstrated that the main crosslinking structures of rubber remain stable and undamaged during the whole production period, although some chemical reactions—such as oxidation, decarboxylation, and devulcanization—occur. The storage stability test results implied that the plant-blended rubberized bitumen exhibits no obvious phase separation after storage at 163°C for 48 h and becomes more stable as the blending time prolongs. The rheological test results indicated that the rubber–bitumen interaction is mainly composed of early stage absorption and swelling of rubber particles, continuous emission of volatile bitumen components, and late-stage partial degradation of fully swollen rubber particles. The surface images of the rubberized bitumen confirmed that as the blending time increases, the surface of rubberized bitumen becomes smoother, as a result of the improved rubber–bitumen interaction.

Investigating the role of swelling-degradation degree of crumb rubber on CR/SBS modified porous asphalt binder and mixture

Porous asphalt pavement is widely used due to its adequate water permeability, noise reduction and skid resistance. The study aims at exploring the potential of using the crumb rubber/styrene–butadienestyrene (CR/SBS) modified bitumen as high-viscosity binder for porous asphalt mixture, and investigating the effect of swelling and degradation degree of crumb rubber as well as SBS dosage on the performance of porous asphalt binder and mixture. The conventional, rheological and engineering properties of CR/SBS modified high-viscosity porous asphalt binders and mixtures were characterized. The results revealed that the CR swelling-degradation degree significantly affected the physical and viscoelastic properties of CR/SBS modified high-viscosity binders. With the swelling time prolonged, the viscosity of rubber bitumen enhanced gradually until reaching the equilibrium state, which kept falling during the degradation process dramatically. The full-swelling binders exhibited the highest complex modulus, zero-shear viscosity, rutting resistance, which deteriorated as the degradation degree increasing. However, the degradation of crumb rubber would be beneficial to improve the workability, thermal cracking resistance and deformation recovery ability of high-viscosity binder. Meanwhile, the incorporation of SBS copolymer could further strengthen both high-and-low temperatures viscoelastic performance of high-viscosity bitumen. In addition, the performance of porous asphalt with CR/SBS modified high-viscosity bitumen could meet the requirements of Marshall stability, air void content, Cantabro loss, run-off loss, anti-rutting, moisture damage resistance and permeability performance. Although the full-swelling asphalt mixture presented the best rutting resistance, it showed the poor adhesive and moisture damage resistance when compared with partial and full-degradation asphalt mixtures.

Investigation of the Effect of Crumb Rubber Powder and Warm Additives on Moisture Resistance of SMA Mixtures

Stone matrix asphalt (SMA) mixtures are one of the most resistant types of asphalt mixtures known to date that the bulk load is borne by the aggregate skeleton. In this research, the effect of crumb rubber powder (CRP), Vestenamer polymer, and warm additives, including Sasobit, ZycoTherm, and a porous and warm mix asphalt (PAWMA), was investigated on the moisture resistance of SMA mixtures. A segregation test was performed to determine the tendency of the polymer to separate from modified polymer bitumen under storage conditions. Also, a drain down sensitivity test was conducted to explore the bleeding phenomena and drain down of SMA mixtures. Finally, a boiling water test, as well as an indirect tensile strength (ITS) test, was applied to examine the sensitivity of mixtures to moisture. The segregation test results indicated that by the use of Vestenamer polymer, a conventional (low speed) mixer can be used instead of using a high-speed mixer, and this will be very important in the cost of rubber bitumen production. The drain down test results showed that cellulose fibers prevented the bitumen bleeding of SMA mixtures. Also, the results of the boiling water test indicated that CRP samples containing ZycoTherm had the highest moisture resistance compared to the other warm additives. Among various mixtures, 8% CRP-modified samples containing ZycoTherm resulted in the lowest amount of stripping in SMA mixtures, even more than the base sample. The ITS test results illustrated that the use of CRP, Vestenamer polymer, and warm additives had a significant effect on the ITS amounts of mixtures. Moreover, the samples containing ZycoTherm had the highest tensile strength ratio (TSR) compared to the other SMA samples.

Performance of asphalt mixtures with a new type of rubber modified bitumen

The rubber modified bitumen 45/80-55 (RMB 45/80-55) product has been used in Hungary as bituminous binder for asphalt mix production since 2013. It is a new kind of rubber bitumen manufactured using patented technology. Over the past 8 years, it has been used to construct or renovate more than 100 asphalt road sections. Originally RMB 45/80-55 was used to replace paving grade bitumen 50/70 in some road construction projects. However, asphalt laboratory results and road construction experience showed that its quality can also achieve or in terms of some parameters exceed that of asphalt mixtures manufactured with polymer modified bitumen 25/55-65 (PMB 25/55-65). Primarily, its excellent resistance to low temperatures and fatigue are outstanding, in this respect; it surpasses the results of asphalts made with polymer modified bitumen. Its favourable fatigue resistance compensates for its lower stiffness; therefore, favourable results were obtained in the case of track structure design too in comparison with PMB. Considering the road construction benefits of this new type of rubber bitumen, as well as the support of the environmentally friendly recovery of waste tyres and fitting into a circular economy, a wider spread of the RMB product is realistically expected in the future.

Investigation of the effect of Crumb Rubber Additive on the Fracture of characteristics of asphalt mixtures in control and asphalt rubber mixtures

The failure of cracking is one of the main concerns regarding the performance of hot mix asphalt (HMA). Since the characteristic of the materials of the mixtures has impact on their cracking potential, the main conception of this research is to evaluate the effect of the type of size and additive percentage of crumb rubber modified (CRM) on the resistance of mixtures to crack at mid and low temperatures. For this purpose, rubber bitumen containing 10% and 15% crumb rubber with fine and coarse sizes with wet process was prepared. Asphalt mixtures with dense and gap grading were designed by using rubber bitumen produced by superpave method. The three-points bending test of semicircle bending sample (SCB) was used to evaluate the fracture characteristics of asphalt mixtures at low and middle temperatures (25°C and -12°C). Accordingly, the failure characteristics of asphalt mixtures were evaluated in two modes with short-term and long-term aging. The failure test results indicated that the produced mixtures with crumb rubbers additive have high resourcing resistance compared to control mixtures (without crumb rubber additive), were also revealed. Mixtures with dense grading and fine crumb rubber have high fracture resistance compared to mix with gap grading and coarse crumb rubber. Also, the increasing of the percentage of crumb rubber improved the resistance of the mixed failure. In general, it can be stated that the addition of crumb rubber increases the fracture resistance of asphalt mixtures which can improve its performance before cracking at mid and low temperatures.

Performance-related and rheological characterisation of natural rubber modified bitumen

This paper is motivated by the limited research available evaluating the comprehensive effects of natural rubber bitumen modification (NR) for pavement applications. A detailed laboratory programme was carried out to evaluate the influence of NR on the high-intermediate-low temperature performance, including rheological characterisations and performance-related tests (fatigue cracking, thermal cracking, fracture and permanent deformation resistance). The main findings indicate some beneficial effects of NR on the performance-related response for fatigue and permanent deformation. Additional benefits were observed regarding the fracture strength and the thermal cracking resistance (ΔTc). The viscoelastic effects of NR produced significant changes in the rheological properties of the base bitumen. Overall, the use of NR at a concentration of up to 7% by weight of bitumen proved to be a reasonable option for use in pavement applications, having more substantial benefits in tropical regions in agreement with its predominant effects on the bitumen modification at intermediate-to-high temperature conditions.

Viability of producing sustainable asphalt mixtures with crumb rubber bitumen at reduced temperatures

The construction and maintenance of road pavements need to be undertaken to ensure proper economic and social growth. Considering the high environmental impact that the production of asphalt mixtures for road pavements entails, in terms of energy consumption and greenhouse gas (GHG) emissions, these operations must follow the global transition towards more sustainable development practices. In response to this, previous research has been focused on the development of manufacturing low temperature asphalt mixtures and the use of recycled modifiers such as tire crumb rubber to improve their durability. However, the use of high dosages of the latter reduces mixture workability, thus requiring high manufacturing temperatures to reduce the viscosity of the binder, and therefore limiting the advancement towards more sustainable mixtures. In this regard, further knowledge is needed on this topic to promote the combination of such techniques to maximise their advantages. This study aims to check the viability of producing asphalt mixtures with high crumb rubber contents at reduced temperatures, testing their workability, stiffness, cohesion, resistance to permanent deformations and resistance to moisture damage. Results show that it is possible to manufacture viable, warm, rubberised asphalt mixtures at 150 °C using a high penetration bitumen and reduce this temperature to 130 °C (45 °C less than conventional rubberised asphalt mixtures) by including warm additives, without compromising their mechanical performance.

Compatibility and Adhesion Properties of Rubber Asphalt

To research the compatibility and adhesion of rubber asphalt, the correlation of the asphalt components and rubber content with conventional properties of rubber asphalt was analyzed. The effects of asphalt component, rubber content, thin-film oven testing, and ultraviolet (UV)-aging testing on the adhesion properties of rubber asphalt were analyzed by measuring the surface free energy and its component based on the theory of surface free energy. Results show that the three major indicators of rubber asphalt are obviously affected by the properties of matrix asphalt, i.e., rubber asphalt has low penetration, high softening point, and movement viscosity processed by the matrix asphalt with high resin and asphaltene content. With increased rubber content, the penetration of rubber asphalt decreases and its softening point increases, but its ductility value is closer. Viscosity decreases when rubber asphalt is stored at high temperature, and viscosity decreases by 60% when stored for 8 h at 180℃. The surface energy of rubber asphalt increases with increased rubber content. After thin-film oven testing of 5, 10, and 15 h, the surface energy of rubber asphalt increases, but the change rate of surface energy decreases. The effect of UV aging on the surface properties of rubber bitumen is not obvious. The surface energies of rubber asphalt processed by different components of matrix asphalt after 10 and 20 d of UV aging differ.

The role of thermodynamics and kinetics in rubber–bitumen systems: a theoretical overview

ABSTRACT Waste tire rubber has been incorporated into asphalt modification for decades due to its various benefits. There are two main mechanisms during bitumen–rubber interaction: rubber swelling and chemical degradation. This study surveys these two processes from the viewpoint of polymer science. The kinetics of rubber dissolution and thermodynamics of rubber swelling are discussed to provide a fundamental understanding of the interaction process and to demonstrate how optimisation of material selection and processing procedures can lead to the desired binder properties. Factors including the interaction conditions and raw material characteristics are analysed based on the previous theories and compared with experimental results.

The Effect of Rubber Crumb Modification on Interfacial Interaction in Rubber–Bitumen Composites

The results of a study of the properties of rubber–bitumen composites obtained using rubber crumb activated by a mechanochemical method are presented. The structure of rubber bitumens is investigated by atomic force microscopy. The efficiency of rubber crumb modification to improve the interaction at the interface between the elastomer and bitumen matrix is shown.

Influences of Surface Characteristics and Modified Asphalt Binders on Interface Shear Strength

Weak bonding between layers of pavement leads to damages on the composite pavement. Bonding plays an important role in the durability and maintenance of composite pavement layers. The present study evaluates the factors effective in bond strength of the interface between concrete and asphalt pavements. The factors considered for this purpose include steel slag percentage in the concrete pavement, different types of modified bitumen, and rates of tack-coat. To measure the bond properties, direct shear and shear fatigue tests were carried out. In addition, texture depth and abrasion resistance were used in accordance with EN 1338 standard to measure the roughness properties of concrete pavement. The test results showed that 50% replacement of steel slag with aggregate resulted in an increase in physical properties and texture depth of concrete pavement. Moreover, the results of the shear strength test of composite pavement revealed that the optimal rate of using tack-coat varies between 0.6 and 0.9 l/m2 and depends on the type of tack-coat. Finally, a higher shear strength was obtained for crumb rubber bitumen containing hydrated lime compared to crumb rubber modified bitumen and control bitumen.

Study on influence factors of asphalt mixtures pavement blistering on Portland cement concrete bridge deck

ABSTRACT This paper aims to discuss the blister properties on Portland cement concrete bridge deck pavement. The deformation characteristic and mechanism of blister are investigated quantitatively by an automatically developed pressurised blister simulation tests and Digital speckle correlation method (DSCM). Two different types of asphalt mixtures (SMA-13 and AC-13) and three different types of asphalt waterproof bonding materials (SBS modified bitumen, rubber bitumen, SBS modified emulsified bitumen) were studied in this paper. The air void of asphalt mixture, test temperature and material types were analysed to explore the influence on the blister deformation. In addition, the initial surface absorption test (ISAT) is used to quantitatively assess the influence of air void. The results indicate the air void of asphalt mixture and the test temperature have different influences on the blister damage performance. The blister failure mode has a direct relationship with air void. For the same asphalt waterproof adhesive layer, SMA-13 asphalt mixture is better than AC-13 asphalt mixture in the resistance of blister deformation.