Polymer-modified Bitumen Research Articles

Effect of plastics in applications of bituminous pavement: A laboratory study

In this study, an experimental investigation has been performed to modify bitumen using plastics. For each mixture sample, plastic content of 1%, 2%, 3%, 4% and 5% by the weight of bitumen are taken. Basic physical tests on conventional and Polymer Modified Bitumen (PMB) batches are carried out and compared. Marshall Stability and Indirect Tensile Strength (ITS) tests are carried out for bituminous mixes. The results are compared and analyzed to determine the optimum bitumen content (OBC) and percentage of plastics to be used. The Marshall Stability value of PMB increased by 69.65% to that of the stability value of the unmodified binder. ITS value of the unconditioned specimen increased up to 0.70 times higher than the ITS value of the unmodified binder. For the conditioned specimen, it increased to 1.50 times higher than the ITS value of the unmodified binder. The optimum percentage of plastic to be used is found to be 3% by weight of bitumen. These overall results obtained showed that the PMB exhibited significantly higher effectiveness in terms of strength, durability, and thus performance as bituminous pavement.

MICROPLASTICS IN LANDFILL LEACHATES IN THREE NORDIC COUNTRIES

We investigated the occurrence of microplastics (size range 5,000-50 µm) in leachates at 11 landfills of different age and operational status in Finland, Iceland and Norway. Collective sampling was carried out by pumping leachate with a stainless-steel submergible pump through a custom-made, stainless-steel filter unit containing filter plates with decreasing pore sizes (5,000, 417 and 47 µm, respectively). Samples were pre-treated and split into particles size classes above 500 μm and above 50 μm, and screened for occurrence of microplastics made of PE, PP, PVC, PS, PET, PA, PU, PC, PMMA, POM, SBR (rubber) or PMB (polymer modified bitumen). Samples were analysed by FT-IR spectroscopy, both to identify and to count microplastic particles (SBR and PMB were merely identified). Most samples tested positive for multiple microplastics. Three leachates, including drinking water (blank), tested positive for SBR particles and/or PMB only. Treated leachate samples exhibited lower total microplastic’s counts than untreated, up to several orders of magnitude. National waste management practices over time, landfill age or operational status do not seem to explain differences in microplastic abundance or counts between leachates. Particle count and calculated loads of microplastic emissions through leachates differed several orders of magnitude between landfills. Results indicate that landfill leachates might be a relatively small source of microplastics (>50 µm) to surface waters compared to untreated and treated sewage or road runoff. Continued data acquisition, improved sample preparation and understanding of variability of microplastics in landfill leachate are necessary, including particles smaller than 50 µm.

Structural characterization and application of bitumen modified by recycled polyethylenes

The use of recycled polyethylene as a bitumen modifier makes it possible to obtain cheap roofing and road construction materials, as well as to dispose of polyethylene waste. Here we discuss the influence of the type of recycled polyethylenes (high-density (r-HDPE), linear low-density (r-LLDPE), and low-density (r-LDPE) polyethylenes) on their compatibility with bitumen and the internal structure of obtained polymer-modified bitumens (PMB). The novel approach was used for assessing of the compatibility of r-PEs with bitumen. Two concentrations of r-PE in PMBs are chosen: 3 wt.% (as for binder in road-building materials) and 7wt.% (as for binder in roofing materials). At 3wt.% of r-PE, the internal structure and rheological properties of PMBs are the same for different types of r-PE. Thus, any type of r-PE can be used for the production of PMBs for road construction materials. The type of r-PE strongly affects the internal structure and rheological properties of PMBs at 7 wt.% of r-PE. Only r-LLDPE forms a polymer network in bitumen. Thus, it should be used for the production of PMBs for roofing materials.

Apparent Molecular Weight Distributions for Investigating Aging in Polymer-Modified Bitumen

The oxidative aging of bituminous binders affects the performance and durability of pavements. In the case of polymer-modified binders, aging involves both bitumen and polymers and has a strong impact on the whole architecture of the material. Rheology may help in understanding these structural changes, and interesting information may be obtained by analysing the evolution of apparent molecular weight distributions. This was demonstrated with a bituminous binder modified with a poly(styrene-butadiene) block copolymer and subjected to prolonged artificial aging. Isothermal frequency sweep tests were used to construct master curves of the phase angle and magnitude of the complex modulus. The master curves were then used to calculate relaxation spectra and apparent molecular weight distributions of the binders, as well as simulated temperature sweep tests. A comparison of the behaviour of the base and modified bitumen highlighted the role of the polymer in aging. Polymer degradation significantly damages the elastomeric network, yet the residual polymer chains still interact with the bitumen molecules and reduce their oxidative aging. The apparent molecular weight distributions were deconvoluted to create an aging index specifically developed for polymer-modified bitumen.

Oscillatory shear rheometry of hybrid polymer-modified bitumen using multiple stress creep and recovery and linear amplitude sweep tests

Modifying bitumen by combining elastomers and plastomers has been reported to result in improved overall performance. However, the assessment of the rheological properties is commonly done in the linear visco-elastic region at low strain levels. In this paper, the rutting and fatigue resistance of modified bitumen was evaluated using multiple stress creep and recovery (MSCR) and linear amplitude sweep (LAS) tests. A base bitumen was modified with styrene butadiene styrene (SBS), crumb rubber (CR), ethylene–vinyl acetate (EVA) and various polyethylene to study the effects of these modifiers on the rheological behaviour of hybrid polymer-modified bitumen (PMB). These effects were measured using the non-recoverable creep compliance (Jnr) and percentage recovery (R%) in MSCR tests and by evaluating the fatigue damage using Viscoelastic Continuum Damage (VECD) analysis in LAS tests. Results showed that combining SBS, recycled polyethylene and sulphur resulted in the highest percentage recovery value, whereas using CR with SBS did not significantly affect the rheological results. Sulphur played an important role as a cross-linking agent. Concerning Jnr, the addition of sulphur help lowers the MSCR characteristic values, hence indicating better rutting performance. From the VECD analysis, the utilization of hybrid polymers improved the fatigue performance when compared with unmodified bitumen. Based on the overall MSCR and LAS results, the utilization of waste polymers such as recycled polyethylene and CR has resulted in highly satisfactory performance for both rutting and fatigue resistance. Hence, the usage of waste polymers can be considered a suitable alternative to replace virgin polymers.

EFFECT OF REJUVENATORS ON PENETRATION AND SOFTENING POIND OF AGED POLYMER-MODIFIED ROAD BITUMEN

The article describes the effiency of polymer-modified road bitumen regeneration with two types of rejuvenators. Two alternative rejuvenators have been selected aromatic oil Nygen 910 and soft road bitumen V12000. PMB 45/80-55 bitumen, which is used in the upper and lower layers of asphalt pavement, was investigated. During the life time of the asphalt pvement, due to the effects of solar UV radiation, temperature and oxygen, of all the layers of the structure asphalt top layer reaches the highest degree of aging. Short-term and long-term aging were performed to simulate the aging of the bitmen under laboratory conditions. To determine the optimal amount of rejuvenator experiments were performed with 8%, 10% ir 14% rejuvenator by bitumen mass. The effect of rejuvenators were evaluated by studying the main physical properties of bitumen: penetration and softening temperature. Ina n experimental study, aromatic oil was found to be more than 2.5 times more effective than soft bitumen.

Critical assessment of new polymer-modified bitumen for porous asphalt mixtures

New experimental polymer-modified bitumen with a high-vinyl content polymer was fabricated for porous asphalt (PA) mixtures. The bitumen with maximum stability was achieved using storage stability, gelation criteria and physical bitumen tests. A dynamic shear rheometer was used to compare the complex modulus, number of fatigue cycles, yield stress, and non-recoverable creep compliance of the experimental bitumen with a reference virgin bitumen 50/70 and a PMB 45/80-65 binder. PA mixtures were also designed to analyze the abrasion resistance and binder drainage characteristics. It was concluded that the experimental bitumen with 4.5% polymer content showed higher elastic response, better fatigue resistance, and improved rutting behavior than the reference PMB. PA mixtures with the new experimental bitumen exhibited higher abrasion resistance, but underwent higher binder drainage, which was addressed by the incorporation of aramid pulp and glass-hybrid fibers.

A novel method for the quantification of tire and polymer-modified bitumen particles in environmental samples by pyrolysis gas chromatography mass spectroscopy

Tire and road wear particles may constitute the largest source of microplastic particles into the environment. Quantification of these particles are associated with large uncertainties which are in part due to inadequate analytical methods. New methodology is presented in this work to improve the analysis of tire and road wear particles using pyrolysis gas chromatography mass spectrometry. Pyrolysis gas chromatography mass spectrometry of styrene butadiene styrene, a component of polymer-modified bitumen used on road asphalt, produces pyrolysis products identical to those of styrene butadiene rubber and butadiene rubber, which are used in tires. The proposed method uses multiple marker compounds to measure the combined mass of these rubbers in samples and includes an improved step of calculating the amount of tire and road based on the measured rubber content and site-specific traffic data. The method provides good recoveries of 83–92% for a simple matrix (tire) and 88–104% for a complex matrix (road sediment). The validated method was applied to urban snow, road-side soil and gully-pot sediment samples. Concentrations of tire particles in these samples ranged from 0.1 to 17.7 mg/mL (snow) to 0.6–68.3 mg/g (soil/sediment). The concentration of polymer-modified bitumen ranged from 0.03 to 0.42 mg/mL (snow) to 1.3–18.1 mg/g (soil/sediment).

Laboratory investigation on rheological, chemical and morphological evolution of high content polymer modified bitumen under long-term thermal oxidative aging

High content polymer modified bitumen (HCPMB) is now mostly used in porous asphalt pavement, and the developed polymer system causes it exhibit more complex characteristics than conventional bitumen. However, the research on the aging behavior of HCPMB is still very limited due to its high polymer content and severe aging degree. In this paper, four types of binders were selected for different time-course aging tests to simulate the aging of the actual pavement. Then, Dynamic Shear Rheometer (DSR), Fluorescence Microscopy (FM), Fourier Transform Infrared (FTIR) Spectroscopy, and Gel Permeation Chromatography (GPC) were conducted to track the rheological, chemical and morphological evolution of the four bitumens during aging. The multiple stress creep recovery (MSCR) test index can capture the decrease of elasticity due to polymer degradation, reflecting the better elastic sensitivity than rutting factor. The black diagram and master curve can better analyze the influence of polymer modification and aging on the viscoelastic properties, and polymer modified bitumen (PMB) showed obvious two-stage characteristics in the graph. The shear stress relaxation (SSR) test showed that aging could weaken the relaxation property of bitumen, which makes it easy to accumulate larger stress and lead to cracking. The micro-chemical test results more intuitively proved that the degradation of the polymer mainly occurs in the early stage of aging, and the oxidation of the bitumen phase is the dominant process of long-term aging. And the more developed the initial polymer network is, the slower the degradation rate of polymer is, thus prolonging the early stage of aging. Principal component analysis (PCA) showed that the complicated relationship between the 12 parameters analyzed in this study could be explained by SBS content and bitumen aging degree. This study can provide insights for exploring the macro and micro change characteristics of binders during the long-term aging process and better understanding the aging mechanism of HCPMB.

Effects of lead time and manufacturing methods applied for polymer-modified bitumen emulsion (PMBE) on microsurfacing performance

The modified microsurfacing mix design procedure for polymer-modified bitumen emulsion (PMBE) is introduced in this study under the influence of emulsifiers, lead time and through application of SBR latex polymer injection techniques, including the co-milling, soap pre-batching and post-blending procedures. The bitumen tests have shown that the type of emulsifier and the residence time of the bitumen emulsion in the colloidal mill, as well as the manufacturing process all affect the PMBE properties. Therefore, each type of emulsifier had different properties; especially the co-milling method of diluted bitumen emulsion had the highest performance in terms of physical and rheological tests due to the higher residence time of the bitumen emulsion in the colloidal mill which enhances bitumen properties. According to the results of the microsurfacing tests, the vertical deformation resistance, moisture damage resistance and bleeding potential were improved by 46.55%, 25.7% and 15.2%, respectively, through modifying in the co-milling method.

Assessment of performance of hot mix asphalt contained various types of mineral fillers and newly polymer modified bitumen

This research aims to test various types of fillers such as (limestone dust, rice husk ash and ordinary Portland cement) and examine their influence on the performance of the asphalt mixture containing Polymer Modified Bitumen (PMB) binder. The research includes designing a regular reference mix for the purposes of comparison and designing several asphalt mixtures with various percentage (25, 50, 75 and 100) % RHA & OPC as mineral filler and PMB. Several tests were conducted to evaluated the mechanical characteristics and performance of Hot Mix Asphalt (HMA) such as Marshall stability, Indirect Tensile Strength (ITS), creep compliance and wheel track test. The results of investigation revealed that, the using of PMB significantly improved the mechanical characteristics and performance of HMA. The results of creep compliance demonstrated that the replacement of conventional MF with 50% RHA or 50 % OPC leads to decrease creep compliance values of HMA contained PMB by 68% and 64 % respectively compared with control mix. Also, for the same percentages of replacement and PMB, the rut depth values decreased by 64% and 48 % respectively compared with the reference mixture.

Evaluation of the effect of the loading frequency on Wöhler’s curve parameters of a high modulus asphalt concrete (HMAC)

The fatigue's behaviour of bituminous materials is affected by the loading frequency. For hot mix asphalt (HMA) with unmodified bitumen, previous research showed a decrease in fatigue life, under strain-control mode, by increasing loading frequency. However, the effect of loading frequency on polymer-modified HMA has not been investigated extensively and researchers have found opposite results using the same testing method in strain-controlled mode. This paper looks at how the loading frequency impacts Wöhler's law parameters (slope and intercept) of a high modulus asphalt concrete (HMAC) made with a polymer-modified bitumen. Under strain-controlled mode, Tensile-Compression tests (TC) on cylindrical samples were carried out at isothermal conditions (θ = 10°C) and three distinct frequencies (5, 10 and 25 Hz). The analysis of covariance (ANCOVA) was considered to compare Wöhler's law parameters from different frequencies. The results showed no statistical difference in the slope and the intercept values from all studied frequencies.

RAP-Added SMA Mixtures: How Do They Fare?

AbstractStone matrix asphalt (SMA) is a highly rut-resistant gap-graded asphalt mixture. The inclusion of supplementary materials such as fiber, filler, and polymer-modified bitumen (PMB) makes the...

Effect of different waste plastic fractions on the thermal kinetics and microstructural behaviour of bitumen used for bituminous mix

The price of raw polymers used for making most of the waste plastics has confined the implementation of polymer modified bitumen (PMB) only to the major road projects. In view of the same, an attempt to make a PMB by such wastes was considered as a “state-of-art” in this investigation. Therefore, the different proportions of waste plastic fractions were blended with the pristine bitumen and the resulting blend characterized by thermal kinetics analysis, microstructural analysis, and Marshall mix design, respectively. The major findings have predicted the highest thermal stability of the blend was achieved by mixing plastic bags, plastic milk pouches, and plastic cups together in proportion of 2:0.25:1 to virgin bitumen with no thermal decomposition. Further, uniform dispersion of “bee-like structure” in that blend has reflected its homogeneity. Besides, such modified bitumen has elevated the Marshall quotient of the bituminous mix by 16%, which can preferentially be used in the rural roads safely, confirmed by Marshall mix design.

Evaluation of performance of hot mix asphalt contained various sizes of Reclaim asphalt pavement and polymer modified Bitumen

The present investigation intends to investigate the performance of Hot Mix Asphalt (HMA) included Reclaim Asphalt Pavement (RAP) and Polymer Modified Bitumen (PMB) binder prepared with Novolac (phenol–formaldehyde solid resin)polymer. In order to assess the mechanical properties and performance of HMA with various RAP contents, several laboratory tests such as Marshall tests, indirect tensile strength testing, moisture damage evaluation, creep compliance test, and wheel track test was performed. The substitution was conducted in two stages: the first stage includes replacing the coarse aggregate with RAP up to 40percent with an increment of 10percent and the second stage includes the substitution of fine aggregate with the same percentages. The PMB binder was prepared by testing several mixes with various percentages of Novolac and its cross-linking agent (Hexamine). The findings of experimental work showed that the use of PMB binder significantly improves the mechanical properties and performance of HMA. Also, it shows that the substitution of coarse aggregate with RAP produces a substantial improvement in mechanical properties and performance of HMA compared with the substitution of fine aggregate or with control mix.

Investigation the effect of newly used polymer modified bitumen on the performance of hot mix asphalt containing reclaimed asphalt pavement

The current research focuses on investigating the effect of using reclaimed asphalt pavement (RAP) on performance of hot mix asphalt (HMA) prepared with polymer modified bitumen (PMB) binder. This PMB used for the first time with HMA contained RAP. The mechanical properties and performance of HMA were assessed using several standard tests including Marshall, indirect tensile strength, creep compliance, and wheel track test. The RAP replacement was conducted up to 70% of total aggregate in HMA with an increment of 10%. The results of investigation showed, that the use of PMB binder prepared by addition novolac (phenol formaldehyde solid resin) and hexamine to conventional bitumen, significantly improved the performance of HMA contained RAP. Also, the optimum percentage of RAP replacement was found to be 50% of total aggregate in HMA. For this level of replacement, the rut depth reduced up to 38% of its original value.

Waste tyres crumb rubber as a sustainability enhancer for polymer-modified and hybrid polymer-modified bitumen

ABSTRACT The increasing amount of waste vehicle tyres has already proved to be hard to dispose of properly and lead to environmental problems, such as soil contamination and toxic blazes. This study aimed to use recycled tyre rubber material (crumb rubber - CR) and combine it with well-known polymers in road engineering, such as styrene–butadiene-styrene (SBS) and/or a combination of SBS and ethylene-vinyl acetate (EVA) to develop hybrid recycled polymer modified bitumen (PMB). Most of the times, CR is only added to neat bitumen at high contents to enhance its properties despite some drawbacks. Physical, chemical, thermal and rheological tests were conducted to evaluate the overall performance of the blends with and without the addition of stabilising agents. CR has shown to increase the viscosity of the bitumen. The addition of EVA into CR/SBS blends has simultaneously improved the rheological properties specifically at intermediate and high temperatures. To conclude, the utilisation of small percentages of recycled tyres in PMBs and hybrid PMBs did not negatively affect the satisfactory performance of SBS-modified bitumen. This consequently encourages greater usage of CR which also mitigates the waste disposal problem at landfills.

Characterizing the properties of sustainable semi-flexible pavement produced with polymer modified bitumen

Semi-Flexible Pavement (SFP) is a composite type of pavement produced by manufacturing of porous asphalt mixes using open graded aggregate gradation to create 20-35% of voids filled with grout (cement paste, cement mortar, etc.….). The resulting pavement has the flexibility of asphalt pavement and some strength of concrete pavement. The current study focused on investigation of using widely available (in Iraq) waste material namely Rice Husk Ash (RHA) to replace the Ordinary Portland Cement (OPC) partially in grout, also, using Polymer Modified Bitumen (PMB) to develop Open-Graded Asphalt (OGA) pavement without using cellulous fibre. The study focused on assessment of mechanical properties of the obtained SFP mixes with and without PMB. The results of study showed that using of PMB increased the Marshall Stability up to 100% and indirect tensile strength up to 50%. The Marshall Retained Stability gave about 90% which is quite higher the minimum required limit (70%). The results also revealed that RHA can be used as replacement for the OPC in SFP mixes. All investigated percentages showed satisfactory mechanical properties.

Influence of morphology on high-temperature rheological properties of bitumen modified with styrene-butadiene-styrene (SBS) copolymer

Different microstructures of the same polymer-modified bitumen (PMB) were obtained by subjecting the bitumen modified with styrene-butadiene-styrene (SBS) copolymer to isothermal annealing at various temperatures. The effects of the morphology on the rheological properties of SBS-modified bitumen were investigated within the high-temperature range. The PMB microstructures were quantitatively evaluated using image analysis. A dynamic shear rheometer was used to measure the rheological parameters of the PMB samples and perform the multiple stress creep and recovery (MSCR) test. A quantitative basis could be established on which to discuss the relationship between the PMB morphology and rheology. The image analysis indicated that conditioning by isothermal annealing evidently led to a difference in the microstructure of the samples. Variation of the thermal history is demonstrated to be a practical way to vary the morphology of the PMB with the same raw materials and formulation. Compared with the two-phase morphology, the single-phase microstructure tended to have a narrower linear viscoelastic (LVE) region of the PMB. Within the LVE region, especially at low frequencies, the homogenous PMB can store more energy when experiencing loadings and is more elastic. Outside the LVE region, based on the MSCR test results, the homogenous morphology could assist in reaching a higher percentage of strain recovery after the creep period.

Properties of bitumen modified by polyethylene and polyethylene glycol with different molecular weights

ABSTRACT Polyethylene (PE) and polyethylene glycol (PEG) with three different molecular weights are employed to modify bitumen, which is denoted as the polymer-modified bitumen (PMB). The samples, PMB-L, PMB-M and PMB-H, indicate PE/PEG modified bitumen in which PEG molecular weight is from low to high. PEGs and PMBs exhibit different crystallisation and melting behaviours measured by a differential scanning calorimeter. Rutting resistance and elastic property of PMBs under high temperature are studied by a rheometer. By analysing the complex modulus variation with temperature increment, it is found that the rheological stability is better for PMB-L and PMB-H, revealing a non-monotonous relationship with PEG molecular weight. The mechanical property of PMBs under low temperature is detected by their tensile behaviour and glass transition temperature, both of which reflect the weak ductility and low-temperature property of PMB-H. The reason for different properties of PMBs is interpreted by the phase structure and their stability, especially by the size and location of the PEG-rich phase.