Multiple Stress Creep And Recovery Research Articles

Investigating the Effect of Artificial Ageing on the Creep and Recovery of SBS-Modified Bitumen

Polymer additives are widely used to improve the performances of road bitumen and mixtures including their oxidative resistance. However, their effect on the oxidative mechanism remains unclear. This study includes the investigation of the changes in the rheological response of Polymer Modified Bitumen (PMBs) prepared with the Styrene Butadiene Styrene (SBS) copolymer and Sulphur as cross-linker. The bitumen samples were aged in the Rolling Thin Film Oven (RTFO) and in multiple cycles of Pressure Aging Vessel (PAV). The rheological properties were measured by means of the Multiple Stress Creep and Recovery (MSCR) test. Results show that in the case of cross-linked SBS modified bitumen the polymer phase mitigates the effect of hardening of the bitumen phase on the rheological response as a function of the polymer concentration. Adversely, in the SBS modified bitumen without cross-linker, the effect of the polymer vanishes after the RTFO.

What are the Alternatives of PG Plus Tests for Modified Asphalt Binders?

For characterizing the polymer modified binders, different state Departments of Transportation (DOTs) use different time consuming and empirical Performance Grade (PG) Plus test methods. Furthermore, the PG Plus tests are silent when asphalt binders are modified with chemicals such as polyphosphoric acid (PPA). But, the effects of the polymer are not accurately identified through these conventional tests such as Elastic Recovery (ER) and tenacity. The main goal of this study is to recommend alternative test method(s), which can possibly be pursued by using, a Dynamic Shear Rheometer (DSR). Thus, Multiple Stress Creep and Recovery (MSCR), ER-DSR, Frequency Sweep, and Binder Yield Energy Test (BYET) are being explored to find their effectiveness. Three PG binders (PG 64-22, PG 70-22 and PG 76-22) have been selected for this investigation. These binders have been prepared with styrene-butadiene-styrene (SBS) polymer, PPA, or a combination of both. Further, chemical tests such as SARA (Saturate, Aromatic, Resin, and Asphaltene) analysis and FTIR (Fourier-transform Infrared spectroscopy) are also being explored to fulfill the objectives. Preliminary findings suggest that the PG Plus tests deem to be obsolete. Also, a single test procedure is not sufficient to identify the presence and effectiveness of modifiers in the PG binders.

Asphalt-rubber interaction and performance evaluation of rubberised asphalt binders containing non-foaming warm-mix additives

Warm mix asphalt (WMA) technology has been increasingly utilised in rubberised asphalt pavements to reduce the production and compaction temperatures and the incidental fumes and odours. This study aims to investigate the high, intermediate and low-temperature performance of crumb rubber modified asphalt binders containing WMA additives. The asphalt-rubber interactions under various mixing combinations of temperature and time were investigated through both microscopic and mechanical methods to obtain the optimum mixing procedure. The effects of WMA additives (wax-based and chemical-based products) on the binder performance were investigated by multiple stress creep and recovery (MSCR) test, linear amplitude sweep (LAS) test and low-temperature frequency sweep test. Results show that rubberised asphalt binders significantly improve the binder performance of base asphalt at different temperature ranges. The effects of WMA additives on binder performance varied with base asphalt and rubberised asphalt binder. In addition, the nonrecoverable compliance difference was found not suitable to characterise the stress sensitivity of rubberised binders and the difference in the nonrecoverable compliance for an incremental change in applied stress was proved to be a more accurate alternative. For the cyclic LAS test, the failure energy was found to have a strong correlation with the predicted fatigue life using simplified viscoelastic continuum damage analysis and therefore can be considered as a simple indicator for binder fatigue performance ranking. Relaxation modulus and rate derived from low-temperature frequency sweep tests produced comparable results for ranking the low-temperature performance of different binders. It is feasible and promising to use a unified DSR test methodology to characterise the binder performance covering the whole service temperature range.

Laboratory evaluation of the effect of SBS and Lucobite on performance properties of bitumen

In this research, the effects of two additives namely SBS (3, 5%) and Lucobite (3, 5%) on the performance properties of binder were evaluated. The binder fatigue and rutting performance was evaluated through linear amplitude sweep (LAS) and multiple stress creep and recovery (MSCR) test, respectively. Results indicated that 3% SBS modified binder has the highest percent recovery value and the lowest Jnr value, but had the highest sensitivity to a sudden increase in the stress level inside the asphalt mixture. The LAS test results demonstrated that the fatigue behavior of asphalt binders modified with 3% Lucobite, is the highest one.

Effect of ageing on the morphology and creep and recovery of polymer-modified bitumens

Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the multiple stress creep and recovery (MSCR) test. The results show that the morphology of the SBS modified bitumen degrades with ageing as a function of polymer concentration and dispersion, with higher dispersion being more resistant. The morphology of the EVA modified bitumen has a low ageing susceptibility irrespective of polymer concentration. The MSCR response of EVA modified bitumens does not differ from that found for unmodified bitumen, where the hardening produces a decrease in the non-recoverable compliance. In the case of SBS modified bitumen, the degradation of the polymer backbone affects the bitumen hardening as much as the polymer phase dispersed and networked in the bitumen phase. Furthermore, in the case of the elastomer, the average percent recovery is in agreement with the variation of the morphology with ageing. Therefore, the use of the average percent recovery as a valuable rheological index of the integrity of the polymer network can be advocated.

Low-Temperature Vacuum Drying Procedure for Rapid Asphalt Emulsion Residue Recovery

Asphalt emulsions are used extensively in tack coats and preservation surface treatments. The current specifications for asphalt emulsion residue recovery in AASHTO PP 72 are based on low-temperature evaporative drying. The shortest residue recovery procedure included in AASHTO PP 72 requires 6 h of conditioning in an oven to dry an emulsion. The ability to recover emulsion residues efficiently is of great interest given the ongoing efforts to develop emulsion performance-graded specifications based on residual binder properties. In this study, a rapid, vacuum drying technology was evaluated for asphalt emulsion residue recovery. The procedure enables the recovery of sufficient residual binder for dynamic shear rheometer (DSR) testing within 20–40 min. Five emulsions of different classifications were evaluated using both the vacuum drying procedure and the AASHTO PP 72 procedures. The vacuum drying procedure leads to similar water loss to the AASHTO PP 72 procedures. Based on the temperature-frequency sweep and multiple stress creep and recovery (MSCR) test results, the vacuum-dried residues are softer and more viscous than residues recovered using the AASHTO PP 72 procedures. Fourier transform infrared spectroscopy (FTIR) was performed to identify if oxidation levels could explain the observed in rheological trends. However, the results suggest no clear trend in the oxidation levels of residues recovered using AASHTO PP 72 compared with the rapid vacuum procedure. Future work is necessary to infer which method best reflects residual binders placed in the field.

Damage characteristics of waste engine oil bottom rejuvenated asphalt binder in the non-linear range and its microstructure

This paper aims to compare the damage characteristics of the waste engine oil bottom (WEOB) rejuvenated asphalt binder with aromatic extract oil rejuvenated asphalt binder in the non-linear range. To fulfil this objective, the aged asphalt binder was prepared by aging SBS modified asphalt binder in the laboratory. High temperature, fatigue and low-temperature damage characteristics in the non-linear range were evaluated by conducting multiple stress creep and recovery (MSCR) test, linear amplitude sweep (LAS) test and double edge notched tension (DENT) test, respectively. The microstructure of rejuvenated asphalt binders was characterized by environmental scanning electron microscope (ESEM). The results showed that although the performance of aged asphalt binder can be restored to some extent with two recycling agents, however after conditioning in the bath for 120 h, the two rejuvenated asphalt binders exhibited different ductile states. The microstructure of rejuvenated asphalt binders revealed that WEOB rejuvenated asphalt binder presented a more gelation transition than aromatic extract oil rejuvenated asphalt binder which could be considered as the main reason for the reduction in the ductile performance of WEOB rejuvenated asphalt binder.

Fatigue Resistance Evaluation of Modified Asphalt Using a Multiple Stress Creep and Recovery (MSCR) Test

Fatigue resistance quantification of modified asphalt is typically time consuming and may not correlate well with mixture fatigue test results. In this paper, the applicability of a multiple stress creep and recovery (MSCR) test on asphalt binder’s fatigue resistance was evaluated. Six binder types with a variety of modifiers and different modifier contents were characterized. The MSCR test was conducted and its sensitivity to binder type and additive content under different aging durations was evaluated. Mixture fatigue tests including a semi-circular bending- Illinois flexibility index test and indirect tensile strength were conducted using control base asphalt and SBS modified asphalt. A ranking between the binder MSCR and mixture fracture test results was conducted to check if the MSCR result was representative of the mixture’s fatigue resistance. Results indicate that the MSCR test at intermediate temperatures (20 °C, 25 °C, and 30 °C) can be performed with good repetitions. It was also found that the MSCR test was sensitive enough to differentiate the fatigue resistance among different binder types and additive contents. The ranking analysis shows that the binder MSCR test at intermediate temperatures showed a similar ranking to the mixture’s fatigue tests, indicating that the binder MSCR test could be potentially utilized to represent a mixture’s fatigue resistance where binder selection is a major concern. It was also found that the SBS modified binder showed the best crack resistance and was less affected by aging.

Investigating the effectiveness of Vacuum Tower Bottoms for Asphalt Rubber Binder based on performance properties and statistical analysis

Numerous studies reported crumb rubber modifier (CRM) as an environmentally friendly additive that is able to improve asphalt performance and helps reduce environment pollutions. However, addition of CRM leads to the viscosity increase and, consequently, increase in the asphalt mixture production temperature and the greenhouse gas emissions in the atmosphere. The objective of this study is to evaluate the effectiveness of Vacuum Tower Bottoms (VTB) in the laboratory performance of Asphalt Rubber Binder (ARB). In order to study mechanical and rheological properties of ARB containing VTB, rotational viscosity (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR) and Multiple Stress Creep and Recovery (MSCR) tests were performed. The results of viscosity test showed that adding 50% and 70% of the VTB into ARB decreases viscosity 32% and 45.6% averagely, respectively. Furthermore, the results of PG tests indicated that the VTB decreases HT continuous grade and increases LT continuous grade of ARB. The VTB was also found to be able to enhance the performance at intermediate temperatures, i.e. fatigue resistance of ARB. MSCR test results shows that addition of CRM leads to an increase of rutting resistance and elastic response, however, VTB lead to an increase of Jnr values of ARB. The results of ANOVA showed that, at the confidence level of 95%, the VTB and CRM have significant effect on HT, LT and PG temperature span of ARB. Finally, Tukey test results indicated that there is significant difference between the means of PG temperature spans at both CRM dosages (15 and 20%) while it is not significant for VTB dosages (50 and 70%).

Effect of Short-Term Aging on Creep and Recovery Response of Asphalt Binders

AbstractThis study evaluates the creep and recovery response of different asphalt binders in unaged and short-term aged conditions. The multiple stress creep and recovery (MSCR) test has been carri...

Towards improved correlations between bitumen properties and rutting resistance of bituminous mixtures – FunDBitS literature review

Bitumen is the most common binder used in the production of bituminous mixtures for road paving, having a fundamental influence on the performance of the pavement. However, it is not yet fully understood which bitumen properties have a significant influence on the behaviour of bituminous mixtures. In this context, the FunDBitS project was developed. Its main objective was to prepare recommendations on the properties of the bitumen to be specified in order to obtain suitable bituminous mixtures, namely in what concerns to its resistance to permanent deformation (rutting), stiffness, low temperature cracking, fatigue cracking and binder/aggregate interaction. In this framework, the research studies that have become internationally available since the BiTVal project were reviewed in order to assess performance-based bitumen characteristics, which may be introduced into bitumen specification standards. This paper specifically presents the main conclusions regarding the properties of bitumen related to the behaviour to permanent deformation of bituminous mixtures. It was concluded that the most promising test is the “non-recoverable creep compliance” (Jnr) from the Multiple Stress Creep and Recovery (MSCR) test method, although Zero/Low Shear Viscosity (ZSV/LSV) by creep or oscillation test method can also give good correlations with permanent deformation of bituminous mixtures.

Comparison of rheological properties and hot storage characteristics of asphalt binders modified with devulcanized ground tire rubber and other modifiers

The ground tire rubber (GTR) modified binder has been affirmed to improve resistance to rutting, moisture susceptibility, low temperature cracking and durability of asphalt pavement. However, the liable phase separation of GTR modified asphalt binders results in a big issue at construction site. Therefore, an alternative crumb rubber, devulcanized ground tire rubber (DGTR), is manufactured with devulcanization process and as an additive to substitute for GTR or styrene-butadiene-styrene (SBS) in PG76 binders preparation process. The objective of this study was to compare the rheological properties and hot storage characteristics of PG76 asphalt binders produced with DGTR and two alternative polymers for future applications. The Brookfield Rotational Viscometer, Dynamic Shear Rheometer, and hot storage test were performed with all modified asphalt binders. The results indicated that PG76 binders modified with DGTR had approaching apparent viscosity values compared to GTR or SBS modified binders. In addition, the application of DGTR could reach the similar modification effect on the High PG critical temperature as well as GTR modified binders with same concentration. While those binders modified with DGTR exhibited remarkable lower tendency of phase separation than other modified binders regardless of base binder source. Moreover, similar trends were observed from the characteristics of creep and creep recovery, and Multiple Stress Creep and Recovery (MSCR) of all modified binders.

Rheological properties of asphalt binders prepared with maize oil

Warm mix asphalt (WMA) has some advantages relative to Hot mix asphalt (HMA), the high temperatures employed during the production of HMA generate negative impacts on the environment and to the health of workers exposed to asphalt fumes. Because of this fact, this research studied the use of maize oil for the production of mixtures WMA. Brazil is a highlight in the ranking of maize cooking oil production, which generates a significant amount of waste that the improper disposal of it, which could seriously affect the sewage pipes, groundwater and soil. This research aims to study the incorporation of 1%, 2% and 3% of maize oil (new and waste) to two types of asphalt binder (pure and with Styrene–Butadiene–Styrene – SBS). The samples were analyzed by penetration index, softening point, rotational viscosity, Performance Grade (PG), Multiple Stress Creep and Recovery (MSCR) and frequency sweep tests. The results of the tests showed that the addition of 1% maize waste oil decreases the temperatures of mixing and compaction around 6°C using the asphalt binder 50/70 and 4°C for the asphalt binder with SBS without compromising the rheological properties. In this research, there was no significant difference in the use of new or waste oil, thus contributing to the ecologically correct use of waste oil.

Advanced mechanical characterization of asphalt mastics containing tourmaline modifier

Tourmaline modified bitumen as an environmentally friendly pavement material has got an increasing attention in recent years in China. In this regard, previous studies mainly focused on the linear viscoelastic properties of asphalt or asphalt mastic. In this paper, multiple stress creep and recovery (MSCR) test, linear amplitude sweep (LAS) test and double edge notched tension (DENT) test were adopted as fundamental performance evaluation methods for high-temperature rutting, fatigue, and low-temperature thermal cracking of asphalt binder, respectively. Moreover, straight run asphalt and polymer modified asphalt containing various percentages of two kinds of tourmaline as asphalt modifier were also prepared to gain the knowledge of the interaction between asphalt and tourmaline. To study the feasibility of applying tourmaline as an alternative modifier and compare its performance with conventional fillers, asphalt mastic containing limestone was also prepared. The results show that small amount of modifier can enhance the mechanical properties of asphalt binder, but different modifiers do not have similar effect. In addition, market available tourmaline additive has different chemical composition and physical properties; asphalt mastic containing tourmaline ions powder showed the best performance among modifiers utilized here.

Effect of warm mix additives on creep and recovery response of conventional and polymer modified asphalt binders

This study appraised the effect of three warm mix additives (sasobit, evotherm and rediset) on the creep and recovery response of a conventional viscosity graded binder (VG 30) and a polymer modified binder (PMB 40). Multiple stress creep and recovery (MSCR) test was done at five different temperatures (30–70°C) and two stress levels of 0.1 and 3.2kPa. The output of MSCR test was simulated using Burger’s four element model and time temperature superposition principle (TTSP) was used to assess the long term creep behavior of the binders at a reference temperature of 50°C. Amongst the three warm mix additives, sasobit improved the resistance to permanent deformation characteristics of the control binders, followed by evotherm. Rediset was found to be ineffective in improving the creep and recovery response of the control binders. Its use led to increase in the unrecoverable creep compliance (Jnr) and reduction in percent recovery. Burger’s model was found to be apposite in simulating the measured response for all the binders at different test conditions. The viscous parameter, ηM could be correlated with the other model parameters using a power law equation and also had an excellent association with Jnr. The long term creep behavior of the asphalt binders indicated that the difference in creep strain is more pronounced at higher loading times. Findley’s power law model was found to be more appropriate for fitting the creep master curves in comparison to Burger’s four element model.

Effect of crumb rubber gradation on asphalt binder modification: rheological evaluation, optimization and selection

The objective of this study was to evaluate the effect of various crumb rubber (CR) gradations on asphalt binder performance leading to the development of a rational asphalt-rubber (AR) binder selection procedure. The scope encompassed advanced asphalt binder rheological characterization and statistical analyses in order to formulate a methodical procedure to select an optimum AR material. A total of twenty asphalt binders covering over 5000 data points were utilized, including two virgin binders, and eighteen laboratory prepared AR binders at one CR dosage of 20% but with varying CR gradations. Temperature-frequency oscillation and multiple stress creep and recovery (MSCR) tests were conducted on all the twenty asphalts. G* shear modulus master curves developed from the oscillation test results indicated that AR binders with finer CR particles in the gradation produced flatter master curves that had high G* magnitudes, which are indicative of high strength, better rutting resistance, and reduced viscosity-temperature susceptibility than those with coarser gradation. MSCR test findings complemented the oscillation test results. Analyses of Variance and Dunnett’s statistical tests were performed on the binder rheological properties. From statistical analyses, it was concluded that the variation in CR gradations could significantly affect the binders’ properties and resistance to distresses. Based on the results of rheological experimentation and statistical analyses, a methodical selection procedure for AR binders was devised by developing Ashby plots for the binder rheological parameters. These Ashby plots are envisioned to assist the pavement engineers and contractors in choosing the best suitable AR binder with the essential properties required to satisfy the performance criteria.

Investigating the performance of rubberised binders used in Iran based on multiple stress creep recovery and performance grading systems

This study investigated the rheological properties of three original and eight rubberised binders based on the performance grading (PG) and multiple stress creep and recovery (MSCR) systems. The results were compared with 8 out of the 13 performance grade binders essential for specific climatic zones in Iran. The other five were not available and, therefore, were not considered in this study. The results of performance grade tests showed that crumb rubber modification (CRM) improved the physical and mechanical properties of rubber-modified binders. In addition, the base binder type showed a meaningful effect on high- and low-temperature quality of the CRM binder. Adding CRM resulted in an increase in the recovery percentage (R) and a decrease in the non-recoverable compliances (Jnr) in the MSCR test. The results of designated grades based on the PG and MSCR systems proved that rubberised binders fully covered the required PGs in Iran, while they did not completely satisfy the traffic-level requirements based on the MSCR method.

Rheological performance of soybean in asphalt binder modification

This study investigated the incorporation of soybean oil, first in the ranking of Brazil production, in a partial substitution to two types of asphalt binder (pure and with Styrene–Butadiene–Styrene – SBS) in order to produce warm-mix asphalt (WMA). The oil was incorporated into two conditions: new and waste, and the mix was obtained with 1%, 2% and 3% of soybean oil. The samples were analysed using the tests of penetration index, softening point, rotational viscosity, performance grade (PG), and multiple stress creep and recovery (MSCR). The results show that the addition of 1% content of new and waste soybean oil improved physical and rheological characteristics of asphalt binders. The decrease in mixing and compaction temperature was obtained in 2.7°C average for 1% of waste oil with pure asphalt binder and 3.4°C average for a 1% of new oil with asphalt binder with SBS, considering only the criterion of the viscosity curve.

Multiple Stress Creep and Recovery of Nanosilica Modified Asphalt Binder

The main objective of this study is to evaluate the effect of nanosilica (NS) concentration on the rutting parameter of based asphalt binder using the multiple stress creep and recovery (MSCR) test. NS with concentrations between 1% to 5% (1% increment) was used to modify asphalt binder. The nanosilica modified asphalt binder (NSMB) were aged using rolling thin film oven (RTFO) before tested. MSCR test was conducted at 64°C with two stress level (100 Pa and 3200 Pa). The results found that the addition of NS reduced the accumulative strain of NSMB. Besides that, non-recoverable creep compliance decreased and recovery strain increased, which indicates an improvement of rutting resistance and elasticity of the binder, respectively. The grade of asphalt binder also improved from heavy (H) grade to extreme (E) grade. Overall, NSMB 2% show the best improvement in terms of Jnr and %R, thus NSMB 2% considered as a optimum percentage.

Ensaios MSCR segundo as normas ASTM D7405-10a e AASHTO T350-14: um estudo de caso envolvendo ligantes asfálticos modificados

Este trabalho tem por objetivo comparar os resultados dos ensaios de fluência e recuperação sob tensão múltipla (MSCR) segundo os protocolos da ASTM D7405-10a e da AASHTO T350-14. A comparação foi feita com base em ensaios realizados com ligantes asfálticos modificados com ácido polifosfórico, borracha moída de pneus e uma combinação de ambos. Os percentuais de recuperação (R) e as compliâncias não-recuperáveis (Jnr) foram calculados e as variações foram quantificadas estatisticamente. O protocolo da ASTM subestimou os valores de R e superestimou os valores de Jnr para todas as formulações, em especial o CAP+borracha e o CAP+borracha+PPA. O CAP+PPA apresentou baixa sensibilidade à tensão e os melhores resultados para R e Jnr a 3.200 Pa, em ambos os protocolos, o que justifica a sua escolha como a melhor formulação. Os resultados obtidos com os ligantes asfálticos modificados serviram para ilustrar a importância de se migrar do protocolo da ASTM para o da AASHTO.