Multiple Stress Creep And Recovery Test Research Articles

Application of the Air-Jet Laser Detection Technology for Asphalt Binders

AbstractA fast and convenient technique for Asphalt Binders was proposed in this paper, which was based on air-jet pressurized and laser to detect the transient deformation and creep recovery of asphalt. Taking five kinds of asphalt and modified asphalt commonly used in China as the research objects, the performance of asphalt were tested and analyzed by adopting the Penetration Test, Dynamic Shear Rheological (DSR) Test, Multiple Stress Creep and Recovery (MSCR) Test and the proposed test technology. The results verified the feasibility of the proposed test technology and the correlation between the traditional tests and the proposed test technology. The results demonstrated that the proposed test technology had good discrimination ability for different kinds of asphalt and could effectively reflect the performance differences. The new test protocol was similar to the Penetration Test. There was a significant correlation between the maximum deformation index and penetration index. The correlation coefficient was above 0.8, and the p value was much less than 0.01. It could be used as a possible alternative to the Penetration Test. The proposed new test was relatively convenient and fast compared with the dynamic shear test. There was a linear correlation between the maximum deflection index and the complex shear modulus G*, and the correlation coefficient between the recovery index and the phase angle is above 0.8, which indicated that the proposed new test and the DSR test had a significant correlation. There was also a good correlation between the creep recovery index of MSCR test and the recovery data of the proposed new test method. The research results provided a new solution for the performance test and evaluation of asphalt in China.

Approach for accurately characterizing nonlinear viscoelastic and nonrecoverable properties of asphalt binders based on MSCR test

The multiple stress creep and recovery (MSCR) test has been widely accepted as a more practical method for accessing the rutting performance of asphalt binders than the conventional Superpave rutting factor test. Nevertheless, there still exists a major concern that 9-s recovery time in each cycle may not guarantee a sufficient recovery of the recoverable viscoelastic strain, especially for modified asphalts, and this could result in a potential inaccuracy in characterizing rutting resistance of binders. To effectively separate the recoverable nonlinear viscoelastic (NLVE) and nonrecoverable responses in the MSCR test, this paper presents a new approach that adopts an additional one-cycle low-stress creep and recovery (LSCR) test and the Schapery’s NLVE model in analyzing the MSCR test data. The LSCR test, covering the entire duration of the MSCR test (200 s), can well determine the linear viscoelastic (LVE) recoverable properties that the Schapery’s model requires for NLVE analysis. The results show that with the recoverable and nonrecoverable responses accurately isolated, the proposed approach rigorously redefines the indicators of the percent recovery R and nonrecoverable creep compliance Jnr in the MSCR test, and therefore effectively eliminates the inaccuracy of the original indicators caused by incomplete recovery of the recoverable strain component in each cycle. Also, the developed method exactly characterizes stress dependence and permanent deformation resistance of asphalt binder, thus offering an effective and accurate approach for high-temperature performance evaluation of asphalt binders.

Developing deterministic and probabilistic prediction models to evaluate high-temperature performance of modified bitumens

This study aims to develop deterministic and probabilistic prediction models for the multiple stress creep and recovery (MSCR) test. For this purpose, crumb rubber, polyphosphoric acid, and styrene–butadiene–styrene bitumen modifiers have been used with different dosages to modify high-temperature performance of PG 58–28 and PG 64–22 base bitumens. The MSCR test has been performed at different temperatures. Deterministic models are developed by the multi-gene genetic programming technique for each modifier individually, and the non-recoverable creep compliance (Jnr) and percent recovery (R) parameters are predicted. The accuracy of deterministic models is suitable and the performance of R models has been better than Jnr models. Furthermore, a comprehensive probabilistic model has been developed by using the logistic regression technique to predict different traffic levels. The accuracy of the probabilistic model is 0.85. The sensitivity analysis has been performed on this model and the effect of changes in the modifier dosage and temperature on the traffic levels have been investigated. Results show that using the probabilistic model, it is possible to find a range of modifier’s dosage in which the traffic level is desired.

Rheological performance of bitumen mixed with laboratory simulated polymerized RAP binders

Researchers have mostly used three artificial aging techniques, namely pressure aging vessel (PAV) binder aging, compacted mix aging (CMA), and loose mix aging (LMA) to simulate recycled asphalt pavement (RAP) binder in the laboratory. RAP binder (RAPB) simulated using different techniques will differ in characteristics and may affect the performance of the base binder differently. Which may affect the parameters used for blending and recycling, such as the selection of base binder, rejuvenator dosage, etc. Therefore, in this study, three RAP binders, namely RAPB-P, RAPB-C, and RAPB-L, were simulated from a polymer modified binder (PMB) with 3.5% SBS content, using PAV aging (100 °C, 20 hrs, 2.1 MPa), CMA (85 °C, 5 days) and LMA (85 °C, 8 days), respectively. These polymerized RAPBs were added to an unmodified binder (AC 30) at three proportions: 15 %, 25 %, and 40 %. These RAPB and AC 30 blends were characterized in terms of their dynamic viscosity, mixing and compaction temperature, and high temperature performance grade (PG). Superpave rutting factor (|G*|/sin δ) and multiple stress creep and recovery (MSCR) test parameters were used to evaluate the rutting performance of the RAPB blended AC 30 binders. Further, resistance to yielding and elastic recovery values were evaluated using the binder yield energy test (BYET). The test results suggested that all three RAP binders affect the performance of the AC 30 binder differently, which was also confirmed by statistical analysis using one-way ANOVA. From MSCR and BYET test results, it may be stated that RAP binder simulated from standard PAV aging may mislead in predicting the high and intermediate temperature performance of AC 30 binder with RAPB. Overall, the present study is helpful for asphalt researchers and practitioners to understand how the selection of different defined aging strategies affects the performance of aged recycled PMB with unmodified base binder.

Correlating the Asphalt-Binder MSCR Test Results to the HMA HWTT and Field Rutting Performance

Asphalt binder is one of the key constitutive components of hot-mix asphalt (HMA) that considerably affects its rutting performance. In particular, the high-temperature rheological properties measured from the multiple stress creep and recovery (MSCR) test are critical for correlating to the HMA rutting resistance. In this study, the Texas flexible pavements and overlays database was used as the data source to investigate the effect of asphalt-binder high-temperature rheological properties on the HMA rutting resistance. The study methodology was based on correlating the results of the MSCR test and the Hamburg wheel-tracking test (HWTT) to HMA field rutting performance. The data matrix for the study included asphalt binder (PG 64-22) from three different sources, three widely used Texas HMA mixes (fine gradation to coarse gradation), and five in-service highway test sections constructed using the same asphalt binders and HMA mixes. In general, the MSCR nonrecoverable creep compliance parameter, Jnrdiff, showed fairly strong correlations with the HMA rutting performance in the laboratory and field. The percent recovery parameter (R), on the other hand, exhibited the potential to ascertain and quantify the presence of modifiers in the asphalt binders. Furthermore, the test results indicated that material source/supplier has an impact on the rheological properties of the asphalt binders with the same performance grade (PG). Overall, the use of the MSCR test to quantify the asphalt-binder high-temperature rheological properties indicated the potential to compliment the laboratory HWTT test for correlating with the field HMA rutting performance in terms of the effects of asphalt binder.

Effects of tetraethyl orthosilicate on rheological behaviors of crumb rubber modified asphalt

The purpose of this work is to study the rheology, fatigue properties and physical changes of crumb rubber modified asphalt (CRMA) after pretreatment of rubber crumbs with tetraethyl orthosilicate (TEOS). Six weight ratios of TEOS to crumb rubber, 0%, 15%, 20%, 25%, 35%, and 50%, were chosen to prepare modified crumb rubber (CR) and use it to prepare CRMA. The effects of TEOS on the physical properties of CRMA were analyzed through softening point, penetration and ductility tests. Mechanical tests including multiple stress creep and recovery (MSCR) test, temperature sweep test, and linear amplitude sweep (LAS) test were conducted to evaluate rheological properties and fatigue resistance. The results show that TEOS addition can effectively improve the physical properties, rheological properties and high temperature stability of CRMA. However, the excessive addition of TEOS can decrease rheological properties and fatigue life of rubber-modified asphalt. The results of temperature scanning test and MSCR test show that CRMA has the best G* and δ under the condition that TEOS content is 25% of CR mass; and it has optimal non-recoverable creep compliance (J(nr)) and percentage of recovery (R%). LAS test results indicate that CRMA has better fatigue life when TEOS content is 25% of CR.

The role of stress sensitivity of modified binders with the same linear viscoelastic properties in evaluating rutting resistance of asphalt mixtures

ABSTRACT In the present study, stress sensitivity of modified binders in the multiple stress creep and recovery (MSCR) test and its relationship with rutting resistance of the asphalt mixtures are investigated. For this purpose, different groups of styrene butadiene styrene (SBS), polyphosphoric acid (PPA) and SBS + PPA modified binders were produced; in each of which, the binders have the same continuous high temperature performance gradings (PGs) and linear viscoelastic (LVE) properties. The MSCR tests were performed at 40°C, 55°C, and at the PG temperatures of the modified binders to consider a wide range of high pavement temperatures. To depict the stress sensitivity, stress levels of 12.8, 25.6, and 40 kPa were added to the MSCR standard procedure and the non-recoverable compliance (Jnr) and percent recovery (R) parameters were obtained at all the stress levels applied. To study the rutting resistance of asphalt mixtures prepared with the same asphalt binders, the flow number (FN) and |E*| parameters were determined at 40°C and 55°C, through the dynamic creep and dynamic modulus performance tests, respectively. Results of the MSCR test show that at the temperature range considered, the standard stresses are not sufficient to enter the modified binders into nonlinear region, thus higher stress levels should be applied to assess the nonlinearity and address the true rutting potential. Results of the mixtures performance tests show great correlations with the results of the MSCR of the modified binders at the nonlinear stress levels, especially with the Jnr parameter, regardless of the test temperatures.

Evaluation of the rheological effect of asphalt binder modification using Linum usitatissimum oil

Warm mixtures are an essential alternative for paving as they minimize costs and environmental impacts, and their performance is similar to hot mixtures. This research evaluated the effect of adding linseed oil obtained from Linum usitatissimum in the contents of 1, 2, 3, 4, 5, and 6% by weight on the physical and rheological properties of the asphalt binder. The asphalt binder was evaluated through tests of penetration, softening point, rotational viscosity, performance grade (PG); these tests were performed before and after the short-term aging procedure; multiple stress creep and recovery (MSCR), and linear amplitude sweep (LAS). It has been verified that the mixing temperature could be reduced by up to 15 °C for the 6% linseed oil content, but it was lost in terms of performance, level of supported traffic, and fatigue life. In the so-called ideal content found, 4% linseed oil, there is a reduction in the mixing temperature of around 10 °C, as well as a maximum temperature of PG, 58 °C, it reduces by only one step compared to the pure binder, 64 °C, in addition to presenting the second-longest fatigue life of the grades studied, being classified as ideal for standard traffic by the MSCR test. Linseed oil proved to be an excellent green alternative for the production of warm mixtures.

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.

Investigating the properties of rejuvenated asphalt with the modified rejuvenator prepared by waste cooking oil and waste tire crumb rubber

WROB modified rejuvenator prepared by waste tire crumb rubber (WTCR) and waste cooking oil (WCO) had tremendous potentiality in reactivating and modifying the aged asphalt. The compatibility, high and low-temperature rheological properties, anti-rutting, aging and fatigue resistance properties were assessed by dynamic shear rheometer (DSR), bending beam rheometer (BBR) and multiple stress creep and recovery (MSCR) tests. The Fourier transform infrared spectrometer (FTIR) test results revealed that WTCR contained in WROB modified rejuvenator could regenerate the aged asphalt. The Cole-Cole curves showed that the WTCR has an active function in boosting compatibility. Moreover, the MSCR test results indicated that the WTCR had a functional effect on ameliorating the anti-rutting performance and reducing sensitivity to rutting of the rejuvenated asphalt. The indexes of anti-aging and G*·sin (δ) values respectively showed the contribution of WTCR to anti-aging performance and fatigue resistance of the rejuvenated asphalt. With 8.5% WROB modified rejuvenator, the high and low-temperature performance grade of the aged asphalt was recovered from 82–16 to 76–28. Besides, all the properties of WROB60 rejuvenated asphalt were outstanding. The properties of WROB regenerated asphalt were slightly decreased when the content of WTCR contained in the modified rejuvenator was greater than 60.

Laboratory study on the suitability of nano-silica as a modifier for asphalt binders

This paper reports the laboratory investigations carried out to assess the effect of nanosilica (NS) on the physical, morphological and rheological properties of asphalt binder. Two base binders (VG 10 and VG 30) are modified using two dosages of laboratory prepared NS (2% and 4%) by weight of the base asphalt binder. Rheological studies (10–70°C) include high temperature performance grading (PG), frequency sweep, multiple stress creep and recovery (MSCR) and linear amplitude sweep (LAS) tests. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies are also done to understand the structural modification process.It is found that NS induces amorphous nature to the base asphalt binder, as observed from XRD. SEM images show inclusions of NS as a layered interlocking network within the base asphalt binder. The true failure temperature, in high temperature PG grading, increased with the increase in percentage of NS. |G*|/sinδ master curve indicates improvement in rutting characteristics with increase in dosage of NS. The extent of improvement is found to be binder dependent. Since the stiffness of the base asphalt binder increases, |G*|·sinδ master curve drawn at 20°C shows loss in fatigue resistance by inclusions of NS. In MSCR test, the rutting resistance of NS modified asphalt binder is found to be higher than the base binder. The addition of 4% NS in VG10 increases the rutting resistance by approximately 6 times, whereas it is approximately 2 times for VG30. In VG10 the stress sensitivity reduces by 48% and 74%, respectively, by addition of 2% and 4% NS. The results from LAS test are not conclusive. Statistical analysis indicates that NS has no significant effect on the fatigue life of base asphalt binders, irrespective of test temperature. In general, it is concluded that NS modification is more beneficial for locations with high pavement temperatures and heavy vehicular loading conditions.

Anti-rutting performance evaluation of modified asphalt binders: A review

Asphalt pavement inevitably suffers rutting distress induced by repeated loads under high temperatures, which can be effectively alleviated by the modification of asphalt binders. This paper summarized the asphalt modifiers for enhancing the performance of asphalt pavement at high temperatures in terms of the modifier type, additive amount and improving effect. Then, the anti-rutting performance evaluation methods of asphalt binder were introduced with details, including the ring and ball (R&B) test, the dynamic viscosity test, the zero/low shear viscosity (ZSV/LSV) test, the dynamic shear rheometer (DSR) test, the repeated creep and recovery (RCR) test, and the multiple stress creep and recovery (MSCR) test. Furthermore, the sensitivity of the evaluation method to asphalt modifier was analyzed using the normalization method. It was found that the indicators from the MSCR test could clearly reveal the influence of asphalt modifiers on high temperature performance of asphalt binder. But it still had some limitations affecting the accuracy of evaluation results, such as the number of creep‐recovery cycles, the stress level and the recovery time. In addition, according to the rutting resistance improvement ratio (RRIR), the styrene-butadiene-styrene (SBS) modifier performed better in improving the rutting resistance of asphalt binder, compared with other modifiers when added within the usual dosage range. • The development history of anti-rutting performance evaluation methods of asphalt binder was systematically analyzed. • The sensitivity of the evaluation method to asphalt modifier was investigated using the normalization method. • The MSCR test could clearly reveal the influence of asphalt modifiers on rutting resistance of asphalt binder. • The SBS modifier performed excellently in improving the rutting resistance of asphalt binder.

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.

Laboratory and Field Evaluation of Pre-Treated Dry-Process Rubber-Modified Asphalt Binders and Dense-Graded Mixtures

Pre-treatment of ground tire rubber is emerging as a popular method to incorporate rubber particles in dense-graded asphalt mixtures. This study investigates the effects of a chemically engineered Dry-Process Ground Tire Rubber (DP-GTR) modification in asphalt binders and mixtures. The DP-GTR is comprised of rubber particles measuring 400 to 600 µm in diameter (minus #30 mesh) coated with a non-elastomeric liquid. No change in aggregate gradation is necessary in DP-GTR modification of asphalt mixtures. In this study, the effects of DP-GTR modification on binder properties were measured by dynamic shear rheometer, Multiple Stress Creep and Recovery (MSCR), and bending beam rheometer tests. Additionally, mixture properties measured by three cracking tests: Disk-shaped Compact Tension (DC[T]) test, Illinois Flexibility Index, and indirect tensile asphalt cracking test and one rutting test (Hamburg wheel track test) were evaluated. Results showed: (a) 10–12°C bump on binder high temperature performance grade with 10% DP-GTR modification by weight of binder; (b) improvement in non-recoverable compliance in MSCR test indicated higher rut resistance; (c) increase in DC(T) fracture energy at low temperatures; (d) decrease in rut depth; and (e) decrease in flexibility index and cracking test index. Field performance of the chemically treated DP-GTR sections located in different states was examined to address discrepancies observed in the cracking tests. The cracking and rutting performance of all the field sections was good-to-excellent, suggesting that some of the currently popular simple cracking tests may not be able to properly assess the cracking resistance inherent in GTR-modified asphalt mixtures.

Rheological properties and microscopic mechanism of rock asphalt composite modified asphalts

In order to improve the low temperature performance of rock asphalt modified asphalt, this work presents a laboratory study to evaluate the rheological properties of rock asphalt composite modified asphalts considering aging effect. The mechanical properties of rock asphalt (RA)/styrene–butadienestyrene (SBS) composite modified asphalt (RA/SBSCMA) and RA/crumb rubber (CR) composite modified asphalt (RA/CRCMA) were assessed based on penetration, softening point and rotational viscosity tests. Experiments, including bending beam rheometer (BBR), dynamic shear rheometer (DSR), multiple stress creep and recovery (MSCR), fluorescent microscope (FM), and Fourier transform infrared spectroscopy (FTIR), were conducted to investigate the rheological properties and microstructure of rock asphalt composite modified asphalts, as well as the effect of polymer modification and aging on asphalts. Results demonstrated that the RA/CRCMA exhibited higher consistency, better deformation resistance and temperature sensitivity than RA/SBSCMA. The performance grade (PG) of RA/CRCMA indicates superior high- and low-temperature performance, of which the RA/CRCMA with 5% rock asphalt and 18% crumb rubber (5R/18C) performed the best. The RTFO and PAV aging reduced the frequency sensitivity, facilitated the internal network structure stability and improved the compatibility of the RA/SBSCMA with 5% rock asphalt and 2% SBS (5R/2S). The 5R/18C presented superior compatibility in different aging states. The MSCR test results showed that the RA/CRCMA exhibits excellent resistance to permanent deformation and superior elasticity and recovery deformation ability. The FM test revealed that grooves and protrusions existed on the surface of RA/CRCMA, and the spheroidal RA particles and the CR particles with irregular linear or mesh structure dispersed in the asphalt phase separately. The FTIR test results proved that the RA/SBSCMA was a primarily physical modification in nature, while the RA/CRCMA was a physical–chemical modification. The CR presented stronger inhibition on the formation of carbonyl and sulfoxide compounds than the SBS resulting in more excellent anti-aging performance of corresponding composite modified asphalt. It is recommended that the optimal percentages of additive materials were 5% for RA and 18% for CR.

Effect of Different Creep and Recovery Times on the MSCR Test for Highly Modified Asphalt Binder

Abstract The development of the multiple stress creep and recovery (MSCR) test represented an improvement in the evaluation of the rutting susceptibility of asphalt binders. However, the creep and recovery times of the current test protocol (1 and 9 s, respectively) may not be adequate to predict performance under extremely heavy and slow traffic conditions or to allow full recovery of polymer-modified binders. Highly modified asphalt binders have been increasingly used in pavements under severe traffic and weather conditions, and, because of the higher polymer content in these materials, they can be more sensitive to variations in loading times and stresses. However, the influence of different loading times has not been investigated in detail for these materials yet. In this article, the effect of longer creep and recovery times on the MSCR test was evaluated for a highly modified asphalt binder, and the results were compared with those obtained for a neat asphalt binder and a regular styrene-butadiene-styrene (SBS) modified binder. Tests were carried out at the high performance grading temperature of each binder. and three situations were analyzed: (i) the increase of creep time to 2, 4, and 8 s; (ii) the increase of recovery time to 240 and 500 s; and (iii) the increase of both times simultaneously, to 2/18 s and 3/27 s. The highly modified binder analyzed was more susceptible to variation in creep and recovery times than the other binders and showed considerable increase in compliance due to nonlinear behavior, although there is no evidence that this was caused by the high polymer amount in this material. The results support the need of further investigation in this subject for future refinements in the MSCR test protocol and the specification criteria for slow or standing traffic, so that the susceptibility to longer loading times can be properly considered.

Rutting resistance, fatigue properties and temperature susceptibility of nano clay modified asphalt rubber binder

In this study, rutting performance, fatigue response and, rheological properties of CRMN (Crumb Rubber Modified Nano-clay) binders were investigated using the Multiple Stress Creep and Recovery (MSCR), Linear Amplitude Sweep (LAS) and, Superpave tests. The physical and rheological tests indicate that adding nanoclay (NC) to asphalt rubber binder (ARB) can decrease temperature susceptibility and improve the aging resistance and rheological properties of ARB. MSCR test results show that the addition of NC reduces the permanent strain and increases the rutting resistance of ARB samples. In addition, the GTR15%+NC4% sample has the best rutting resistance, which improves performance grade from PG 58S-22 to PG 70H–28. LAS test indicated that the presence of a polymer network in ARB at low strain increases the fatigue life, however, increasing the strain causes the slipping and destruction of the polymer network. The addition of NC led to a delay in the oxidation process and improve the aging resistance, hence increasing fatigue life of ARB binders. Finally, the ANOVA and Tukey analysis showed that increasing GTR and NC have a considerable effect on rutting performance, PG teخهe range and temperature susceptibility of ARB.

Investigation of the High-Temperature Behavior of Asphalt Binders Modified by Warm Additives through Performance Grade and Multiple Stress Creep and Recovery System

AbstractRecently, a new test method, multiple stress creep and recovery (MSCR), was suggested to improve the current performance binder tests. In the MSCR test method, the behavior of binders in hi...

Evaluation of Bleeding Resistance in Chip Seal and Asphalt Emulsion Residue Rheology

Chip seal bleeding is influenced by many factors, including design inputs, material properties, and project-specific conditions. It reduces the surface texture of the pavement and thus compromises the safety of the traveling public. Even though factors that bring about premature bleeding are known, currently, no laboratory test methods for evaluating bleeding in chip seals have been specified. The objective of this paper is to present the results of an investigation of the influence factors of asphalt emulsion residue properties measured by the ASTM D7405 multiple stress creep and recovery (MSCR) test, as well as other factors related to chip seal bleeding resistance as measured by the modified loaded wheel test (MLWT). In this study, the MSCR test was used as a tool for evaluating the performance of asphalt emulsions because it has been identified as a potential test related to bleeding in the field. In addition, MLWT was selected as a tool for evaluating chip seal bleeding performance in the laboratory. The results of the MLWT showed that the emulsion application rate (EAR), aggregate gradation, and emulsion properties were significant factors affecting bleeding. The MSCR test was found to be a promising tool for the performance evaluation of asphalt emulsion residue, as the test was able to differentiate between emulsion chemistries and modifications in terms of sensitivity to both temperature and stress. In relation to chip seal bleeding resistance, only the creep compliance (Jnr) obtained from the MSCR test results was identified as a significant property affecting potential for bleeding.

Influence of Chemical Constituents of Asphalt Binders on Their Rheological Properties

The goal of this study is to investigate the chemical constituents and rheological properties of three different binders used in the State of Qatar. Binders were designated as WL (source 1, low density), WH (source 1, high density) and AH (source 2, high density). Binder composition analysis was carried out using the saturates, aromatics, resins and asphaltene determinator (SAR-AD) technique. The percentages of saturates, aromatics, resins and asphaltenes were measured, and from those, the total pericondensed aromatics (TPA), absorbance aging index (AAI), and colloidal instability index (CII) were obtained and their relationship to rheological test results was investigated. In the rheological investigation, the linear viscoelastic properties of these binders were evaluated using a frequency sweep test. The rutting characteristics were evaluated using the percentage of recovery and non-recoverable creep compliance values from the multiple stress creep and recovery (MSCR) test, while the fatigue resistance was assessed using the linear amplitude sweep (LAS) test. The WL binder was found to have the highest stiffness, which is associated with the highest TPA content. From the MSCR test, the AH binder had the lowest rut resistance. This binder also had the lowest CII value, which represents the balanced chemical composition of this material. Out of the three binders, WH had the highest AAI value which is related to the least fatigue life as measured in the LAS test.