Master Curves

This paper presents recent modifications of the Leak Before Break procedure of the A16 appendix from French RCC-MR nuclear code and the improvements that will be proposed. The first part of the study deals with the prediction of the crack size at penetration. In the case of small initial defect the validity of the Master Curve used in the A16 appendix is confirmed for pipes. For large initial defects, a correction to the A16 procedure is proposed to take into account the effect of large initial crack length on its size at penetration. The second part of this paper focuses on the crack shape evolution after penetration, which is characterized by two stages: first straightening of the crack shape and then crack growth at both inner and outer surfaces. This typical behaviour is confirmed by numerical and experimental works for which particular loading conditions have been investigated.

The Accelerated Loading Facility (ALF) was used to validate the Superpave asphalt binder parameter for rutting, namely, G*/sin(delta), and several laboratory mixture tests that have been developed to predict or compare rutting performance. The ALF is a full-scale, pavement testing machine that applies one half of a single rear truck axle load. The asphalt binders used in this study were AC-5 AC-IO, AC-20, Novophalt, and Styrelf I-D, having Superpave hightemperature continuous Performance Grades (PG's) of 59,65, 70, 77, and 88, respectively. This is the temperature at 2.20 kPa after rolling thin-film oven aging. A dynamic shear rheometer was used to obtain these data. All five binders were used with an aggregate gradation having a nominal maximum aggregate size of 19.0 mm. The PG 59 and 70 binders were also used with a gradation having a nominal maximum aggregate size of 37.5 mm. Pavements with these materials were tested by the ALF. The relationship between G*/sin(delta) and ALF pavement rutting performance at temperatures ranging from 46 to 76 C was poor. However, the trend was correct for the unmodified binders, and the 2.20-kPa criterion used by the Superpave binder specification appeared to be valid. The main discrepancy was provided by the two modified binders, which were both highly resistant to rutting. The G*/sin(delta) for Styrelf was higher than for Novophalt, but the pavement with Novophalt was more resistant to rutting. This discrepancy was not resolved, although tests performed on mastics indicated that the relative rutting performances of the modified binders may have to be based on mastic properties. The ALF, French Pavement Rutting Tester, Hamburg Wheel-Tracking Device, Georgia Loaded-Wheel Tester, an unconfined repeated load compression test, and six Superpave Shear Tester measurements ranked the five 19.0-mm mixtures the same as ALF based on the average test data. The rankings based on statistics were generally different, but they were similar to ALF. Therefore, any of these tests can be used to estimate the effects of various asphalt binders on rutting. Four mixtures, consisting of the two gradations with the PG 59 and PG 70 binders, were used to determine the effect of increased nominal maximum aggregate size and the associated 0.85-percent decrease in optimum binder content on rutting performance. None of the laboratory mixture tests matched the ALF pavement rutting performances of the four mixtures. The tests listed above were sensitive to binder grade but not to aggregate gradation. The PURWheel was sensitive to gradation but did not distinguish the PG 59 binder from the PG 70 binder. The sensitivities of these tests to other key mixture variables need to be determined in future studies.

In this study, the rheological properties and physical significations of an incompressible viscoelastic (inCVE) the inCVE model was investigated by employing molecular dynamics calculations. Polypropylene (PP) and polystyrene (PS) polymers were selected as candidate materials, the corresponding cell models consisting of five chains of 80 (PP) and 30 (PS) units were built successively. The energy minimization and anneal treatment were launched to optimize the unfavorable structures. The periodic boundary condition, COMPASS force field and the Velocity-Verlet algorithm were employed to calculate the shear flow behavior of chains. The sample data were collected and fitted based on the Matlab platform, and the analysis of the variance (ANOVA) method was performed to determine the validity of the model. Experimental results reveal that the inCVE model matches well with the pseudo-plastic fluids. Compared with the Ostwald-de Waele power law model and Cross model, it is effective and robust, and exhibits a three-stage rheological characteristic. Moreover, it characterizes the stress yield, activation energy, temperature dependence and viscoelastic response of polymers.

The time-temperature superposition principle was used to develop long-term compression creep and recovery models for southern pine exposed to constant environmental conditions using shortterm data. Creep (1 7-hour) and recovery (40-hour) data were obtained at constant temperature levels ranging from 70 F to 150 F and constant equilibrium moisture content (EMC) of 9%. The data were plotted against log-time, and the resultant curve segments were shifted along the log-time axis with respect to the curve for ambient conditions to construct a master curve applicable to ambient conditions (70 F, 9% EMC) and a longer time period. The master curves were represented by power functions, and they predicted up to 6.4 years of creep and 5.8 years of recovery response. The validity of the master curves for predicting creep of wood exposed to the normal interior environment in buildings was tested by conducting ten-month creep tests in the laboratory. The fluctuating environment caused geometry changes in the surface of the specimens affecting the collected long-term data. Therefore, a good comparison between the master curves and the long-term data was not possible.

The non-isothermal flow during compression molding of thermoplastic-based composites having a planar, randomly oriented fiber structure has been investigated. Local interactions at the bundle-bundle level were measured and a constitutive equation was derived to describe the shear and squeeze flow of the composites. This equation contains only micro-mechanics-related variables, and accounts for the temperature dependence of the interaction forces. The flow of the material under industrial processing conditions can thus be related to the deformation mechanisms of the reinforcement structure at the scale of the individual fibers. Good agreement was obtained between the predicted and experimentally observed rheological behavior of the composites in both shear and squeeze flow. The use of this approach to analyze the industrial molding of complex-shaped parts is discussed.

The non‐isothermal flow during compression molding of thermoplastic‐based composites having a planar, randomly oriented fiber structure has been investigated. Local interactions at the bundle‐bundle level were measured and a constitutive equation was derived to describe the shear and squeeze flow of the composites. This equation contains only micro‐mechanics‐related variables, and accounts for the temperature dependence of the interaction forces. The flow of the material under industrial processing conditions can thus be related to the deformation mechanisms of the reinforcement structure at the scale of the individual fibers Good agreement was obtained between the predicted and experimentally observed theological behavior of the composites in both shear and squeeze flow. The use of this approach to analyze the industrial molding of complex‐shaped parts is dis cussed.

This paper discusses the results obtained by applying the Moisture Damage analysis to one asphalt mixture that was designed by the Superpave® method. The characterization of materials included: rheological, chemical, mechanical and performance tests using eight types of asphalt whose penetration was 80-100 (1/10mm). One of them was named original, S0, and the others seven (S3, S6, S9, S12, S15, S18, S21) were water conditioning during 21 months. Taking in to account that moisture damage is usually determined by the Tensile Strength Ratio-TSR test, which considers a basic conditioning by temperature and humidity, this research also performed the Moisture Induced Sensitivity Test-MIST test, including the effect of water, temperature and pressure applied for the vehicles, which increase the pores pressure of the mix and could cause some kind of detachment (stripping). The comparison between the TSR and MIST results showed how important it is to consider the dynamic loads and the temperature when we need to study Moisture Damage. In addition, it was possible to study the influence of the water on the asphalt properties and its impact on the rutting of the asphalt mixture.

The rheological properties of asphalt binders change with time. Asphalt mixtures get stiffer and more prone to fatigue cracking with aging. This study is a part of a comprehensive study undertaken to develop improved protocol for asphalt mixture conditioning in the laboratory to simulate asphalt mixture aging due to the climate conditions in the State of Qatar. In this study, asphalt mixtures were prepared by mixing Gabbro base aggregate with Pen 60-70 binder. Initially, mixtures were conditioned at short-term aging temperature of 135°C for different time periods (2, 4 and 6 hrs). Long-term aging was completed after compaction of test specimens to the desired air void level of 7 ± 0.5% by using Superpave gyratory compactor. Three different long-term aging temperatures (i.e., 75, 85 and 95°C) and four different aging levels (0, 2, 6, and 10 days) were evaluated in this study. Then, the specimens were tested in an AMPT to determine dynamic modulus and phase angle. Results of this study were presented by plotting a series of mastercurves obtained from performance testing of the aged specimens. The results showed that aging temperature and duration have significant effects on the viscoelastic properties of asphalt mixtures.

T he suitability of a polymer to be processed by injection molding is called moldability. The technicians in injection molding companies tend to estimate moldability by using a parameter named Melt Flow Index (MFI), which however can be often misleading since it represents the ability of a melt to flow in specific conditions, very different from the ones that the polymer encounters during injection molding. A much significant parameter is the so-called flow-length, which is the length reached by a polymer during injection molding in a thin cold cavity. In this work, three commercial grades of polypropylene were injection molded in a cold thin cavity and the flowlengths were measured in function of injection pressure and temperature. The results obtained were correlated with the rheological parameters. The results demonstrate that the MFI is misleading as a technical parameter for the moldability of polypropylene. An empirical equation is proposed to describe the flow-length of polypropylene in function of injection pressure.

During mechanical recycling, polypropylene typically is reprocessed using a single- or twin-screw extruder. The degradation of polypropylene during this reprocessing reduces the polymer’s molecular weight and, consequently, limits the performance of the recycled resin. This work investigated the impact of a quad screw extruder (QSE), which has greater free volume, on the reprocessing of an impact copolymer polypropylene. To mimic the recycling process, the polypropylene was subjected to three processing cycles using a QSE and a comparable twin-screw extruder (TSE) operated at three screw speeds. The reprocessed materials were characterized for their rheological, morphological, and mechanical properties. For both extruders, increasing the number of reprocessing cycles and the screw speed resulted in higher melt flow indices, decreases in zero-shear viscosity, and shifting of the crossover points for the storage and loss moduli, which indicate reductions in the molecular weight and na...

Warm Mix Asphalt (WMA) technology allows a reduction in temperatures at which asphalt mixes are produced and placed. This offers the benefits of reduced mixing and compaction temperature, reduced energy consumption, and greenhouse gas/toxic gases emission, extending cold paving season and long-hauling distance, and enhanced sustainability. On the other hand, nano anatase Titanium Dioxide (TiO2) particles can trap and decompose harmful environmental substances like NOx, SO2, and VOCs through photocatalytic oxidation. An infrastructure sustainable system that combines the benefits of WMA technology and photocatalytic properties of TiO2 to capture and degrade organic and inorganic particles in the air was examined. A 19.0 mm wearing course warm mix asphalt mixture containing PG 70-22 binder was considered. A chemical additive was incorporated into PG 70-22 binder to produce WMA. Four levels (0-, 3-, 5-, 7% by the weight of the binder) of crystallized anatase-based titanium dioxide powd...

Abstract: The report pertains to the laboratory evaluation of hot mix asphalt modifiers (HMA-M). These modifiers are defined as materials that are added to hot mix asphalt (HMA) to improve its working capacity, whether for permanent deformation, fatigue/low temperature ...

An asphalt-rubber hot mix asphalt (AR-HMA) design was created using a Superpave 12.5mm gradation and a #30 (-) mesh crumb rubber at 20% total weight of the asphalt binder. At this point in time, asphalt rubber has only been used with HMA that contains a more open graded nature, such as open graded friction course (OGFC). However, OGFC is limited on it use due to its potential problems (i.e. clogging and winter maintenance). However, a 12.5mm Superpave mix may be used on almost any roadway in New Jersey and is most commonly found as the surface course. It is used for both new construction and rehabilitation projects. Therefore, this mix type has the largest potential for usage, meaning that more tires can eventually be recycled. However, two factors need to be considered prior to acceptance; performance and cost. Four HMA mixes were constructed and tested in this study. Three baseline mixes using a PG64-22, PG70-22, and a PG76-22 asphalt binder, as well as the AR-HMA mix which used crumb rubber blended with the same PG64-22 asphalt binder. The influence of crumb rubber particle size on the compaction properties during the mixture design procedure was also evaluated. This would provide a method of comparing the final mixture performance of different performance graded binders to the AR-HMA mix. This type of methodology of testing the mixtures is extremely important due to the necessity of ensuring the crumb rubber complying to the aggregate gradation volume limitations, and how the crumb rubber interacts with this volume limitation under performance testing. Therefore, a number of different performance tests were conducted on the four different HMA mixes: 1) Asphalt Pavement Analyzer, 2) Repeated Load Permanent Deformation testing using the Simple Performance test specifications, 3) Dynamic Modulus, 4) Repeated Shear at Constant Height, 5) Frequency Sweep at Constant Height,and 6) Simple Shear at Constant Height. The results from the mixture design portion concluded that to provide consistent compactibility when using crumb rubber in a 12.5mm Superpave design, the maximum particle size should not be greater than a #30 mesh. The performance tests concluded that the AR-HMA mix performed as well as or better than the PG76-22 for every test conducted. For example, the dynamic modulus test results showed that the AR-HMA had similar stiffnesses to the PG76-22 at the high test temperatures, however, the AR-HMA had a much less stiffness at the low test temperature. This indicates that the AR-HMA mix design in this study will provide excellent rut resistance, while also providing excellent low temperature cracking resistance. Essentially, by adding the crumb rubber to the PG64-22, the working temperature range of the asphalt binder increased on both the high and low sides. Also, by performing similarily to the PG76-22, Bayshore Recycling now can establish a cost comparison using the difference in cost between a HMA with a PG64-22 and a PG76-22.

The rheological properties of asphalt binders change with time. Asphalt mixtures get stiffer and more prone to fatigue cracking with aging. This study is a part of a comprehensive study undertaken to develop improved protocol for asphalt mixture conditioning in the laboratory to simulate asphalt mixture aging due to the climate conditions in the State of Qatar. In this study, asphalt mixtures were prepared by mixing Gabbro base aggregate with Pen 60-70 binder. Initially, mixtures were conditioned at short-term aging temperature of 135°C for different time periods (2, 4 and 6 hrs). Long-term aging was completed after compaction of test specimens to the desired air void level of 7 ± 0.5% by using Superpave gyratory compactor. Three different long-term aging temperatures (i.e., 75, 85 and 95°C) and four different aging levels (0, 2, 6, and 10 days) were evaluated in this study. Then, the specimens were tested in an AMPT to determine dynamic modulus and phase angle. Results of this study were presented by plotting a series of mastercurves obtained from performance testing of the aged specimens. The results showed that aging temperature and duration have significant effects on the viscoelastic properties of asphalt mixtures.

Ceramics, concretes and asphalt-mixtures are the most popular building materials in Hungary, because of the highway programme of the government. In spite of their large popularity, some of the mechanical properties of ceramics, concretes and asphalts are not investigated enough till today. Particularly, there is no mechanical model usable to understand and explain the rheological behaviours of these materials with different compositions of mineral raw materials. It is well known, that the viscosity of viscous materials, viscoelastic materials, and viscoplastic materials dynamically decreases, as the temperature increases. The decrease of viscosity by leaps and bounds could be extremely dangerous in case of asphalt pavements in the range of 55 – 75 °C, due to the crossing of cars on the low viscosity pavements which suffer inelastic deformation, as a result. Using a Rheo-tribometer instrument developed by L. A. Gömze and others, the authors have investigated and tested asphalt mixtur...

This research work evaluates several parameters that can affect Asphalt Rubber (AR) binder performance and applies the AR technology to the development of an innovative renewable bio-binder that can fully and cost-effectively replace asphaltic bitumen derived from petroleum in flexible pavement construction. The "Binder Accelerated Separator" method was used to divide the constituents of the Asphalt Rubber and bio-binder (residual binder and swelled rubber). The physical and chemical changes in the Asphalt Rubber and bio-binder and in the residual binders (residual bitumen and residual bio-oil) were evaluated. The results demonstrate that the produced bio-binder is suitable for use in flexible pavements with properties comparable to those of conventional and Asphalt Rubber binders.

The applicability of X-ray tomography techniques to image an asphalt concrete core in three dimensions and study the aggregate structure was demonstrated with four examples. It was found that rutting performance of mixes in WesTrack could be qualitatively related to aggregate structure. It was found that various aspects of a 450-mm full-depth core can be analyzed, including the aggregate structure at its interface and the void distribution and structure. Imaging a core at various stages of compaction in a gyratory compactor enabled the study of the process of compaction. The uneven distribution of asphalt in the FHWA accelerated loading facility pavements was illustrated by X-ray microtomography.

Bituminous mixes are becoming increasingly important in the road industry. The road engineers identify rutting as a major source of distress in Hot Mix Asphalt (HMA) pavements. The Asphalt Mix Design Marshal method adequately addresses the aggregate and asphalt binder properties that contribute to permanent deformation. However, there is no laboratory test currently at hand to quickly predict permanent deformation susceptibility of HMA. The main purpose of this paper is to provide practical information of laboratory samples for practitioners and mix designers. Thus, relevant test procedures and results of tests conducted are reported in this paper. Two resilient behaviours of cracked sealed asphalt concrete were studied by varying temperature and time of loading to understand the crack sealed pavement behaviour under Iran conditions.

Different volume fractions of polycarbonate (PC) were incorporated to improve thermal stability of red mud (RM) filled polypropylene (PP). Effects of PC addition in RM filled PP on shear stress, melt viscosity, and melt elasticity have been determined under different shear rates by using a capillary rheometer. With the increase in shear rate, addition of PC in RM-filled PP reduced its shear stress and melt viscosity. However, recoverable shear strain increased with PC content in the blend.

The qualitative and quantitative information concerning the dependence between the kinematic viscosity and the activation energy of the viscous flow by the polyvinyl chloride – thermoplastic polyurethane blends composition were obtained. The results reveal that the blend composition and the melt temperature are the most important parameters that control the PVC – TPU blends melt processing. A high injection speed increases both the tensile strength and the breaking elongation. The shorter time for the mould loading increases the tensile strength and decreases the breaking elongation. The measurement of the rheological properties based on the MFI methods is a good instrument for the estimation of the rheological properties of the polymeric blends in practical conditions

The use of crumb rubber from vehicle tyres in hot mix asphalt production has been a very promising option in the field of waste recycling and sustainability. The disposal of used vehicle tyres has been a serious and difficult issue. Due to their indestructible nature the options are burning or disposal, none of these are desirable in our global environment. The trials for using crumb rubber in hot mix asphalt started in the 1920s; these early applications used the so called dry method, where the rubber is considered as part of the aggregate instead of the binder. This method did not deliver the expected higher performance, and researchers have been looking into the so called wet process since the 1960s, where the rubber is added to the binder, modifying its properties. The modified binder is then added to the aggregate during asphalt production. Although many countries utilise the crumb rubber using the wet process, there is an ongoing problem with this technology, similarly to the application of polymer modified bitumens (PmBs): the storage stability of the product. This short-term segregation problem has been preventing the wide application of crumb rubber bitumen in road construction. Additionally, the high viscosity of product may cause difficulties during manufacturing and paving which should be considered when selecting aggregate grading. MOL Plc. developed and patented a procedure for producing chemically stabilized rubber bitumen (CSRB); the pilot scale production started in 2012 and the facilities are capable to produce 5000 tonnes of CSRB-equivalent of 150,000 tyres-in their Zala Refinery, Hungary. This paper discusses an asphalt research program conducted at Budapest University of Technology on a 10mm nominal aggregate size wearing coarse hot mix asphalt. This study presents the comparative analysis of asphalts containing PmB and CSRB separately. Prepared samples were subjected to performance based and related mechanical testing. The findings summarised in this paper suggest that performance of asphalt mixes produced with CSRB binder are similar or equivalent to asphalt mixes produced with PmB with regard to moisture sensitivity, stiffness and wheel tracking, while the low temperature cracking test showed higher and superior performance.

In contrast to conventional binder grading system relying basically on needle penetration and viscosity, performance grading system can be used for classification of both neat and modified binders and constitute one of the most prominent focus area for Bituminous Binders Technical Committee CEN/TC 336. In this study, the four different penetration grade bitumen samples from the all four crude oil refineries of Turkey, one is of distinctly higher asphaltene content, were modified with SBS, Elvaloy, SBR and Lucobit modifiers. Both unmodified and polymer modified bitumens were subjected to conventional and SHRP binder performance tests, namely penetration, softening point, force ductility, rotational viscometer (RV), rolling thin film oven (RTFO), dynamic shear rheometer (DSR) and bending beam rheometer (BBR). Additionally, SARA (saturates, aromatics, resins and asphaltenes) contents of neat bitumens by thin layer chromatography and polymer dispersion of modified binders by fluorescent...

Aging of an asphalt binder causes the changes in the microstructure and, consequently, in the nanomechanical and rheological properties of the aged asphalt binder. Short-term aging on asphalt binders was simulated using rotating thin film oven (RTFO). These changes in the microstructure and nanomechanical and rheological properties were measured using atomic force microscope (AFM) and dynamic shear rheometer (DSR). The results indicated that (1) the adhesive force of the asphalt binder from AFM tests was increased after RTFO aging; (2)G*of the asphalt binder from DSR tests increased after RTFO aging; (3) the results from AFM were consistent with those from DSR, explaining the mechanism of the changes of rheological properties.

Crumb rubber modifier (CRM), made from scrap tires, has been introduced into the production of different types of Hot Mix Asphalt (HMA) in either wet or dry process. There has been few research about the interaction between asphalt and the crumb rubbers added in the dry process. In the study, dynamic shear rheometer (DSR) and atomic force microscopy (AFM) were used to explore the interaction between the asphalt binder and CRM in dry and wet process. The results indicated: (1) rubberized binder in dry process have similar modulus, phase angle and complex viscosity with wet process, regardless of unaging or short-term aging, (2) rubberized asphalt in dry process has lower roughness of topographical image than wet process before short-term aging. However, the short-term aging may decrease the difference of the microstructures of the binders in two processes, i.e., wet and dry processes.

Several test methods are in practice to assess the rutting potential of a mixture. The commonly used procedures are Diametral tests, Uniaxial test, Triaxial tests, Shear tests, Empirical tests, and Simulative tests. Of all these test methods, simulative test methods are relatively easier to use and ready for immediate adoption. The APA test is the most widely used simulative test. It is imperative that the rut depth criteria for the APA test should be developed for its employment. In a recent study conducted at NCSU, it was concluded that the APA could clearly detect poorly performing mixtures. With the limited availability of data, a reasonable correlation was observed between the APA tests and Repeated Shear at Constant Height (RSCH) tests. A comprehensive research study was conducted on all surface mixtures of NCDOT. The rut depths measured from the APA test were compared with the corresponding shear strains of the RSCH test. In addition, the shear and APA tests were fine-tuned b...

Tin stabilizers are among the best thermal stabilizers for PVC. A novel tin stabiliser di-(mercaptopropyl-trimethoxysilane)dibutyl tin, with siloxy groups has been synthesised and its performance characterised during thermal processing of PVC. This new stabiliser, called SnMS3, showed good stabilisation by both static and dynamic tests when compared with a commercial stabilizer (T83 1) (DEMOSA). Both stabilizers were compared using the static Congo Red test for hydrogen chloride evolution when incorporated into PVC. The nature and level of wax lubricants used in the PVC formulations were also examined via a capillary rheometer. Stabilisation times were determined for formulations with dierent contents of lubricants together with Sn-MS3 and a model thermal stabilizer (2,2-dibutyl-2-tin-1,3-dithiocyclohexane). Formulations at an appropriate lubricants ratio were de®ned and evaluated in PVC for the stabilising eect of Sn-MS3.

The aim of this study is to search for a substitute for the natural coarse aggregate in various regions of the world, such as Amazon-Brazil, where this type of material is lacking. The asphalt binder AC 50/70 is mixed with an aggregate obtained from the sinterization of a calcined clay (SACC) as a possible alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones. The dynamic modulus |E * | of this mixture was measured under strain control mode and in tension control mode. The results are compared with those obtained from AC 50/70 mixed with pebbles, which is currently used as the coarse aggregate in this region. For pavements that work at high temperatures, such as 40˚C, and low frequencies, the mixture with SACC appears to be a viable alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones.

The aim of this study is to search for a substitute for the natural coarse aggregate in various regions of the world, such as Amazon-Brazil, where this type of material is lacking. The asphalt binder AC 50/70 is mixed with an aggregate obtained from the sinterization of a calcined clay (SACC) as a possible alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones. The dynamic modulus |E * | of this mixture was measured under strain control mode and in tension control mode. The results are compared with those obtained from AC 50/70 mixed with pebbles, which is currently used as the coarse aggregate in this region. For pavements that work at high temperatures, such as 40˚C, and low frequencies, the mixture with SACC appears to be a viable alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones.

The French pavement design method provides a very comprehensive, probability-based design approach. It also provides a fairly sophisticated method for establishing the equivalent pavement temperature, which has been used worldwide for different applications. The objective was to analyse the applicability of the French method for calculating the equivalent pavement temperature for Hungarian climatic conditions. It considers the thickness of the pavement structure and facilitate pavement temperature distribution. It was found that the French method provides a comprehensive approach and can facilitate variable climatic conditions and pavement temperature distribution while considering the thickness of the pavement structure. This provides fit for purpose solutions and eliminates the overly simplified approach to use a single equivalent pavement temperature for variable climatic and pavement conditions. Real pavement temperature data provided crucial input into the accuracy of the metho...

Most of the polymers currently used as additive in bitumen are not economically attractive. Thus, employing recycled materials in flexible highway instead of virgin ones has become a fundamental case for researchers especially in terms of cost efficiency and environmental awareness. To date, many studies have been made to investigate using of recycled polymers in bitumen and generally improved mechanical properties of bitumen were determined. This paper aims to present the modification of bitumen by maleic anhydride (MAH) grafted recycled low density polyethylene treated by irradiation (g-LDPEr-g-MA). Maleic anhydride was dissolved and mixed with recycled polyethylene which was proved by the Fourier infrared (FT-IR) spectrum. Subsequently, pre-treated LDPEr granules were subjected to gamma irradiation doze of 10kGy to provide formation of free radicals and some functional groups which can contribute to creation of strong chemical bonds between polymer modifier and bitumen. Six different binders (one base and five modified) were prepared to investigate the effects of g-LDPEr-g-MA modifier on properties of bitumen. The dispersion of g-LDPEr-g-MA modifier in bitumen was examined by florescent microscope. Conventional tests and rotational viscosity test was used to determine physical properties of bitumens. Complex shear modulus (G*) and phase angle (δ) of base and modified bitumens were measured by means of dynamic shear rheometer (DSR) for different traffic speed and in-service pavement temperature. Tests results reveal that a gradually increment in g-LDPEr-g-MA modification leads to a decrease in penetration and an increase in softening point. According to DSR test results, g-LDPEr-g-MA modifier provides an increased rutting parameter. Thus, flexible pavement could become more resistant against permeant deformations by g-LDPEr-g-MA modification.

In the paper, the X-ray study of cross-linked polyethylene with isopropenyl styrene or acrylonitrile was carried out. It is shown that cross-linking leads to a significant decrease in the area of the exothermic peak, an increase in the resistance of the structured system to thermal oxidation. These data confirm that the increase in resistance to thermal aging of polyethylene crosslinked with acrylonitrile or isopropenyl styrene fraction.

The degradability and processability of new renewable materials based on starch and PVOH were studied using the melt flow index (MFI) method by measuring the melt rheological properties which depend not only on the extrusion conditions and material formulation but also on the macromolecule characteristics which can be modified by chemical degradation. These results were correlated with other material properties like color and cross-linking degree. The obtained results show that flowing in the melted state of the studied materials is accompanied by a second process of chains chemical degradation. It was observed that, at the same level of additivation, under identical extrusion conditions, the melted blends with corn starch as main component are highly mechanically sensitive and degrade mostly by chains scission and those with PVOH as major component are highly temperature sensitive and degrade mainly by cross-linking. The obtained results show also that each PVOH-starch blend requir...

This review addresses the effects of the modifications with nanomaterials, particularly nanosilica, nanoclays, and nanoiron, on the mechanical performance and aging resistance of asphalt mixtures. The desire for high-performance and long-lasting asphalt pavements significantly pushed the modification of the conventional paving asphalt binders. To cope with such demand, the use of nanomaterials for the asphalt binder modification seems promising, as with a small amount of modification an important enhancement of the asphalt mixture mechanical performance can be attained. Several studies already evaluated the effects of the modifications with nanomaterials, mostly focusing on the asphalt binder properties and rheology, and the positive findings encouraged the study of modified asphalt mixtures. This review focuses on the effects attained in the mechanical properties of the asphalt mixtures, under fresh and aged conditions. Generally, the effects of each nanomaterial were evaluated with the current state-of-art tests for the characterization of mechanical performance of asphalt mixtures, such as, permanent deformation, stiffness modulus, fatigue resistance, indirect tensile strength, and Marshall stability. Aging indicators, as the aging sensitivity, were used to evaluate the effects in the asphalt mixture's aging resistance. Finally, to present a better insight into the economic feasibility of the analyzed nanomaterials, a simple cost analysis is performed.

This study addresses the New England state transportation agencies concerns associated with the use of Re-refined Engine Oil Bottoms (REOB) in asphalt binders and mixtures. The effect of REOB on the physical and rheological properties of a straight run asphalt binder was investigated after short-term and long-term aging and after extended long-term aging. Also, the effect of REOB modified binders on the performance of asphalt mixtures after short and longterm aging was evaluated in terms of moisture damage, rutting, and cracking. Rheological results showed that the addition of REOB caused the binders to age more relative to the straight run binder. The results also indicated that the use of higher dosages of REOB can cause increased binder aging. Overall, when the results from the particular mixture tests used in this study were plotted on a Performance Space Diagrams, the diagrams did not provide evidence that using REOB decreases performance.

This standard is issued under the fixed designation D 1238; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

This paper focused on predicting the performance of asphalt mixes modified with nano-montmorillonite (NMMT) and nano silicon dioxide (NSD) using the Quality-Related Specifications Software (QRSS), which is a simplification to the Pavement ME Design. The nanomaterials were thoroughly mixed with the binder at a temperature of 145 ± 5°C. The conventional and the rheological properties were determined for the penetration grade 60-70 control binder as well as binders modified by 3, 5 and 7% of NMMT and NSD by the weight of asphalt. The optimum nanomaterial content was found for each modifier and was then used for preparing asphalt mixtures by the conventional Marshall method. Finally, Witczak 1-40D complex shear modulus (G*) based predictive model was used to estimate the dynamic modulus (E*) for the control and nanomodified asphalt mixtures. The field performance in terms of asphalt concrete (AC) layer rutting and fatigue cracking was predicted using the QRSS software for two typical pavement sections and three different climatic locations in Egypt (Alexandria, Cairo and Aswan). The simulation runs revealed that both nanomodified asphalt mixtures exhibited superior pavement performance in terms of AC rutting compared to the control mix without a significant effect on fatigue life.

A series of blends of Acrylonitrile-Butadiene-Styrene (ABS) and Polycarbonate (PC) and another series of polyvinylidene fluoride, PVDF, and low density polyethylene, LDPE, were prepared and characterized for some of their rheological properties. The blends of a series were prepared by mixing the components, with different weight % composition, in a molten state using Brabender Plastograph. Visco-elastic parameters were measured using the capillary rheometer (Melt Index 3/80). Die-swelling rate, (B), was determined for different composition samples and correlated with the end pressure drop, (Pend), the end correction, (e), the apparent shear rate, (a), the apparent shear stress, (a), and the length-radius ratio, (L/R). The effects of blending composition on the die-swell rate, (B), the end correction, (e), and the shear strain, (SR) were also studied for the prepared series of blends.

The present study evaluates the mechanical performance of a Hot Mix Asphalt – Type II (HMA-2) modified with carbon nanotubes and carbon nanofibers (CNTF). CNTF were made by means the Catalytic Vapor Deposition (CVD) technique at 700° C using a Nickel, Copper and Aluminum (NiCuAl) catalyst with a Cu/Ni molar relation of 0,33. In order to properly assess HMA-2 performance, three different mixtures were analyzed: 1) HMA-2 modified with purified CNTF; 2) HMA-2 modified with non-purified CNTF and, 3) a Conventional HMA-2 (control). Samples manufactured in accordance with the Marshall Mix Design were tested in the laboratory to study rutting, resilient modulus (Mr) and fatigue. In addition to the aforementioned dynamic characterization, the effect of CNTF purification on the asphalt mixture’s mechanical properties was analyzed. In short, a comparative study was designed to determine whether or not CNTF should be purified before introduction into the HMA-2. This investigation responds to the growing demand for economical materials capable of withstanding traffic loads while simultaneously enhancing pavement durability and mechanical properties. Although purified CNTF increased HMA-2 stiffness and elastic modulus, non-purified CNTF increased the asphalt mixture’s elastic modulus without considerable increases in stiffness. Thus, the latter modification is deemed to help address fatigue-related issues and improve the long-term durability of flexible pavements.

This study presents experimental investigation results on evaluation of rutting resistance characteristics of asphalt binder containing two types of Styrene-Butadiene-Styrene (SBS). In the present study, pure asphalt binder (40-50 PEN) typically used in the middle and southern regions in Iraq was obtained from two sources and blended with different amounts of SBS, 3, 6, 9%, based on the total weight of the asphalt binder. The Dynamic Shear Rheometer (DSR) was used to evaluate the modifier asphalt binders at various temperatures, i.e., 25, 35, 50 and 60 °C. Good multiple linear relationships between log transformation of rheological properties and the amount of SBS asphalt modifier were obtained from this study. The SBS contents, temperatures and applied frequency are significant variables. It was found that the addition of SBS modifier generally increases the asphalt binder resistance against rutting. It was observed that an increase in SBS content causes an increase in G*/sinδ and enhanced the viscosity at high temperature by increasing the values of low and zero shear viscosity.

This project investigated the long-term performance of hot asphalt mixes containing crumb rubber modifiers (CRM) added in dry or wet processes. A total of eight asphalt mixtures—four Porous European Mixtures (PEMs) and four Stone Matrix Asphalts (SMAs)—were designed with PG 76-22 modified with CRM, which was added in either a dry or wet process. These mixtures were compared to control mixtures using an SBS-modified PG 76-22. Mixtures incorporating a “hybrid”-modified PG 76-22 were also evaluated. First, the samples were weathered in the Georgia Weathering Asphalt Device (GWAD) for 1,000 hrs and 3,000 hrs and tested to determine their dynamic modulus, fatigue life, rutting, and Cantabro. Binders extracted from the weathered samples were then evaluated using a dynamic shear rheometer (DSR), gel-permeable chromatography (GPC), and Fourier transform infrared spectroscopy (FTIR). Second, the interactions of dry- and wet-processed CRM with asphalt binder were compared during storage and paving. Results indicated: 1) adding TOR to the CRM binder improved PG grade and separation resistance; 2) the dynamic modulus, |E*|, of both rubberized PEM and SMA in dry process did not differ significantly from that of the control mixtures or mixtures using the “hybrid”- modified binders before and after weathering; 3) the fatigue life (Nf) of unaged rubberized PEM and SMA in the dry process was similar to that in wet process, although lower than that of control SBS; 4) after 3000-hrs aging, the fatigue life of the dry-processed rubberized SMA is similar to that of the wet-processed but lower than that of hybrid and SBS SMA, regardless of strain and stress levels or test temperatures; 5) the rutting and Cantabro loss of the rubberized PEM and SMA in dry process were higher than those of control SBS after weathering; 6) CRM and asphalt binder interact during the production and paving stages based on DSR, GPC, FTIR, and AFM results. The effect of weathering on the properties of the asphalt binders in rubberized, dry-processed PEMs and SMAs was similar to that in the wet-processed mixtures but greater than that in the control SBS.

We investigate the high temperature and separation properties of asphalt rubber (AR) added with Trans-polyoctenamer (TOR). Addition of TOR in the AR can increase effectively the G * /sin(delta) of the binders. Addition of TOR in AR can also decrease the phase angle of binders. Addition of the TOR can decrease significantly the separation of the binders. a b s t r a c t Cross-linking agent has recently been introduced into asphalt rubber (AR) as an additive, mainly with the goal of improving workability of this material. This study was performed to investigate the high temperature properties of AR when combined with Trans-polyoctenamer (TOR) at 0%, 3% and 6% of the weight of crumb rubber. High temperature properties were evaluated using the Dynamic Shear Rheometer (DSR) and the separation properties by Tubes in conjunction with DSR method. Results showed that (1) addition of TOR in the AR can effectively increase the G * /sin(delta) of the binders in both the original state as well as RTFO residue, with up to a 20% increase in G * /sin(delta) found for a dose of 6% TOR; (2) addition of TOR into AR can also decrease the phase angle of the binders in the original state as well as RTFO residue; up to a 1.8% decrease in phase angle was found for a dose of 6% TOR; (3) addition of the TOR can significantly decrease the separation of AR binders, as evaluated by DSR testing. An absolute difference in failure temperatures of 20% less than the control was found for a dose of 3% TOR in PG 67-22 asphalt. The influence of TOR on the separation of AR made with PG 64-22 asphalt was less than that of AR made with PG 67-22 asphalt. Published by Elsevier Ltd.

An investigation of the performance of asphalt binders of identical grade but varied chemistries was conducted to determine if binder performance is captured by the Superpave binder specification. The emphasis of this effort was on polymer modification of asphalt binders and their type and mode of incorporation. A single crude was used in the production of nine modified binders that included air blowing, chemical modification (e.g., polymer grafting), and polymer blending. Both plastomeric and elastomeric polymers were evaluated in this study. The materials selected represented a divergent group of modifiers that have been placed in pavements. The initial target grade was a PG 76-28. The modified asphalts came within 1ºC of the high temperature target and 2ºC of the low temperature target. Continuous grading specification values were determined on all the materials in addition to generating rheological mastercurves, and Black Diagrams. The rut resistance of mixes containing these bi...

Fatigue sensitivity of four different asphalt binders and three different asphalt mixes was evaluated in the study. Binders were subjected to Linear Amplitude Sweep (LAS) test at three temperatures of 10, 20, and 30 ∘ C. Four-point beam bending test (4PBBT) was conducted on the asphalt mixes at a temperature of 20 ∘ C for strain amplitudes varying from 200 to 1000 microstrains. Tests like retained Marshall Stability and indirect tensile strength (ITS) were also carried out to judge the mix performance. Experimental studies demonstrated that elastomeric modified binder and mixes gave the best performance in fatigue. Plastomeric modification was found to be highly strain susceptible and resulted in poor fatigue performance. The fatigue life of stone mastic asphalt (SMA) was found to be almost five times higher than the dense graded mixes. For similar strain levels, the results of LAS test could be linearly correlated with the 4PBBT results.

Wael Bekheet, Ph.D., P.Eng. Pavement Engineer Stantec Consulting 49 Frederick Street, Kitchener, Ontario, Canada, N2H 6M7 Ph: (519) 585-7465, Fx: (519) 579-6733 Email: wbekheet@stantec.com ... Stephen Goodman, M.Eng., P.Eng. Senior Pavement ...

The rheology of a variety of polyolefin resins, and resin blends, has been examined under conditions of constant strain rate elongation. These include high, low, and linear low density polyethylene, as well as polypropylene, commercially modified polypropylene, and elastomer blends with polypropylene. Two distinctly different classes of behavior are apparent in the viscosity growth patterns during uniaxial extension. Some resins display unbounded stress growth even at low strain rates. Others quickly attain a time independent value of extensional viscosity even at increased strain rates. The former behavior is identified with favorable blow molding behavior, while the latter was characteristic of resins unsuitable for such processing. The class of elongation behavior depends not only on resin type, but may be influenced by molecular weight distribution or blend morphology.

This research work focused on the investigation of the properties of asphalt binder modified with different percentages of nanoclay (NC), and nanosilica. The nanosilica was manufactured from two different sources: silica fume (NSF) and rice husk (NSH). Results showed that, NSF tends to decrease the penetration and increase the softening point temperature (SFT) and rotational viscosity (RV). However, NC content more than 3% was found to increase the penetration and decrease both RV and SFT. Using smaller percentages of NC increased both SFT and RV and decreased the penetration. Up to 3% of NSH exhibited improvement in penetration, SFT, and RV, however slight or no improvement was observed at higher contents. The Dynamic Shear Rheometer (DSR) results showed obvious improvement in the Superpave performance grade. Both NSF and NC were found to improve Marshall stability of the asphalt mixtures.