Asphalt Materials Research Articles

Dual roles played by manganese dioxide filler in asphalt pavement material: Chemical modification and healing improvement

The special physical and chemical features of manganese dioxide filler (MDF) provide feasibility for its application in asphalt pavement. At the physical level, MDF can absorb microwave energy and generate heat. The characteristic is expected to promote the induction healing capacity of asphalt concrete. At the chemical level, MDF is able to oxidize certain organic substances at high temperature. The property makes the utilization of MDF in asphalt modification possible. The research was induced to verify the application feasibility of MDF and clarify its action mechanism. Research efforts were paid on the effects of MDF on chemical composition, rheological properties and healing properties (inherent healing capacity and induction healing capacity) of asphalt materials. As results indicate, MDF changes the chemical composition of asphalt as predicted. As for rheological properties, MDF strengthens elastic characteristics and increases the high temperature stability of asphalt mastic. In contrast, MDF partially decreases the low temperature performance. Besides, MDF improves both inherent and induction healing capacities with different mechanisms. Statistical analysis implies MDF partly realizes above performance changes and healing promotion through changing chemical composition of asphalt.

Investigation on the use of reclaimed asphalt pavement along with steel fibers in concrete

Poor disposal and handling of asphalt material in construction activities has a great effect on the environment. Despite the use of asphalt material in other activities, a high percentage of it is poorly handled in Uganda. For this, the present study aimed to investigate the mechanical performance of reclaimed asphalt pavement (RAP) along with steel fibers in concrete and the variation of mechanical behavior concerning different curing times with the optimal RAP aggregate-substitute ratio. The result showed that the mechanical and physical properties of the fine and coarse aggregates used suited the replacement when compared with BS EN standard. Workability of fresh concrete is reduced as the percentage RAP increases in the mixture. This reduction was caused due to the asphalt mortar coating on the RAP aggregates, dirt particles and the irregular shape of aggregates. The compressive strength increases and decreases afterward with the increase of the percentage RAP replacement ratio. This occurred due to the presence of oils in the bitumen and weak bond between the asphalt binder coating around the RAP aggregates. When the steel fibers increase, the split strength increases along with curing time. A maximum savings of 6.13% of RAP was accomplished by incorporating 60% RAP replacement mix. For the Uganda scenario, this work serves as a guide for excess RAP application in construction activities. Using reclaimed asphalt materials provides a long-term solution for reducing the cost of materials and end-of-life materials disposal in the landfill.

A cohesive viscoelastic-elastoplastic-damage model for DEM and its applications to predict the rate- and time-dependent behaviour of asphalt concretes

Asphalt concrete is a composite heterogeneous material comprised of aggregates bonded together by bitumen binder. The mechanical behaviour of this material shows great dependence on loading rates and time (e.g., creep, relaxation). Such heterogeneity in the internal structure and complex behaviour of asphalt concrete present a challenge for numerical methods to fully capture its responses under different loading rates and durations, especially when large deformation and crack development are present in the material. This study proposes a modelling approach capable of capturing the behaviour of asphalt concrete under different loading rates and durations. In this approach, the heterogeneous internal structure of asphalt concrete is naturally reproduced by the discrete element method (DEM). In parallel, a new inter-particle contact model is developed for the DEM to describe the grain-level behaviour of asphalt concrete. This contact model couples a viscoelastic-damage law with a cohesive-elastoplastic-damage law, enabling the contact model to characterise the rate and time dependency, viscoelastic damage, and plastic-damage behaviour of asphalt concrete. Moreover, thanks to the use of DEM, the proposed approach can naturally capture crack initiation and development. Through comparisons and verifications with a wide range of experiments on asphalt concrete, including the relaxation test, creep test, and dynamic semi-circular bending test, the proposed approach shows its capability of overcoming the limitations of previous DEM models in reproducing the complex behaviours of asphalt material under various loading conditions. Insights into the failure mechanisms of asphalt material under complex loading conditions and its transitional behaviours from diffuse to localised failure can be thus naturally derived from the proposed DEM approach. This study demonstrates the effectiveness of the proposed approach for investigating the behaviour of asphalt concrete.

Application of Atomic Force Microscopy as Advanced Asphalt Testing Technology: A Comprehensive Review.

In the past three decades, researchers have engaged in the relationship between the composition, macro performance, and microstructure of asphalt. There are many research results in the use of atomic force microscopy (AFM) to study the microstructure and related mechanisms of asphalt. Based on previous studies, the performance of asphalt from its microstructure has been observed and analyzed, and different evaluation indices and modification methods have been proposed, providing guidance toward improving the performance of asphalt materials and benefiting potential applications. This review focuses on the typical application and analysis of AFM in the study of the aging regeneration and modification properties of asphalt. Additionally, this review introduces the history of the rheological and chemical testing of asphalt materials and the history of using AFM to investigate asphalt. Furthermore, this review introduces the basic principles of various modes of application of AFM in the microstructure of asphalt, providing a research direction for the further popularization and application of AFM in asphalt or other materials in the future. This review aims to provide a reference and direction for researchers to further popularize the application of AFM in asphalt and standardize the testing methods of AFM. This paper is also helpful in further exploring the relationship between the microstructure and macro performance of asphalt.

Laboratory development and evaluation of an oleylamine curing Epoxy Asphalt

ABSTRACT There are still some deficiencies in the development and applications of epoxy asphalt materials, and the chemistry and curing mechanism of epoxy asphalt materials remain unknown. Based on the curing mechanism of commercial epoxy asphalt, an oleylamine curing epoxy asphalt (OCEA) material was prepared, and it was systematically described from the perspective of engineering application and reaction mechanism. The viscosity properties of OCEA were mainly used to predict its reserved time range and temperature during construction. The tensile properties of OCEA and commercial epoxy asphalt are evaluated to show the mechanical properties. The fluorescence microscopy and infrared spectroscopy of the OCEA were analyzed to understand its micromorphology and curing mechanism, and its current advantages are further explained in combination with the tensile properties of OCEA. The results show that the OCEA has the advantage of high strength and toughness. The asphalt phase can participate in the curing reaction of epoxy resin, enhancing the miscibility between constituents, which further enhances the miscibility of the asphalt binder and epoxy resin. This study can provide new materials for engineering epoxy asphalt and implications for further research on epoxy asphalt materials.

Dry Addition of Recycled Waste Polyethylene in Asphalt Mixtures: A Laboratory Study.

The circular use of resources (i.e., reuse and recycling of materials) aiming for zero waste is also gaining increasing attention in pavement engineering. In this regard, the possible use of waste plastics in asphalt materials is of strategic importance since a considerable amount of plastic waste from construction and demolition waste and municipal solid waste is generated every year. Given this background, this experimental study aimed to investigate the feasibility of recycling waste polyethylene (PE) into asphalt mixtures. For this purpose, the dry addition of plastic shreds was evaluated to overcome the drawbacks observed in a previous interlaboratory research on PE-modified bituminous binder (i.e., instability/inhomogeneity of blend as well as the need for PE grinding). A comparative laboratory study was carried out on dense graded asphalt mixtures containing different amounts of waste plastics (i.e., 0%, 0.25%, and 1.5% by weight of the mixture). The selected asphalt mixes were investigated in terms of workability, linear visco-elastic characteristics, stiffness, strength, resistance to permanent deformation, and moisture sensitivity. Overall, the experimental findings show that the mixes prepared with the dry addition of plastic wastes were able to guarantee almost the same workability and moisture resistance as the reference material while leading to enhanced performance in terms of stiffness and permanent deformation resistance, with better responses for the higher investigated PE dosage.

Using two and three-parameter Weibull statistical model for predicting the loading rate effect on low-temperature fracture toughness of asphalt concrete with the ENDB specimen

Loading rate can affect significantly the load bearing capacity and cracking resistance of asphalt mixtures that are basically visco-elastic materials. On the other hand, the scatter of mechanical test results obtained from the asphalt mixtures (as multi ingredients and randomly distributed heterogeneous materials) would be high. Therefore, in this research the effect of loading rate on mode I fracture toughness of a fixed hot mix asphalt (HMA) mixture is investigated experimentally using several test replicates and the obtained data are analyzed using two and three parameter Weibull statistical models. The Edge Notch Disc Bend (ENDB) specimen, (that is a circular disc containing an edge crack along the diameter and loaded by three point bending) is utilized for conducting the KIc experiments under three loading rates of 0.5, 5 and 10 mm/min. For each loading rate, twenty five ENDB specimens are tested at a fixed low temperature of −12 °C and the probability of failure and Weibull distribution curves are obtained. It is shown that both two and three parameter Weibull models can be utilized successfully for predicting the mode I fracture behavior of tested asphalt material in the considered range for the loading rate. By increasing the loading rate from 0.5 to 10 mm/min, the mean KIc values and other Weibull parameters are increased. The Weibull distribution parameters obtained experimentally from the loading rates of 5 and 10 mm/min, are also predicted in terms of the Weibull parameters of the ENDB specimen tested at loading rate of 0.5 mm/min considered as a reference case.

The comparative study on the performance of bamboo fiber and sugarcane bagasse fiber as modifiers in asphalt concrete production

Highway pavement structures are expected to be adequately strong and durable for their design life which can be achieved only when the pavements are properly designed, constructed, maintained, and managed. In Ethiopia, most of the asphalt pavement is suffering from fatigue, creep, and rutting in long term. These stresses may be occurred due to the shortage in the mechanistic properties of either the binder or the asphalt mixtures as well as due to the increase in traffic loads. Failures of some roads can be attributed to the poor design of the asphalt mixes and materials being used. The properties and dosage of additive materials in hot mix asphalt affect the overall performance of pavement structure. Hence, modifying the properties of asphalt is necessary to enhance the performance of HMA. This study aims to investigate the performance of bamboo fiber and sugarcane bagasse fiber on the mechanical properties of Hot Mix Asphalt production. This research was conducted by using an experimental research design method and Non-Probability sampling techniques were adopted to collect samples. A sample preparation method of asphalt mixture specimens for asphalt mix design was performed based on AASHTO, ASTM and EN Standard specifications. The tests required were aggregate tests, a Bitumen test, Marshall test, and performance tests such Indirect Tensile Strength test and Rutting Test (RT) were conducted to evaluate a comparative study on the performance of bamboo fiber and sugarcane bagasse fiber as a modified Hot Mix Asphalt production. The preparing HMA mixes using crushed stone coarse aggregate, Fine aggregate, Mineral fillers 60/70 Bitumen, and by using bamboo and sugar cane bagasse fiber as additives were used to compare the results at a varying bitumen content of 4.5,5,5.5,6% bitumen. The Asphalt additives were used in the range from 0.2% to 0.5% of the total weight of the sample. Then, finally, the results of the laboratory were compared to standards of specifications. The optimum both fibers content obtained at 0.3% and OAC & OMF (5.2% & 4%) respectively, suggests that using both BF & SCBF fibers in asphalt concrete mixture improves the performance of asphalt pavements to resist external loads. Both fibers at 0.3% content better modify asphalt marshal stability, ITS of HMA, and Rutting resistance of AC. Finally, based on this study it was proved that the performance and properties of Asphalt concrete are affected by Fiber type and its content.

State of art review on the incorporation of fibres in asphalt pavements

This paper provides an in-depth and comprehensive review of the incorporation of fibres in asphalt pavements, focusing on the use of fibres in asphalt materials in respect to fibre classification, dosages, methods of incorporation and handling, performance evaluation, critical issues and sustainability. The type of fibre determines important properties that are crucial to the effectiveness in its incorporation into asphalt. As fibre and asphalt are two of the oldest engineering materials that are still in high demand today, this paper provides insights on the challenge and future study on the fibre-reinforced asphalt pavement. Further studies are recommended on the compatibility between fibres and asphalt mixtures, quality control of fibres in mixtures, extraction and harvesting fibres in a cost effective and sustainable manner, quantification of cost effectiveness and environmental impacts of fibre-reinforced asphalt pavements, true roadway performances with fibres deterioration in the harsh environment, as well as recyclability at its end-of-life.

Performance Evaluation and Characterization of Extracted Recycled Asphalt Binder With Rejuvenators

Rejuvenators are used in the asphalt industry to improve the performance and durability of aged binders and facilitate the use of recycled asphalt materials. The purpose of this study was to evaluate the impact of rejuvenator type and dose on the laboratory performance of asphalt binders. For this study, recycled asphalt pavement (RAP) and extracted RAP binder were obtained from an airfield reconstruction project located in Atlantic City, NJ. One petroleum-based (aromatic extract) and three organic-based (corn oil, tall oil, and modified vegetable oil) rejuvenators were evaluated in this study. Each rejuvenator was used at two different rejuvenator doses (6% and 12% by total RAP binder weight) and was aged at three different levels. Performance grade testing, frequency sweep tests, critical temperature differential (ΔTc ), and Fourier transform infrared spectroscopy (FTIR) tests were conducted. Results showed that the use of rejuvenators lowered the high and low performance grade of extracted RAP binders, in particular organic-based rejuvenators had a greater impact on the performance grade. ΔT c was also improved through the use of rejuvenators. In fact, the extracted RAP binder exceeded the high severity ΔTc threshold (−5°C), whereas the rejuvenated RAP binders improved ΔT c to values greater than the low severity threshold (−2.5°C). Similar findings were observed from the Glover-Rowe parameter as well, in which rejuvenated RAP binders improved the cracking resistance of the extracted RAP binder. When assessing the aging susceptibility, modified vegetable oil and corn oil rejuvenators showed the smallest change in performance between aging levels.

Characteristics of highly reflective and fluorescent TiO2 quantum dots modified asphalt binder

With strong absorption of solar irradiation, black asphalt material contributes to high pavement temperature, which subsequently speeds up pavement deterioration and shortens its service life. TiO2 quantum dots (QDs) as an interesting zero-dimensional nanocrystal, feature exceptional reflective and fluorescent characteristics. This study is dedicated to design and characterize highly reflective and fluorescent TiO2 QDs modified asphalt binder for cool pavement application. TiO2 QDs modified asphalt binder was prepared by incorporating TiO2 QDs into asphalt binder with varied sizes of 5–20 nm and concentrations of 5–20%. The results unveil that solar reflectance of TiO2 QDs modified asphalt binder reaches up to 15% compared to 3% of traditional asphalt binder. Meanwhile, fluorescent intensity of asphalt binder is enhanced by up to 10.9 times after adding TiO2 QDs. Additionally, as content of TiO2 QDs rises, the penetration and ductility of modified asphalt binder decrease while softening point and viscosity of modified asphalt increase. Superpave performance characterization of asphalt binder demonstrates that TiO2 QDs modified asphalt binder exhibits superior rutting resistance and inferior low-temperature cracking resistance as well as fatigue resistance than conventional asphalt binder; TiO2 QDs modified asphalt binder exhibits the same performance grade with base binder except asphalt binder with 30% TiO2 QDs. Chemical analysis has revealed that TiO2 QDs modified asphalt binder is modified through physical modification process. Moreover, it is found that the addition of TiO2 QDs imposes negligible impact on thermal properties of asphalt binder. The research outcome fastens the utilization of TiO2 QDs modified asphalt binder as a promising cool pavement technology.

Effect of fiber characteristic parameters on the high and low temperature rheological properties of basalt fiber modified asphalt mortar

Fiber has an important influence on the performance of asphalt materials. However, the effect of fiber characteristic parameters (length, type, etc.) on the function of asphalt mortar is still lack of understanding. Therefore, a systematical experimental plan was conducted to evaluate the effects of the selected parameters of filler-binder ratio, fiber type, fiber content and fiber length on the rheological properties of asphalt mortar, including five filler-binder ratios (0.6, 0.8, 1.0, 1.2 and 1.4), four fiber types (three chopped basalt fibers with different coating agents named A, B and C and one flocculent basalt fiber), five fiber contents (1%, 2%, 3%, 4% and 5%) and three fiber lengths (6 mm, 9 mm, 15 mm). Then, Dynamic Shear Rheological (DSR) tests and Bending Beam Rheological (BBR) tests were employed to evaluate the rheological behavior of each asphalt mortar. The corresponding reinforcing mechanism was subsequently analyzed by Environmental Scanning Electron Microscope (ESEM) test. The results show that basalt fiber can obviously enhance the high-temperature rheological properties of asphalt mortars, while strengthen the stress dissipating ability at low temperatures to some extent. Besides, the fiber type, fiber content and fiber length all impact the rheological properties of asphalt mortars. The asphalt mortars with type A basalt fiber present the superior rheological performance at both high and low temperature, with the optimum fiber content of 2% and fiber length of 9 mm, respectively. The test results of ESEM reveals that basalt fiber shows spatial distribution in asphalt mortar, presenting the function of stabilization and reinforcement.

Recycling Non-Metallic Powder of Waste Printed Circuit Boards to Improve the Performance of Asphalt Material.

Non-metallic fractions (NMFs) from waste printed circuit boards (PCBs) are mostly composed of cured resin and fiber. In this study, NMF material from a PCB was ground into powder and added into matrix asphalt to produce PCB-NMF-modified asphalt. To improve the compatibility of PCB-NMF and asphalt, a compatibilizer consisting of tung oil and glycerol was also developed. The optimum compatibilizer content was determined to be 8% by weight of the PCB-NMF through a series of laboratory tests, including the softening point, penetration, ductility, and softening point difference (SPD). The micro-mechanism of NMF powder-modified asphalt was analyzed through Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope test (SEM). The performances of PCB-NMF-modified asphalt were evaluated by the dynamic shear rheology (DSR) test and the low-temperature bending beam rheometer (BBR) test. The optimum compatibilizer content was 8% by weight of the NMF powder and the optimum content of NMF powder was determined to be 30% by weight of the asphalt based on a comprehensive evaluation. The results show that PCB-NMF can significantly improve stiffness, rutting resistance, high-temperature stability, and temperature sensitivity of asphalt material at an appropriate content. The BBR tests revealed that PCB-NMF slightly weakened the cracking resistance of asphalt at low temperatures. The SEM test showed that the addition of a compatibilizer can increase the compatibility by making the NMF powder evenly dispersed. The FTIR test results implied that a chemical reaction may not have happened between PCB-NMF, compatibilizer, and the matrix asphalt. Overall, it is a promising and sustainable way to utilize PCB-NMF as a modifier for asphalt material and reduce electronic waste treatment at a low cost.

Simulation of micro-crack initiation and propagation under repeated load in asphalt concrete using zero-thickness cohesive elements

The fracture resistance of asphalt materials under repeated traffic loads significantly influences the service life of asphalt pavements. The numerical simulation of asphalt materials based on a form of fracture mechanics is considered as an efficient way to model fracture damage. Unlike traditional fracture mechanics approaches assuming the existence of infinitely sharp crack tips leading to stress singularities preceding the crack tips, an alternative approach, called Cohesive Zone Modelling (CZM), is presented to model crack initiation and propagation. To make the CZM more consistent with reality and thus yield more reliable results, a heterogeneous model was developed to explicitly model the different material phases (aggregate and asphalt mastic) captured by X-ray Computed Tomography (CT) (with a resolution of 0.014 mm3). A Two-Dimensional (2D) Finite Element (FE) model was reconstructed; the model embedded zero-thickness cohesive elements both in asphalt mastic and at interfaces between mastic and aggregates, in conjunction with viscoelastic material properties. Crack paths in asphalt mixture samples at different deformation levels in the Indirect Tensile Fatigue Test (ITFT) were compared to simulation results. The 2D model was then applied to predict crack initiation and propagation at 25 ℃. It is found that high resolution X-ray CT applied on small-size samples is a suitable method to visualize detailed crack geometry of asphalt concrete and reconstruct realistic aggregate morphology for simulations. The 2D FEM developed can approximately model the whole cracking process. Based on the model, it is found that factors such as aggregate size and distance between aggregates can affect crack initiation. At 5 ℃ microcracks tend to initiate predominantly at aggregate-binder interfaces. At 25 ℃ microcracks tend to initiate and propagate within the mastic; as the microcracks propagate. At both temperatures, microcracks were observed develop continuously throughout the modelling fatigue process.

AN EXPERIMENTAL STUDY ON THE PERMANENT STRAIN OF DENSE-GRADED ASPHALT AND POROUS ASPHALT USING UNIAXIAL CYCLIC COMPRESSION TEST WITH CONFINEMENT

This study investigated the permanent strain of dense-graded asphalt and porous asphalt material using uniaxial cyclic compression test with confinement. Based on the test results, the comparison of the permanent strain was carried out. The results showed that the permanent strain resistance of porous asphalt material was better than that of the dense-graded asphalt material. In addition, the use of higher performance-graded asphalt binder improved remarkably the permanent strain resistance of porous asphalt material. The analysis of the two prediction models showed that the power model performed better in prediction of the permanent strain. In future, more studies need to be conducted to investigate the effect of other factors such as moisture, freeze/thaw cycle on the mechanical performance of the porous asphalt material.

Statewide Assessment of Balanced Mixture Design for New York State’s Asphalt Mixtures

As state agencies want greater assurance that their asphalt materials will last longer, the inclusion of performance testing during mixture design and production has gained popularity. In particular, the concept of determining the asphalt content that optimizes asphalt mixture rutting and fatigue cracking resistance, called balanced mixture design (BMD), is being explored in the U.S. In this study, the New York State Department of Transportation (NYSDOT) orchestrated a statewide evaluation of their asphalt mixtures under the BMD concept. Eleven asphalt mixtures, representing a majority of what is utilized as surface courses on New York (NY) asphalt pavements, were first volumetrically verified and then evaluated using BMD to determine the range of asphalt content where rutting and fatigue cracking resistance optimization are achieved. Three laboratory rutting tests (asphalt pavement analyzer [APA], Hamburg wheel tracking [HWT], and high temperature indirect tensile strength [HT-IDT]), and three fatigue cracking tests (overlay tester, semi-circular bending [SCB] flexibility index, and indirect tensile asphalt cracking test [IDEAL-CT] index) were utilized during the performance testing. The results showed that 6 of the 11 volumetrically designed asphalt mixtures were under-asphalted with respect to achieving minimum fatigue cracking resistance based on the laboratory tests. None of the volumetrically designed asphalt mixtures were determined to have rutting issues. The addition of polymer modification in the asphalt binders was found to increase the range of asphalt contents achieving a balanced condition. The study also showed that, when appropriate performance criteria are selected, it is possible to utilize different test methods.

Determination of SARA fractions in asphalts by mid-infrared spectroscopy and multivariate calibration

The SARA fractions in petroleum asphalts for road paving play a dominant role in the pavement performance of asphalt binders. In this study, a rapid and accurate determination method of SARA fractions in asphalts was proposed using Mid-Infrared (MIR) spectra and Partial Least Square Regression (PLSR) modeling method. Firstly, the blending and progressive aging process employed in this study successfully prepared 84 asphalt samples with fair differences in their Saturates, Aromatics, Resins and Asphaltenes (SARA) fractions. Secondly, the SARA fractions and MIR spectra of these samples were measured and collected by standard test methods, respectively. Finally, four quantitative calibration models were developed for each fraction using MIR spectra and PLSR method, and the validation results verified the high consistency between the measured values and the predicted values as well as the reproducibility and repeatability of the proposed method. This MIR-PLSR method was able to provide a faster SARA determination than the standard test methods through a single MIR spectrum. It could probably be used for the real-time quality control of asphalt production and the in-situ quality inspection of asphalt materials in road construction using portable equipment.

Evaluating the Sensitivity of Intermediate Temperature Performance Tests to Multiple Loose Mixture Aging Conditions Using the FHWA Accelerated Loading Facility’s RAP/RAS Experiment

With the advancement of Balanced Mixture Design (BMD), laboratory performance tests for asphalt materials are being assessed for their relation to cracking performance in the field. However, most BMD applications do not account for long-term aging. This gap limits the appropriateness of thresholds and the potential of BMD to improve pavement performance as more amounts of the additives and reclaimed materials available can behave in drastically different fashions between early, intermediate, and late stages of service. In this study, five mixtures with documented field performance from the Federal Highway Administration’s Accelerated Loading Facility were subjected to long-term oven aging (LTOA) protocols. In addition to reheating loose mixtures containing reclaimed asphalt pavement and shingles, the two LTOA methods were 8 h at 135°C and 3 d at 95°C. The objective of this paper is to compare aging approaches, particularly whether equivalence between long-term aged procedures exists, and to highlight the sensitivity (or lack thereof) of common laboratory mixture performance tests. The Indirect Tensile Cracking (IDEAL-CT), Illinois Flexibility Index, Asphalt Mixture Performance Tester cyclic fatigue, and dynamic modulus tests were employed. The results show a collapse in mixture cracking indices when LTOA is incorporated, raising concerns over BMD implementation using criteria established exclusively with short-term oven aging. Use of [Formula: see text] presented a universal and logic shift in response from the reheated to LTOA state, affirming utility as an aging index. Blending insights can possibly be gleaned from the data, although 95 and 135°C LTOA procedures yield mostly equivalent linear viscoelastic and cracking indices.

Influence of Type of Filler and Bitumen on the Mechanical Performance of Asphalt Mortars.

This article presents a new methodology of analysis based on a fast-running experimental procedure to characterise the mechanical response of asphalt mortars in terms of stiffness, ductility, and fatigue resistance. This was achieved using the DMA (Dynamic Mechanical Analyser) three-point bending configuration. The study was carried out by considering the employment of different types of fillers such cement and CaCO3 and different types of binders such as conventional asphalt binder (B35/50) or modifided polymer-modified bitumen (PMB 25/55–65). From the results of this study, the filler was found to have a greater influence on the stiffness and ductility of the asphalt material, while bitumen had a higher effect on the fatigue life of the asphalt mortar. Fatigue life was observed to increase with the use of a polymer-modified binder, while a lower degree of permanent deformation and higher bearing capacity achieved by the use of cement instead of calcium carbonate as active fillers.

Waste Polyethylene Terephthalate granules modified by gamma irradiation and their effect as fine aggregates on moisture damage of asphalt mixtures

Recently, the excessive quantity of waste polyethylene terephthalate (WPET) creates a significant environmental concern globally. One way to reuse WPET is in the pavement industry as secondary materials. Nevertheless, based on works of literature review on the use of WPET in asphalt materials, inconsistent findings were reported with an increase and decrease in mechanical properties. To overcome this issue, gamma radiation has been utilized on the WPET. This study investigated the effect of using non-irradiated and irradiated WPET on some engineering properties of asphalt mixes. Marshall Samples incorporating a various amount of WPET (Plastiphalt); 0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5% by weight of total aggregates were tested based on Marshall Stability (MS), indirect tensile strength (ITS), and resistance to moisture damage. The results of x-ray diffraction (XRD) on the irradiated WPET showed that the degree of crystallinity had increased. The results of Marshall Stability (MS) showed an enhancement with increasing WPET content up to 2.0% for the plastiphalt mixes. Marshall Quotient, and ITS show a decreasing trend with increasing WPET amount for the plastiphalt mixes. Furthermore, results on moisture damage resistance indicated that indirect tensile strength and Marshall Stability ratios were marginally increased for plastiphalt mixes compared to the reference mixture (0% WPET). Comparing the moisture sensitivity tolerance results for the WPET modified mixes shows that irradiated WPET plastiphalt mixes had a better outcome than non-irradiated WPET plastiphalt mixes.