Bitumen Modification Research Articles

Utjecaj recikliranog PET-a i TEOA-e na svojstva bitumena

In this study, the recycled PET is used in bitumen modification by applying a different process in order to eliminate the phase separation problem. For this purpose, modified bitumens are obtained by adding the triethanolamine (TEOA) chemical (wt. 2.5 %) and PET (wt. 2, 4, 6, 8, 10 %) to pure bitumen. The properties of modified bitumens are determined by chemical, physical, and rheological tests. According to the test results, bitumen reacts with PET, and 6 % PET ratio is a critical value. At this ratio, the resistance of bitumen to deformations at high and low temperatures increases significantly.

Preparation process and performance of thermoplastic polyurethane/amorphous poly alpha olefin compound modified bitumen

As a bitumen modifier, waste thermoplastic polyurethane (TPU) could effectively improve the intermediate and low temperature pavement performance of bitumen and increase the recycling rate of waste. However, the high temperature performance of TPU modified bitumen is insufficient, which limits the application of TPU modified bitumen in pavement engineering. The objective of this study is to improve the high temperature performance of TPU-modified bitumen by compounding amorphous poly alpha olefin (APAO). The orthogonal test of TPU/APAO modified bitumen was conducted to determine the preparation process parameters. The physical and rheological properties of TPU/APAO modified bitumen were investigated by penetration, softening point, ductility, elastic recovery, viscosity, dynamic shear rheometer (DSR, including temperature sweep and multiple stress creep recovery), and bending beam rheometer (BBR) tests. The compatibility and modification mechanism of TPU/APAO modified bitumen were studied by storage stability, fluorescence microscopy (FM), and Fourier transform infrared spectroscopy (FTIR) tests. The test results show that the optimum preparation process of TPU/APAO compound modified bitumen is 5000 rpm for 60 min at 190 °C. The addition of APAO reduces penetration and ductility, increases softening point and viscosity of TPU modified bitumen. The low temperature performance is not sacrificed with the improvement of the high temperature PG grade. Besides, the anti-aging properties and creep recovery rate of compound modified bitumen are optimal at 2% TPU and 6% APAO. The proper content of APAO can improve the compatibility between TPU and bitumen. APAO is physically mixed with bitumen, but the free isocyanate in TPU can react with the polar carboxyl group (asphaltene) and their product is closely related to the PU bond.

High‐performance atactic polypropylene modified bitumen blends fabricated via conventional, hot, and in‐situ blending techniques

AbstractThis research presents an investigation on the incorporation of atactic polypropylene (APP) as a modifier in bitumen at weight concentrations from 0 to 30 wt%. An APP‐modified bitumen (APPMB) was prepared by conventional, hot, and in situ blending and characterized for mechanical, morphological, thermal, structural, and physical properties. APPMB specimens using maleic anhydride (MA) functionalized polymer at its optimized concentration of 20 weight percentage (wt%), along at several other concentrations, were prepared using in situ and hot blending methods using an overhead stirrer mixer at a blending temperature of 160°C for 2 h. Fourier transform infrared revealed a strong interaction of APP or APP‐g‐MA with bitumen. The ultimate compressive strength, acquired in Mega Pascal (MPa) units, was increased from 0.24 MPa at 5 wt% APP to 0.70 MPa at 20 wt% APP loading. Scanning electron microscopy micrographs manifested dispersed phases of APP in bitumen due to the high temperature and shearing application with overhead stirring. In situ and hot blended specimens exhibited better mechanical, thermal, and structure–property relations. This research highlights the novelty in terms of property optimization and advancements at a high‐weight percentage of the modifier (i.e., 20 wt%) along with emphasizing the comparison of three different fabrication techniques; however, the previous research manifested the advancements in the properties of polymer and bitumen blends at low concentrations of polymers.

Engineering Properties of Palm Oil Clinker Fine-Modified Asphaltic Concrete Mixtures

Palm oil clinker (POC) is a non-biodegradable palm mill by-product typically discarded in dumpsites. This study analyzed the performance of POC powder (POCF) as bitumen modifier in terms of conventional and engineering properties of bitumen and asphalt mixture. For the study, base bitumen of 60/70 penetration grade was utilized and different POCF dosages (0, 2, 4, 6, and 8% by weight of bitumen) were added. The base bitumen was effectively modified with POCF and then characterized. The conventional and engineering properties of the modified bitumen and asphalt mixtures were assessed. From the characterization results, the formation of Si-O crystalline structure and a new Si-OH functional group was identified. Furthermore, a meandering pattern was observed due to the modification of the base bitumen with POCF. Based on the conventional test results it was revealed that the addition of POCF to the base bitumen resulted in a stiffer blend compared to unmodified bitumen. The addition of POCF improved the modified mixtures’ Marshall stability relative to the unmodified mixtures. Analysis of variance (ANOVA) and regression modeling showed the influence and significance of POCF-MB, with R2 values of (95-99%). Finally, the 4-6% POCF dosage was found to be the optimum dosage, yielding the best performance in terms of the engineering properties evaluated.

Impact of Crumb Rubber Concentration and Plastic Coated Aggregates on the Rheological Performance of Modified Bitumen Asphalt

The diminution of natural resource exploration, the retrieval of waste, and the structural modification of polymers by additives are the main contributions to sustainable development. The properties of bitumen are enhanced by the crumb rubber through effective bitumen modification techniques, which have environmental and economic advantages. In this study, plastic waste, plastic-coated aggregate (PCA), and bitumen were blended in order to enhance the engineering properties of the flexible pavement. In order to compute the composition of crumb rubber modified bitumen (CRMB), the adopted materials were subjected to the relevant experiments. PCA was a very effective material when compared to the standard bitumen road pavement. The recycling of waste crumb rubber and plastic was tested by adding them into the hot mix asphalt. The Marshall properties of standard (virgin) bituminous mix, CRMB grade 55, and plastic mix asphalt were studied in detail to explore the solutions for a sustainable environment. The comparison was performed between these two materials with the standard bitumen, which resulted in the CRMB and plastics being found as the most effective additions with robust properties such as low-cost material, high strength, long life usage, and un-harmful to nature. The optimal bitumen content was found to be 6.166%, 6.1%, and 5.833% for standard bitumen, crumb rubber modified bitumen, and plastic-coated aggregate, respectively.

Selection of recycled waste plastic for incorporation in sustainable asphalt pavements: A novel multi-criteria screening tool based on 31 sources of plastic

This study investigated the suitability of 31 recycled waste plastic samples obtained from 15 major recycling companies across Australia and New Zealand to be used as bitumen/asphalt modifiers. The plastics have been selected to be representative of recycled waste plastic around Australia and New Zealand. The recycled waste plastics belonged to either the post-industrial or post-consumer collection scheme. A new classification scheme was developed to rank each recycled waste plastic based on their chemical and physical properties against those of bitumen/asphalt. Specifically, density, polarity, melting point, solubility and melt flow index of the samples as well as the presence of contaminants, fillers and additives were analyzed for each recycled waste plastic material and their virgin counterpart. These 8 properties were used to rank various sources of recycled low-density poly(ethylene), linear low-density poly(ethylene), high density poly(ethylene) and poly(propylene) in addition to commingled plastics based on their suitability for bitumen modification (wet method). The modification of asphalt via replacement of virgin quarry aggregate with plastic aggregate (dry method) by recycled acrylonitrile butadiene styrene and poly(ethylene terephthalate) was also assessed by considering four criteria of purity, polarity, recycling contamination and hazardous additives. This new multi-criterion ranking approach revealed that low-density and linear low-density poly(ethylene) and acrylonitrile butadiene styrene and poly(ethylene terephthalate) should be preferentially used as bitumen/asphalt modifiers. This tool has been developed for recycling companies and bitumen/asphalt contractors to determine the suitability of recycled waste plastics within asphalt roads by a series of experimental techniques.

Effect of maleic anhydride grafted and gamma-irradiated waste polypropylene on rheological properties of asphalt binder

ABSTRACT Waste polymers have been employed as a modifier in bitumen to improve the performance of the binders and reduce plastic pollution. Grafting of maleic anhydride (MA) is a method to increase the chemical and physical consistency between the polymer and binder. In this study, maleic anhydride grafted waste polypropylene was employed as a bitumen modifier. Gamma irradiation is applied to waste polypropylene to improve the compatibility. The effects of MA-grafted irradiated waste polypropylene (PP-γ-MA) on physical and rheological properties of bitumen were investigated through a test program. Storage stability tests signifies that the gamma irradiation could diminish the phase separation between the modifier and bitumen. The thermorheological tests showed employing PP-γ-MA improves the high temperature performance, whilst it has a slightly adverse effect on low temperature performance of bitumen. The results of multiple stress creep recovery (MSCR) test indicate that PP-γ-MA reduces the non-recoverable deformation and enhanced elastic recovery of the material, whereas the linear amplitude sweep (LAS) test result signifies PP-γ-MA improved the fatigue life of asphalt by increasing fatigue damage resistance under different strain levels. The rheological test results emphasised on the usability of PP-γ-MA as a modifier in binders.

Rheological analysis of bitumen modified by reclaim rubber pyrolytic oil residue

Heavy fraction pyrolytic oil of waste tire reclaim rubber vacuum pyrolysed at 600 °C (HR6) was produced. Then, it was considered as a rheological modifier for road bitumen. Addition of HR6 to bitumen was increased penetration and decreased softening point. Rutting temperature and temperature susceptibility of bitumen was improved using this rheological modifier. The bitumen containing 5% of HR6 showed optimum level in comparison to different concentration was used. Ductility of modified bitumen has significantly increased. Rheological behavior of modified samples was studied through static and dynamic tests, which showed good improvement in complex viscosity, modulus and damping factor; respectively. Very good low temperature flexibility observed by bending beam rheometer (BBR) test proposing flexible behavior in winter. Moreover, the aging by rolling thin film oven (RTFO) and storage stability was studied and reported.

Thermal ageing behaviour of isocyanate-based bitumen additive

Asphalt modification has been a good way to improve and prepare pavements to bear increasing traffic loads and temperatures; however, it is important that the additives used have a positive impact throughout the entire life cycle of the pavement. Since the performance enhancing capabilities of isocyanate-bitumen modification have already been documented, in this study, the focus lies on the ageing behaviour of this novel additive from a chemo-mechanical perspective. The chemical oxidative ageing was studied using infrared spectroscopy (ATR-FTIR), while the mechanical/rheological ageing, on the other hand, was studied using different tests performed with the dynamic shear rheometer (DSR), such as BTSV, frequency-temperature sweeps and cryogenic stress tests. Five different samples of unmodified, isocyanate-modified and SBS-modified bitumen were submitted to standard and extended laboratory short and long-term thermal ageing, respectively. Since the isocyanate-based bitumen modification has shown to enable warm-mix asphalt production, one variant was subjected to a short-term ageing at a lower temperature to consider this aspect. From a chemical perspective, the ATR-FTIR measurements show that the isocyanate-modified bitumen produced a higher chemical ageing after short-term thermal ageing compared to the SBS modification. However, on the long-term, this effect disappears. On a rheological level, the different methods used suggest that the mechanical ageing of the isocyanate-modification is comparable to the SBS modification. Moreover, a lower short-term ageing temperature appears to have a benefit on the chemical ageing but not on the mechanical/rheological ageing.

The Effects of Iraq Natural Asphalt on Mechanical Properties of Bituminous Hot Mixtures

The increasing rate of traffic every day requires the roads to be made more stable. In order to improve the low and high temperature properties of the bituminous mixtures forming the coating layer of the flexible pavements, the binder in the mixture is often modified with various polymers. The most commonly used polymer in the modification is styrene-butadiene-styrene (SBS). However, SBS, which is very successful in improving the mechanical properties of the mixtures, is expensive and has brought the search for cheaper alternative additives. In this context, natural asphalts (NA) which are not subjected to any processes are used as additive. In this study, natural asphalt obtained from Zaho region of Iraq was used in 20%, 35% and 50% of bitumen modification by weight. The mechanical properties of mixtures prepared with different amount of NA modified bitumen were compared with 4% SBS modified bituminous mixtures. As a result, NA modification significantly improved the properties of bituminous mixtures. In particular, above 35% NA, the mixtures exhibited a superior performance by significantly resisting the effect of repeated loads. It was found that an average of 17.3% NA modification exhibited similar behavior with 4% SBS modification and provided significant economic savings.

The Effect of Additives on Water Vapor Condensation on Bituminous Surfaces

Abstract Water condensation and freezing on asphalt roads can lead to slippery conditions, which are responsible for many winter accidents and have caused an overreliance on mostly environmentally damaging and pavement degrading deicing chemicals and salt, which requires active maintenance. Bitumen is a mechanically and chemically complex material mainly consisting of various hydrocarbon-based chemicals groups. Additionally, bitumen makes up approximately 5 wt.% of the asphalt concrete mixture because of its binder role and coating function of the aggregates, can control the bulk mechanical properties and surface properties of the asphalt mixture. Condensation as the first step and later freezing phenomena are investigated in this study and from ambient humidity toward understanding the fundamentals of icing on bituminous surfaces. Condensation experimental results show selective wettability of chemically and mechanically district bitumen surface domains. The effect of different bitumen modifiers of polyethylene terephthalate, polyamide (PA 66), polyacrylonitrile, and Sasobit wax at 1 wt.% were studied on condensation freezing and bitumen water affinity.

DEVELOPMENT EXPERIENCE FOR PRODUCTION OF WATER PROOF BITUMEN- POLYMER MATERIALS WHERE THE MIXTURES OF RECYCLED POLYMER WERE USED

Modification of bitumen with polymers is one of the most common ways to improve their properties and costliness. The article is devoted to the investigation of the effect which is achieved by the secondary polymers and their mixtures on the properties of petroleum bitumen. Bitumen-polymer composite materials with improved physical and mechanical properties and technical and economic indicators have been developed. The softening temperature of the developed bitumen-polymer compositions and their adhesion to concrete were investigated taking into account the type of polymer additive. The research has shown that if petroleum bitumen of recycled polymers has been used, mechanical characteristics and thermal integrity get better. It influences directly on the price of bitumen-polymer materials, because it reduces. Several characteristics of the material get higher when the recycled polymers are used.

Aging Characteristics of Rubber Modified Bitumen Mixed with Sulfur after Terminal Blend Process

The influence of sulfur on the chemical, rheological, and aging resistance of terminal blend rubberized bitumen (TBRB) was studied. TB hybrid bitumen (TBHB) was prepared from with different sulfur contents (0.1, 0.2, 0.3, 0.4 wt%) and TBRB prepared with neat bitumen and crumb rubbers at 20% content. TBHB binders were aged by rolling thin film oven test (RTFOT) and pressure aging vessel (PAV), respectively. The chemical composition of TBHB binders was monitored by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Rheological properties of all TBHB samples were tested. Chemical composition results show that TBHB can inhibit the degradation of polybutadiene compared with TBRB in the RTFOT stage, and the polybutadiene degradation is the main process of TBHB in the RTFOT stage, while the TBHB is mainly desulfurized after PAV aging. Meanwhile, the increase in sulfur content in the TBHB can improve the desulfurization degree of the TBHB binder after PAV. TBRB containing sulfur can improve the mechanical properties and elasticity and reduce the hardening degree during aging. Moreover, blending sulfur into the TBRB caused a lower complex modulus aging index after aging, which indicates that TBHB has superior aging resistance.

A Temperature-Independent Methodology for Polymer Bitumen Modification Evaluation Based on DSR Measurement.

Owing to the continuous increase of traffic loads, bitumen modification has been manifested as an efficient methodology to enhance asphaltic pavement performance. Currently, the modification index, defined as the ratio of mechanical properties (e.g., complex modulus) before and after bitumen modification, is extensively adopted to evaluate the modification degree. However, bituminous materials behave as temperature-dependent, which indicates that the mechanical property varies with measured temperatures. As a result, the calculated modification index also shows temperature-dependent property, which inhibits the use of modification index. For this reason, this study introduced a method to eliminate the temperature-dependency of the modification index. In specific, a mathematical model considering the properties of modifiers was firstly established to predict the modification index-temperature curve (MI-T curve). In what follows, the temperature-dependency of modification index was analyzed to verify the proposed model on three types of modifiers, which were graphene, Styrene-Butadiene-Styrene (SBS), and Ethyl-Vinyl-Acetate (EVA), respectively. The results indicated that the developed model could efficiently predict the MI-T curves. Besides, the effective modification area (EMA) and optimal modification index (OMI) were two reasonable indicators that evaluate the bitumen modification without considering the temperature-dependency.

Effect of Different Types of "Dry Way" Additions in Porous Asphalt Mixtures.

Polymers are widely used to improve the mechanical performance of asphalt mixtures. Among them, styrene butadiene styrene (SBS) is the most commonly used, especially in the wet modification of virgin bitumen. This method, which is extensively utilized, has several advantages, but also some disadvantages, concerning its performance (such as the risk of instability or a lack of homogeneity) and logistical management (such as the need for special equipment, the transport of materials, and the dependence on the refinery that modifies the bitumen). This paper analyses the use of the most conventional types of polymers (two types of SBS, one type of BS, and rubber from end-of-life tires), dry added, as an alternative method. They have been used in porous asphalt mixtures. This type of bituminous mixture is usually designed with commercial polymer-modified bitumen, due to the mechanical requirements, and it is very sensitive to the properties of the binder used. The mechanical behavior of experimental porous asphalt mixtures has been significantly improved, especially in the case of SBS, although the performance did not reach that of commercial polymer-modified bitumen. The results have shown that the dry method is a suitable and feasible option to manufacture modified mixtures, especially considering its advantages, from a logistical viewpoint, in comparison with the wet method.

Research on the Rheological Properties of Asphalt Binder Modified by Fume Silica and Crumb Rubber Compound

This study investigates the effect of using Fume Silica (Aerosol 300) alone and together with crumb rubber (CR) in bitumen modification on the traditional and rheological properties of the binder and compares it to the SBS modified binder. Using the aerosol additive in the binder at the rates of 0.5%, 1%, 1.5%, and 2% were determined as the most convenient ratio and CR+aerosol modified binders were prepared per this ratio. The binders were subjected to the softening point, viscosity, frequency sweep, bending beam rheometer (BBR), and Fourier Transform Infrared spectroscopy (FTIR) tests in the context of the study. Besides, the optimum conditions were determined according to the response functions by designing an experiment with statistical regression according to the Response surface methodology (RSM). The results indicate that the optimum aerosol ratio is 1.5%. With the use of 1.5% aerosol in 6% CR modification per bitumen weight, it was found that (1) the softening point increases and the temperature sensitivity decrease in comparison to other binders, (2) the consistency of the binder increases, (3) the complex modulus values increase and become more resistant to rutting, (4) the low-temperature parameters enhance by performing more flexible behavior, (5) there may be physical changes in the structure even though there is no chemical reaction in the binder with the use of CR and aerosol additives, and (6) the experimental data and theoretical data obtained from the RSM method are consistent as per the statistical analysis.

Harmless treatment and environmentally friendly application of waste tires—TPCB/TPO composite-modified bitumen

Waste tires are produced in large quantities and cause serious pollution. Moreover, it is challenging to dispose of waste tires safely. Pyrolysis treatment is an economic, environmentally friendly, and high-recovery-efficiency solution, but the recycling applications of pyrolysis products, such as pyrolysis carbon black (TPCB) and pyrolysis oil (TPO), have not been widely studied. In this study, TPO and TPCB were applied to composite-modify 70# base bitumen. The modification mechanism of TPO/TPCB-modified bitumen (TPO/TPCB-MB) was studied by Fourier transform infrared spectrometry (FTIR), gel-permeation chromatography (GPC), X-Ray diffraction (XRD), and scanning electron microscopy (SEM). The physical performance and rheological performance of the bitumen with and without TPO/TPCB were investigated to determine the design and preparation parameters of TPO/TPCB-MB and investigate TPO/TPCB’s effects on the technical performance of bitumen. In addition, the road performance of TPO/TPCB-MB concrete was extensively studied. In the results, no large agglomeration phenomenon was observed between the TPCB particles. Furthermore, the molecular weight of TPO was much lower than that of 70# bitumen, indicating that TPO can increase the light components of bitumen. TPCB and TPO mixed with the bitumen in a physical manner, and the multi-layer spacing of TPCB remained basically unchanged. The TPO/TPCB was also shown to have good thermal and structural stability. TPO and TPCB, moreover, provided component balance and powder hardening effects in the TPO/TPCB-MB. No significant difference was observed between the technical performance of the 70# bitumen and the 0.9% TPO + 15% TPCB-MB. The water stability, low-temperature, and anti-fatigue performance of the TPO/TPCB-MB mixture was significantly better than that of the 70# bituminous mixture. Meanwhile, the high-temperature performance showed no obvious difference. Therefore, TPO was found to balance TPCB’s oppositive effect on the performance of bitumen and its mixture. The composite modification of bitumen with TPCB and TPO thus represents a harmless treatment and alternative use for waste tires.

Comparison of Response Surface Methodology and Artificial Neural Network approach in predicting the performance and properties of palm oil clinker fine modified asphalt mixtures

Recently with the increase in traffic loading, the traditional materials used for road construction deteriorate at a faster rate due to repetitive traffic loading which greatly necessitates bitumen modification to improve its quality. Amid an ever-increasing waste generation and disposal crisis, researchers came up with multiple ideas, however, the implementation was halted due to different practitioners' policies. Palm oil clinker (POC) waste is a prevalent waste dumped around the oil palm mill that pollutes the environment. To harness sustainability, this study utilizes varying dosages of POC fine (POCF) at 2%, 4%, 6%, and 8% to produce the POCF modified bitumen (POCF-MB). Also, the conventional and microstructure properties were evaluated. The objective of this study is to utilize response surface methodology (RSM) and artificial neural networks (ANN) to optimize and predict the stiffness modulus and rutting characteristic of asphalt mixtures prepared with POCF modified bitumen (POCF-MB). The conventional test results revealed that the incorporation of POCF improves the plain bitumen properties with enhanced stiffness and temperature susceptibility. Microstructural analysis highlighted that a new functional group Si-OH was formed because of the crystalline structure of Si-O that indicates bitumen properties enhancement with POCF inclusion. Two input and output variables were considered which are POCF dosage, test temperature, and stiffness modulus and rutting depth respectively. Results showed that all mixtures containing POCF-MB show better performance than the control mixture. Though, 6% POCF dosage shows improved performance compared to other mixtures increasing stiffness by 33.33% and 57.42% respectively at 25 °C and 40 °C, while rutting at 45 °C shows increased resistance by 25.91%. For both approaches, there was a high degree of agreement between the model-predicted values and actual. For the model statistical performance index, the RSM indicates that R2 for stiffness and rutting response were (99.700 and 99.668), RMSE (266.091 and 0.597), and MRE (68.793 and 3.841) respectively. The ANN R2 for stiffness and rutting response were (99.972 and 99.880), RMSE (61.605 and 0.280), and MRE (12.093 and 2.044) respectively. The ANN use 70% data for training, 15% data for testing, and 15% data for validation processes. The ANN model outperforms the RSM model for the prediction of POCF-MB asphalt mixtures' stiffness modulus and rutting properties.

Influence of zinc oxide/expanded vermiculite composite on the rheological and anti-aging properties of bitumen

The bitumen modifier, zinc oxide (ZnO)/expanded vermiculite (EVMT) composite (ZnO/EVMT), was introduced into the bitumen with a dosage of 4%, 5%, and 6%. The surface morphology of EVMT and ZnO/EVMT was characterized by a field emission scanning microscope (FESEM). Further, the Superpave continuous grade of bitumen containing different amounts of ZnO/EVMT was determined by the dynamic shear rheometer (DSR) test and bending beam rheometer (BBR) test. The bitumen samples were aged by thin film oven test (TFOT), pressure aging vessel (PAV) aging test and ultraviolet (UV) aging test, and the influence of different amounts of ZnO/EVMT on both physical and rheological properties of the bitumen before and after aging were investigated. Moreover, the influence of ZnO/EVMT on the molecular distribution during aging was investigated by analyzing the change in the proportion of large molecular size (LMS) obtained from gel permeation chromatography (GPC). The FESEM result shows the ZnO particles are uniformly supported on the EVMT surface. Moreover, ZnO/EVMT slightly influences the high-temperature performance and improves the low-temperature cracking resistance of bitumen. In addition, no matter what aging method is adopted, ZnO/EVMT effectively increases the retained penetration and phase angle aging index, and decreases the viscosity aging index and complex modulus aging index of the bitumen, demonstrating the effectiveness of ZnO/EVMT in both resisting the thermo- and photo-oxidative aging of bitumen. Meanwhile, 6% and 4% ZnO/EVMT exhibit the best inhibitory effect on thermo- and photo-oxidative aging of bitumen, respectively. According to the GPC results, the composite inhibits the transformation of small molecules to large molecules during aging, resulting in a lower LMS increment and better anti-aging properties of the modified bitumen.

Influence of Mixing Conditions of Modified Bitumen on Moisture Sensitivity of Asphalt Compounds

Modification of bitumen allows an improving the properties of bitumen, which can be a useful technique to enhance asphalt’s characteristics. Therefore, this research intended to study the effect of mixing time of different percentages of epoxy resin, between 0 to 8%, doped into bitumens on the moisture sensitivity of asphalt compounds containing two types of aggregates, i.e. limestone and siliceous. For this aim, the Sessile Drop Method (SDM) was employed, and moisture resistant parameters associated to surface free energy concept such as surface free energy components, work of cohesion, work of adhesion, work of debonding, adhesion bitumen to aggregate, and wetting bitumen around aggregate surface were assessed. The results revealed that the effect of the mixing time of bitumen and epoxy resin on moisture resistance properties of asphalt compounds significantly depends on the percentage of epoxy resin used in bitumen mixture. For bitumens with 4 and 6% epoxy resin, adhesion and wetting parameters had a similar performance for both mixing times of 10 and 60 minutes. However, asphalt compounds containing 2 and 8% epoxy resin modified bitumens prepared for 10 min mixing time had a better adhesion and wetting performance than those prepared for the longer mixing time, 60 minutes. The effect of mixing time of bitumen modified with epoxy resin on the bitumen and asphalt compound’ performance depend on the percent of additive in the bitumen.