Warm Mix Asphalt Additives Research Articles

Effect of moisture in aggregate on adhesive properties of warm-mix asphalt

Warm-mix asphalt (WMA) is one technology that has been found to have potential in minimizing the environmental harm caused by road construction activities. Its low mixing and compacting temperatures have opened great opportunities for more sustainable development. However, because WMA is mixed at low temperatures, the drying process of the aggregate may fail to dry the WMA completely. The binder-aggregate adhesion property can be damaged by moisture remaining from incomplete drying. The present study investigated the effects of aggregate moisture on the binder-aggregate interfacial characteristics of WMA by evaluating its surface free energy and adhesive bond strength. The results showed that for the Pen 60-70 binder type, the aggregate AG in general showed the higher bond energy and aggregate SD showed the lowest bond energy among three aggregate types. Also, the bond energy diminishes with increasing aggregate moisture contents but the percent drops in bond energy is less when WMA additives was included. For the PM binder, SL aggregate group showed the highest bond energy and SD aggregate group showed the lowest bond energy. For the work of adhesion, the results showed that with aggregate with 10% moisture contents has destructive effects on the work of adhesion which may decrease to 50% compare to dry aggregate condition. Finally, the four quadrant diagrams can be used to combine two distinct property of the bond energy and the work of adhesion as the hybrid performance indicator to rank the effect of moist aggregate to the adhesion properties at binder-aggregate interface.

Permanent Deformation Characteristics of Warm Asphalt Binders under Reduced Aging Conditions

Warm Mix Asphalt (WMA) technologies allow a 20 to 40°C reduction in production temperatures of asphalt mixes. These technologies are often synergistically combined with modified asphalt binders to tackle the increased production temperature requirements with these binders. Because of lower production temperatures, the asphalt binders containing WMA additives undergo reduced short-term aging and thus need to be examined for permanent deformation behavior at different reductions in production temperatures. The present study evaluates permanent deformation characteristics of warm asphalt binders as function of short-term aging temperature, modified binder type, and various dosages of a wax-based WMA additive: Sasobit. Experimental variables included are: three short-term aging temperatures (163°C, 143°C, and 123°C), two modified asphalt binders (polymer, and crumb rubber modified), and three contents of WMA additive (1%, 2%, and 3%). Warm binders as well as control binders are characterized in terms of viscosity, failure temperature, temperature sweep, frequency sweep, and multiple stress creep and recovery tests. WMA additive compensates the reduced stiffness of binders on being aged at lower temperatures, as rheological parameters of warm binders aged at 143°C and 123°C compare well with control binders. Statistical models for the rheological parameters as function of the experimental variables are also developed.

Impacts of WMA Additives on Viscosity and Cracking of Asphalt Binder

Abstract The basic concept of warm mix asphalt (WMA) technologies is to reduce the asphalt binder viscosity, which allows the asphalt to attain a suitable viscosity to coat the aggregates and thus to compact asphalt mixtures at lower temperatures. A main concern for adding WMA additives to asphalt is that it might reduce the rutting resistance at high temperatures and the cracking resistance at low temperatures. To address these concerns, this article presents the impacts of various amounts of WMA additives on the viscosity and low-temperature cracking of asphalt binder. The test results at 135°C show that the viscosity of asphalt reduced significantly when 0.5 % of Additive B was added; the viscosity did not decrease when up to 1.0 % of Additive A was added. When the temperature was lowered to 120°C, however, a more drastic reduction in viscosity was observed when just 0.5 % of additives were added, and the viscosity remained relatively steady as the dosage was increased up to 3.0 %. These viscosity test results confirm that the higher amounts of WMA additives do not necessarily reduce the viscosity of asphalt binder. To characterize the low temperature property of the asphalt binder, the asphalt binder with WMA additives were tested using the asphalt binder cracking device (ABCD). As the WMA additives were increased from 0.5 % to 3.0 %, the cracking temperature increased slightly but remained steady near the cracking temperature of the virgin asphalt binder. The ABCD test results confirm that the cracking temperature of asphalt binder is not significantly affected by WMA additives.

An investigation into the impact of warm mix asphalt additives on asphalt mixture phases through a nano-mechanical approach

This paper presents the results of a novel investigation to evaluate the effect of Sasobit, Rediset WMX and Rediset LQ on the mechanical properties of asphalt mixture phases, aggregate, interfacial transition zone (ITZ) and mastic using Nanoindentation. All warm additives improved the nano-mechanical properties of the ITZ if the reduction in the production temperature was not more than 10 °C for an asphalt mixture with the 40/60 hard binder and 20 °C with the 100/150 binder. The nano-mechanical properties of mastic for all WMAs manufactured at 20 °C lower than the control using 40/60 mix were less than the control mix. However, as the reduction in the production temperature decreased to 10 °C, the modulus and hardness of the mastic and ITZ for all WMAs significantly increased. While, 20 °C reduction in the production temperatures was achieved using 100/150 with inclusion of warm additives and the values of nano-mechanical properties of ITZ and mastic was same or even higher than the control mix. It can therefore be concluded that, in order to produce a warm asphalt mixture that performs the same or even better than the traditional HMA, the effect of production temperature must be addressed. In summary, Nanoindentation provides new insight about the effect of warm additives on the nano-mechanical properties of asphalt mixture phases and predicts level of bonding between aggregate and binder.

Case Study: Evaluation of the Effect of Extraction Temperature on WMA Binder Containing Sasobit Additive

Abstract The current experimental methods for the extraction and recovery of asphalt binder from asphalt mixtures were designed for hot mix asphalt (HMA); however, it was not ascertained whether or not these methods could also be used for warm mix asphalt (WMA). There are concerns about the inability of current methods to fully extract and recover WMA additives from WMA mixtures, such as Sasobit wax, that can crystallize at room. Therefore, this study investigated the effectiveness of current HMA binder extraction methods for WMAs containing Sasobit additive. An experimental program was designed to evaluate the effect of extraction temperature. The loose mixes for HMA and Sasobit were prepared and subjected to three different aging levels (2 hours, 15 hours, and 5 days) and were extracted at an intermediate temperature (25°C) and an elevated temperature (80°C), respectively. Sasobit can be extracted at 80°C, which was confirmed by the results from the rheological properties test (performance grading, multiple stress creep and recovery test, and frequency sweep test) and a chemical analysis test (Fourier transform infrared spectroscopy test) for the HMA- and Sasobit-extracted binders. Four field Sasobit WMA projects further verified the feasibility of an 80°C extraction temperature for the Sasobit binder. It was also found in this study that the effect of Sasobit on the base binders became less significant after it was subjected to long-term aging in the field.

Fatigue Resistance Characterization of Warm Asphalt Rubber by Multiple Approaches

Warm asphalt rubber (WAR) mixture is a sustainable paving material with advantages including waste recycling and noise reducing. A comprehensive understanding of the fatigue performance of WAR specimens is helpful to its wide application. However, research on evaluating the fatigue performance of WAR binder and mixtures is very limited. This paper applies five fatigue analysis approaches to evaluate the fatigue life of WAR samples with three different warm mix asphalt (WMA) additives. The conventional G*sinδ, linear amplitude sweep (LAS), indirect tensile fatigue test (ITFT), and four-point bending beam (4PB) test were conducted based on available standards. In addition, a novel shear fatigue test was performed on WAR mortars. Test results indicated that the incorporation of crumb rubber has a significantly positive effect on fatigue resistance. WAR with chemical and foaming additives exhibited a poorer performance than asphalt rubber (AR), but their fatigue performance was still greatly superior to the non-rubberized samples. Finally, LAS as well as mortar shear fatigue and 4PB tests provided the same prediction of fatigue resistance, while the results of G*sinδ and the ITFT were inconsistent. It is recommended to use LAS, the mortar shear fatigue test, and the 4PB test for the fatigue resistance evaluation of rubberized specimens. The validation of the findings with more materials and field performances is recommended.

Effect of short-term ageing on high-temperature performance of SBS modified binder containing warm mix asphalt additives

Warm Mix Asphalt (WMA) additives have been utilised to reduce working temperatures of Styrene-Butadiene-Styrene modified (SBS) binder to make sustainable pavement with enhanced pavement performance and lower energy consumption. Such modification may change the physicochemical structure of SBS binder and can influence rheological properties. The present study aimed at investigating the effect of short-term ageing on SBS binder containing various types of WMA additives. The experimental design included SBS binder, three WMA additives (Fischer Tropsch wax based- FT, chemical surfactant based- CS and water-based- WB) in three different dosages. The SBS binder was modified with mentioned WMA additives using a high shear mixer. In such way, 10 asphalt binders (one SBS binder and nine WMA modified SBS binders) were prepared. The short-term ageing of asphalt binders was performed using thin film oven. The high-temperature performance of unaged and short-term aged binders was evaluated using Superpave rutting parameter, high temperature performance grade (PG), multiple stress creep and recovery test (MSCR), and frequency sweep test. Based on the results, the short-term ageing showed an adverse effect on high-temperature performance of SBS binder, indicating degradation of SBS binder. Also, WMA additive type and dosages showed a significant effect on SBS binder in unaged and short-term aged condition. Considering the combined effect of WMA additive and short-term ageing, FT and WB additives reduced ageing susceptibility as well as improved rutting resistance of SBS binder. On the other hand, CS modification was able to lower ageing susceptibility, however, degraded high-temperature performance of SBS binder. Based on optimal high-temperature performance and lower ageing susceptibility, SBS binder can be modified with an effective dosage of 1% FT, 6% WB and 1% CS additive (by weight of asphalt binder).

Fatigue characterisation of modified asphalt binders containing warm mix asphalt additives

Fatigue is one of the major distresses in asphalt pavements and is strongly influenced by the properties of asphalt binder. Use of warm mix asphalt (WMA) additives allows production of asphalt mixes at lower temperatures than conventional hot mix asphalt. Lower production temperatures reduce the oxidative ageing of binders and thus addition of WMA additives may significantly impact fatigue performance of the binders and the mixes. The existing Superpave specifications prescribe the parameter G*sin δ as an indicator for fatigue behaviour of asphalt binder. In view of critical weaknesses associated with G*sin δ, several test procedures have been proposed for evaluating the fatigue performance of asphalt binder. The current study investigated fatigue characteristics of two modified binders (polymer- and crumb rubber-modified, PMB and CRMB) containing different dosages of two WMA additives: an organic additive, and a chemical additive. A total of twelve binders including ten warm asphalt binders and two control binders were studied. Five binder fatigue test procedures were employed in the study: Superpave fatigue parameter G*sin δ, linear amplitude sweep (LAS) test, DSR-based elastic recovery (DSR-ER) test, elastic recovery from MSCR (MSCR-ER) test, and binder yield energy test (BYET). Additionally, mixes were prepared and evaluated for fatigue using indirect tensile fatigue test. Results of the study showed that PMB and CRMB binders containing the chemical additive performed better in fatigue than the control binders and the binders containing the organic additive. The trends of mix fatigue life corroborated the binder fatigue results. Further, the results showed that monotonic test procedures (DSR-ER and BYET) produced the best correlations with mix fatigue results.

Rheological Behavior and Its Chemical Interpretation of Crumb Rubber Modified Asphalt Containing Warm-Mix Additives

The microstructure and chemical composition of asphalt binders have a significant effect on their rheological properties and, therefore, their performance as road paving binders. This study aims to investigate the effects of warm-mix asphalt (WMA) additives, organic type and chemical type, on the rheological properties and chemical internal structure of base asphalt and crumb rubber modified asphalt (CRMA). A set of dynamic shear rheometer (DSR) tests was conducted to obtain the rheological parameters (e.g., complex viscosity, complex modulus, phase angle) of asphalt binders. The flow activation energy was calculated from Arrhenius equation based on viscosity data to rank the thermal susceptibility. Black diagrams and master curves of complex modulus and phase angle were utilized to analyze the rheological properties. The molecular weight distributions of asphalt binders were inverted from the phase angle master curve to evaluate the molecular weight characteristics. It was found that the the addition of crumb rubber into base asphalt improves the rheological properties of enhanced modulus and elasticity. Organic and chemical types of WMA additives have different chemo-physical effects on both base asphalt and CRMA. Phase angle inversion method provides a powerful tool to monitor the molecular structure change and, therefore, the chemo-physical interactions of asphalt binders induced by modifications. Finally, there is a good correlation between flow activation energy and molecular weight.

Evaluation of intermediate temperature cracking performance of warm mix additive modified asphalt binders

In the present study, intermediate temperature cracking performance of different types of asphalt binders containing warm mix asphalt (WMA) additives was evaluated using three test methods namely, Superpave fatigue parameter, linear amplitude sweep (LAS) and double edge notch test (DENT). The Superpave fatigue, LAS, and DENT tests are based on dissipated energy, viscoelastic continuum damage (VECD) and work of fracture approaches, respectively, and thus each of the tests may result into different performance ranking of asphalt binders. The outcome of the Superpave fatigue, LAS and DENT tests are G∗sinδ, number of cycles to fatigue failure (Nf), and critical tip opening displacement (CTOD) based on which cracking potential of asphalt binder can be assessed. An asphalt binder having a low Superpave parameter, high Nf and high CTOD values are expected to have better intermediate temperatures cracking performance. The present study selected three control binders namely virgin (AC), styrene-butadienestyrene (SBS) and crumb rubber modified (CRM) binders were modified using three WMA additives namely Fischer-tropsch (FT) wax based, chemical surfactant (CS) based and water based (WB). Control binders were modified with 2%, 6% and 2% (by weight of asphalt binder) of FT, WB and CS, respectively, using a mixer. The results showed that, based on G∗sinδ and CTOD parameters, CS modification reduced stiffness (reduced G∗sinδ) and improved ductile performance (increased CTOD) of control binders. However, WB and FT modification increased stiffness and degraded the ductile performance of control binders, except for SBS with 6%WB binder which showed higher CTOD than control SBS binder. On the other hand, considering performance based on Nf parameter, WMA additive modification improved fatigue life of control binders, except for SBS with 2%CS binder which showed lower Nf as compared to control SBS binder. Control binders with and without WMA additives were ranked based on G∗sinδ, Nf and CTOD parameters. AC and CRM binder with and without WMA additives followed similar performance ranking based on G∗sinδ and CTOD parameters. It is difficult to conclude over the best suitability of intermediate temperature performance parameter as mentioned tests involve different loading conditions and analysis approaches. Hence, further investigation on asphalt mixes is necessary to identify the best suited intermediate temperature performance parameter of asphalt binders, and its possible correlation with mix performance.

The effects of laboratory ageing on rheological and fracture characteristics of different rubberised bitumens

Ageing of bituminous materials can result in loss of the durability of a flexible pavement. Using rubberised bitumens can enhance pavement performance while at the same time it solves a serious waste disposal problem. Combining Warm Mix Asphalt (WMA) additives with rubberised bitumens reduces the difficulties associated with the production of asphalt mixtures using this modified binder. This work was conducted to study the effect of ageing using fundamental parameters based on performance, i.e., CTOD and Glover-Rowe parameters have been related to pavement cracking. Different unmodified bitumens and rubberised bitumens were short-term aged using the Thin Film Oven Test (TFOT) and long-term aged using the Pressure Ageing Vessel (PAV). The rheological and fracture properties of the binders were studied before and after laboratory ageing. The results indicated that rubberized bitumens are more resistant to laboratory ageing. However, the pre-treatment with Sasobit® seemed to be detrimental when the materials were evaluated based on their fracture properties. The results also showed that base bitumen properties can affect the ageing mechanism of rubberised bitumens. Using softer bitumen could produce rubberised bitumens with superior anti-ageing properties when the analysis is based on linear viscoelastic properties using the Glover-Rowe parameter. However, these improvements were significantly reduced after ageing when the analysis is based on fracture properties.

Comparative Evaluation of WMA Additives Effects on Conventional and Polymer Modified Asphalt Pavements

This study is mainly focused on the evaluation of the effect of Warm Mix Asphalt (WMA) additives on the performance grade of straight and polymer modified asphalt binder and the performance of asphalt mixtures. In order to analyze these effects, the Performance Grade (PG) of asphalt binder and the degree of compaction of WMA mixtures with various additives were examined initially. Moreover, the degree of compaction was evaluated in field test sections. Lastly, the effect on WMA performance were evaluated using wheel tracking test and indirect tensile (IDT) strength test for the rutting resistance, moisture susceptibility and crack resistance, respectively. Based on the laboratory and field test results, it can be concluded that WMA additives can affect the PG grades of conventional but not for polymer modified asphalt binder while viscosity related to mixing and compaction results in conversely. From the field test, the rutting and crack resistances of WMA pavements are higher than HMA pavements in most cases.

Workability and mechanical property characterization of asphalt rubber mixtures modified with various warm mix asphalt additives

Warm mix asphalt (WMA) technology offers a promising solution to address the workability concern of asphalt rubber (AR) mixture. Warm asphalt rubber (WAR), the combination of AR and WMA, is expected to be a sustainable paving technology that integrates energy conservation, waste management, noise reduction, and performance optimization. This study aims to characterize and compare the engineering properties of WAR mixture prepared with various WMA additives. To achieve this goal, WAR mixtures were prepared with 40-mesh crumb rubber and five different WMA additives, including Evotherm-DAT, Evotherm-3G, Sasobit, 56# paraffin wax and Aspha-min. Comprehensive laboratory tests were conducted to characterize their workabilities and engineering properties, including moisture susceptibility, stiffness modulus, dynamic modulus, and rutting and fatigue resistance. According to the experimental results, by using WMA additives, a 16 °C reduction in construction temperature can be achieved without significantly deteriorating the mixtures’ compactability. WMA additives influenced both the stiffness modulus and dynamic modulus of AR mixture. All WMA additives compromised the rutting resistance of AR mixture except for Sasobit, and the influence of WMA additives on the moisture susceptibility was insignificant. In terms of the fatigue performance, only Evotherm-DAT provided a positive effect. Finally, effects of WMA additives on AR binders and mixtures’ properties followed the similar tendency, except for the fatigue performance.

Tribological characterization of bituminous binders with Warm Mix Asphalt additives

Warm Mix Asphalt (WMA) technologies allow reducing production, laying and compaction temperatures of bituminous mixtures, leading to relevant environmental and technical benefits. According to recent studies, some WMA additives lead to this temperature reduction by potentially improving the lubricating properties (i.e. the tribological behaviour) of the bituminous binder. In this study, the effect of a chemical and a wax additive on the tribological behaviour of two base bituminous binders was investigated, by considering different percentages of additive. All the binders were preliminarily characterized with Fourier Transform Infrared Spectroscopy (FTIR) and viscosity analysis. After optimizing the test procedure, tribological tests were carried out with a ball-on-three-plates fixture at 85 °C and 120 °C. A statistical analysis was also performed on the tribological results to evaluate the statistical significance of the differences between the binders. Results showed that the additives might alter the oxidative state of the binder, the chemical additive is able to modify the tribological behaviour of the binder, the wax additive acts solely on the viscosity and the effect of the additive depends on the chemical composition of the base binder. Moreover, a correlation between the minimum friction and the viscosity was found.

Effects of WMA additives and hydrated lime on high-stress and high-temperature performance of Elvaloy®- and PPA-modified asphalt binder

Addition of Poly Phosphoric Acid (PPA) and polymer modifiers such as Elvaloy® found to improve the rheological performance of asphalt binders. However, such modification has also shown an increase in mixing and compaction temperature. Use of Warm Mix Asphalt (WMA) additives has shown a reduction in construction temperature, hence making such modification environmentally sustainable. Therefore, a control binder (an AC-30 asphalt binder modified with PPA and Elvaloy®) was modified using three different types of WMA additives: Sasobit®, Evotherm® and Advera®. In addition, considering moisture susceptibility of WMA-modified control binders additives, hydrated lime was further added to asphalt binder combinations. The current study involves the performance evaluation of different asphalt binder combinations using (a) Superpave rutting parameter, (b) time–temperature superposition data of complex modulus over a wide range of frequency and (c) multiple stress creep recovery test with application of different stress levels (0.1, 3.2, 6.4, 12.8 and 25.6 kPa). The addition of Sasobit® observed to enhance stiffness, rut resistant and recovery characteristics, whereas, Advera® and Evotherm® addition led to degrade the stiffness, rut resistant and recovery characteristics of a control binder. HL addition to control binder and control binder containing Advera® were observed to have an undesirable effect on rutting resistive performance. However, HL addition to control binder containing Evotherm® and Sasobit® showed improvement in rutting resistivity potential. Overall, high stress levels observed to have a significant effect on all asphalt binder combinations; hence, consideration of higher stresses can play a vital role in binder selection process.

Experience with The Use of Warm Mix Asphalt Additives in Bitumen Binders

Abstract In most European countries, Hot Mix Asphalt (HMA) technology is still being used as the standard for the production and processing of bituminous mixtures. However, from the perspective of environmental acceptability, global warming and greenhouse gas production, Slovakia is making an effort to put into practice modern technology, which is characterized by lower energy consumption and reducing negative impacts on the environment. Warm mix asphalt technologies (WMA), which have been verified at the Department of Transportation Engineering laboratory, Faculty of Civil Engineering, Slovak University of Technology (FCE, SUT) can provide the required mixture properties and can be used not only for the construction of new roads, but also for their renovation and reconstruction. The paper was created in cooperation with the Technical University of Ostrava, Czech Republic, which also deals with the addition of additives to asphalt mixtures and binders. It describes a comparison of the impact of some organic and chemical additives on the properties of commonly used bitumen binders in accordance with valid standards and technical regulations.

Performance of WMA additives under freeze–thaw action

Warm mix asphalt (WMA) is an energy-saving and environmental-friendly technology with a broad prospect for application in highway construction. When compared with hot mix asphalt (HMA), WMA reduces the mixing and compaction temperatures (by 25–30°C) and hence reduction in energy consumption and emissions of harmful gases while maintaining the workability of HMA. In this study, three different additives, namely, Sasobit (organic wax additive), Evotherm (emulsion-based chemical additive) and Zycotherm (anti-stripping chemical additive) were evaluated for their laboratory performance under repeated weathering actions. HMA and WMA laboratory samples for Marshall stability, indirect tensile strength and tensile strength ratio were cast and subjected to 0, 2, 4, 6 and 8 freeze and thaw cycles (F&T cycles) in numbers and then tested. A comparative study was performed among HMA and three WMA mixes (control and weathered), that is, Sasobit-WMA (S-WMA), Evotherm-WMA (E-WMA) and Zycotherm-WMA (Z-WMA) to analyse the trend of variation in strength and properties with varying F&T cycles. Aggregate coating and compactibility were also analysed.

Effects of Sasobit and Deurex additives on asphalt binders at midrange and high temperatures

ABSTRACTThe Warm mix asphalt (WMA) industry has attracted considerable attention due to the additives’ability to reduce the mixing and compaction temperatures of the asphalt mixture. Deurex has showed its potential of being a new additive in this industry. However, properties of Deurex-modified binders have not been studied in details. The objective of this study was to investigate the rheological properties of binders containing various types of WMA additives through conventional test, viscosity, failure temperature, frequency and amplitude sweep. The study included three binder sources (two 60/80 pen asphalt, and styrene–butadiene–styrene (SBS)-modified asphalt), two types of WMA additives (Deurex and Sasobit) and control binders. The results indicated that both Sasobit and Deurex had similar effect on viscosity reduction regardless of asphalt types. The results also indicates that binders containing Deurex had better high-temperature rutting resistance, concerning increased softening point, fail temperature, stiffness and storage modulus. In addition, temperature sweep, frequency sweep and amplitude test show that the Sasobit-modified asphalt binders exhibit a slightly higher storage modulus and complex modulus but a lower phase angle than the Deurex-modified asphalt.

Effect of warm mix asphalt chemical additives on the mechanical performance of asphalt binders

Warm mix asphalt (WMA) has become very popular in asphalt pavement construction because it allows reducing both energy consumptions and carbon emissions. WMA can be obtained by using different types of additives and can be produced, applied, and compacted at temperatures 20–40 °C lower than hot mix asphalt. WMA additives allow reducing the working temperatures without compromising the final performance of the asphalt concrete. Many WMA additives are available on the worldwide market and some of them reduce the viscosity of asphalts binder (organic additives or foam) whereas others do not act on this sense (chemical additives). This study focuses on the effect of chemical additives on the performance of asphalt binders for WMA production. To this purpose, a neat bitumen, a polymer modified bitumen (PMB) and two different chemical additives were selected. All the binders were characterized through conventional tests, DSR, MSCR, FTIR and microscopic analysis. The result clearly showed that the influence of the chemical additives on the neat bitumen is negligible or non-existent. On the contrary, significant changes were observed in the modified bitumen properties. Specifically, chemical additives reduce the viscosity temperature susceptibility of PMBs in the temperature range between 80 and 140 °C, increase the rutting resistance potential and the elastic response of PMBs at high temperatures. Moreover, a morphological inspection supported the modifications observed in the rheological properties of PMBs.

Laboratory investigation of rutting performance of warm mix asphalt containing high content of reclaimed asphalt pavement

ABSTRACTIn this research, the influence of warm mix additives on the properties of warm-mix asphalt (WMA) containing recycled asphalt pavement (RAP) was investigated and compared with the same graded hot-mix asphalt (HMA). WMA mixtures were produced using Sasobit and Zycotherm as organic and chemical WMA additives, respectively. Mixtures were prepared containing RAP in different proportions (0%, 25%, 50% and 75 % of total aggregates). Dynamic creep and wheel track tests were used to investigate the resistance of specimens to permanent deformation. Zycothem WMA mixtures showed less resilient modulus and rutting resistance than Sasobit WMA mixtures. It was also concluded that increasing the amount of RAP in mixtures improves resilient modulus and rutting resistance of all mixtures.