Reclaimed Asphalt Pavement Materials Research Articles

Effect of Fractionation Process and Addition of Composite Crumb Rubber-Modified Asphalt on Road Performance Variability of Recycled Asphalt Mixtures with High Reclaimed Asphalt Pavement (RAP) Content

The application of reclaimed asphalt pavement (RAP) can help reduce resource waste and environmental pollution in road construction. However, so far, only a small percentage of RAP materials can be used in road construction. The key obstacles to the application of a recycled asphalt mixture (RAM) with high RAP content are the variability of RAP materials and the difficulty of fully rejuvenating aged asphalt. However, there is still a lack of research on the effect of the variability of RAP materials and recycled asphalt on the quality control of a RAM. Therefore, this study investigates the effects of sieve pretreatment of RAP material using 4.75 mm sieve mesh and the use of composite crumb rubber-modified asphalt (CCRMA) to reclaim aged asphalt on the road performance and frame variability of reclaimed asphalt mixtures. Therefore, this study investigates the effects of the fractionation process of RAP material using 4.75 mm sieve mesh and the use of CCRMA to reclaim aged asphalt on the road performance of a RAM. The results show that the fractionation process can effectively reduce the mitigation of RAP agglomeration and reduce the variability of gradation, which in turn reduces the variability of road performance. The incorporation of CCRMA can effectively improve the high-temperature stability performance and low-temperature cracking resistance. The dynamic stability and the fracture energy of the CRAM (RAM prepared using CCRMA) were four and one and a half times as large as that of the NAM (RAM prepared using base asphalt), respectively. The fractionation process of RAP material and the utilization of CCRMA could help reduce the variability of the RAM while improving the road performance of the RAM.

Tailored enhancement of reclaimed asphalt pavement with waste engine oil/vacuum residue blend as rejuvenating agent

In recent years, there has been a noticeable increase in the production of Reclaimed Asphalt Pavement (RAP) resulting from the maintenance and rehabilitation activities conducted on asphalt pavements. However, the presence of aged binder in RAP gives rise to asphalt mixtures with unfavourable characteristics. To address this concern, the use of rejuvenating agents has been examined as a viable solution to restore the properties of aged asphalt. In this study, an investigation was undertaken to assess the efficacy of incorporating waste engine oil (WEO) and vacuum residue (VR) as hybridized rejuvenating agents for RAP. Various characteristics including penetration, softening point, ductility, viscosity, and stiffness were measured to ascertain the optimal dosage of the hybridized rejuvenating agent. Subsequently, the performance of the rejuvenated asphalt was evaluated through Marshall tests, indirect tensile strength (ITS), moisture damage, and Kim tests, comparing it with different samples. Moreover, the Creep compliance, semi-circular bending (SCB), and Cantabro loss measurements were employed in the evaluation. The findings of the study indicate that a 6.5% hybrid rejuvenator composed of WEO and VR effectively rejuvenates asphalt mixtures containing 30% RAP material by softening the aged binder. Furthermore, the rejuvenated mixture exhibited significant improvements when compared to both the virgin asphalt and RAP mixtures. In conclusion, the incorporation of WEO and VR as a hybridized rejuvenating agent showcases promising results in enhancing the performance of RAP mixtures. This, in turn, contributes to sustainable and efficient pavement practices.

Material and mix design aspects of hot recycled asphalt mixes: A review.

Sustainability in road construction can be achieved by integrating recycled materials in the production of new pavement. One such approach is using reclaimed asphalt pavement materials (RAPM) in hot mix asphalt (HMA). Successful implementation of RAPM in HMA can only be achieved by having good comprehension of the essential material characterisation and design process. The main objective of this review is to summarise the literature and provide a keen understanding of the characterisation of materials involved (RAPM and rejuvenators) and mix design, by giving due consideration to the interaction of virgin and recycled materials. Widely used techniques for extraction and recovery of reclaimed asphalt pavement (RAP) binder have been reviewed. The advantages and disadvantages of different characterisation techniques are identified. The effect of various factors on the volumetrics of the recycled mixes is presented. Insight in to the requirements of a rejuvenator by taking into account the changes in binder after ageing is provided. Aspects that need further exploration to normalise and increase the confidence of RAPM in HMA are also highlighted as the future recommendations.

Study on the Adhesion Characteristics of Asphalt-Aggregate Interface in Cold Recycled Asphalt Mixtures

The reclaimed asphalt pavement materials have been used for sustainable cold-recycling, significantly benefiting air quality and resource conservation, while its microscale interface properties greatly affected road performance during the cold-recycling processes. In this investigation, the cold recycled asphalt mixtures were prepared with different mixing proportions, considering the effects of cement content and mixing water amount. The adhesion characteristics of the asphalt-aggregate interface in different cold recycled asphalt mixtures have been comprehensively investigated based on the atomic force microscopic (AFM). The microscale morphology and the adhesion properties, including roughness, inclination angle, adhesion force, Derjaguin–Muller–Toporov (DMT) modulus, and dissipated energy were evaluated at the interface and noninterface regions. The micromorphology results showed that the addition of cement could enhance the roughness and inclination in interface regions. In addition, the content of mixed water showed the most significant effect when the water amount was 80%. The results showed that the adhesion force, DMT modulus, and dissipated energy increased with the addition of cement, indicating that the cement could improve the microscale mechanical properties of cold recycled asphalt mixtures. With the increase of mixing water content, the adhesion characteristics showed varied results, and the optimum water content of 80% contributed to the adhesive properties. In addition, the adhesion force, DMT modulus, and dissipated energy were all higher in the interface region by comparing with the noninterface region. The correlations between the macroscale splitting tensile strength and microscale adhesion characteristics of cold recycled asphalt mixtures were established.

A mechanistic-empirical approach to estimate the degree of Reclaimed Asphalt Pavement (RAP) bitumen activity

Coating studies and other mechanical methods to estimate DoA necessitate sophisticated equipment, skilled workforce, and huge amount of RAP material for testing. Hence, the present study proposes a simple mechanistic-empirical approach to estimate DoA with reasonable accuracy without requiring experiments on RAP material. Coating studies were carried out on several experimental combinations with varying mixing parameters and RAP characteristics. It was found that the liquid bridge theory along with a shift factor function can successfully be used to estimate DoA. A regression model with an adjusted coefficient of determination (R2-adj) of 0.70 was developed to establish the shift factor function.

Influence of epoxy resin polymer on recycled asphalt binder properties

Utilization of high-performance pavement materials with a high reclaimed asphalt pavement (RAP) content is gradually gaining importance given the impetus of green environmental policies. Epoxy resin polymer (EP) can greatly enhance the reuse of RAP materials in asphalt mixture. The influence of EP on the properties of aged asphalt binder was investigated wherein mechanical and chemical properties, and the micro-morphology of binders composed of aged asphalt binder and EP were also evaluated. EP significantly improved tensile, high-temperature, low-temperature, and fatigue properties of aged asphalt binder, and simultaneously reduced concentration of sulfoxide and carbonyl of aged asphalt binder. Increasing EP content reduced the impact of asphalt ageing degree on mechanical properties, micro-morphology, and chemical composition. Furthermore, the construction allowance time of the binder was increased with increasing EP content. At 40% EP content, an effective network structure was formed in the aged asphalt binder, leading to higher tensile elongation, high-temperature rheological properties, and fatigue life as compared to virgin asphalt binder. Meanwhile, low-temperature modulus and sulfoxide and carbonyl concentrations were lower than those of virgin asphalt binder. For application, a recommended EP content of 40% is suggested.

Laboratory Evaluation of Emulsion-Treated Base Layer Mixes Incorporating Reclaimed Asphalt Pavement Materials

Emulsion-Treated Base (ETB) is one of the most preferred base layer stabilization methods in which dense graded aggregates are treated with a slow setting bituminous emulsion. To reduce the cost of ETB and minimize the need for virgin aggregates, it is essential to evaluate the possibility of incorporating higher dosages of Reclaimed Asphalt Pavement material (RAP) in ETB. The present study evaluates the effect of RAP incorporation in ETB at dosages of 0%, 25%, 50%, 75%, and 100%. The effects of RAP incorporation were studied in terms of RAP mixing and RAP blending methods. RAP mixing is a process in which a definite proportion of RAP is added to virgin aggregates of a given gradation without a target gradation, while in RAP blending, virgin aggregates of required aggregate sizes are blended to RAP with the objective of achieving a targetted dense aggregate gradation. In this study, RAP was characterized using cohesion tests, fragmentation tests, and other physical properties recommended by the International Union of Laboratories and Experts in Construction Materials, Systems, and Structures (RILEM) Technical Committee. When 50% RAP was added to ETB using the RAP mixing method, the Maximum Dry Density (MDD) of the mix decreased by 4.4%, but in using RAP blending, the reduction in MDD was only 1.3%. ETB prepared with up to 75% RAP, 3% emulsion, and 1% cement, using the RAP blending method, was found to satisfy the minimum indirect tensile strength requirement of 225 kPa (specified by TG 2 2009 and IRC 37 2012), and exhibited appreciable rutting resistance and a tensile strength ratio of more than 0.7. This study identified that 50% RAP incorporation in ETB using blending gives the best performance in terms of cohesive and adhesive strength, moisture resistance, and resistance to permanent deformation.

Kajian Nilai Keawetan Reclaimed Asphalt Pavement Dengan Pemanfaatan Buton Granular Asphalt Pada Lapis Perkerasan Ac-Wc

Reclaimed Asphalt Pavement (RAP) is the residual waste generated from the dredging of damaged road pavements. Usually this RAP material is thrown away so it is rarely reused. In fact, RAP material that has become waste and is no longer used can be used as an added ingredient in the manufacture of new asphalt concrete with rejuvenator. This study aims to determine the durability value of reclaimed asphalt pavement with the use of buton granular asphalt (BGA) as a rejuvenating agent in the gradation of the Laston mixture (AC-WC) against the IRS value. The first testing stage is to test the characteristics of the reclaimed asphalt pavement material and then continue with the marshall test. The optimum asphalt content value obtained after testing is at 5,28% of the total aggregate. The reference used in testing the characteristics of Marshall and IRS is the specification of Bina Marga in 2018 revision 2. The results of the IRS test using the optimum asphalt content of 5,28% with the addition of BGA show that along with the increase in the level of BGA in the AC-WC mixture by using RAP, the ability of the mixture to withstand the load increases and the flexibility of the mixture decreases, so that the asphalt's durability increases, represented by the IRS test of 30 minutes and 24 hours which shows the durability value with 0% BGA content, the value is 112,70%, with the addition of BGA 1% obtained a value of 118,87%, BGA 2% 121,50% and with the addition of 3% BGA content which was 125,11% in the Laston mixture (AC-WC). So from the test results, the IRS value meets the requirements of the 2018 Highways Specification of 90%, so it is concluded that the results of the tests carried out meet the durability requirements and can be applied in the field.

Research on pavement performance of recycled asphalt mixture based on separation technology of asphalt and aggregate in RAP

Asphalt-aggregates separation of reclaimed asphalt pavement (RAP) with bio-oil as solvent is an economical, simple, and efficient method to recycle RAP materials. The byproducts of asphalt-aggregates separation of RAP are recycled aggregates and blends of bio-oil and old asphalt (BBOA). In this paper, to improve the recycling rate of BBOA and recycled aggregate after asphalt aggregate separation, Buton Rock Asphalt (BRA) is used as a high-temperature property modifier to compensate for the aging resistance and high-temperature of BBOA. The physical properties of rock asphalt modified bio-oil asphalt (RMBA) with different amounts of BBOA were studied by viscosity, frequency scanning, multiple stress creep, bending beam rheology, and aging tests. At the same time, recycled aggregates of different particle sizes and RMBA were used to prepare asphalt mixture with diverse mix design methods. The pavement properties of the recycled asphalt mixture were evaluated by rutting resistance, low-temperature bending beam, freeze–thaw splitting, and fatigue tests. The results show that RMBA realizes the complementary advantages of BRA as a high-temperature modifier and BBOA as a low-temperature performance modifier. The recommended dosage of RMBA is 20 %rock asphalt and 7 %BBOA. Under different preparation methods, the pavement performance of rock asphalt modified bio-oil asphalt mixture, asphalt mixture containing coarse recycled aggregate, and asphalt mixture containing oil sand meet the requirements of asphalt pavement design specifications, the preliminary realization of 100% recycling of RAP.

Effect of Additive Addition on RAP (Reclaimed Asphalt Pavement) as an Aggregate Substitution Against the Upper Surface Layer of The Road

As development in the field of infrastructure increases, it will require more materials of natural origin. The availability of materials from nature will be reduced and more limited. Meanwhile, the construction of infrastructure continues to run every year for the improvement and comfort of the community. With this, the importation of goods will also increase, especially for bulk asphalt materials, and it is possible that later the stone that becomes one of the main materials for hot asphalt mixture will also bring in from abroad. If waste from peeled asphalt (RAP) can be reused, it will automatically reduce the use of materials from nature and reduce import activities of goods which results in reduced state expenditure. The thesis task will discuss the reuse of peeled asphalt (milling) on the highway, starting from the benefits of RAP, the advantages of RAP, testing RAP materials and new materials, and how to produce RAP asphalt at the Asphalt Mixing Plant. The composition of the RAP used is 60% with SW1 rejunevile material of 3.8%, the addition of new aggregates of 40%, and the addition of new asphalt of 3.3%. The results of the compaction experiment in the field (trial compaction) which will be used for work reference are initial compaction (tandem roller 2 passing), intermediate compaction (tire roller 16 passing), and final compaction (tandem roller 1 passing), and the resulting density of hot mix beds of 98.36%.

Evaluation of the structural performance of the geocell-stabilized flexible pavement

Geocell can provide sustainable solutions for the pavement infrastructure as it allows the utilization of reclaimed and inferior quality base aggregate materials as infill materials. The benefits of using geocell have been well established in the literature; however, lack of knowledge regarding the field performance hinders transportation agencies from designing flexible pavement with such products. This study aims to determine the contribution of geocell towards pavement system performance based on non-destructive field testing. The existing road section of a Farm to Market Road was replaced with different thicknesses of geocell-reinforced base layer filled with reclaimed asphalt pavement (RAP) material. The performance of the reinforced sections was verified with the profiler test and rutting measurements. Falling weight deflectometer (FWD) tests were conducted on different test sections to capture the pavement responses. Field data showed that geocell allowed the maximum usage of RAP material and enhanced its performance. The back-calculated in-situ modulus showed that the additional confinement provided by the geocell ranged between 8 and 20 psi. The increase in confinement indicated an increase in resilient modulus, which was further calculated for each geocell-reinforced section. Geocell also helped to restrict the differential movement of the subgrade by providing uniform support, which resulted in a smoother road structure with less rutting and longitudinal cracking.

Utilization of reclaimed asphalt pavement (RAP) materials in HMA mixtures for flexible pavement construction

Production of more RAP material waste arises the problem of deposition. To overcome this problem, RAP materials are recycled and re-used in different layers of pavement which will reduce the cost of pavement construction, reduce the environmental pollution. So, partial replacement with natural aggregate (NA) is an alternative for conservation of natural resources. RAP materials contain bitumen on their surface which will reduce the amount of natural bitumen. Replacement of RAP materials with natural aggregate needs suitable blending proportion. This paper represents laboratory evaluation of replacement of Reclaimed Asphalt Pavement (RAP) materials, a varying percentage of 0 to 30% blended with natural aggregate in terms of Marshall Stability, Indirect Tensile strength and Tensile Strength Ratio to be used in hot mix asphalt (HMA) mixtures for construction of surface course of flexible pavement. Marshall Stability, Indirect Tensile strength and tensile strength ratio (wet and dry condition) of natural aggregate blended with RAP 0%, 10%, 20% and 30% were tested and found 20% RAP mix is suitable for the bituminous road construction.

Rheological Characterization of Reclaimed Asphalt Binder Blended with The Neat And Sbs-pma Binders

Reusing reclaimed asphalt pavement material guarantees a substantial optimization of non-renewable material resources, emissions reduction, and decreasing landfill space, along with the economic benefits associated with saving the costs of purchasing and transporting new aggregate and asphalt binder for asphalt concrete mixture production. This study aims to investigate the influence of aged asphalt binder from reclaimed asphalt pavement on the virgin asphalt binder’s rheological properties. Therefore, different dosages of RAP binder (20%, 30%, and 40% by weight of the total mix) were blended with neat asphalt binder (40-50), penetration grade (P40), and SBS polymer asphalt (SBS-PMA) binder. Using both traditional and Superpave performance testing methods, the effects of RAP on the blend's consistency, viscosity, softening, elastic recovery, rutting (permanent deformation), fatigue cracking, and low temperature cracking were evaluated. The results revealed that the RAP binder decreased the penetration value of both neat and SBS-PMA binders. The neat asphalt binder’s viscosity and softening point increased with the increase in RAP content, whereas they decreased for SBS-PMA. The RAP binder decreases the SBS-PMA elastic recovery. where the neat asphalt experienced a little improvement in elastic recovery when blended with the RAP binder. The Superpave test results revealed that the RAP binder deteriorates the performance of the SBS-PMA binder at high, intermediate, and low testing temperatures. With the addition of 20%, 30%, and 40% RAP, the high-temperature PG grade of SBS-PMA blends decreased by 0.64%, 0.95%, and 1.10%, respectively, while the low-temperature PG grade increased by 23%, 31%, and 32%, respectively. In contrast, the RAP improves the neat asphalt blend's high-temperature performance grade and deteriorates intermediate and low-temperature performance grades. The addition of 20%, 30%, and 40% RAP increased the neat asphalt blends' high-temperature properties by 1.5%, 3.3%, and 4.5%, respectively. whereas the neat asphalt low-temperature PG grade increased by 5%, 11%, and 15% with the addition of 20%, 30%, and 40% RAP, respectively. In summary, the performance of virgin and RAP binder blends depends on the individual characteristics of the blended asphalt binders

Laboratory and numerical investigation on the behavior of reclaimed asphalt pavement (RAP) as railway track subballast layer

The use of asphalt mixtures in different places of the structure of railway tracks has been increased, given their acceptable performance and properties. Using bituminous materials in subballast layers is of great importance due to the structurally, vibrationally, and geometrically improving properties of these infrastructures. In order to enhance the mechanical behavior of railway tracks under heavy loads and high-speed trains, the tendency to use sustainable development approaches such as reuse of discarded and recycled materials has increased. The asphalt is recycled in the maintenance activities of road pavements and, in some cases, reused in the road construction and pavement industry, raising the question of whether reclaimed asphalt pavement (RAP) mixtures can be utilized in railway tracks? Has not been so extensively studied on RAP materials to be used as an interlayer in the structure of railway tracks. Accordingly, the present study seeks to investigate the behavior of these materials as the railway tracks subballast by experimental and numerical through structural approach. Given the complex behavior of these materials due to their bitumen aging, researchers are concerned about the quantity of them that can be reused. In this study, subballast layers containing RAP with percentages varying from 25 % to 100 % without any additive material and thicknesses from 5 cm to 20 cm were numerically modeled. At first, the behavioral models of the RAP materials without any additive material in a laboratory were determined for the model inputs. Using the dynamic modulus and relaxation behavior remarkably helped to identify the behavior of these materials. Numerical models were developed for RAP materials by assuming the linear elastic (LE) behavior for granular materials and linear viscoelastic (LVE) behavior for RAP materials. A conventional ballast track model with granular subballast was also simulated for validation and comparison. Eventually, by evaluating the effect of using RAP on the track settlement, the tensile strain of the bottom of the subballast layer, and compressive stress imposed on the subgrade, the subballast layer with 100 % RAP and a thickness of 20 cm was found to have the best performance, reducing the mentioned Strain and Stress parameters by 40 %. Accordingly, such a layer can be utilized as a simple permanent solution to improve the stiffness and performance of tracks.

Assessment of suitability of reclaimed asphalt pavement material for use in cement concrete pavements

W artykule przedstawiono ocenę przydatności destruktu asfaltowego do zastosowania w składzie nawierzchniowej mieszanki betonowej. Omówiono wyniki parametrów 6 destruktów asfaltowych pozyskanych z nawierzchni komunikacyjnych i oceniono pod względem możliwości zastosowania do mieszanek przeznaczonych na nawierzchnie betonowe. Czynniki zewnętrzne, które w czasie użytkowania oddziaływały na nawierzchnię, mogą wpływać na starzenie spoiwa i powodować zmiany proporcji związków chemicznych w jego budowie wewnętrznej. Z uwagi na powyższe konieczne było analizowanie parametrów kruszywa pochodzącego z recyklingu nawierzchni i mieszanek mineralno-asfaltowych, szczególnie pod kątem tekstury, absorpcji wody, właściwości lepiszcza, a także charakterystyki powierzchni cząstek pokrytych lepiszczem asfaltowym. W artykule zaproponowano ponowne wykorzystanie destruktu asfaltowego pochodzącego z eksploatowanych nawierzchni komunikacyjnych w składzie mieszanek betonowych przeznaczonych do wbudowania w nawierzchnie drogowe. Omówiono wyniki podstawowych parametrów betonów z dodatkiem wytypowanych destruktów.

Sustainable use of reclaimed asphalt pavement (RAP) in pavement applications-a review.

The purpose of this review is to examine the innovative usage ofReclaimed Asphalt Pavement (RAP) in flexible pavement applications. RAP is elucidated as isolated pavement earthly materials consisting of asphalt and aggregates. When the existing/old asphalt is removed for reconstruction, and resurfacing, these materials are generated. Now, it is highly required to classify the available RAP for further essential use in road construction. RAP addresses the issues regarding the diminishing of Virgin Aggregate (VA) sources, storage of material and disposal of RAP material nearby the site. The utilization of RAP includes social benefits like depletion of manufacturing waste, conservation of non-renewable natural stockpiles and low energy expenditure. The reviewed literature reveals that RAP has been utilized mainly for base and sub-base materials on the roads. To summarize, 100% replacement of VA by RAP possessed lesser strength and little resistance to creep and long-lasting deformations. Hence, RAP can be appended with natural aggregate or blended with cement or other admixtures like Fly ash (FA) or confined with geocell. It also accelerates the strength and stiffness of the base and sub-base of pavement as it degrades the failure like rutting and fatigue cracking of pavement due to dynamic loads.

Analisis Karakteristik Campuran Laston Menggunakan Material Perkerasan Jalan Lama Dengan Peremaja Limbah Minyak Goreng

One alternative way to reduce the use of natural aggregate and asphalt is the use of recycled materials of old road pavement or Reclaimed Asphalt Pavement (RAP). The asphalt within the RAP generally had become stiffer due to ageing, therefore it needs to be mixed with a rejuvenating agent. An alternative organic oil-based refining agent that can be used for rejuvenating rigid asphalt is Waste Cooking Oil (WCO). The purpose of this study is to analyze the characteristics of asphalt mixtures at Optimum Bitumen Content (OBC) and at best WCO content. The asphalt mixture manufacturing method used was Marshall Method. The variation of RAP materials was 25% and 50%, with added aggregate material to meet the ideal mid gradation. For each variation of RAP content, was produced mixtures with variation of of 2%, 4%, 6%, 8%, and 10% (by weight of total asphalt) where for each of those variation of RAP with variations of WCO rejuvinating materials, were made asphalt content variation of 5%; 5.5%; 6%; 6.5%; and 7%, then the OBC was determined. For the mixture with 50% RAP, the OBC was 6.3%, with best result on 8% WCO. On misture with 25% RAP the OBC was 6.2%, with best result on 4% WCO. The Marshall characteristics met the specifications. The mixture of 50% RAP with 8% WCO has lower stiffness and deformation resistance, however the performance of this mixtre was good enough on fatigue test.

Microscopic studies of binder blending on laboratory recycled asphalt mix

ABSTRACT During blending between the binders in hot mix recycling, two physical processes occur, namely blending due to diffusion and blending due to mechanical agitation. In the present study, an experimental approach is developed to observe these processes directly on the laboratory recycled asphalt mix samples. Atomic Force Microscopy (AFM) and Confocal Laser Scanning Microscopy (CLSM) are used as the probing tools. The binder concentration profile is estimated at different locations around the reclaimed asphalt pavement material (RAPM) aggregate. Diffusion is observed to be predominant in some of these locations, while, in some other locations, mechanical mixing is observed to be predominant. Assuming that pure Fickian diffusion is happening at those diffusion-spots, the coefficient of diffusion is estimated from the concentration profile at those locations. It is envisaged that the proposed approach would provide a microscopic perspective of the extent of blending during the recycling process.

Rheological and anti-moisture characteristics of rubberized reclaimed asphalt pavement with interfacial bond behavior

The application of recycled materials in terms of reclaimed asphalt pavement (RAP) and crumb rubber, as an environmental-friendly and sustainable strategy, has become an important topic in the pursuit of long-term growth in the pavement construction field. However, the interfacial bonding behaviors of rubberized reclaimed asphalt were still ambiguous, causing the deteriorated life-performance of pavement. This study analyzed the interfacial bonding characteristics of various rubberized RAP binders with binder bond strength (BBS) test, in terms of two crumb rubber with different mesh sizes and contents, and two RAP sources with different age levels and contents. The high-temperature rheological properties were evaluated through Dynamic Shear Rheometer (DSR) test. Additionally, softening point test was also adopted to characterize the high-temperature performances. Moreover, comprehensive mechanical performance tests, including Hamburg wheel track (HWT) test, water boiling test for visual interpretation and indirect tensile strength (ITS) test were conducted to assess the feasibility of rubberized RAP mixture as pavement construction materials. It was reported that the PG temperature of asphalt was increased from 73rom ed thand the stripping of mixture under moisture reduced from 11.98% to 9.20% at least. Finally, a surface interaction model of rubberized RAP binder with colloid structure and statistical analysis were established. This research demonstrated that the reuse of end-of-life materials in pavement was feasible and provided comparable service performance. The surface interpretation with the light components trapping within gel-phase of rubber and the chemical composition oxidization of RAP would ultimately affect the bonding characteristics and properties of rubberized RAP materials, whose interfacial bond mechanism was recommended investigation before application.

Laboratory Investigation of Reclaimed Asphalt Mixtures Containing Cyclogen and Vacuum Bottom Rejuvenators

The use of reclaimed asphalt pavement (RAP) to create recycled asphalt mixture is attracting great interest because of landfill space decrease and natural resources saving. Also, incorporating rejuvenators is an effective method to promote the utilization of RAP materials in hot mix asphalt (HMA) production. The main goal of this study was to evaluate the effect of Cyclogen and vacuum bottom (VB) rejuvenators on the performance of RAP mixtures against moisture sensitivity, rutting resistance, and tensile strength. In this regard, mixtures were constructed with different RAP contents (0, 35, and 70% by asphalt mix weight) and virgin aggregates. Furthermore, three contents of Cyclogen (0, 5, and 10%) and VB (0, 15, and 30%) by the weight of RAP binder were used. The laboratory test results revealed that RAP materials enhanced the indirect tensile strength, rutting resistance, and moisture sensitivity of asphalt samples. Moreover, increasing RAP content improved the rutting resistance and permanent deformations of asphalt samples. The addition of RAP also enhanced the resilient modulus and tensile strength of asphalt samples; this increase was subject to RAP content applied. Furthermore, the effect of rejuvenators on the performance characteristics of RAP mixtures showed that adding VB and Cyclogen decreased tensile strength, resilient modulus, and strain creep and increased the moisture sensitivity of RAP mixtures.