Virgin Binder Research Articles

Quantitative Characterization of Binder Blending

The current tendency in the asphalt paving industry is to increase the use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS). However, a major concern that limits the use of RAP or RAS is the uncertainty about how much of the aged binder in RAP or RAS can be blended into virgin binder. Studies have focused on the diffusion between old and new binders. However, little research has been conducted to determine how much recycled binder could be mobilized and made available to coat aggregates. This study developed a laboratory procedure to quantify the rate at which aged binder was mobilized for recycled mixtures containing up to 80% RAP and 10% RAS. A new term, “large molecular size percentage (LMSP),” was derived from gel permeation chromatography testing and used to characterize recycled and virgin binders as well as their blends. Blending charts were generated for virgin–aged binder blends containing 0% to 100% RAP or RAS binder in LMSP. The relationship was found to be linear between LMSP and RAP or RAS binder content. An experiment was conducted to validate the method proposed for determining the mobilization rate. The results showed that the RAP binder mobilization rate decreased with the increase in RAP percentage in the mixture, which could be close to 100% at low RAP contents (10% and 20%); the rate dropped from 73% to 24% when the RAP percentage increased from 30% to 80%. For RAS, the mobilization rate reached a peak at 5% RAS content and then started to decrease with the increase in RAS content.

Determining optimum rejuvenator dose for asphalt recycling based on Superpave performance grade specifications

The changes in Superpave performance grade (PG) of Reclaimed Asphalt Pavement (RAP) binder were determined after addition of two doses of six rejuvenators. The high and low PG temperatures were reduced linearly with an increased dose while the penetration grew exponentially. It was found that the grade sum of rejuvenated RAP binder is always higher than that of the corresponding virgin binder. Based on these conclusions a procedure for optimizing the rejuvenator dose to satisfy the Superpave PG requirements was developed to account for the inevitable variability of the RAP binder due to differences in aging and source.

Investigating the blending of reclaimed asphalt with virgin materials using rheology, electron microscopy and computer tomography

The nature of blending of virgin materials with reclaimed asphalt pavement (RAP) has been investigated using a multi scale approach using the dynamic shear rheometer (DSR), electron microscopy and computer tomography (CT). In order to simplify the visualization of the blending of the virgin and reclaimed materials five specially engineered hot asphalt mixtures were produced incorporating large mineral fraction (8/11mm) of virgin aggregates and small fraction (2/4mm) from RAP mixed with virgin bitumen. The complex modulus and phase angle of reclaimed binder from the blended mixtures were found to be between that of RAP and virgin binder. The CT slices of compacted cylindrical samples (150mm diameter×120mm height) could incorporate the effect of compaction on the blending. They show lumped regions with virgin large aggregates as well as lumped regions of RAP aggregates. Using micro CT the spatial distribution of the different binders was investigated at the micro-scale. Millimeter size distinct clusters of virgin binder and clusters of RAP binder could be distinguished. The existence of RAP binder next to large virgin aggregates indicated the migration of the old RAP binder from the RAP aggregates to the virgin aggregates. From these CT images, it was not possible to verify if blending between the virgin and old binders occurred. Using electron microscopy micro-crack formations in the zone between old and new binder were identified suggesting weak spots that could lead to larger crack formation and propagation. However, using energy-dispersive X-ray spectroscopy good qualitative distribution of titanium dioxide tracer in the virgin binder in the mixture could be seen, indicating good blending at the investigated location. Hence, the results show that blending is not homogeneous throughout the sample. Some locations show good blending whereas other locations appear non-blended with micro-cracks forming at the binder boundaries.

Rheological, microscopic, and chemical characterization of the rejuvenating effect on asphalt binders

With the increasing environmental awareness and rising costs of virgin binders, reclaimed asphalt pavement (RAP) has been used as an alternative for energy and cost saving in asphalt pavements. However, RAP binders have been aged to different extents during pavements’ service life and adding rejuvenating agents provides a practical means for restoring the mechanical properties of the aged binders reducing the needed additional virgin binder. In many studies, the rejuvenating effect has been evaluated in terms of the improvement of rejuvenated binders’ rheological properties whereas the fundamental rejuvenation mechanism remains unclear. In this research, two different asphalt binders from the Materials Reference Library of the Strategic Highway Research Program (SHRP) were aged, and rejuvenated by complete blending with two commonly used rejuvenators. The rheological properties of the virgin, aged, and rejuvenated binders were tested using the dynamic shear rheometer and the bending beam rheometer. Furthermore, in order to better understand the rejuvenating effect, surface microscopic properties and chemical composition of the binders were measured using atomic force microscopy (AFM) and SARA (Saturates, Aromatics, Resins, Asphaltenes) fractionation, respectively. Results indicated that the bulk mechanical properties (complex modulus and viscosity) of the rejuvenated binders were in between those of the virgin and aged binders. Aging and rejuvenation led to morphological changes as compared to their virgin binders; however, the rejuvenated binders did not always reproduce the microstructures of the virgin binders. Microscopic measurements on adhesion and dissipation of virgin, aged, and rejuvenated samples were qualitatively consistent with the bulk rheological results. SARA separation results suggested that changes in chemical fractions were responsible for the stiffening effect of aging and the improvement of mechanical properties with the addition of the rejuvenators. Such a systematic approach of characterizing the rejuvenating mechanism will benefit the effort of producing more sustainable RAP-containing asphalt pavements.

Ageing characteristics of RAP binder blends – what types of RAP binders are suitable for multiple recycling?

Two rolling thin-film oven-aged asphalts were blended with 15% and 50% of extracted reclaimed asphalt pavement (RAP) binders to investigate the effect of RAP content and properties on the long-term laboratory ageing characteristics of asphalt binders. The results from both chemical and rheological analyses indicate that the ageing characteristics of blended binders are dependent on fresh asphalt binders and that different virgin binders interact with different RAP binders differently and the performance grade (PG) adjustment is asphalt and RAP binder dependent. Some asphalts require higher PG adjustment than others. The mixing of virgin binders with RAP binders contributes to different stiffening effects based on the virgin asphalt–RAP interaction. The results show that the change in stiffness increase as a function of ageing times for RAP-blended binders is similar to that of a typical chemical ageing kinetic model, where the stiffness initially increases rapidly and then levels off at longer ageing times.

Blending efficiency of Reclaimed Asphalt Pavement: An approach utilizing rheological properties and molecular weight distributions

Different mixing conditions are expected to have a large influence on the ability for Reclaimed Asphalt Pavement (RAP) and virgin binder to blend in an asphalt pavement mixture. This study investigates the influence of mixing time, mixing temperature, and the inclusion of Warm Mix Asphalt (WMA) additives on the ability to RAP and virgin binder to blend. A large virgin aggregate and a small RAP were blended with virgin binder in defined mixing scenarios. The aggregates were then separated, the binder was recovered, and the rheological and chemical properties were investigated using the Dynamic Shear Rheometer (DSR) and Gel Permeation Chromatography (GPC). This research found that there is a limit to which mixing time has an influence on binder blending, mixing temperature may have a significant effect, and the inclusion of WMA additives has a positive effect on blending.

Impact of recycled asphalt pavement material variability on pavement performance

In recent years, recycled or reclaimed asphalt pavement (RAP) has been used increasingly due to its advantages in building sustainable pavement infrastructure. In the meantime, concerns have been raised regarding the performance of mixtures involving RAP. One of the major concerns comes from the material variability because it is believed to possibly result in poor pavement performance, particularly for mixtures with high RAP content. To address this issue, this study is conducted along two steps hierarchically. First, RAP samples were collected from four field stockpiles. RAP material variability was established based on laboratory testing. Second, a factorial design was carried out for designing mixtures with varying RAP contents ranging from low (10%) and medium (25%) to high (40%). In particular, different blending conditions between RAP and virgin binders, including zero, partial, and full blending, were considered. The Mechanistic–Empirical Pavement Design Guide was used to predict pavement performance including distresses and ride quality for each design scenario. The relationships (1) between the RAP content and performance variability and (2) among the variabilities of different performances due to RAP material variability are finally revealed.

Blending and diffusion of reclaimed asphalt pavement and virgin asphalt binders

An experimental study to understand the properties of reclaimed asphalt pavement (RAP), virgin binder and their respective blends was conducted. It was found that the current AASHTO (American Association of State Highway and Transportation Officials) M 323 specification recommendation to use one-grade softer performance graded asphalt at>15% RAP addition may not be justified. It is demonstrated that a binder grade change is not necessary up to 25% RAP in most blends. The ability of RAP and virgin binders to blend by diffusion at typical asphalt-mix production and placement temperatures and times was measured by a dynamic shear rheometer. A simulation showed that a complete binder blending in both hot-mix asphalt and warm-mix asphalt applications is reached within minutes after mixing. Nevertheless, binder layer thickness in the mix has a significant impact in these simulations and further understanding of binder film thickness in asphalt mix is necessary to accurately estimate degree of blending. Real mix data from Carpenter and Wolosick [(1980). Modifier influence in the characterization of hot-mix recycled material. Transportation Research Record, 777, 15–22] were successfully fitted with the diffusion model, demonstrating that the diffusion as measured for binders follows the same fundamental processes in the asphalt mix.

Low-temperature properties of plant-produced RAP mixtures in the Northeast

The impact of reclaimed asphalt pavement (RAP) materials on pavement performance is an important topic of study in the industry due to environmental and cost benefits. The primary concern for increasing allowable RAP percentages in hot mix asphalt relates to the presence of aged materials, which may embrittle the mixture and decrease cracking resistance. Low-temperature cracking is a major distress in cold temperature climates, such as the Northeastern United States. Currently, there are several procedures to analyse low-temperature performance of asphalt binders and mixtures. However, these methods use different starting (initial) temperatures and cooling rates that may not represent actual field temperatures and cooling rates. This paper presents the results of a study on low-temperature performance of plant-produced RAP mixtures. Eighteen mixtures from three states were tested with varying RAP contents (0–40%) and different virgin binder grades. The objectives of the study were to: (1) evaluate the impact of cooling rate and starting temperature on the critical cracking temperature of RAP materials; (2) evaluate the impact of RAP content on the low-temperature properties of mixtures; (3) evaluate the benefit of using softer virgin binder grades to mitigate the impact of the aged RAP binder in the mixture; and (4) to compare the low-temperature cracking properties determined from different mixture and binder tests. Based on the results, warmer starting temperatures and faster cooling rates result in warmer critical cracking temperatures for all mixtures. Through use of the uniaxial thermal stress strain test, it was found that the addition of RAP alters fracture behaviour from ductile failure towards a brittle failure. Based on results from the indirect tensile test, tensile strength increases with RAP content. However, due to a faster-building thermal stress, warmer critical cracking temperatures result. It was also determined that degree of blending may impact the effectiveness of using softer binder grades at higher RAP percentages to improve low temperature cracking resistance. The data also show that analysis procedure and test protocols can have a profound effect on critical cracking temperature. The conclusions presented reinforce the need for more accurate representation of RAP materials, and careful selection of analysis parameters.

Laboratory evaluation of asphalt mixtures with reclaimed asphalt shingle prepared using the wet process

The objective of this study is to conduct a laboratory evaluation of asphalt mixtures containing recycled asphalt shingles (RAS) prepared using the newly developed wet process. In the proposed wet process, the RAS material is blended with the binder at high temperature prior to mixing with the aggregates. The proposed wet process offers the potential to better control the Superpave Performance Grade of the binder blend, to stimulate chemical and physical interactions taking place in the blend between asphalt cement (AC) in shingles and virgin AC in the mix, and to reduce maintenance issues at the plant due to the high content of fines and fibres in RAS. To achieve this objective, AC blends were prepared using the wet process and an asphalt mixture with a nominal maximum aggregate size of 12.5 mm was designed according to the Superpave design protocol. The mechanistic properties of asphalt mixtures containing RAS materials were evaluated as compared to conventional asphalt mixtures. Laboratory testing evaluated the rutting performance, fracture performance, and low-temperature resistance of the produced mixtures using the Hamburg Loaded-Wheel Tester, the Semi-Circular Bending test, and the Thermal Stress Restrained Specimen Test. Based on the results of the experimental programme, it was determined that the use of RAS through the wet process allows the reduction of the virgin binder content with no adverse effects on the laboratory performance of the mixture as compared to the conventional mixture with no RAS. Results also indicated that the blending of RAS directly with its regular processed size at the recycling plant with no additional processing in the wet process is feasible with no foreseen adverse effects on the mixture performance. However, it is recommended that the RAS be processed to the finest processing size possible at the recycling facility to stimulate chemical and physical interactions between recycled and virgin materials. Based on these results, additional work is needed to simulate plant operations using the newly developed wet process. Furthermore, research is needed on the shingle AC availability factor and its variation for the dry and wet recycling processes.

Effects of Reclaimed Asphalt Pavement on Hot-mix Asphalt

Abstract This study examined the effects of reclaimed asphalt pavement (RAP) on the structural properties and performance of hot-mix asphalt (HMA) and the rheological properties of asphalt binder in the laboratory. As a first step, dynamic modulus (|E*|) and indirect tensile strength (ITS) tests were conducted on a set of HMA samples prepared with RAP and a set of HMA samples without RAP. The moisture susceptibility of samples with and without RAP was evaluated based on the |E*| ratio of wet to dry conditioned samples. Bending beam rheometer tests and direct tension tests were conducted on virgin binder, extracted binder, and RAP and aggregate mastics (mixture of binder and RAP and aggregate passing #200 to #50 sieves) to evaluate the low-temperature cracking. The results show that RAP materials caused an increase in |E*| and a decrease in ITS and had a negligible effect on moisture susceptibility. The RAP samples produced 15 % less permanent strain in |E*| testing than samples without RAP, which means that the RAP mixes were less susceptible to rutting. However, RAP mixed binder was more susceptible to low-temperature cracking as measured by the m-value (slope of the curve of stiffness versus time) and brittleness.

Multiscale Evaluation of the Composite Asphalt Binder in High–Reclaimed Asphalt Pavement Mixtures

AbstractIn this paper, various nanomechanical and macromechanical techniques were used to study the effect of a reclaimed asphalt pavement (RAP) binder on the microstructure and properties of a virgin asphalt binder and to evaluate the degree of blending that occurs between those binders. To this end, different atomic force microscopy (AFM) experiments (i.e., AFM tapping mode imaging, AFM nanoindentation, AFM force spectroscopy experiments) were conducted on a virgin asphalt binder, a recovered RAP binder, and their composite. In addition, dynamic shear rheometer (DSR) tests were conducted on the evaluated binders, and the dynamic modulus tests were performed on mixtures prepared using those binders to evaluate the degree of RAP blending and compare it with those obtained using the AFM test results. The results of the AFM images indicated that blending between the RAP and virgin binders occurs at the nano/microscale level in the composite binder at a fairly uniform manner. Furthermore, the nanoindentation...

Rutting Evaluation of Aged Binder Containing Waste Engine Oil

The stiffness of aged binder is highly contributed to the workability problem. Rejuvenating agent such as waste engine oil (WEO) is one of the sustainable modifiers that can be used to improve and attain the desired performance of the aged binder. However, concern arises on the consistency of the engine oil properties due to its unknown history usage. This study focused on the rutting properties evaluation of the partial aged binder integrating with engine oil (new and waste sources) using Dynamic Shear Rheometer (DSR). The findings showed that, the addition of WEO affects the rutting performance under ageing condition. From the isochronal curve, the complex modulus, G* of the rejuvenated binder was found lower than the aged binder at un-aged condition. However, after ageing process, the stiffness of the rejuvenated binder was increased and the phase angle, δ decreased obviously compared to virgin binder. The critical temperature of the binder was not differing substantially particularly under ageing. Meanwhile, the ageing index rutting factor (AIRF) clearly summarised that the rejuvenated binder with WEO with higher mass loss more susceptible to ageing.

The Performance of Aged Asphalt Materials Rejuvenated with Waste Engine Oil

The ability to recycle large amounts of asphalt pavement hinges on the capability of restoring the properties of the aged asphalt binder contained within the old pavement to that of virgin binder. Common practice in asphalt pavement recycling is to blend reclaimed asphalt pavements (RAP) with a recycling agent to chemically restore the aged asphalt binder. Waste engine oil from automobiles has been shown to improve asphalt binder when applied in small quantities, with the added advantage of being a waste product itself. Using waste engine oil as a chemical additive to restore the properties of RAP uses one waste material to increase the recyclability of another, which is environmentally and socially desirable.In this study, a PG 58-28 neat, virgin binder was blended with reclaimed asphalt binder (RAB) and waste engine oil. The blends were then tested to study the interactions between RAB and waste engine oil. Using Fourier-Transform Infrared Spectroscopy (FT-IR), the differences in the samples were compared using the structural indices associated with asphalt binder aging. This testing revealed a decrease in the two aging indices of the blended asphalt binder, indicating that waste engine oil has the ability to chemically restore aged asphalt binder.Asphalt mixture testing was then performed with mixtures of virgin asphalt, virgin binder, RAP and waste engine oil, in quantities similar to the binder testing, to see if the rejuvenation shown in FT-IR led to an improvement in the performance of the pavement specimens. After specimens were created, testing for freeze thaw durability, and rutting susceptibility was conducted. The results of the mixture testing failed to show an improvement of the freeze thaw durability or rutting susceptibility of specimens created with RAP and waste engine oil when compared to mixtures containing only new materials.

Characteristics of Virgin and Recycled Asphalt Shingle Binder Blends

Application of recycled asphalt shingles (RAS) into hot-mix asphalt have been well accepted by many transportation agencies in recent years. However, limited information on virgin-RAS binder blends is available. This study focused on the rheological and chemical characteristics of different blends. Two virgin binders (PG 64-22A and PG 64-22B) and three RAS binders (original RAS binder, extracted RAS binders from tear-off, and manufacture waste asphalt shingles) were used. Different from the well-known linear blending of virgin and reclaimed asphalt pavement binders, the virgin and RAS binder blending followed a nonlinear trend. The nonlinear behavior was found to relate closely to the asphaltene content of the virgin and RAS blends. Furthermore, the identified nonlinear behavior could be described by a simple linear equation because the normalized increase in high-temperature performance grade varied linearly with the increase in the RAS binder content. The Christensen–Anderson (CA) model and the Williams–Landel–Ferry (WLF) shifting equation successfully described the complex shear modulus behavior of different blends of virgin and RAS binders. The results also showed that adding RAS binders to virgin binders had a similar impact as that of aging on rheological parameters such as the rheological index, crossover frequency, and WLF parameters. The addition of RAS binder reduced the temperature susceptibility of virgin binders. In addition, the study found that the carbonyl area measured with a Fourier transform infrared-attenuated total reflectance spectroscopy was highly related to the CA model and the WLF shifting parameters.

INVESTIGATING EFFECTS OF AMINE BASED MODIFIER ON RECYCLED ASPHALT SHINGLES BLENDING

A laboratory study was conducted to investigate the effects of Amine based modifier on rheological characteristics of particle filled viscous medium such as asphalt binder in presence of Recycled Asphalt Shingles (RAS). In this study, virgin asphalt binder (PG 64-22), three different percentages (20, 30 and 40%) of tear-off shingles and modifiers; Rediset, Evotherm and Bio-binder were used. The tear-off shingles acquired from local reroofing company in Greensboro, North Carolina; were finely grinded (85% passing of sieve # 200). The virgin binder and different percentages of RAS were then blended at 180°C using shearing speed of 400 rpm. Following that themixture was blended with 1.5% of Rediset, 0.5% of Evotherm and 5% of bio-binder. The properties of the blended binder were studied using the Rotational Viscometer (RV) equipped with two different spindle types:- One was Smooth Cylindrical spindle (SC4-27D) and the other one was Vane spindle (V 73). The analysis showed that the viscosity was increased with increasing the RAS percentage. Furthermore, the viscosity measured by vane spindle was continuously higher than the value measured by smooth spindle; however the difference between the two measurements reduced as the blending were improved using modifiers. Moreover, temperature found to be the main contributor to reduction of the viscosity in both spindles cases. In addition the coefficient of variation was significantly lower in the case of vane spindle, indicating that the vane spindle could be more appropriate in measuring viscosity of particle filled viscous medium such as RAS asphalt. Based on the experimental result an empirical index called blending index was introduced in this study to measure the blending behavior and status for modified mixtures. As expected it was found that the blending index increases as the temperature and rotational speed increases. In other word, higher temperature and shearing rate could enhance blending resulting in higher blending index. The blending index was further used as a laboratory measure to compare effectiveness of various additives in enhancing blending of RAS modified mixtures. It was shown that among three modifiers used in this study, the bio-binder was more effective to increase the blending index.

Innovative Testing Protocol for Evaluation of Binder-Reclaimed Aggregate Bond Strength

The durability of asphalt mixtures is strongly related to the adhesion properties developed at the interface between binder and aggregates. The loss of adhesion implies a rapid deterioration (e.g., stripping or raveling) of pavement layers under traffic loads, especially when the pavement is affected by the presence of moisture. Adhesion is a complex phenomenon related to the mineralogical and morphological nature of aggregates as well as to the chemical binder composition and the environmental conditions. The evaluation of adhesion has become even more complicated as an increasing percentage of reclaimed asphalt pavement (RAP) is used in the production of new asphalt mixes. Therefore, adhesion properties are also related to the mechanisms developed at the interface between virgin binder and aged binder that coats the RAP aggregate surface. An innovative procedure to evaluate the compatibility of the system virgin binder–RAP aggregate was proposed in this study. This procedure allowed the substrate of a RAP aggregate to be simulated in the laboratory and could integrate the binder bond strength test currently used to investigate bonding properties and water sensitivity of the system binder and virgin aggregates. Tests were performed with various aggregate sources, several modified binders, and two conditioning types (dry and wet). It was found that the procedure was able to discriminate different test configurations and variables. In particular, the artificial reclaimed aggregate substrate ensured higher adhesion performance compared with the virgin aggregate, especially in the wet condition, regardless of the modification level of the virgin bitumen.

Application of Diffusion Mechanism

There are many concerns about the blending between virgin and aged binders in reclaimed asphalt pavement (RAP). Determining the extent of the blending and identifying the main factors affecting the blending between two binders have gained great interest in recent years. Viscosity as a function of temperature, exposure time, and film thickness have been mentioned as the main factors controlling the blending between two binders that are in contact. The in-contact blending between two binders is hypothesized to be governed by a diffusion phenomenon in which material is transferred through a medium because of the Brownian motion of molecules. This study aimed to estimate the rate of diffusion of virgin binder (as the diffusing matter) into the RAP binder, which controls the blending of two binders during exposure. The effect of temperature, which was considered as the main factor influencing the diffusion rate, was evaluated at varying levels. Fick's law calculations and dynamic shear rheometer (DSR) measurements were fitted to estimate the diffusion rate. The results showed a high dependency of diffusion on the temperature (viscosity) of binders. The blending development was also found to be a function of the diffusion rate and exposure time. A DSR test method was applied to RAP mortars (mix of RAP fine particles and fresh binder) to verify the effect of time and temperature on the blending level between fresh and actual RAP binders. The results of mortar testing verified the factors affecting the diffusion phenomenon.

Turning Back Time

Countermeasures to the aging of bituminous asphalt binders is a highly important topic for service-life extension of asphalt in the field and for recycling old pavements into new structures with similar functional requirements as the original structure. Countermeasures are usually achieved by applying additives that restore the adhesive and mechanical properties of the original bituminous binder. The additives are commonly termed (asphalt) rejuvenators. This study examined the performance of two very distinct rejuvenating agents. The effectiveness of rejuvenators is usually measured by comparing the penetration and softening point of the rejuvenator-aged bitumen blend with reference values of the virgin binder. The study used a dynamic shear rheometer to evaluate the rejuvenating capabilities of the two additives. The microstructures of the virgin binder and the rejuvenated blends were obtained by atomic force microscopy. Subsequently, the rheological results were related to the microstructure morphologies. From the rheological experiments, both rejuvenators exhibited the desired softening and property-restoring performance. However, there was a strong difference in the amount of rejuvenator needed to achieve complete rejuvenation. By correlating rheology to the microstructural observations, the effects of the rejuvenators were found to be distinct at microscopic length scales: rejuvenation was achieved by distinct chemophysical mechanisms. One of the rejuvenators restored the virgin microstructure, whereas the other rejuvenator generated a new morphology. Thus, the study demonstrated that by combining rheological and microstructural techniques, the mechanism and performance of rejuvenation can be understood. This finding may help guide future designs and optimization of asphalt-rejuvenating agents.

Evaluation of Production, Construction, and Properties of High Reclaimed Asphalt Pavement Mixture

In 2007, the Virginia Department of Transportation (DOT) introduced specifications to allow reclaimed asphalt pavement (RAP) percentages of up to 30% in asphalt surface mixtures without a change in the virgin binder grade. Since 2007, increasing material costs and a growing awareness of the quantity of RAP available for use have sparked interest in asphalt mixtures having a higher percentage of RAP. Recently, the Virginia DOT began to consider the feasibility of allowing the use of surface mixtures with RAP contents of up to 45%, and in June 2013 a trial was constructed containing mixtures with 20%, 30%, 40%, and 45% RAP for evaluation. The initial construction and laboratory data (including volumetric, modulus, and flow number results) and a discussion of the lessons learned from this experience are presented. In general, mixtures containing up to 45% RAP can be successfully designed, produced, and constructed if proper procedures are followed and if attention to detail is paid during design, production, and construction. In addition, dynamic modulus and flow number test results indicated that no significant difference in performance should be expected between the mixtures evaluated, despite slight differences in volumetric properties.