Aged Pavement Research Articles

Utilization of Multiple Recycled Materials in Asphalt Concrete: Mechanical Characterization and Cost-Benefit Analysis.

This study examines the strategic incorporation of various recycled materials into asphalt concrete, specifically focusing on municipal solid waste incineration bottom ash (MSWI BA), recycled asphalt shingle (RAS), and recycled concrete aggregate (RCA). Due to the high porosity of MSWI BA and RCA, and the significant asphalt binder content (30-40%) found in RAS, there is a need to increase the amount of liquid asphalt used. RAS is posited as an efficient substitute for the asphalt binder, helping to counterbalance the high absorption characteristics of MSWI BA and RCA. The research objective is to quantitatively evaluate the effect of the combined use of RAS, MSWI BA, and RCA in Hot Mix Asphalt (HMA). This study encompasses several laboratory evaluations (i.e., rutting and tensile strength tests) and a cost-benefit analysis, which is a life cycle cost analysis. The results indicate that the combined use of these materials results in a higher tensile strength and rut resistance when compared with the control (with virgin aggregate). According to the cost-benefit analysis result, when the three recycled materials are used for an HMA overlay over an existing aged pavement, it could be 60-80% more cost-effective compared to a conventional HMA overlay, thereby offering significant economical savings each year in the field of road construction.

A Review on Virgin or Waste Polymers in Bitumen Modification for Ageing and Rejuvenation

AbstractThe physicochemical behavior of polymer‐modified binders suggests suitability for rejuvenating aged pavements and meets base bitumen parameters. The strengthening effect is mainly due to their electronic structures, which interact with asphaltene via CH‐π interactions and crosslinkage reaction with S–H and O–H bonds of base bitumen, along with the virgin and waste polymers used. The functional groups in bitumen play a vital role in enhanced paving resistance after modification. This review aims to provide an overview of the current knowledge on the role of polymers in bitumen modification and to identify research gaps. It also discusses underutilized technologies, methods, and future research perspectives to implement more effective road networks for an environmentally sustainable development.

Development of an Estimation Method for Depth of Spalling Damage in Concrete Pavement by Ultrasonic Velocity Measurement

As the amount of aged pavement increases, functional damage, such as spalling, occurs frequently on Portland Cement Concrete pavement (PCC) in South Korea. However, the existing management method does not properly reflect the scope of deterioration of the pavement causing early damage. To overcome the problem of the existing repair method, this study evaluated the deterioration of functional damage on the surface of the slab as soundness through ultrasonic velocity measurement method among non-destructive testing (NDT) techniques and suggested a method to estimate the depth of deterioration. To develop a method for estimating the depth of the deterioration a slab, a preliminary investigation was conducted to check the range of ultrasonic velocity of concrete pavement in South Korea and to evaluate the variability of NDT equipment. Based on the ultrasonic velocity, the sound rating of concrete pavement was graded from 5 for “very good” to 0 for “very poor”, and the tendency of the ultrasonic velocity to increase according to the depth of the deteriorated areas was confirmed.

Functional characterization of a Cold-In place-Recycled pavement at different stages of the curing process

Cold-In place-Recycled (CIR) pavements are an environmentally friendly option for road rehabilitation operations on aged pavements. These pavements are generally employed as base layers, and a surface treatment is performed on them. However, the design of new additives and enhancements in the technique for constructing CIR pavements have enabled such pavements to be used as wearing courses in some cases. In this context, research on the functional characteristics of CIR pavements is required for characterizing their performance and, therefore, broaden their knowledge and use as a noise mitigation measure. The aim of this study is to analyze some of these functional characteristics: tire/pavement sound levels, texture, and dynamic stiffness. An experimental test track section was evaluated during the pavement curing process (very short term) by means of laboratory and field auscultation. Different measurement campaigns were conducted at different stages of the pavement curing process. According to our results, the changes in the pavement during curing lead to higher tire/pavement sound levels due to the evolution of the dynamic stiffness of the pavement. The increase in tire/pavement noise levels is mainly located at the peak frequencies (800–1250 Hz) of the sound spectra, with values from 76.2 dB(A) to 81.5 dB(A) at 800 Hz. The differences among the mean values of the macrotexture (Mean Profile Depth — MPD) do not explain the different overall tire/pavement noise levels measured at the different stages of curing. However, the texture spectrum undergoes an evolution. The initial texture levels, with wavelengths between 100 mm and 500 mm decrease during the curing process.

Performance Evaluation of Fiber-Reinforced, Stress Relief Asphalt Layers to Suppress Reflective Cracks

In this study, the performance of the fiber-reinforced, stress-absorbing membrane interlayer (F-SAMI) method was evaluated to suppress reflective cracks, which usually occur when the overlay method is applied for the maintenance of existing aged pavement. The F-SAMI method has an effect of suppressing the occurrence of reflective cracks by constructing a material composed of emulsified asphalt, fibers, and aggregates between the surface layer and the base layer. The mechanical performance of the F-SAMI was evaluated through both small-scale (model mobile load simulator 3, or MMLS3) and large-scale (accelerated pavement testing, or APT) pavement acceleration tests on the specimen and pavement structures, respectively, with the F-SAMI layer applied between the surface layer and the base layer. In this study, the base layer was made with an asphalt mixture or a concrete mixture, and the surface layer was made with polymer-modified stone mastic asphalt (PSMA). Evaluation was conducted by applying four types of F-SAMI layer, according to the content of asphalt and aggregate and compared with the case where general tack coating was applied. In order to induce the occurrence of reflective cracks, a notch was made in the center of the base layer. As a result of the experiment, it was shown that regardless of the mixture type of the base layer, the specimen or pavement with the F-SAMI method was much more resistant to reflective cracking than those with the tack coating. In addition, it was found that the F-SAMI method with aggregates was more resistant to reflective cracks than that without aggregates.

Short- and long-term rheological and chemical characteristics of nanomodified asphalt binder

Due to the special characteristics of nanoparticles, pavement engineers have used nanoparticles as an additive in asphalt pavement to improve pavement performance. This study focuses on characterizing modified asphalt performance using nanoclay particles compared to the unmodified asphalt binder. For this evaluation, 3% of nanoclay particles were added to a neat binder to prepare the nanomodified binder. Then, the modified and unmodified binders underwent a short- and long-term aging process using the Rolling Thin Film Oven (RTFO) and two cycles of Pressure Aging Vessel (PAV). Finally, the Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), and Fourier-Transform Infrared Spectroscopy - Attenuated Total Reflection (FTIR-ATR) tests were carried out in each aging step to assess and monitor the rutting, fatigue, low-temperature performance, durability, and chemical changes of binders during the aging process. The results of this study proved the enhanced properties and performances of the nanomodified binder compared to the unmodified binder. These results can pave the path with the use of nanomodified binders in the recycling of aged pavement and construction of roads that experience poor weather conditions and high traffic loads.

Development of representative section selection method for large-scale concrete pavement remodeling project based on trial and error correction approach

In this study, a method to identify the representative section (RS) which can represent the pavement conditions of entire aged concrete expressway pavement (CEP) sections for the large-scale remodeling project, was developed based on pavement management system (PMS) data and an optimized approach. To fulfill this objective, various PMS data sets on the target section (TS) of concrete expressway pavement that exceeded 20 years of design life were collected with 100m intervals. Then, the first version of the optimized 100 RSs, which was a reasonable amount of data for analysis of aged CEP condition, was selected based on the different severity levels of surface damage and international roughness index (IRI) data. Secondly, another crucial PMS factor: the alkali-silica reaction (ASR) severity level, was considered and substituted partially in the previously selected 100 RSs to provide additional and reasonable representative characteristics. Finally, the characteristics of the RS were evaluated and verified by considering whether the various distress size rankings of the RS were uniformly distributed within the entire distress size ranking of the total jointed concrete pavement (JCP) and continuously reinforced concrete pavement (CRCP) TS. It was found that the RS selection approach and corresponding criteria proposed in this study, based on the optimization approach, could be successfully used to determine the future large-scale remodeling priority of the old concrete expressway pavements.

Sustainable and Cost-Effective Pavement Preservation Method: Micromilling and Thin Overlay

AbstractTo respond to funding shortages and sustainably preserve their aged pavements, transportation agencies are forced to go beyond conventional thinking to develop innovative, cost-effective pa...

Laboratory and Field Investigation of the Effects of Biosealant Applications to the Surface of Asphalt Pavement

AbstractPavement preservation plays a significant role in maintaining aging pavement infrastructure under severe budget constraints. An important component in this is the application of sealants to...

Rheological characterization of asphalt binders treated with bio sealants for pavement preservation

Pavement preservation is playing an increasingly significant role in maintaining our aged pavement infrastructure under severe budget constraints. One important component is the use of surface treatments based on application of sealants. Recently, a number of new products, called bio sealants, have been used to treat aging pavement surfaces. The objective of this study is to investigate rheological properties of the binders treated with these materials to understand the mechanism by which they may improve pavement performance. One plain asphalt binder and four types of sealants, two oil-based sealants, one water-based sealant, and one traditional emulsion were used in the experimental work. The results obtained using a dynamic shear rheometer and a bending beam rheometer were used to determine the changes in rheological properties and the change in performance grade. It was observed that the oil-based sealants have a significant softening effect of the control binder compared to the water-based sealants. The transverse cracking histories from field investigation were used to verify the laboratory findings.

Incorporating the transverse profile of the wearing course into the control of the hot in-place recycling of asphalt concrete

The hot in-place recycling (HIR) of asphalt concrete (AC) is one of the least CO2 emissive reuse techniques. It allows for 100% reuse of material in-situ in the same application, at a reduced need for the material transport to and back from the construction site, as well as the reduced price in comparison with the fresh wearing course overlay. Finland uses the technique predominantly to fill wheel path ruts caused by the studded tire abrasion, to retain structural capacity and prevent hydroplaning. During the HIR process, the aged AC material is heated up in-situ, milled to the approximate depth of 40 mm, blended with fresh AC admixture and rejuvenator. However, the amount of the aged material and the amount of the aged bitumen that undergoes rejuvenation depends on the pavement transverse profile. The rut depth, width and shape determine the minimum volume of admixture necessary for refill during the process in order to retain the structural capacity, as well as the amount of the aged binder requiring rejuvenation. In favor of achieving homogenous rheological properties in the final product, the proportion between the aged binder and the fresh binder should be controlled, as it influences the required amount of rejuvenator. Therefore, the rut cross-sectional area and furthermore, the rut volume is one of the previously unrecognized or ignored major variables of the hot in-place recycling process in Finland that should be incorporated to the HIR process control. This article demonstrates the methodology of incorporating the transverse road profile measurements by 17 vehicle-mounted laser sensors into the calculation of required rejuvenator amounts. This can be done during the procurement preparation phase or during the paving work as a continuous in-situ process control. In the rheological optimization the apparent Newtonian viscosity concept and the rotational viscosity are utilized in the viscosity based blending equation, which then allows the use of oily rejuvenators. The method reduces the need for aged pavement sampling compared with the determination of the calibration curve between rejuvenator concentration and the rheological response. Additionally, the apparent Newtonian viscosity corrects the complex viscosity by the phase angle derived correction factor, opening a previously unexplored opportunity of targeting desired viscoelastic characteristics. The approach is less sensitive to the frequencies and temperatures at which the shear measurements are conducted. This makes proposed calculative method of the desired proportioning of the aged binder, the fresh binder and the rejuvenator a promising tool for the industry. The combined algorithm presented allows for: the discrimination of sites where HIR type maintenance of pavement in question would result in a substandard product; the choice of the most promising material combination of the admixture and rejuvenator, as well as for the adjustment of the admixture and rejuvenator amount in-place.

Resistivity, Penetrability and Porosity of Concrete: A Tripartite Relationship

Abstract Demands for using electrical resistivity techniques (surface and bulk resistivity) as an alternative to the rapid chloride penetrability test (RCPT) have been growing, for example by a number of transportation agencies in North America, to give an indication of the relative penetrability of concrete. While resistivity measurements may reflect the quality of pore structure in the cementitious matrix, their accuracy might be affected by a multitude of parameters including the concentration of ionic species in the pore solution, particularly when supplementary cementitious materials (SCMs) are incorporated in the binder. Hence, a systematic investigation on the resistivity of concrete and its corresponding physical penetrability is warranted. The main objective of this study was to establish a tripartite relationship (nomogram) to correlate surface resistivity with penetrability (migration coefficient) and porosity of concrete using a wide range of concrete mixtures, taking into account the effect of key mixture design parameters (water-to-binder ratio, air-entrainment, SCMs, and type of cement). Relationships between surface and bulk resistivity as well as migration coefficient and porosity of concrete were also established. In addition, a penetrability classification of concrete based on the corresponding ranges of surface resistivity, migration coefficient, and porosity has been proposed. The efficacy/practicality of the proposed classification was evaluated by comparing the predicted migration coefficient and porosity, based on surface resistivity of concrete, to the measured ones for field cores extracted from concrete pavement in Winnipeg, Canada. For newly constructed and aging pavement, the nomogram and penetrability classification provided reasonable assessment for the condition of field concrete.

Density Observations from a Full-Scale, Untrafficked Test Section with Guidance for Dryback Methods

This paper presents a discussion with data on factors related to the in-place density measurement of asphalt pavements. A review of the literature traces changes to asphalt density measurement technologies over the past 60 years. Two phases of investigation then are presented in which in-place density was evaluated for an ongoing study of environmental effects at a test section in Columbus, Mississippi. A series of laboratory and field activities was performed in Phase 1. In Phase 2, studies were made of laboratory drying practices of specimens that were cored after an extended period of field aging. The key conclusion from these efforts was that ASTM D7227 might not remove sufficient moisture from some specimens to achieve accurate density measurement when pavements have been exposed to moisture for extended periods of time. This paper presents a case with an average error in air void measurement of 0.9% (measured 9.1% when 10% was correct) for specimens that were cored, dried according to ASTM D7227, and then measured for mass in air 1 day later. This finding is of most concern to rehabilitation and research work in areas in which aggregates have high potential for absorption but is of no concern to new construction projects. Furthermore, the work presented here validated the use of ASTM D7227 in circumstances in which mixtures were exposed to moisture for short periods of time. The work also suggested three options to take to accurately measure in-place density for performance testing of aged pavements that contain high-absorption aggregates (i.e., dry in oven, develop correlation equations, or dry for several weeks).

Constitutive modeling of coupled aging-viscoelastic response of asphalt concrete

Oxidative aging is one of the most important processes affecting the time-dependent response of asphalt concrete materials, which subsequently results in brittleness of the material and fatigue damage. This paper proposes a mechanistic-based constitutive relationship of oxidative aging based on the evolution of a physically-based aging state variable. The aging constitutive relationship is coupled to the viscoelastic response of asphalt concrete by making both the creep compliance and relaxation time terms a function of the aging variable. The coupled oxidative aging-viscoelastic constitutive relationship is calibrated by analyzing the results of dynamic modulus testing conducted at different temperatures and frequencies on aged and unaged laboratory specimens with different air void contents ranging from 4% to 10%. The coupled constitutive relationships is validated against multiple repeated creep-recovery tests conducted on aged and unaged specimens at different stress levels, temperatures, and air void contents. The results illustrate the capabilities of the coupled oxidative aging-viscoelastic constitutive relationship to predict the viscoelastic response of aged asphalt concrete materials. Finally, the effect of oxidative aging on viscoelastic performance of aged pavement structures is investigated by: (a) applying a state-of-the-art experimental-computational method to determine oxygen diffusivity of asphalt concrete mixtures, and (b) conducting 2D finite element (FE) simulation of aged and unaged pavements.

Evaluation of a Traffic Lane Closure and Pavement Repair for a Certain Period (Focusing on the Gimcheon~Sunsan Project)

PURPOSES : This study supports the evidence that it is possible to rehabilitate a damaged pavement with a lane closure specifically based on the Gimcheon~Sunsan project. METHODS : The prediction results from the simulation programs were compared with field monitoring, which focused on traffic management planning, congestion (length, time, and passing speed), bypass, and user cost, among others. RESULTS : The research results showed that lane closure application and pavement repair of the aged pavement in Korea were possible, even though the prediction results were minimally different from the field monitoring. The road agency contributes to service life extension of the rehabilitated pavement using this method. CONCLUSIONS : A marginal effect caused by the lane closure was observed on travelling users or vehicles, and the user cost of pavement repair decreased. Therefore, introducing the repair method or rehabilitation in Korea is possible. Information dissemination through various media was properly done to execute the project well. Moreover, the construction area traffic utilized nearby alternative roads. Therefore, improving the repaired pavemen`s service life while ensuring that the pavement management agency can provide a road with comfortable user riding quality was possible.

Rheological, chemical and thermal investigations on an aged binder rejuvenated with two non-edible oils

The aged pavement material from a defunct pavement – commonly known as reclaimed asphalt pavement (RAP) – contains stiffened binder caused by loss of volatile materials and oxidation. Therefore, addition of a high amount of the RAP to asphalt mix, in case of pavement recycling, may make it prone to fatigue failure. Due to this reason, the addition of RAP to asphalt mixture in substantial amount has been a challenge so far. “Rejuvenators” are generally used to restore the properties of the aged binders in the recycled mixes. The present study deals with the assessment of two non-edible oils, that is, pongamia oil and composite castor oil (a composite rejuvenator having castor oil and coke-oven gas condensate) as asphalt rejuvenators to achieve 100% RAP recycling. The study mainly comprises rheological characterisation studies such as rutting behaviour, fatigue behaviour, dynamic mechanical analysis and creep-recovery studies of the rejuvenated binder specimens. Chemical investigations using infrared spectroscopy also affirmed use of these oils in effectively restoring the properties of aged binders. In addition, for assessment of the long-term performance in terms of thermostability of the rejuvenated binders, a thermal analysis was carried out using a simultaneous thermal analyser, which confirmed the adequate thermal stability of the rejuvenated binders. From the investigations taken up under this study, it was concluded that 5% oil (for both pongamia and composite castor oil) rejuvenated aged binder could show desirable rutting and fatigue behaviours and sometimes even better than the virgin binder. However, its confirmation can be laid only after suitable mix performance studies.

Urban pavements used in Brazil: Characterization of solar reflectance and temperature verification in the field

This paper presents the results for the solar reflectance and temperature of 20 types of pavements used in Brazil for roads, parking lots, squares and sidewalks. New and aged pavement samples were tested. Some asphalt mixtures and Portland concrete mixtures were developed in the laboratory, with the addition of colored pigments in different percentages. The standard method ASTM E1918 and the procedure E1918A were used to measure solar reflectance of the pavements in the field. The difference between the surface reflectance values for surfaces with a lighter (white Portuguese mosaic) and darker (Reference CPA asphalt mixture) appearance was approximately 48%, and the corresponding difference in the measure surface temperature was 18.4°C. A correlation between the solar reflectance and the temperature measured in the field is reported. The results obtained can be used as a reference to design public spaces, contributing to reducing the urban heat island (UHI) and improving the thermal comfort of the users.

Performance Evaluation of Aged Asphalt Mix for Hot In-Place Recycling

Abstract Despite increasing application, limited knowledge is known of in situ and laboratory properties of asphalt mixes placed through hot in-place recycling (HIR). This study conducted a preliminary investigation to inspect the individual and joint effects of binder (aged or rejuvenated) and gradation (decayed or normal) on respective performance indicators. Three mixes were designed and the properties were determined, including mix A collected from aged asphalt pavement, mix B designed with the same gradation of mix A but using virgin materials, and mix C designed with the initial construction aggregate gradation of the aged pavement section using virgin materials. The experimental program was carried out at the binder/aggregate, mortar and mix levels. The binder property, aggregate quality, and gradation of mix A were changed compared to the initial design, and the proper dosage of rejuvenator is able to restore the binder properties largely except for ductility. Asphalt mortars of mixes A and B were prepared and submitted for repeated shear at constant height (RSCH) and frequency sweep at constant height (FSCH) tests and found that the former has a better rutting resistance in terms of the Gv (viscous component of creep stiffness) and complex shear modulus G*, whereas poorer low-temperature and fatigue performances in terms of the glassy modulus G*g and NP20. At the mix level, master curves of the three mixes were developed by dynamic modulus tests and revealed disparate viscoelastic properties, of which mix C is mostly desired. Binder aging and gradation decay work contradictorily, determining flow number test results so that mixes A and C have close and higher flow number values than mix B. Fatigue and low-temperature fracture properties were evaluated by semi-circular bending tests and indicated the poorest performance for mix A because of binder aging and gradation decay.

Valoración de la fisuración refleja ante cargas dinámicas interponiendo geosintético a diferentes niveles de la capa de refuerzo asfáltico

Load demands on pavements, due to repeated vehicle loads and environmental conditions, generate a constant deterioration of the structure, which causes the loss of mechanical properties, thereby producing a structural and functional loss on the road. Nowadays, one of the most common problem, which is difficult to control due to these load demands, is reflective cracking, a phenomenon that explains the propagation of existing cracks in lower layers or coinciding with joint movements of an aged pavement, towards the new reinforcement layer, which copies the pathology of the same. The study evaluates the behavior of reflective cracking while varying the location of the geosynthetic material between each asphalt mix layer, and subjecting the system to dynamic loading. The geosynthetic reinforcement considerably delays the progression of the crack, and the greatest effectiveness is obtained when this material is located nearest to the most stressed fiber of the reinforcement layer. Rev. ing. constr. [online]. 2015, vol.30, n.3, pp. 201-209. ISSN 0718-5073. http://dx.doi.org/10.4067/S0718-50732015000300005

Addressing Durability of Asphalt Concrete by Self-healing Mechanism

Every year a huge amount of energy and economic resources are employed in preservation and renovation of the existing pavements. In the last years, rejuvenators are being used in road maintenance works by restoring the original properties of the aged pavement. The main problem is that once the rejuvenator is spread on the road surface to be effective it must penetrate into the pavement not only in the first centimeters. An innovation procedure to solve this problem is the addition of encapsulated rejuvenators into the asphalt mixes. Once the rejuvenator is released, it will be in contact with the bitumen around restoring the original properties of the binder and increasing the self-healing rate by closing the cracks or limiting its growth. In the present work two encapsulation methods developed by the authors are described. The first one, porous aggregates with the rejuvenator embedded were prepared; the second one polymeric shell microcapsules containing the rejuvenator were synthesized. After preparation and encapsulation of the healing agent, the capsules were embedded into the bituminous matrix. Finally, the autonomous repairing capability was validated through a variety of comparative laboratory tests. Results from this study indicate that the self-healing chemistry developed has a high potential for its use in asphalt pavements by increasing its durability.