Pavement Rehabilitation Techniques Research Articles

Forecast of post-overlay flexible pavement roughness progression: a random coefficient linear regression with autocorrelation model

Abstract A pavement roughness progression model is an essential component in a pavement management system. Asphalt overlay is a typical pavement maintenance and rehabilitation (M&R) technique. To schedule asphalt overlay in a timely fashion, the relationship between the asphalt overlay design and post-overlay roughness progression is required. However, due to difficulty in data compilation and model development, the effect of endogenous overlay design and continuous variation of asphalt overlay thickness on post-overlay roughness progression is not documented. This study aims to develop a comprehensive post-overlay flexible pavement roughness model with long-term pavement performance (LTPP) data. The asphalt overlay projects from the LTPP SPS-3, SPS-5, and GPS-6 programs were incorporated for data analysis. A random coefficient linear regression with autocorrelation (RCLRA) model is proposed to simultaneously address endogenous overlay design issue, between-section heterogeneity issues, and within-section serial correlation issues in the post-overlay roughness progression. By addressing the within-section serial correlation, the proposed post-overlay roughness model can reduce the mean absolute percentage error (MAPE) from 21.26 percent to 2.19 percent. The model estimation results provide some new insights into the relationship between post-overlay roughness and asphalt overlay design factors. An endogenous overlay design indicator, continuous variation of asphalt overlay thickness, the relative fatigue cracking area, and severe rutting indicator are first identified to have significant effects on post-overlay roughness progression.

Characterization of Cold Bituminous Mastics Prepared with Different Active Fillers at High and Intermediate Temperature

Cold recycling of asphalt mixes is becoming a usual pavement rehabilitation technique. The use of active fillers in conjunction with bituminous emulsion changes the properties of the mixes, mainly on the mastic characteristics. The use of active filler can make the mastic more brittle, but limited data are available on this aspect. In this study, emulsion-active filler mastics were prepared with two different mixing methods. Two different active fillers, ordinary Portland cement and fly ash, were used at four different contents with a single emulsion and an inert filler. Once cured, the mastics were tested with a dynamic shear rheometer (DSR) to get the viscoelastic properties at high temperature and with the double-edge-notched tension (DENT) test to look at the cracking potential at intermediate temperature. The results show that the order that the materials are incorporated during the mixing of the mastics does have a significant effect on the properties. Also, in terms of stiffness, the optimum amount of active filler is different for the cement than for the fly ash. For the cracking resistance, the results have shown that the addition of both active fillers does have an impact on the cracking resistance, but in the amount tested, no brittle fracture was observed. The results have shown that the type and quantity of active filler are important since it changes the fracture performance and the viscoelastic properties of bituminous mastic.

Economic and Environmental Cost Analysis of Cold In-Place Recycling

The purpose of this study is to evaluate and quantify the construction costs, energy costs, and environmental benefits of using cold in-place recycling (CIR) as a pavement rehabilitation technique. For this study, the costs of using CIR mixes prepared using either asphalt emulsion (CIR-E) or foamed asphalt (CIR-F) were compared with conventional 5.1-cm (2-in.) hot-mix asphalt (HMA) mill and overlays. Three different costs were considered for the production of each pavement rehabilitation technique: (1) construction, (2) energy, and (3) environmental costs. To facilitate the cost comparisons, an equivalent pavement structural analysis was conducted between each pavement rehabilitation technique using a standard design method. The results of the study showed that initial construction costs of using CIR are less than the conventional HMA mill and overlay. The energy and environmental costs were also found to be much lower for CIR mixtures compared with the HMA mill and overlay, with energy savings of up to 63%. Overall, when considering all costs, the use of CIR has lower costs compared with traditional HMA overlays. Cost savings of approximately $34,000–$39,000 were observed when using CIR with HMA overlays, with a total cost savings between 41% and 47% over traditional HMA mill and overlays. This study gives an overall procedure for assessing the economic and environmental costs of different pavement rehabilitation techniques and provides further evidence of the cost benefits associated with CIR to practitioners.

Developing specifications for precast concrete highway pavements

ABSTRACT Precast Concrete Pavements (PCP) can be used as an accelerated rehabilitation technique for concrete pavements. The goals of this research study was to develop a PCP system approval process for potential implementation by state Departments of Transportation (DOTs) using current PCP specifications and practices. For this, a survey was conducted among 18 states regarding their specifications that are used for PCP and their approval processes for implementation of PCP. Based on the survey conducted, eight state specifications have been developed for PCP. Each specification focuses on four major PCP components: (i) dimensional and strength requirements, (ii) base stabilization materials, (iii) panel placement and alignment, and (iv) encasement grout materials. Based on the specifications and recommendations of state DOTs, a general approval process was developed for PCP systems. The generalized approval process included verification of PCP (i) material properties and precast plant capabilities and (ii) historical performance. The approval process outlines three different tracks in which the PCP contractor can describe past performance (ranging from low to high risk for state DOTs). Overall, this study provides state DOT agencies the necessary specifications and general approval process to improve and accept PCP systems as a pavement rehabilitation technique.

Review of Agency Pavement Recycling Construction Specifications

Cold in-place recycling, cold central plant recycling, and full depth reclamation are cost-effective, environmentally conscious pavement rehabilitation or reconstruction techniques. Although these techniques are not new, they have not been widely adopted among state agencies. There has, however, been a recent resurgence in interest in these techniques. To date there are no national specification guidelines for these processes to assist in their widespread implementation, and those specifications that do exist often have a wide range of requirements. This paper presents the results of a review of state and local agency specifications for pavement recycling techniques and offers suggestions to help agencies achieve a better and longer-lasting product when specifying pavement recycling techniques.

Life cycle assessment of asphalt pavement maintenance and rehabilitation techniques: a study for the City of St. John’s

Although pavement maintenance and rehabilitation (M&R) techniques are usually examined in economic terms, there is a growing need to address their environmental footprints. The objective of this study is to assess the environmental impacts of M&R techniques. Life cycle assessment (LCA) can help in the decision-making process of selecting suitable maintenance techniques based on their environmental impacts. This study investigates: patching, rout & sealing, hot in-place recycling, and cold in-place recycling. Global warming potential (GWP), acidification potential, human health particulate, eutrophication potential, ozone depletion potential, and smog potential are estimated as environmental impacts for each maintenance activity. Materials, equipment use (for construction and M&R), and transportation were the main elements considered. A sensitivity test is performed to identify the significant factors for the LCA. The study concluded that GWP was the most important impact category. Rout & sealing and cold in-place recycling produced the lowest GWP emissions. Notably, pavement patching and hot in-place recycling showed significant detrimental environmental impacts.

Numerical analysis of rehabilitated concrete pavement using crack-and-seating technique

ABSTRACT Crack-and-seating is a Portland cement concrete (PCC) pavement rehabilitation technique that has been practically used to mitigate reflective cracking, however, the mechanism is not well understood. This study applied the coupling discrete-continuum modelling method to a field project, which is aimed to evaluating the effect of hammer-introduced crack on the stress at the tip of joint and at the tip of crack that control the reflective cracking of a rehabilitated PCC pavement with asphalt concrete (AC) layer. Particle Flow Code (PFC) was used for modelling asphalt overlay and the fractured PCC pavement while Fast Lagrangian Analysis of Continuum (FLAC) was used for modelling base and subgrade soil. The numerical simulation and analysis has validated that crack-and-seating can effectively reduce the shear stress at the tip of joint. Reducing the distance from the location where the hammer-introduced crack is introduced to the joint can effectively reduce the shear stress, and such distance is recommended to be 0.1–0.2 m. When the hammer-introduced crack’s length is 0.225 m, that is, the tip of crack is 1/10 of the thickness of PCC slab distant from the PCC slab surface, reflective cracking that would ultimately occur in the AC overlay can be effectively mitigated.

Environmental footprint of a road pavement rehabilitation service in Spain

Road surfaces are subject to wear and tear due to materials ageing, weathering and the action of road traffic. Periodic rehabilitation or reconstruction is needed in order to restore them. This manuscript presents an environmental assessment of a traditional road pavement rehabilitation technique (with hot mix asphalt) in Spain by means of a life cycle approach. The environmental footprint method was selected for presenting the results, which have a similar range as those obtained in earlier studies. Extraction of raw materials and the manufacturing of processed materials are the stages with the most environmental impacts. Therefore, the use of recycled asphalts in an adequate percentage is advisable for reducing the total environmental impact. This is the first complete study carried out in Spain. Its results could be used as a baseline for comparison with both newer restoration techniques and the use of advanced materials in the country.

Real-Time Monitoring of Asphalt Concrete Pavement Density during Construction using Ground Penetrating Radar: Theory to Practice

Accurate real-time density monitoring is crucial in quality control and quality assurance during the asphalt concrete (AC) pavement construction process. Ground penetrating radar (GPR) technology has shown great potential in the continuous real-time density prediction of AC pavement. However, it is not accepted as a routine method by transportation agencies in the United States due to the lack of validation under field testing conditions. In this study, three field tests were performed using GPR to estimate AC pavement density. The Al-Qadi-Lahouar-Leng model was used to predict the density from GPR signals. The reference scan method was used to remove the effect of surface moisture during construction. The gradient descent-based non-linear optimization method was used to reconstruct the overlapped GPR signals result from the use of thin AC overlay, which has been widely implemented as an AC pavement rehabilitation technique. Digital filtering and other signal processing methods were used to de-noise the signal. GPR results using the proposed methods were compared with field core data and nuclear gauge results. The results show that the proposed methods were effective in estimating in-situ AC pavement density using GPR. Continuous density estimation by installing GPR on the roller is suggested to provide real-time compaction monitoring during the AC pavement construction process.

Comparative eco-efficiency analysis on asphalt pavement rehabilitation alternatives: Hot in-place recycling and milling-and-filling

With the ever-increasing road mileages worldwide, the focus of pavement construction has been shifted from new pavement construction to pavement maintenance and rehabilitation (M&R). The corresponding huge environmental burdens and capital consumptions posed big challenges in achieving the target of sustainable development. In this study, an eco-efficiency analysis (EEA) framework was developed and applied to compare two common asphalt pavement rehabilitation techniques: hot-in-place recycling (HIRP) and milling-and-filling (M&F), by integrating the life cycle assessment (LCA) and life cycle costing analysis (LCCA), which followed by a sensitivity analysis to investigate the eco-efficiency performances of the two alternatives under different life extension scenarios. The eco-efficiency portfolio positions of hot-in-place recycling and milling-and-filling provided by the eco-efficiency analysis clearly indicated that hot-in-place recycling was more eco-efficient than milling-and-filling under the same assumed service life (15 years) for the cases studied. Hot-in-place recycling could save 5% cost and reduce 16% overall environmental impacts than milling-and-filling, while milling-and-filling saved 7% energy consumption than hot-in-place recycling. When the life extension ratio of the two alternatives reaches 12/15 (HIPR/M&F), milling-and-filling starts to show its advantages in both environmental and economic aspects in the long-term perspective. These findings indicated that if the hot-in-place recycling technique could ensure its treatment effectiveness. Its wider adoption would be championed for more sustainable transportation infrastructure development. The method and results of this study were expected to serve as a reference for decision-makers to make well-informed project decisions on the optimum rehabilitation alternative from the view of eco-efficiency.

Effects of existing concrete pavement condition on performance of unbonded jointed plain concrete overlay

Abstract Unbonded concrete overlay (UBCO) is the most used pavement rehabilitation technique across United States with an overall usage of 47% amongst all the rehabilitation methods. It is aimed to improve the performance of any deteriorated/cracked jointed plain concrete pavement (JPCP). Unbonded JPCP overlay involves placement of a separation layer of hot mix asphalt (HMA), which acts as a stress relief layer between the existing concrete pavement and the overlay. There are numerous factors that affect the design and performance of UBCOs and out of these, existing pavement condition or the severity of damage of existing pavement is a prime factor. The severity of damage is described by the distressed elastic modulus thus, accurate determination of the distressed elastic modulus of the existing concrete pavement is essential for predicting the accurate performance of the unbonded overlay. This study focuses on analyzing the impact of distressed modulus by conducting simulations in the AASHTOWare pavement ME design software version 2.3 and evaluating the predicted performance of JPCP overlay for two different climatic regions. The results indicated that the distressed modulus of existing concrete pavement affects the performance of the overlay with regards to transverse cracking, joint faulting and pavement roughness. Transverse cracking is the most affected performance parameter with a change of 0.27%–2.31% with a unit change in distressed modulus. The impact of climatic conditions on the performance of unbonded overlay was also observed. The adverse effects of distressed modulus can be minimized by reducing the joint spacing or increasing the overlay slab thickness.

Evaluation and Compaction of Laboratory-Produced Recycled Asphalt Pavement in Cold In-Place Recycling

AbstractCold in-place recycling (CIR) is a pavement rehabilitation technique that can eliminate significant structural distresses while providing a sound, semibound base layer. Although various res...

Nondestructive In Situ Characterization of Elastic Moduli of Full-Depth Reclamation Base Mixtures

State highway agencies are searching for more cost-effective methods for rehabilitating roads. One sustainable solution is full-depth reclamation (FDR), which is a pavement rehabilitation technique that involves pulverizing and reusing materials from existing distressed pavements in place. However, there is little information on the long-term properties of these recycled materials. An important property, the elastic modulus, indicates the structural capacity of pavement materials and is highly recommended for design purposes by the Mechanistic–Empirical Pavement Design Guide. The elastic modulus directly affects selection of the overall pavement thickness; therefore, an accurate estimation of the modulus is key to a cost-effective pavement design. This research investigated the elastic modulus trends of three in-service pavements rehabilitated with the FDR technique during the 2008 Virginia Department of Transportation construction season. Foamed asphalt (2.7% with 1% cement), asphalt emulsion (3.5%), and portland cement (5%) were used as stabilizing agents for the FDR layers. The results of the moduli measured for the recycled base materials varied significantly over time. These changes were attributed to curing after construction, seasonal effects, and subgrade moisture. The structural capacity of the pavements improved irrespective of the stabilizing agent used.

Cold In-Place Recycling Characterization for Single-Component or Multiple-Component Binder Systems

AbstractCold in-place recycling (CIR) is a pavement rehabilitation technique that has been used for decades. During this time, single-component binder (SCB) systems have governed the market. Single-component binders are defined as those with one binder or two if the secondary binder dosage is 1% or less (e.g., 3% asphalt emulsion with 1% hydrated lime). In contrast, this paper investigates multiple-component binder (MCB) systems (e.g., 2.5% emulsion with 2% portland cement). This paper’s objective is threefold: (1) present a universal CIR design framework applicable to any cementitious and/or bituminous material; (2) demonstrate MCB sustainability advantages; and (3) conduct an extensive SCB and MCB characterization. Universal design framework components include specimen preparation, curing, and testing protocols. Nine binder combinations were tested for wheel tracking, permeability, modulus, strength, and cracking response. Cement SCBs yielded low cracking resistance, high rutting resistance, and favorab...

Environmental comparison of two alternative road pavement rehabilitation techniques: cold-in-place-recycling versus traditional reconstruction

Based on a road reconstruction case study, the advantages and disadvantages of two alternative road pavement rehabilitation techniques, a hypothetically defined comparable traditional approach and an actually used cold-in-place-recycling approach, both of which enable a comparable extension of road service life of about 20 years, were investigated by means of Life Cycle Assessment. The results showed that the considered environmental impacts of the traditional approach exceeded those of the cold-in-place-recycling approach: by only 1% with regard to Global Warming, by 18% with regard to Acidification, by 15% with regard to the Abiotic Depletion of Fossil Fuels, and by 16% with regard to primary energy consumption. In the case of the traditional approach, the use of larger amounts of natural aggregate and the transportation of materials significantly contributed to emissions and the consumption of fossil fuels and energy, whereas the cold-in-place-recycling approach was sensitive to the use of cement, whose production results in relatively high emissions, especially of greenhouse gasses. In the case of the traditional approach, sensitivity analyses were carried out with regard to the use of aggregate from a quarry instead of a gravel pit, and to the delivery distance of material hauled away from the distressed road during rehabilitation works (extending the one-way delivery distances from 20 to 100 km). It was found that, if aggregate from a quarry is used instead of from a gravel pit, then the various environmental impacts of the traditional approach would exceed those of the cold-in-place-recycling approach by factors which range between 1.3 and 1.7. Increasing the transportation distance of hauled-away materials from 20 km to 100 km, the impacts of the traditional approach would exceed the impacts of the cold-in-place-recycling approach by a factor of 1.4 (Global Warming) and 1.6 (Acidification and Abiotic Depletion of Fossil Fuels). A further sensitivity analysis was carried out in the case of the cold-in-place-recycling approach, with regard to the use of Portland cements containing different amounts of clinker. It was found that the use of cements with a higher clinker content results in an increase in the Global Warming impact to a level significantly higher than that of the traditional approach.

Behavior of Cold Recycled Mixes in the Range of Low Temperatures – Experimental Study

Cold recycled mixes are used in many parts of the world as a standardized pavement rehabilitation technique. The quality of the mixes has been so far assessed by strength characteristics, water susceptibility and stiffness. In some cases frost resistance is determined as well. Nevertheless, especially for regions with winter seasons where temperatures are reaching values below 0°C, there are no standardized procedures and sufficient findings related to resistance to cracking and fracture behavior. Experimental study done at CTU in Prague describes three types of tests performed on 15 different cold recycled mixes. In parallel three standardized hot asphalt mixes were selected and used as well for a comparison of behavior in the range of low temperatures. Finally specimens acquired from an existing construction site where cold recycled technology was applied have been cored and tested mainly for crack propagation test. In general three tests have been selected and include crack propagation text on semi-cylindrical specimens, flexural strength test and relaxation test. Behavior in low temperature range and resistance to cracking has been tested in the temperature range of 0°C to-10°C.

Laboratory Investigation of Cement-Treated Reclaimed Asphalt Pavement Material

Cold in-place recycling is considered as a pavement rehabilitation technique that is more environmentally friendly than the common practice of simply constructing a new hot-mix asphalt (HMA) overlay on the existing wearing surface. This paper describes a laboratory experimental study for the formulation and mechanical characterization of cement-treated reclaimed asphalt pavement (RAP) material to be used as a base layer during the rehabilitation of pavements. RAP content was varied between 0 and 100% in order to study the effects of this parameter on the mechanical properties. Portland cement content was kept constant at 6% by weight of dry constituents. Results have shown that an increase in RAP content results in a decrease in compressive strength, flexural strength, indirect tensile strength, and elastic modulus. However, for any RAP content of 60% or less, acceptable mechanical properties for a pavement base layer were achieved. Unrestrained shrinkage testing showed statistically insignificant change in shrinkage strain with RAP content.

Evaluation of rehabilitated urban recycled asphalt pavement

Recycling of pavements is a relatively new technique for India and is gaining popularity in recent times due to several merits the technique has over conventional pavement rehabilitation techniques. The first recycling work of flexible pavements in India was undertaken a decade ago and since then the option of milling and recycling of bituminous layers has been adopted in some parts of urban and high-volume roads in India. However, no research studies were conducted on these works. Foamed bitumen recycled pavement work, which was undertaken on some urban roads of Kolkata city in India, has been reported in this paper. Detailed investigations conducted on the milling and foamed bitumen recycling work have been presented in this paper. Laboratory investigation was carried out on the milled and recycled material. Field evaluation of the pavements was done before and after rehabilitation using falling weight deflectometer. Results indicate that foamed bitumen recycling is a very promising alternative to rehabilitate bituminous pavements and to address the concern of conservation of energy and natural resources.

Time-Dependent Structural Response of Full-Depth Reclamation

Innovative pavement rehabilitation techniques, such as in-place recycling, are becoming more prevalent as highway agencies face an ever-increasing list of pavement maintenance needs and declining or stagnant budgets. Full-depth reclamation (FDR) has been shown to be a cost-effective alternative to deep milling and repaving to rehabilitate deteriorated flexible pavements. The results of previous FDR studies that investigated pavement structural capacity through the use of deflection testing suggest that long-term strength gain may be achieved through curing; however, such a strength gain has not been well quantified. This study documented the in situ structural testing, with a falling weight deflectometer, of three FDR projects constructed in 2008. Deflection testing was performed periodically at the project sites in the first 2 years after reclamation. This study showed that an accurate estimation of the final structural capacity of an FDR project may not feasibly be achieved immediately after the project has been completed and that it could vary greatly depending on the stabilizing agent used. If data from early-age testing are used to calculate design parameters for future projects, the parameters may be too conservative and result in the loss of potential cost savings through the use of unnecessary overlay materials. A cost analysis, based on data collected in this study, showed that these potential cost savings could approach $37,000 per lane mile. Further mechanistic-based studies of the time-dependent structural response of FDR materials are recommended.

Performance Prediction of the Dowel Bar Retrofit Technique Using Statistical Modelling

ABSTRACT Dowel Bar Retrofitting (DBR) is a pavement rehabilitation technique commonly adopted to increase the service life of pavements in the United States. This method involves either preventative or corrective maintenance of structural cracks or joints in jointed concrete pavement structures. The performance of DBR installations is typically measured using the Load Transfer Efficiency (LTE) parameter based on deflections. In this study, DBR was modeled using finite element analysis considering geometric, material, and support parameters. Statistical analyses were used to develop equations to predict performance of DBR in terms of stress transfer across joints or cracks. The use of stress-based load transfer provides engineers a more direct ability to determine what effect the load transfer mechanism has on reducing bending stress in the slab. This allows for proper retrofit strategies to be adopted thereby reducing fatigue mechanisms and extending the service life of rigid pavement systems.