Pavement Overlays Research Articles

CONCEPTS FOR RIGID PAVEMENT OVERLAY DESIGN

This scientific article introduces innovative concepts for the design of rigid pavement overlays, developed by Austin Research Engineers Inc. under the FCP Research Project SD, sponsored by the Federal Highway Administration. The key objective is to enhance the rehabilitation of existing Portland cement concrete pavements through overlays of either Portland cement concrete or asphaltic concrete. The article details a comprehensive procedure refined into a computer program, accompanied by a user’s manual, that encompasses evaluation of existing pavements, determination of design inputs, and overlay thickness analysis based on condition surveys and deflection measurements. The authors focus on a universal design approach that tailors overlay thickness to varying pavement conditions along roadways, thus optimizing economic efficiency. The methodology integrates advanced theories on fatigue and reflection cracking, leveraging elastic layered theory for stress computation and utilizing fatigue equations to determine life expectancy of the overlay. Additionally, a stress relief layer is considered in the design to minimize reflection cracking, further ensuring the durability of the overlay. The procedural workflow, illustrated through several flowcharts, aids in systematically assessing and classifying pavement conditions, determining traffic loads and environmental impacts, and analyzing material properties through both laboratory tests and field measurements. This integrated approach allows for the customization of overlay thickness based on specific pavement conditions and anticipated traffic loads, providing a robust framework for pavement rehabilitation that balances performance, cost, and longevity. (Abstract generated by AI tool ChatGPT 4)

Improvements to the bonding condition of ultra-thin concrete overlays for airport rigid pavements

ABSTRACT Ultra-thin concrete overlay (UTO) is an effective solution for repairing functional deficiencies in airport rigid pavements, with interface bonding properties critical to pavement performance and longevity. This study systematically investigates methods to enhance UTO interface bond strength under heavy dynamic loads. Aircraft dynamic simulations were performed to analyze stress states during landing, taxiing, and turning, identifying the required ultimate bond strength to prevent interface failure. Laboratory tests measured the shear and pull-out strengths of new and old concrete interfaces. A styrene–butadiene rubber (SBR) modified cement quartz mortar adhesive was developed with optimal curing conditions, and the effects of grooving intervals on bonding strength were assessed. Results demonstrated that the interface treatment increased the safety factor for tensile failure from 0.69 to 1.25 and for shear resistance from 0.61 to 1.12 under dynamic loads. This research provides a scientific basis for enhancing UTO applications in the functional rehabilitation of airport rigid pavements, offering a practical solution to improve safety and durability in high-stress environments.

Evaluation of Paris law-based approach on asphalt mixture reflective cracking performance modeling

Reflective cracking is a major distress for asphalt pavement overlays. To model asphalt mixture reflective cracking performance, various models and tests have been developed in the past. Among the different methods, Paris law combined with the overlay test has been one of the most popular approaches to assess the reflective cracking resistance of the asphalt mixtures. This study evaluated three variants of ΔK-based Paris law models, specifically Methods A, B, and C, as well as one ΔJR-based Paris law model. The evaluation was conducted using overlay test data from two mixes at three different temperatures. For ΔK-based Paris law, three different models consistently demonstrate that asphalt mixtures have better reflective cracking resistance as temperature increases from 4 °C to 18 °C. However, they diverge in terms of mixture rankings. Specifically, when using the Paris law coefficients to predict the crack growth, Method A matches exactly with the experimental observation since it is a self-validation, while Methods B and C display different crack growth patterns. This may be attributed to the fact that Method A was originally developed based on the overlay test while Methods B and C were calibrated based on the field performance. For ΔJR-based Paris law, inconclusive results have been obtained and the cause of such results are explained on the basis of differences between the experimental details of the present study and the one that originally developed the approach.

Prediction of effective equivalent linear temperature gradients in bonded concrete overlays of asphalt pavements

PurposeThe time-varying equivalent linear temperature gradient (ELTG) significantly affects the development of faulting and must therefore be accounted for in pavement design. The same is true for faulting of bonded concrete overlays of asphalt (BCOA) with slabs larger than 3 x 3 m. However, the evaluation of ELTG in Mechanistic-Empirical (ME) BCOA design is highly time-consuming. The use of an effective ELTG (EELTG) is an efficient alternative to calculating ELTG. In this study, a model to quickly evaluate EELTG was developed for faulting in BCOA for panels 3 m or longer in size, whose faulting is sensitive to ELTG.Design/methodology/approachA database of EELTG responses was generated for 144 BCOAs at 169 locations throughout the continental United States, which was used to develop a series of prediction models. Three methods were evaluated: multiple linear regression (MLR), artificial neural networks (ANNs), and multi-gene genetic programming (MGGP). The performance of each method was compared, considering both accuracy and model complexity.FindingsIt was shown that ANNs display the highest accuracy, with an R2 of 0.90 on the validation dataset. MLR and MGGP models achieved R2 of 0.73 and 0.71, respectively. However, these models consisted of far fewer free parameters as compared to the ANNs. The model comparison performed in this study highlights the need for researchers to consider the complexity of models so that their direct implementation is feasible.Originality/valueThis research produced a rapid EELTG prediction model for BCOAs that can be incorporated into the existing faulting model framework.

An in-situ method to evaluate the interlayer bond between hot-mix asphalt and portland cement concrete surface

Proper bonding between different layers of a composite pavement is a major factor in ensuring that the entire structure acts as a monolithic layer under load. This paper studies the bonding between hot mix asphalt (HMA) overlay and Portland cement concrete (PCC) pavement using tack coats. An in-situ pull-off test method was developed for use on project sites on a routine basis to screen and test the quality of bond between asphalt layer and concrete layer. This test replaces the arduous process of coring through often times very thick concrete layer with steel rebars, transporting the core to a lab, trimming the concrete side of the core to fit the shear jig, and finally conducting a shear test. Results show that the in-situ pull-off test method developed in this study is strongly correlated to the laboratory based direct shear test. Limits were also suggested to indicate an adequate bond strength in the PCC–HMA interlayer on the basis of laboratory and field testing. This study also evaluates the influence of various factors on the performance of the interlayer bond in laboratory. These factors include the type of tack coat, application rate, the texture of the concrete pavement surface, the surface cleanliness and the surface moisture. Results indicate that sandblasting and hydro-demolition textures offer the best interlayer bond strength, the influence of application rate is not significant on the interlayer bond strength and the influence of surface moisture and cleanliness are dependent on the type PCC surface texture.

Laboratory investigation into the crack propagation mechanism of geosynthetic reinforced asphalt concrete using digital image correlation technique

ABSTRACT Geosynthetic reinforcement has proven effective in mitigating reflective cracking in new pavement overlays. This study aimed to compare the ability of five different geosynthetic reinforcement products to alleviate cracking in overlays. Each product was sandwiched within a two-layered asphalt concrete (AC) beam specimen and subjected to a four-point notched beam fatigue test. The study monitored crack propagation, understood crack propagation mechanisms, and quantified crack lengths in different geosynthetic-reinforced AC beam specimens during a notched beam fatigue test using the digital image correlation (DIC) technique. The DIC analysis generated full-field displacement and strain contours, depicting the damage mechanisms of geosynthetic reinforcement products in AC overlays under fatigue loading. The quantitative analysis measured the cracked areas caused by each product. The interfacial damage observed in various geosynthetic-reinforced beam specimens under different test conditions suggested that the failure modes of AC beam specimens reinforced with different products varied, and choosing the right product for a project depended on the pavement conditions, geosynthetic product properties, and tack coat properties. Finally, the predictive algorithms presented in this paper allow for predicting the failure mode generated by different geosynthetic products for different overlay conditions in the field, providing valuable insight for pavement engineers.

An Approach for Adjusting the Laboratory-Determined Dynamic Modulus Master Curve of Asphalt Layers Based on Falling Weight Deflectometer Measurements

Structural assessment is critical for designing asphalt pavement overlays, estimating the remaining life of pavements, and selecting an appropriate rehabilitation strategy for existing pavements. The falling weight deflectometer (FWD) serves as the primary nondestructive test used for evaluating the in situ properties and structural capacity of asphalt pavements. The current procedure involves analyzing the FWD response and estimating layer moduli by assuming an elastic response. However, the response of asphalt layers is viscoelastic (i.e., temperature- and frequency-dependent). This study proposes an approach that combines FWD data with laboratory measurements of the dynamic moduli of field cores to determine the in situ viscoelastic properties of asphalt layers. This approach is implemented by analyzing FWD data from four pavement sections in Qatar. Furthermore, the paper includes a comparative analysis of the response of pavement sections in which the asphalt layers are modeled using dynamic modulus master curves obtained from laboratory tests and those obtained using the approach presented in this study. It was found that using the laboratory-based master curves overestimated pavement performance (i.e., underestimated pavement distresses). It is recommended to use the dynamic moduli from the method presented in this paper for a more accurate estimation of pavement response and performance.

Evaluation of Three Federal Highway Administration Targeted Overlay Pavement Solutions for Asphalt Pavements Based on Their Performances and Potential to Increase Pavement Service Life

The Federal Highway Administration Targeted Overlay Pavement Solutions (TOPS) program presents innovative overlay solutions for both asphalt and concrete pavements. The objective of this study was to conduct a comparative evaluation of three TOPS types for asphalt pavements, namely, Asphalt Rubber Gap-Graded, Stone Matrix Asphalt and High-Performance Thin Overlay as regards performance, how they extend pavement service life, and whether they can be used interchangeably. Asphalt binders from two sources were used in each of these three TOPS types, thus, providing a total of six TOPS mixtures. All TOPS passed the mixture performance tests where the test had a State Transportation Agency (STA) specified or a preliminary criterion, and the test results indicated that all three TOPS types can be used interchangeably. More specifically, all six TOPS mixtures met the Massachusetts Department of Transportation’s TOPS pilot specification criteria for rutting, moisture damage, and intermediate-temperature cracking. They also passed the mixture performance tests for reflective cracking and raveling based on criteria established by other STAs. AASHTOWare® Pavement Mechanistic-Empirical Design predictive models for bottom-up fatigue cracking indicated that 2 in. of a TOPS mixture placed on an existing in-service pavement can extend pavement service life between 11.2 and 14 years depending on the type of TOPS and source of binder. The maximum difference in service life between the six TOPS was slightly less than 3 years, although most of them were within 2 years of each other. Furthermore, none of the three TOPS types could be chosen to be the best TOPS.

The Evaluation of Equivalent Axle Load Equation Based on Deflection Value before and after Overlay Flexible Pavement

Some of the factors causing early damage to Indonesia’s flexible pavement system in Indonesia were allegedly caused by several things, including the Equivalent axle load (EAL) equation incompatible with Indonesia’s situation where most heavy vehicles carry overloaded loads. One effort that can be done to avoid severe damage to the road is overlaid pavement. It is suspected that the overlay on the flexible pavement will affect the shape of the EAL equation. This paper will discuss the EAL equation before and after the flexible pavement is overlaid by measuring the pavement deflection’s value using a falling weight deflectometer (FWD). The data obtained in the form of pavement deflection value is then analyzed using the regression analysis method with the permanent deformation theory approach. From the research analysis, it is obtained that the power rank value for applying the maximum load limit regulation and the type tandem axle dual wheel (TADW) shall follow determined EAL before and after overlay to the type single axle dual wheel (SADW).

Evaluation of the Polymer Modified Tack Coat on Aged Concrete Pavement: An Experimental Study on Adhesion Properties

This study addresses the challenges of overlaying old concrete pavement with asphalt by introducing a new trackless tack coat material containing polymer. The aim is to enhance the durability of asphalt concrete overlay pavement on old cement concrete pavement. It contributes to the development of improved construction techniques for pavement rehabilitation and highlights the need for reliable adhesion performance evaluation based on different spray amounts and surface conditions. Additionally, to evaluate the effect of the adhesion performance based on the spraying amount, a tensile adhesion test was conducted by applying spray amounts of 0.30, 0.45, and 0.60 l/m2 on different surface conditions. The basic and adhesion performances of the polymer-modified tack coat material are evaluated through direct tensile and shear bond strength tests. The test outcomes demonstrated that the newly developed polymer-modified tack coat material had considerably greater adhesion strength compared to the traditional rapid-setting products. Its adhesive strength was 1.68 times higher on concrete and 1.78 times higher on asphalt. The new trackless tack coat material exhibited an adhesion performance of 1.05 MPa in direct tensile strength at 0.45 l/m2, which was 1.21 times higher than the rapid-setting tack coat. Results also confirmed that the new tack coat material exhibits values 1.90 times greater than the conventional rapid-setting tack coat material in shear bond strength, respectively. By simulating the process of separation and re-adhesion of pavement layers caused, the new tack coat material shows a tensile adhesion strength of 63% of the original state, which is advantageous for securing the durability of the pavement. Overall, the newly developed polymer-modified trackless tack coat has been shown to effectively enhance the adhesion performance between pavement layers without process delay, highlighting the potential of the new tack coat material to enhance the durability of asphalt concrete overlay pavement on old cement concrete pavement.

Comprehensive Laboratory Evaluation of Crack Resistance for an Asphalt Rubber Stress-Absorbing Membrane Interlayer (AR-SAMI)

Reflective cracking is a common distress of semi-rigid base asphalt pavements and overlay pavement projects. An asphalt rubber stress-absorbing membrane interlayer (AR-SAMI) prepared by waste tires is an effective engineering solution for treating reflective cracking. This method can also reduce black pollution. However, there is no unified test method and index for crack resistance evaluation. In this work, AR-SAMIs with different air voids and gradations were investigated. A small beam bending test (BBT) at −10 °C and 15 °C, crack expansion SCB (CE-SCB) test, low-temperature SCB (LT-SCB) test, and Overlay Test (OT) were performed to evaluate the crack resistance of AR-SAMI comprehensively. Statistical analysis was also performed. Results showed that the crack resistance of AR-SAMI improved as the air voids decreased. The crack resistance of 10-A gradation with more fine aggregate was excellent. However, the AR-SAMI with more coarse aggregate had better crack extension resistance under the condition of pre-existing cracks. There are differences in the evaluation results of different test methods due to the various evaluation focus. The −10 °C BBT, CE-SCB, and OT were recommended to evaluate the crack resistance comprehensively. Research results can guide the evaluation method or index selection of crack resistance and the optimization of AR-SAMI mixture design under different working conditions.

Finite Element Analysis of Continuously Reinforced Bonded Concrete Overlay Pavements Using the Concrete Damaged Plasticity Model

In this study, cracking patterns and widths were analytically investigated in a continuously reinforced bonded concrete overlay (CRBCO), as they developed due to temperature change and drying shrinkage, as the environmental load for the sustainable management of deteriorated concrete pavements. The parameters of the concrete damaged plasticity (CDP) model used for the nonlinear finite element analysis (FEA) of the continuously reinforced concrete pavement were determined through comparison of the FEA results with the field crack survey results so as to be used in the nonlinear FEA of the CRBCO pavement. The total temperature change, which combines the actual temperature change with the temperature change converted from the drying shrinkage, considering stress relaxation, was adopted in the FEA as the environmental load applied to the CRBCO pavement. The locations and movements of the reflection and transverse cracks in CRBCO were investigated via FEA. The reflection cracks occurred in the overlay at all of the joints of the existing pavement. Only one secondary crack, with a width that was 5–6 times narrower than that of the reflection cracks, occurred between adjacent reflection cracks under various conditions. Thus, the crack width of the CRBCO was predominantly affected by joint movement in the existing pavement. In addition, the crack widths predicted by the CDP model were narrower than those predicted using the elastic model by approximately 10%. Therefore, crack movement in a CRBCO pavement can be reasonably predicted by the CDP model.

Investigation of factors affecting bond strength of thin epoxy overlay pavements

ABSTRACT This study investigated the factors influencing the bond strength between existing pavement and thin epoxy overlay via laboratory and field tests. Laboratory tests revealed that the highest bond strength occurred at a general temperature and relative humidity of 25 °C and 60%, respectively. The concrete surface profile (CSP) of the specimen was found to have no impact on the bond strength between the latex-modified concrete (LMC) and epoxy binder under favorable conditions. Field testing of well-maintained concrete pavements indicated that neither the existing pavement's pre-treatment process nor its resulting CSP affected the bond strength. However, the bond strength decreased with environmental and vehicle loadings six months after the overlay. A second field test conducted on a deteriorated bridge deck with an LMC pavement revealed that most of the damage occurred at a shallow depth in the existing pavement, demonstrating low bond strength just two days after construction owing to inadequate removal of the deteriorated section. The initially low bond strength increased over time as the epoxy binder permeated the deteriorated area and hardened at greater depths, thus making it necessary to thoroughly remove all deteriorated sections of the existing pavement before constructing a thin epoxy overlay.

Extension of AASHTO Load-Spreading Method to Include the Full Benefits of Pavements for Reliable Load Rating of Buried Culverts

This paper develops a two-step procedure to extend the AASHTO Ad Hoc Method (AAM) for live-load spreading through soil to include the full benefits of pavement overlays. The two-step procedure is called AAMP-θ* (“P” for pavements), which combines the Fox two-layer elasticity solution for peak stress at the pavement–soil interface with the improved AAM-θ* theory for load spreading through soil. The AAMP-θ* procedure is applicable to all culvert analysis tools commonly used for Load and Resistance Factor Rating (LRFR) analysis ranging from simple frame models to sophisticated two-dimensional finite element model (2D-FEM) soil structure models. The AAMP-θ* procedure is rigorously and completely developed wherein all approximations are shown to be conservative so that the predicted benefits of pavements are trustworthy and not overstated. This is why the more accurate AAM-θ* load-spreading method is used instead of the simpler but unconservative AAM-30° method. Application of AAMP-θ* for LRFR load rating of buried culverts is described for simple frame models as well as 2D-FEM pavement–soil structure models. Lastly, the AAMP-θ* procedure is validated by comparing structural response predictions from 2D-FEM solutions with strain-gage measurements in a buried corrugated steel culvert loaded by a three-axle truck. One set of strain-gage measurements was made before, and another set of measurements was made after, asphalt pavement was installed. The correlation between field data and 2D-FEM/AAMP-θ* predictions is remarkable and underscores the bottom-line message that AAMP-θ* should be used when performing LRFR analysis on buried culverts to determine realistic rating factor values and avoid predicting false unsafe values.

Estimated Fatigue Life of Recovery Reclaimed Asphalt Pavement Binder

It is necessary to investigate the physical, chemical characterization and amount of RAP binder in asphalt pavement containing large amount of RAP in order to select suitable pure asphalt binder grade to blending. This research aims to investigate the rheological characteristics and estimation fatigue life of the asphalt binder extraction from two years overlay asphalt pavement. The asphalt was taking from the process of extraction and recovery. Dynamic shear rheometer (DSR) test was conducted on the recovered asphalt to calculate the different variables, complex, elastic and viscous shear modulus, complex viscosity and the phase angle. The main pavement failure modes, rutting and fatigue cracking were addressed by these output parameters of DSR. Fatigue life is related to the energy absorbed during repeated load to pavement layer. The test results indicated that the asphalt extracted from the selected sections were stiff enough to resist rutting and fatigue failure Keywords: Reclaimed asphalt pavement binder, fatigue criteria, VECD, dissipated energy, energy stiffness ratio.

Mechanistic-empirical model to predict transverse joint faulting of bonded concrete overlays of asphalt

Transverse joint faulting is a distress observed in bonded concrete overlays of asphalt pavements (BCOAs). However, to date, there is no predictive faulting model for BCOAs. Therefore, the objective of this research is to develop such a model. First, models were developed to predict the structural response of BCOAs due to environmental and traffic loads. Previously-developed artificial neural networks that rapidly estimate the structural response of BCOAs at the joint due to these loads was used to relate the structural response to the damage using the differential energy (DE) concept. Next, DE was related to faulting through an incremental analysis considering traffic, climate, and joint deterioration. Finally, a calibration using performance data from existing BCOAs throughout the continental United States and an extensive sensitivity analysis on the model’s prediction capabilities was performed. This faulting prediction model has been incorporated into the BCOA-ME design guide developed by the University of Pittsburgh.

Statistical Analysis Framework to Evaluate Asphalt Concrete Overlay Reflective Cracking Performance

The purpose of this paper is to provide a robust process to statistically analyze reflective cracking field performance data. There is often a lack of consistency and transparency in statistical analysis of pavement field performance data, which may not satisfy ANOVA or regression modeling assumptions. Twelve full-scale asphalt concrete (AC) overlay pavement test sections located at the MnROAD test facility are used to demonstrate the statistical framework. The percentage of cracking reported at joint locations (%RC) is used to represent reflective cracking performance, and its relationships to pre-overlay load transfer efficiency (LTE), truck traffic, overlay thickness, and common performance indices determined from laboratory tests are investigated. The three laboratory tests considered in this study are the disk-shaped compact tension (DCT), semi-circular bend (SCB) and overlay tester (OT). Logistic regression models are used for estimation. Predictive abilities of various models are compared in relation to the percentage odds (%odds) of reflective cracking. Model output is binary: it estimates not the relative amount of reflective cracking but instead the probability of a given pavement structure cracking. Varying ability to perform asphalt mixture laboratory performance testing is assumed. One such model, where no laboratory performance testing variables are included, shows that a one-unit increase (1-in.) in AC overlay thickness may result in approximately a third decrease in the %odds of reflective cracking. A logistic regression model developed that considers laboratory performance data from DCT, SCB, and OT results in the optimal model balancing best fit and best prediction properties without overfitting.

EFFECT OF STEEL FIBER PROPORTION ON SIFCON MECHANICAL PROPERTIES

Slurry Infiltrated Fiber Concrete (SIFCON) is a relatively new high-performance material that may be thought of as a high-fiber content version of fiber reinforced concrete. This matrix is comprised of flowing mortar that must penetrate the fiber network implanted in the molds sufficiently. SIFCON combines excellent mechanical properties with a high ductility and toughness grade. SIFCON is utilized in applications that demand a high degree of ductility and energy absorption, most notably seismic-resistant reinforced concrete structures and structures exposed to abnormal or explosive loads. Additionally, pavement overlays, prestressed beam repair, and structural reinforced concrete element restoration have all been effective. The main aim of this study is to determine the effect of hooked-end steel fiber and micro-steel fiber on the strength of SIFCON specimens exposed to flexural and splitting loading. Three volume fractions of steel fiber (8,10, and12) % were used in this investigation. By weight of cement in SIFCON slurry, the proportion of Silica Fume SF substitution was 10%. Flexural strength was determined by testing specimens of (100×100×500) mm, and splitting tensile strength was determined at 7 and 28 days using cylindrical specimens with dimensions (150mm × 300m).. The results obtained from these tests were compared with SIFCON containing micro steel fiber. The test results show superior characteristics of SIFCON containing hooked-end steel fiber, as compared with micro steel fiber. For example, the flexural strength and splitting strength are 24.89 MPa and 10.14 MPa, respectively for SIFCON with 8% hooked-end steel fiber and 17.51 MPa and 9.1 MPa for control specimens with micro steel fiber.

Field Tests on Bond Strength and Skid Resistance of Thin Epoxy Overlay Pavements

Field Tests on Bond Strength and Skid Resistance of Thin Epoxy Overlay Pavements

Impact of warming temperature on asphalt pavement overlay performance and cost: case study in New Jersey

This study aimed to quantify the impact of warming temperatures on flexible pavement overlay performance with the effects of various in-place air voids. The performance models in Mechanistic-Empirical (ME) Pavement Design were locally calibrated and used to predict pavement distresses. The findings indicated transverse cracking due to low temperatures would become less problematic with milder winters, while more extreme high temperatures in summers contributed to faster pavement deterioration especially in the fatigue cracking. The analysis results showed that using the historic climate inputs in pavement design would overestimate the service lives for asphalt pavement overlays. As the in-place air void increases from 5% to 7% under the climate change scenario, the predicted pavement life decreases by 3–4 years. Further analysis showed that, with the effects of warming temperatures, agency costs could be reduced by controlling in-place air void through pay adjustment in quality assurance of the pavement construction.