Hot-mix Asphalt Overlays Research Articles

From data to decision: integrated approach to pavement preservation in Iowa through treatment effectiveness analysis

ABSTRACT This investigation seeks to enhance ‘Iowa's Pavement Preservation Guide’ with a data-informed decision-making framework. Iowa DOT's databases were used as the data source for evaluating pavement performances under different preservation treatment regimens and determining the effectiveness of those strategies. Five preservation treatment methods for flexible and composite pavements, namely, crack sealing-and-filling, microsurfacing, slurry sealing, patching, and thin hot mix asphalt (HMA) overlays were evaluated using historic data from about 7000 road segments between 1998 and 2020. The data included various attributes describing pavement, road, and traffic characteristics required for analysing condition-based performance and treatment impacts. Two key indicators, service life extension (LE) and index benefit (IB), were defined and used to quantify treatment effectiveness in terms of pavement condition improvement and impact on deterioration rate. The treatment-effectiveness indicators were then factored into the cost analyses to assess the cost-effectiveness of preservation strategies. The results of the treatment effectiveness analysis were used to develop decision matrices that provide insights for selecting preservation treatments based on benefit–cost analysis considering both the overall condition and the dominant distress. This approach to treatment effectiveness highlighted the distinction between an optimum pavement preservation strategy and one that targets maximum service life extension.

Performance Comparison of Break and Seat and Rubblization Rehabilitation Techniques for Reflection-Crack Mitigation: Case Study in Louisiana

Hot mix asphalt (HMA) overlays are constructed on Portland cement concrete (PCC) pavements to improve long-term performance. A significant disadvantage of using HMA overlays on PCC pavements is the development of reflection cracks. Reflection cracks are influenced by traffic loads and periodic temperature changes. The objective of the study was to compare field performance of two slab-fracturing (i.e., break and seat, and rubblization) techniques commonly used in Louisiana, U.S. Four PCC pavement rehabilitation projects with at least one slab-fracturing technique and a corresponding control section were evaluated. Field structural capacity and performance data were collected and analyzed to determine the effect of each reflection-crack mitigation technique on performance. Resilient modulus (Mr) of the existing subgrade was found to significantly influence the structural and functional performance of the pavement sections evaluated. Pavement sections with weaker subgrades were shown to be not suitable for slab-fracturing rehabilitation techniques. For the four field projects evaluated, rubblized test sections showed higher cracking resistance than the control sections. The break and seat technique did not consistently improve or reduce the crack resistance of pavement sections compared with their corresponding control sections because of variations in subgrade Mr values. Sections with smaller sized (i.e., 6 in. break pattern and rubblized particles) fractured particles exhibited higher cracking resistance. Rubblized and selected break and seat sections for the field projects evaluated exhibited lower overall performance compared with their corresponding control sections, which is attributed to other underlying subsurface conditions. Additional study is required to continuously monitor the pavement sections.

Comparison of Bond Strength Evaluation Methods Between Pavement Layers

Tack coats are generally used to facilitate a bonding between pavement layers in construction of hot-mix asphalt pavements and overlays. The goal of applying a tack coat material is to ensure the new or consecutive pavement layers respond monolithically under loading and avoid premature failure caused by debonding, mat slippage, or fatigue cracking. Multiple different in-situ and laboratory tests have been developed to evaluate bond strength of tack coat materials under tension, shear, and mixed-mode loading mechanisms. However, there is no universally accepted bond strength test method or performance criteria for tack coats within the United States. While some specifying agencies have gained familiarity and comfort with a particular bond strength test, a gap exists for many states that have not adopted a testing procedure. The objective of this paper is to compare current and newly developed tack coat bond strength tests to help determine which is most indicative in predicting field performance. Field cores from four different pavement sections with varying traffic loading conditions and early bond strength performance were sampled and tested in the laboratory using four different bond strength evaluation methods. Statistical analysis of bond strength testing results shows a strong linear correlation between pull-off and shear strength testing. Meanwhile, a novel approach to tack coat bond testing under cyclic tensile loading was explored and showed appreciable discrimination between sample locations and agreement with early field performance.

Analysis of airfield composite pavement rutting using full-scale accelerated pavement testing and finite element method

Rutting is a typical distress of hot-mix asphalt (HMA) overlays on airfield composite pavements (ACPs). An approach is needed that can provide comprehensive and reliable evaluation of ACP rutting characteristics. In this study, we developed a finite element model (FEM) that was based on parameters derived from laboratory and field tests performed in China. The FEM exhibited satisfactory accuracy after validated by the full-scale accelerated pavement testing (APT) [1]. The test results indicate that a typical dual-wheel rutting profile of ACP exhibits a non-uniform W-shaped deformation with double peaks in a two-stage development process. Variations in temperature, driving states, and interface bonding conditions influence ACP rutting characteristics significantly in terms of increasing deformations (uplift and sag) and changing profiles (with double peaks or single peak). The aircraft load level and overlay thickness only affect the degree and scope of rutting deformations. Rut depth has a power-function relationship with temperature and load cycles, but has a linear relationship with tire pressure and overlay thickness. The uplift coefficients are stable between approximately 0.26 and 0.29 when the influential factors are varied.

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.

Correlations and preliminary validation of the laboratory monotonic overlay test (OT) data to reflective cracking performance of in-service field highway sections

Reflective cracking is one of the dominant distress modes occurring when hot-mix asphalt (HMA) overlays are placed over existing cracked flexible and/or jointed rigid pavements. In the laboratory setting, there are various tests – both of dynamic and monotonic loading modes – that can be used to measure, characterize, and quantify the cracking resistance potential of HMA mixes. However, one key challenge with most of these laboratory tests is correlations and validation with field performance data. Quite often, field data availability is a challenge or otherwise, needs costly long-term performance monitoring. Using the Texas flexible pavements and overlays database, namely the Texas Data Storage System (DSS), as the data source, this study was conducted to correlate and preliminarily validate the laboratory monotonic-loading overlay tester (OT) to the field crack performance of in-service highway sections. As excerpted from the DSS, four HMA mixes and six in-service highway sections (overlays) were used. Overall, the monotonic-loading OT test exhibited promising potential as a repeatable test (coefficient of variation [COV] < 30%) for evaluating and quantifying the cracking resistance potential of HMA mixes in the laboratory relative to the field performance of in-service highway sections. In particular, the following HMA fracture parameters, fracture energy (FE), tensile strength (σt), FE Index, and peak load (Pmax) from the monotonic-loading OT test, with COV values less than 30%, were able to statistically differentiate the HMA mixes (statistical groups ≥ 2) and also correlated well (coefficient of determination [R2] > 60%) with the measured field cracking performance data.

Mitigating reflective cracking in composite pavements through the use of a ductile concrete interlayer

Reflective cracking of composite pavements refers to the phenomenon that cracks propagate from a deteriorated Portland cement concrete (PCC) slab to the newly constructed hot mix asphalt (HMA) overlay at locations where there are joints and cracks in the underlying PCC pavements. It is one of the predominant failure modes of composite pavements, often resulting in premature failure and limited service life of HMA overlays. To improve the resistance of composite pavements to reflective cracking, in this study, a new ductile concrete interlayer made of Engineered cementitious composite (ECC) was proposed and experimentally evaluated. ECC is a type of high-performance fiber-reinforced cementitious composites that features high tensile ductility, high fracture resistance, and high deformation capacity. It is expected that by constructing a thin ECC interlayer between exisiting PCC pavement and HMA overlay, reflective cracking can be prevented or significantly delayed. In the current paper, small lab-scale sandwich-type composite pavement specimens with and without ECC interlayers were constructed and tested under fatigue loadings that simulates repeated traffic loadings. The experimental result indicated that the ECC interlayer successfully suppressed reflective cracking and altered the failure mode of the composite pavement. As a result, specimens with ECC interlayers exhibited significantly (30 to 47 times) higher fatigue life as compared to the control specimens without interlayers. This result demonstrated that ECC interlayer is effective in reflective cracking mitigation.

Structural Characterization of Fractured Portland Cement Concrete Pavements in Pennsylvania from Falling Weight Deflectometer Data

Hot mix asphalt (HMA) overlays on fractured Portland cement concrete (PCC) is a common rehabilitation alternative used for PCC pavements in Pennsylvania. Several fracture techniques including rubblization, crack and seat (C&amp;S), and break and seat (B&amp;S) have been used for decades to minimize reflective cracking by reducing the effective slab length and, with it, expansion/contraction movement. The design of this type of overlay requires knowledge of the structural capacity of the fractured PCC layer. The AASHTO 93 and Pavement ME design methods are used by the Pennsylvania Department of Transportation (DOT). These methods and the Pennsylvania DOT documentation recommend certain values to characterize the structural capacity of the fractured PCC. However, the guidance envisaged the selection of these values provided by these design methods and the Pennsylvania DOT documentation is limited. The objective of this study is to determine realistic Pennsylvania-specific elastic modulus (EPCC) values and layer coefficients (LC) to characterize the in situ behavior of fractured PCC layer for jointed reinforced concrete pavements (JRCP) and jointed plain concrete pavements (JPCP). To obtain these structural properties, 11 different rehabilitation projects located in Pennsylvania were analyzed using falling weight deflectometer (FWD) data, backcalculation programs, and statistical methods. Based on this analysis, the recommended values of EPCC and LC for C&amp;S overlay design are 360 ksi (kips per square inch) and 0.32, respectively. In the case of B&amp;S overlay design, these values correspond to 400 ksi and 0.34, respectively. The variability of the slab fracturing process and the reduction of the structural capacity caused by fracturing were also analyzed in this investigation.

Field and simulated rutting behavior of hot mix and warm mix asphalt overlays

Research implementing new pavement technologies often focuses on material characterization; however, expanding the research to study and validate how new technologies influence pavement design is needed for continual improvement. Numerical analysis approaches use laboratory mixture data to predict field performance. This study compares predicted rutting by MEPDG design, estimated rutting from Finite Element (FE) simulations, and actual rutting performance in the field. Ten years ago, warm mix asphalt research was underway to measure the effect of warm mix asphalt (WMA) additives and lower production temperatures on performance. WMA benefits include reduced mixing/compaction temperatures, reduced fuel consumption, and improved compatibility. In 2009, three asphalt overlay projects were constructed in Iowa using both hot mix asphalt (HMA), and WMA mixes to compare their performance. A series of dynamic modulus tests were conducted to determine dynamic modulus and phase angles of HMA and WMA mixtures. The dynamic modulus results were used to develop FE viscoelastic simulations to predict the rutting of HMA/WMA pavement sections. Iowa’s pavement management system provided field rutting of WMA/HMA sections. Also, pavement sections were evaluated using mixture input parameters in the Mechanistic-Empirical Pavement Design Guide (MEPDG). The results showed MEPDG based on linear elastic theories might overestimate the rutting of asphalt pavements, especially overlays placed on Jointed Plain Concrete Pavement (JPCP). In contrast, the FEM based on viscoelastic theories more accurately predicted the rutting of pavements. Calibration coefficients are proposed by this study, which may be useful for design engineers and industrial applications to correct and modify MEPDG overlay design thicknesses for HMA/WMA mixes placed on HMA and JPCP surfaces.

Laboratory evaluation of grid-reinforced HMA beams using the flexural bending-beam fatigue (FBBF) test in load-controlled mode

ABSTRACT Interlayer grid-reinforcement is one of the maintenance and rehabilitation (M&R) strategies often used to mitigate reflective cracking in hot-mix asphalt (HMA) overlays. However, there is no standardised laboratory test methodology for screening and selecting grid materials during the HMA overlay design stage. This laboratory study was conducted to comparatively evaluate, characterize, and quantify the crack resistance potential of grid-reinforced HMA using the flexural bending beam fatigue (FBBF) test based on the AASHTO T 321 concept. Two grid materials, denoted as FA-30 and FA-75, were comparatively evaluated against Control (unreinforced) HMA beam samples as the reference datum. The study findings indicated that the FBBF test setup, in a load-controlled mode based on the AASHTO T 321 concept, has promising potential as a test method for evaluating and screening grid materials in the laboratory. Overall, the grid-reinforcements used in the study exhibited over 4.0 times superiority in terms of laboratory flexural cracking-resistance performance improvement with the potential of over 25% reduction in the HMA layer thickness. The average laboratory interlayer crack performance benefit factor (ICPF), computed based on the indicative mirroring of the AASHTO R 50-09 concept, was 10.60 for FA-75 versus 5.14 for FA-30 with respective to laboratory performance.

State-of-the-Art Review of the Evaluation of Asphalt Mixtures’ Resistance to Reflective Cracking in Laboratory

Reflective cracking is one of the major forms of deterioration in pavements and is very common when hot-mix asphalt (HMA) overlays are constructed over a base with discontinuities in its surface. This issue has not received proper attention compared with classical fatigue cracking. However, it is a major concern during the selection of asphalt mixture surface courses for pavements with an underlying cracked base. This work identified the most appropriate testing device for investigating the resistance of asphalt mixtures to reflective cracking in the laboratory. An in-depth review of the available literature was conducted and 17 reflective cracking testing devices were evaluated, among which best three were chosen based on their availability, ease of use, variability, repeatability of the test results, and field validation. It was concluded that the Hamburg wheel tracking tester (HWTT), the wheel reflective cracking (WRC) apparatus, and the upgraded Texas Transportation Institute (TTI) overlay tester are the best available devices to examine resistance to reflective cracking in the laboratory.

Accelerated Pavement Testing for Rutting Evaluation of Hot-Mix Asphalt Overlay under High Tire Pressure

AbstractThis study focused on the rutting characteristics of two typical hot-mix asphalt (HMA) overlays in airfield composite pavement under high tire pressure: asphalt concrete (AC) and stone mast...

A Framework for Introducing Climate-Change Adaptation in Pavement Management

Greenhouse gas emissions have caused global temperatures to rise since the mid-20th century accompanied by sea-level rise (SLR). Temperature increases and SLR-induced groundwater rise have been shown to cause premature pavement failure in many roadway structures. Hybrid bottom-up/top-down (hybrid) adaptation approaches have shown promise by initially investigating an asset’s response to incremental environmental change and then identifying the timing of critical effects for budgetary planning. This improves practitioners’ understanding of the asset’s climate resiliency and informs adaptation-plan development to minimize both cost and risk. In this study, a hybrid approach to pavement adaptation with climate-change-induced temperature and groundwater rise is demonstrated at a case-study site in coastal New Hampshire. The hot-mix-asphalt (HMA) thickness that achieves a minimum of 85% reliability is calculated for 70 combinations of incremental temperature and groundwater rise. Increasing the base-layer thickness improves resiliency against rising temperatures, but rising groundwater diminishes this improvement demonstrating that both HMA and base-layer thickness increases are needed. Thirteen adaptation pathways are evaluated for pavement performance, life-cycle costs, and road-surface inundation over a 60-year pavement management period. A stepwise and flexible adaptation plan is developed that includes HMA overlays with prescribed thickness and application timing, base-layer rehabilitation options, and re-evaluation opportunities.

Analysis of airfield composite pavement responses using full-scale accelerated pavement testing and finite element method

Abstract This study focuses on the critical responses of airfield composite pavements that are composed of hot-mix asphalt (HMA) overlay and Portland cement concrete (PCC) pavement. Accelerated pavement testing (APT) and a finite element (FE) method were employed to investigate the effects of three influential factors: temperature, interface bonding, and load level. A full-scale test field was constructed for this study and instrumented with 20 strain gauges and 32 temperature sensors. A finite element model was developed based on the parameters derived from laboratory and field tests and the model was then validated through measurements. The results indicate that longitudinal strain is more critical than transverse strain in an HMA overlay when subjected to moving loads. Moreover, the results underscore that temperature significantly affects the responses of HMA overlays and that the relationship between temperature and pavement responses is sigmoidal. Furthermore, a good interface bonding is able to significantly reduce the critical strain in an HMA overlay and the interface bonding strength is very sensitive to the amount of tack coat. The positive strain near to the surface of HMA overlay is due to high compressive stress, which is different from the tensile strain used in fatigue testing.

Comparative assessment of the interlayer shear-bond strength of geogrid reinforcements in hot-mix asphalt

With the increasing use of geogrid reinforcements to mitigate reflective cracking in hot-mix asphalt (HMA) overlays, interlayer (interface) bonding has become an even more critical aspect of HMA placement/construction to mitigate delamination and debonding of the HMA overlay. To comparatively evaluate the interlayer bond strength due to the effects of the geogrid reinforcements, the shear bond strength test was conducted in this laboratory study, using unreinforced control HMA samples as the reference datum. Cylindrical HMA samples (150 mm diameter) gyratory compacted in two 75-mm lift thicknesses, with the geogrid reinforcement in-between the two lifts, were used for testing at room temperature under a monotonically shear loading rate of 5 mm/min. Emulsified asphalt was used as the interlayer tack coat and six different geogrid materials, which are polyester-based (FA) and fiberglass-based (FG), were comparatively evaluated. As theoretically expected, the control (unreinforced) HMA samples exhibited superiority followed closely by samples reinforced with polyester-based geogrids. Although comparable to the values reported in the literature, HMA samples reinforced with fiberglass-based geogrids performed the poorest with the lowest interlayer bond strengths – that is the polyester-based outperformed the fiberglass-based geogrids. Overall, the interlayer bond strength exhibited a general decreasing trend with a decrease in the geogrid mesh size (open area), increase in the geogrid strand thickness, and material grade. Thus, in as much as reflective crack mitigation is structurally desired, due diligence must be cautiously exercised when selecting the geogrid type/grade for use in HMA reinforcement to ensure sufficient interlayer bonding and minimize any potential delamination/debonding problems in service.

Influence of geosynthetic-interlayers on the performance of asphalt overlays on pre-cracked pavements

The functions of geosynthetic-interlayers in retarding reflection cracking and improving fatigue performance of hot mix asphalt (HMA) overlays in flexible pavements are evaluated in this study. The delamination or debonding mechanisms of the overlays are studied when geosynthetic-interlayers are adopted. A polyester grid coated with polymer modified binder (G1), a woven geo-jute mat (G2), and a bi-axial polypropylene grid (G3) interlayer are examined based on their adhesion properties. A two stage experimental program, in which, during the first stage, the performance of the geosynthetic-interlayers sandwiched between the pre-cracked old pavement and new asphalt layers are evaluated using flexural fatigue testing. A digital image correlation (DIC) technic was employed to record the failure modes and the corresponding tensile strains in the overlay system. During the second stage, the effect of interlayers on the interface bond strength was evaluated with the help of shear and tensile bond strength tests. The results show that the inclusion of interlayers retards the propagation of reflection cracking, however, results in the delamination of overlays. The debonding effect is prominent in G3 interlayers due to their high initial stiffness. Overall, interlayers with high interfacial shear and pull-off tensile bond properties proved effective in controlling the reflection cracking and increasing fatigue life of the overlays.

Highly Modified Asphalt Binder for Asphalt Crack Relief Mix

Reflective cracking is a common issue with respect to rehabilitated asphalt pavements, especially when the rehabilitation is done by applying a hot-mix asphalt overlay on the existing damaged pavement. Several approaches can be adopted to delay reflective cracking. They include an increase of the overlay thickness and the use of a stress relief asphalt mixture (SRAM), which is a fine-graded, flexible, and thin asphalt interlayer. Because the efficiency of a SRAM is highly related to the properties of the asphalt binder used in the mixture, it is of interest to use a highly modified asphalt (HiMA) binder. This paper describes a field test comprising three sections at BR-116 (a heavily trafficked highway in Brazil). One of the rehabilitation strategies used for a cracked asphalt pavement was a 2.5-cm SRAM (produced with a HiMA binder) and 5-cm styrene–butadiene–styrene (SBS) hot-mix asphalt (HMA). The other two strategies were to apply SBS HMA overlays of different thicknesses (7.5 cm and 10.5 cm). The aim was to evaluate and compare the capability of these solutions to control reflective cracking. Rheological properties and multiple stress creep and recovery tests were performed on the asphalt binders, and the semicircular bending test was performed on the asphalt mixtures. The surface conditions were monitored, and the results for each section were compared. After a 29-month period, the section that received the interlayer had the lowest cracked area and showed better resistance than the overlays did to reflective cracking and better maintenance of the original thickness of the pavement.

Mechanical response of flexible pavements enhanced with geogrid-reinforced asphalt overlays

The use of geosynthetic reinforcements placed underneath asphalt overlays, which has been typically used to minimise problems associated with reflective cracking, is evaluated in this study as an approach to improve pavement structural capacity. Whereas geosynthetics have been used to increase the pavement structural performance when used to reinforce the base aggregate, as reported in numerous laboratory and evaluations experiments, such improvement has not been evaluated for the case of geosynthetics within asphalt layers. Accordingly, this paper presents the results of large model tests involving both reinforced and unreinforced hot mix asphalt overlays. Cyclic wheel loads were applied using an accelerated pavement test facility that was specifically developed for this research. A number of pavement sections were constructed using a polyvinyl alcohol geogrid as reinforcement inclusions. The results show a considerable increase in pavements structural performance, as quantified by reduction of strains in the asphalt concrete layers, in the vertical stresses within the pavement layers and in the resilient displacements at the wearing surface. The use of geogrid reinforcements was also found to lead to reduce rutting and permanent lateral movements in the surface layer. Overall, the use of geogrids within asphalt overlays was found to act as a reinforcement element that provide enhanced structural capacity to flexible pavements.

Adaptation of NCHRP Project 1-41 Reflection Cracking Models for Semirigid Pavement Design in AASHTOWare Pavement ME Design

Semirigid pavements are composite pavements that comprise a surface asphalt concrete (AC) layer overlying a cement stabilized base, granular subbase, and subgrade foundation. When subjected to traffic and climate loading, semirigid pavements provide good performance through resistance to rutting or deformation of base and subgrade, moisture damage, and AC fatigue. However, semirigid pavements can develop fatigue and transverse shrinkage cracks in the underlying cement stabilized base layer, which ultimately propagates through the surface AC thickness with repeated applications of axle loads and temperature cycles (i.e., reflection cracking). Although new semirigid pavements have been designed and constructed in the United States since the 1960s, a new semirigid pavement design methodology was not included in Version 1.0 of AASHTOWare Pavement ME Design software. This methodology was omitted because developers and researchers at that time concluded that there were no suitable existing mechanistic-based fatigue or transverse reflection cracking models available to be adapted and included in the design procedure. Under NCHRP Project 1-41—Models for Predicting Reflection Cracking of Hot-Mix Asphalt Overlays, mechanistic-based AC fatigue and transverse reflection cracking models were developed. The models were developed to be compatible and thus easily adaptable into the AASHTOWare Pavement ME Design framework. Work done to adapt the NCHRP Project 1-41 reflection cracking models for the design of new semirigid pavement in AASHTOWare Pavement ME Design is presented.

CAM and SMA mixtures to delay reflective cracking on PCC pavements

Reflective cracking potential in hot mix asphalt (HMA) overlays on Portland cement concrete (PCC) pavement depends on the condition of PCC pavement in terms of slab stability at discontinuities (cracks and joints) and asphalt material characteristics in terms of their ability to resist reflective cracking. To develop a more comprehensive HMA overlay on PCC pavement program that minimizes reflective cracking potential and thus improves HMA overlay performance, TxDOT employed evaluation tools for both continuous deflection measurement of PCC slabs and overlay mix material characteristics. Rolling Dynamic Deflectometers (RDD) evaluate deflections on pavement surface continuously, providing valuable information on the stability of concrete slabs and load transfer efficiencies at discontinuities such as cracks and joints. Overlay testers (OT) evaluate the capacity of asphalt mixtures to resist reflective cracking. Since the performance of HMA overlay on PCC pavement depends on the extent of reflective cracking, design criteria should be developed for both slab stability and asphalt material properties. To that end, RDD and OT were utilized for the evaluations of HMA overlay on PCC pavements in four projects in Texas: (1) IH20, (2) SH225, (3) SH12, and (4) US96, with the objective of developing design criteria. This paper documents the efforts made to evaluate the PCC pavement condition before overlay, overlay material properties, and long-term performance of the four sections. CAM and SMA mixtures have been used successfully to retard reflective cracking, as they have exceeded eight years of life expectancy. Threshold values were validated for slab stability and asphalt materials, and applied for the designs of three rehabilitation projects.