Overlay Performance Research Articles

Overlay control solution for high aspect ratio etch process induced overlay error

In the semiconductor manufacturing process, especially in the high aspect ratio etch process of 3D NAND, overlay remains a constraint in an increasing device yield. With the increase in 3D layers, the etch process shows extreme inconsistency for different lots with different etch chambers, which makes it difficult to control within the budget. This article gives a systematic analysis on how the overlay feedback model reduces the overlay and which method should be used to reduce the etch-induced overlay residue. The linear and nonlinear inter- and intrafield models are used, and the overlay reduction performance is limited. Then, a correction per exposure (CPE) method is used, which shows the minimum residue. The feedforward overlay method together with the linear and nonlinear CPE method shows the best performance with only 20%–30% overlay residue. Two methods are recommended during the CPE model applied to control overfitting. One is to choose the best CPE order by judging the mark number of each exposure field, and the other is to define the fitting parameter range in a suitable range. Different CPE models are used and compared, and the verification results demonstrate that the suggested method has a great overlay fitting performance and overlay residue even if some parameters are excluded. That is, the study shows a method to balance the process variation, machine performance, feedback model, and metrology data.

Performance Evaluation and Prediction of Preservation Asphalt Overlay in Louisiana

The Louisiana Department of Transportation and Development (LaDOTD) has been using thin asphalt overlay (2 in.) as a preservation technique for asphalt-surface pavements. Although LaDOTD has specified the triggers for its application, it was not always applied on the recommended timing. It is unclear how the application timing affects the overlay performance. Additionally, no studies have been conducted to determine optimal application timing for the overlay and predict its performance using the available tools such as AASHTOWare Pavement Mechanistic-empirical design (Pavement ME) software. The objectives of the study are (1) to evaluate field performance of the preservation asphalt overlay and develop performance prediction models, (2) to determine optimal application timing for the overlay, and (3) to investigate if Pavement ME models are able to predict performance of the overlay by modifying model coefficients. To achieve the objectives, 33 preservation asphalt overlay projects were selected, and their performance was evaluated and predicted, then the optimal application timing was investigated based on the benefit and cost analysis. The results indicate that 58% of the preservation asphalt overlays had 10–20 years’ service life, and 42% had 7–10 years’ service life in relation to Pavement Condition Index threshold of 70. Additionally, good precondition or flexible base (asphalt concrete or unbounded base) can result in a longer service life in the overlay. It is also found that an average value of optimal timing of the next overlay application is the 9th year after construction. Finally, the rehabilitation models of asphalt overlay in Pavement ME software could be used for preservation asphalt overlay by modifying model coefficients.

Fast flow cloud: A stream dataflow framework for cloud FPGA accelerator overlays at runtime

AbstractCloud FPGAs provide new energy‐efficient opportunities to design dataflow accelerators. Nevertheless, FPGAs still have challenges to overcome for widespread usages, such as programmability, compilation time (minutes to hours), and hardware knowledge, mainly because it is highly challenging for beginners to learn and use FPGAs. The READY tool recently provides compilation time reduction to the range of microseconds using a CGRA overlay and a friendly, high‐level C++ interface for the Intel/Altera HARPv2 FPGA cloud platform. However, the HARPv2 is not available in any commercial cloud platform. This work extends READY by creating the fast flow cloud framework (FFC). First, FFC offers a simple browser‐based graphical interface for less experienced FPGA users. Second, we improve the CGRA overlay portability to include Xilinx FPGAs and a transparent design flow to deploy in the widespread commercial Amazon AWS F1 cloud. Third, we improve the CGRA reconfiguration engine. Also, we compare the overlay performance of HARPv2 and AWS F1 to an eight‐thread XEON processor. Finally, the framework is open‐source for collaborative development and has clearly defined application programming interfaces for future extensions.

Performance of Asphalt Rubber Mixture Overlays to Mitigate Reflective Cracking.

Adequately predicting overlay behaviour is essential for flexible pavement rehabilitation to reach the predicted lifespan. Reflective cracking is one of the main failure mechanisms affecting overlay performance. This failure may occur due to cracks in the lower layers that propagate to the overlay due to traffic loads, temperature variations, shrinkage cracking of cement-treated layers, and subgrade movements. This work aims to assess the reflective cracking phenomenon of asphalt rubber mixtures as an overlay through laboratory tests and numerical simulation. Four-point bending equipment and the reflective crack device were used to perform the laboratory tests. A numerical simulation through the finite element method was accomplished to estimate the von Mises strain and develop reflective cracking fatigue laws. The results showed that the asphalt rubber mixtures are suitable for extending overlay lifespan considering reflective cracking. The evaluated asphalt rubber mixtures presented reflective cracking resistance almost eight times greater than the conventional ones.

DEM analysis of the evolution of reflection cracks in old cement concrete pavement with an ATB layer

ABSTRACT The discrete element method (DEM) is one of the most popular methods used to study the performance of pavement materials. However, few studies use the DEM to evaluation the damage performance of asphalt overlays on cement pavements. This paper focuses on the establishment of discrete element models to simulate the reflective crack development of asphalt overlays on cement pavement. Three contact models are selected to realise the pavement structure layer. The results show that under flexural tensile loading and shear loading, the development of reflective cracks can be inhibited with increasing asphalt overlay thickness, while the influence of the interlayer bond strength on the crack development is not obvious. In addition, the flexural tensile load can promote the development of cracks more than shear load. Under the action of thermal fatigue stress, the opening degree of crack displacement increases with the fatigue stress ratio, while the increase in interlayer bond strength can slow down the development and expansion of cracks. Moreover, thermal fatigue stress causes reflective cracks in the overlay to develop earlier and faster.

Mechanistic–Empirical Analysis of Pavement Performance Considering Dynamic Axle Load Spectra Due to Longitudinal Unevenness

Pavement distresses are induced by mechanistic responses in pavement structure subjected to dynamic loads of moving vehicles. Pavement surface evenness deteriorates as pavement distresses propagate, which results in dynamic axle loads and faster pavement deterioration. It is vital to consider the dynamic axle load spectra to predict pavement deterioration using traffic-monitoring data. This study aimed to evaluate the effect of dynamic loads and overweight traffic on asphalt pavement overlay performance using mechanistic–empirical (M–E) pavement analysis. The relationship between dynamic load coefficients (DLCs), axle loads, and international roughness index (IRI) was obtained for accurate quantification of dynamic axle loads. Then the dynamic axle load spectra were derived by shifting the static axle load spectra in weigh-in-motion (WIM) data, given the DLC value. AASHTOWare Pavement ME software was used to analyze pavement performance with static and dynamic axle load spectra, and the impact of overweight traffic on asphalt pavement overlay performance. The impact of dynamic loads on reflective fatigue cracking was distinguished at an early stage of the service period and eliminated after the 10-year analysis period, when the propagation of reflective cracking reached a specific level. On the other hand, the consideration of dynamic axle loads increased the impact of overweight truck traffic on pavement distresses, and pavement structures of major highways tend to be more sensitive to overweight traffic because of greater DLC excitement at higher operational speeds.

Survival of Prosthodontic Restorations Luted with Resin-Based versus Composite-Based Cements: Retrospective Cohort Study.

The purpose of this study was to evaluate clinical performance, survival, and complications of indirect composite inlays, onlays, and overlays on posterior teeth. Digital records of 282 patients treated between 2014 and 2018 were accessed and analyzed retrospectively. The included patients received 469 composite restorations luted with seven different resin-based types of cement, i.e., Filtek Ultimate Flow, Enamel Plus, Relyx Ultimate, Harvard Premium Flow, Relyx Unicem, Filtek Bulk Fill Flowable, and Filtek Ultimate. The restorations had been clinically and radiographically evaluated annually. The mechanical and clinical complications, e.g., debonding, fracture, and secondary caries, were evaluated and recorded. The examined restorations exhibited a high survival rate (84.9%), and failure was found in only 71 cases. Fracture was the most common cause (n = 36), followed by prosthetic work release (n = 19) and secondary caries (n = 16). There was a statistically significant difference between failure and cement material (Sig. < 0.001); the composite-based cements (87.2%) had a high survival rate compared to the resin-based cement (72.7%). Similarly, the cements with high viscosity (90.2%) had significantly higher survival rates than the low-viscosity cements (78.9%). Moreover, onlays showed higher longevity compared to overlays (Sig. = 0.007), and patients aged under 55 years showed less complications (Sig. = 0.036). Indirect composite restoration was a successful solution to tooth structure loss. The material of the cementation is an important part of the success. Higher survival rate was found in our study when the fixation materials with high viscosity were used, thus suggesting using these materials with indirect restorations. Composite-based cements had significantly higher survival rate than resin-based cements.

The Performance Optimization of Big Data Processing by Adaptive MapReduce Workflow

The discussion context of this paper is big data processing of MapReduce by volunteer computing in dynamic and opportunistic environments. This paper conducts a series of simulations to explore the relationship between the overall performance of volunteer overlays responding to different workload of big data problems. The discovery from the simulations includes some optimization points in overlay size, going over which by adding more volunteers brings little benefit for the overall performance. Based on the discovery of optimization points, this paper proposes a bootstrapping protocol, which can adapt volunteers into variable-sizes overlays, enabling workflow of single-round MapReduce or multiple-round MapReduce, and a single or multiple overlays for each round. The variable overlays aim to create adaptive workflow during MapReduce processing, so that the optimization points can be caught. As another benefit, the unnecessary computing-capacities can be released during computing when the optimization points are reached. The case study shows a few optimization workflows that are formed by the proposed bootstrapping protocol to process the big data cases. The workflows lead to the optimization points and dynamically balance the workload at the same time. The experiment results have demonstrated that the optimization strategies have either achieved 36% or 71% higher performance than the plain MapReduce workflow and minimized the use of computing resources by releasing 12.5% to 75% volunteers during computing, where the original plain MapReduce must hold all the volunteers to the end of computing. The extensibility of the simulation parameterization to more diverse real-world applications have been clarified.

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.

Evaluation of joint activation and joint spacing in concrete overlays

Optimized joint spacing is crucial to ensure concrete overlay performance and service life. While pavement joints are used to control cracks in concrete slabs and help relieve stresses, not all sawn joints crack or “activate” initially. If cracks do not form below saw-cut joints, the effective slab length is high, potentially leading to excessive movements at the activated joints and increasing the risk of random cracking. Non-destructive testing (NDT) approaches, such as MIRA, are proved to be effective on detecting whether a saw-cut has been activated. The saw-cutting joints from 54 concrete overlay project sites in Iowa were evaluated using a MIRA. The data indicated that approximately 60% to 70% of joints assessed were activated for the shorter joint spacing, while more than 95% of joints were activated for conventional joint spacing. These results were used to develop recommendations with respect to optimized joint spacing of concrete overlays. .

Multi-Level Laboratory Performance Evaluation of Conventional and High Polymer-Modified Asphalt Mixtures

Asphalt concrete (AC) overlays have been one of the most common treatments used by the Virginia Department of Transportation (VDOT) for maintaining/rehabilitating pavements. However, when the overlay is placed on existing composite pavements or cracked AC pavements, differential movements across any cracks or joints can result in physical tearing of the AC overlay. Thus, the long-term performance of many AC overlays will highly depend on their ability to resist cracking. The purpose of this study was to assess the viability of using high polymer-modified (HP) AC mixtures in Virginia as a crack mitigation technique or when deemed appropriate as a tool for increased resistance to rutting and cracking on higher volume facilities. Another objective was to assess the ability of various testing protocols to discern the performance of pavements through a comprehensive evaluation of three conventional polymer-modified (PMA) and five HP field-produced mixtures placed in Virginia. This included laboratory testing at multiple levels of complexity (basic, intermediate, and advanced) on collected asphalt binders, plant-produced asphalt mixtures, and field cores. The performance characteristics of PMA and HP mixes were evaluated in the laboratory in relation to durability and resistance to rutting and cracking. Based on the mixes tested, stone matrix asphalt (SMA) mixes showed better performance than dense-graded surface mixes (SM) regardless of the asphalt binder type. Moreover, HP mixes showed better performance than PMA mixes regardless of the mixture type. Overall, SMA-HP mixes showed the most promising performance among all evaluated mixes.

Mechanical system and dynamic control in photolithography for nanoscale fabrication: A critical review

AbstractAs one of the most advanced and precise equipment in the world, a photolithography scanner is able to fabricate nanometer‐scale devices on a chip. To realize such a small dimension, the optical system is the fundamental, but the mechanical system often becomes the bottleneck. In the photolithography, the exposure is a dynamic process. The accuracy and precision of the movement are determined by the mechanical system, which is even more difficult to control compared with the optical system. In the mechanical system, there are four crucial components: the reticle and wafer stages, the linear motor, the metrology system, and the control system. They work together to secure the reticle and substrate locating at the correct position, which determines the overlay and alignment performance in the lithography. In this paper, the principles of these components are reviewed, and the development history of the mechanical system is introduced.

Performance of Two Thin Epoxy Overlays on New Concrete under Laboratory and Outdoor Exposure Conditions

Thin epoxy overlays are used for improving the condition and extending the service life of bridge decks. The tensile bond pull-off strength, evaluated as per ASTM C1583, is used as the performance indicator. A failure in the substrate with a tensile strength of 250 pounds per square inch (psi) or greater is considered acceptable. However, the performance of in-service bridge decks when evaluated shows inconsistent results. Such studies failed to record and correlate the parameters that influence overlay performance during testing to clarify the observed variations. Laboratory studies by several researchers have documented a distinct performance difference when the overlays are exposed to room temperatures in comparison with elevated temperatures. However, the most influential parameters, such as the variation of substrate moisture against temperature and epoxy softening under elevated temperatures, were not measured and correlated to the observed performance. This study was initiated to provide clarification of the observed performance differences by evaluating the impact of concrete age at the time of epoxy application, concrete mix ingredients, exposure conditions, concrete microstructure development, and substrate moisture and temperature on the performance of two epoxy overlays. Experimental results confirm that (i) the performance of epoxy overlays improves when the concrete mix contains slag and (ii) substrate moisture vapor pressure and epoxy softening under elevated temperature negatively affect the overlay performance.

Real-time deep learning semantic segmentation during intra-operative surgery for 3D augmented reality assistance

PurposeThe current study aimed to propose a Deep Learning (DL) and Augmented Reality (AR) based solution for a in-vivo robot-assisted radical prostatectomy (RARP), to improve the precision of a published work from our group. We implemented a two-steps automatic system to align a 3D virtual ad-hoc model of a patient’s organ with its 2D endoscopic image, to assist surgeons during the procedure.MethodsThis approach was carried out using a Convolutional Neural Network (CNN) based structure for semantic segmentation and a subsequent elaboration of the obtained output, which produced the needed parameters for attaching the 3D model. We used a dataset obtained from 5 endoscopic videos (A, B, C, D, E), selected and tagged by our team’s specialists. We then evaluated the most performing couple of segmentation architecture and neural network and tested the overlay performances.ResultsU-Net stood out as the most effecting architectures for segmentation. ResNet and MobileNet obtained similar Intersection over Unit (IoU) results but MobileNet was able to elaborate almost twice operations per seconds. This segmentation technique outperformed the results from the former work, obtaining an average IoU for the catheter of 0.894 (σ = 0.076) compared to 0.339 (σ = 0.195). This modifications lead to an improvement also in the 3D overlay performances, in particular in the Euclidean Distance between the predicted and actual model’s anchor point, from 12.569 (σ= 4.456) to 4.160 (σ = 1.448) and in the Geodesic Distance between the predicted and actual model’s rotations, from 0.266 (σ = 0.131) to 0.169 (σ = 0.073).ConclusionThis work is a further step through the adoption of DL and AR in the surgery domain. In future works, we will overcome the limits of this approach and finally improve every step of the surgical procedure.

Performance-Based Approach for Deciding the Age of New Concrete for Thin Epoxy Overlay Application

A thin epoxy overlay application is a capital preventive maintenance activity. Epoxy overlays reduce the rate of chloride ion ingress and extend bridge deck service life. Highway agency policies and manufacturer specifications require maintaining a 28-day curing period (7-day wet and 21-day dry curing) before the application of an epoxy overlay on bridge decks requiring new concrete for patches and repairs. Consequently, the contractors wait for 28 days to apply an epoxy overlay. Delaying application time increases project completion time and the cost of construction and mobility. The suitability of new concrete to receive epoxy overlays and the performance of overlays depend on several parameters including concrete strength, moisture, and tendency to crack. Such parameters depend on concrete mixture ingredients and wet and dry curing periods. This paper presents a performance-based procedure for evaluating the possibility of reducing the 28-day waiting period for a thin epoxy overlay application on new concrete. An experimental program was developed and executed to evaluate the impact of epoxy overlay application parameters and overlay performance using a tensile bond pull-off strength test. The results support developing a performance-based procedure for deciding on the suitable age of new concrete to receive a thin epoxy overlay. The pull-off bond strength of epoxy overlays applied at 7, 14, and 21 days, following a 7-day moist curing, shows the possibility of applying an epoxy overlay before the end of the 28-day curing period stipulated in the current specifications.

Impact of Concrete Mix Ingredients and Surface Treatments on Epoxy Overlay Performance

Epoxy overlays are applied on bridge decks after curing concrete in patches and repairs for 28 days. A tensile bond pull-off strength of at least 250 pounds per square inch (psi) is expected from a properly applied overlay. Even though the overlay performance at room temperature is mostly satisfactory, the performance at elevated temperatures is not convincing. The degradation of mechanical and adhesion properties of epoxy, shear stress at the concrete/overlay interface caused by thermal incompatibility, and the interface moisture vapor pressure are the commonly cited parameters for poor bond strength at elevated temperatures. A combined effect of these parameters results in the most unfavorable failure mode (which is bond failure at the concrete/overlay interface) at a strength lower than the specified limit of 250 psi. The moisture migration through concrete depends on many factors including moisture content along the depth of concrete, pore microstructure, exposure condition, and drying period. This study investigated the impact of concrete mix ingredients and surface treatments on the thin epoxy overlay bond strength. The results show that the use of concrete mixes with slag and penetrating sealant pretreatment improves the bond strength.

Performance of AC overlays using geogrids on PCC contraction joints

It is widely known that vertical displacements and strains occur on the joints and these cause defects on the asphalt concrete (AC) overlays on existing Portland cement concrete (PCC) pavements. Various approaches were introduced to minimize these defects. In this study, the effect of joint support formed using the geogrid material with grout mortar on the vertical displacement of PCC and the strain at the bottom of the AC layer. Produced layers were exposed to 1,186,000 Equivalent Single Axle Load (ESAL) in an APT (Accelerated Pavement Test) facility and the results were monitored. According to the obtained results, the use of AC overlay reduces vertical displacement in the PCC by 75%. When geogrid reinforced AC overlay was used, an additional reduction in displacement by 41.2% was achieved. Geogrid reinforcement reduced strain values formed at the bottom of the AC layer from 29.5% to 92.5%. The use of geogrid at joints instead of increasing the thickness of the AC layer from 50 to 80 mm resulted a more significant reduction in both strain and displacement. Besides, the usage of a geogrid interlayer instead of increasing the thickness of the AC layer also provided a significant cost reduction of 57.9% in overall cost.

Influence Function Measurement Technique Using the Direct and Indirect Piezoelectric Effect for Surface Shape Control in Adaptive Systems

Since the introduction of adaptive systems for corrective measures, static and dynamic disturbances have been reduced through the manipulation of surface shape in a well-controlled manner. One important application where adaptive systems are highly needed is in the future photo-lithography machines, particularly the wafer table where disturbances affect overlay and focus performance. To reduce overlay and focus errors, a dense array of actuators must be integrated into the wafer table to apply both in- and out-of-plane corrective deformations to the wafer surface. To realize a certain wafer shape, influence functions are linearly superimposed. Accurate models of the influence functions result in an accurate prediction of the final wafer shape. To reduce calibration errors, the influence function of every actuator needs to be determined. Here, we propose a technique to rapidly measure the influence function: the influence function measurement (IFM) technique. Using the actuate-sense property of piezoelectric materials, the influence function is determined by activating one piezo-actuator and measuring the charge induced on the neighboring piezo-actuators. The measured charges are compared to the results of finite element simulations and the absolute difference of 0.3 &#x0025; is reported for the inter-actuator charge coupling parameters. This clearly indicates the potential of the proposed technique. <i>Note to Practitioners</i>&#x2014;A critical step during the integrated-circuit lithographic fabrication process is the exposure. A particular practical challenge in this step is to correct for the mismatch between the optical image plane and the wafer surface, caused by wafer deformations. The mismatch negatively impacts the overlay and focus performance. To reduce the mismatch, actuators can be embedded into the wafer table to counteract wafer deformations, where the overall wafer surface shape is a superposition of each actuator&#x2019;s influence function. As part of the calibration for the embedded actuators, their influence functions are measured and stored. However, errors arise when influence functions are not measured for every actuator. Additionally, for different wafers, the influence functions vary hence the calibration should be done per wafer. This calibration process takes time and should not influence throughput. Our paper presents a viable approach that reduces the calibration time of active wafer tables, which is also relevant for other adaptive systems such as deformable mirrors. Since the technique requires the actuators to be mechanically coupled, it is limited to continuous surfaces. The proposed technique is numerically tested and experimentally verified to demonstrate performance.

Analysis of critical factors to asphalt overlay performance using gradient boosted models

Traditional pavement performance predictions based on empirical equations typically utilize only a limited number of parameters to form relatively simple models, thus fail to generate predictions of satisfactory accuracy. With the ever-increasing size of pavement data, model-free methods such as analytical learning algorithms have become promising alternatives. Therefore, to improve the accuracy of pavement performance prediction and take advantage of the existing large dataset, this study introduced an analytical approach, the gradient tree boosting model (GTBM), to predict asphalt overlay performance and identify key factors affecting it. Five indicators were selected to represent the overlay performance, including roughness (in international roughness index, IRI), rutting, fatigue cracking, transverse cracking, and longitudinal cracking. All data were collected from the Specific Pavement Studies 5 (SPS-5) in the Long-Term Pavement Performance (LTPP) program. The results showed that pre-overlay rutting and transverse cracking were crucial to the development of overlay performance, thus pretreatment of repairing existing rutting and transverse cracking on the old pavement is essential to prolong the service life of asphalt overlay. The initial value of overlay IRI was the most critical factor for the IRI prediction. Besides, overlay roughness was found to be strongly related to the asphalt content and gradation of hot mix asphalt (HMA); fatigue cracking exhibited a close relationship with the thickness of underlying pavements and asphalt viscosity; transverse cracking was strongly associated with the air voids of HMA; non-wheel path longitudinal cracking was relevant to the asphalt content and gradation of HMA.

Effects of Concrete Age on Coefficient of Thermal Expansion of Paving Mixes and Its Significance in Unbonded Overlay Design

Abstract With the advancement in rigid pavement design and advent of AASHTOWare Pavement Mechanistic-Empirical (ME) Design (American Association of State Highway and Transportation Officials, Washington, DC) as the latest design tool, increasing emphasis is being laid on the coefficient of thermal expansion (CTE) of concrete. The CTE affects the performance of rigid pavements in a significant manner, with a higher CTE corresponding to greater curling and resulting in greater pavement distresses. Prior research has conflicting views regarding CTE variation with age, and there has been very little to no research on the effects of CTE on the performance of unbonded concrete overlays (UBCOs). This study is performed to investigate the variation of CTE with concrete age through laboratory testing and further quantify the effects of CTE variation on UBCO design. To facilitate, four concrete paving mixes with different types of coarse aggregates and different mix properties from different districts of New Mexico were collected. The cast specimens from each of the mixes were tested for CTE as per the AASHTO T-336, Coefficient of Thermal Expansion of Hydraulic Cement Concrete, protocol, at the ages of 7, 14, 28, 60, 90, 120, and 180 days, respectively. The test results were analyzed, and it was observed that there is an increase in CTE over the range of 3.49 % to 9.77 %, between 28 days and 180 days. Further analysis was conducted with simulations in Pavement ME Design Version 2.3® that indicated a significantly deteriorated performance of the UBCO with increased CTE. The impact on transverse cracking and joint faulting is the most significant, with up to 13.3 % increase in cracking and up to 19.7 % increase in faulting distress. An unbonded overlay designed with 28 days CTE value may not perform for the design life because of the increase in CTE with age progression.