Search

In this investigation, four types of sands as alternatives to river sand, namely, crushed sand (CS), marine sand, fine recycled concrete aggregate (FRCA), and fine reclaimed asphalt pavement (FRAP), were studied for their potential for cement-concrete pavement applications. Initially, the physicochemical and morphological characteristics of these sands were understood and later linked to the hydration kinetics and the behavior of cement-mortar systems in both the fresh and hardened states. Due to their evenly graded particle size distribution, CS and FRCA exhibited higher packing densities despite having more gradient angularity, whereas the interlocking capacity of FRAP was found to be affected by the agglomerated particles. Morphology, fineness modulus, and chemical composition of the sands were observed to be the dominating parameters affecting the hydration kinetics and thus the performance of the mortar mixes. Improving these parameters, especially the grain size distribution, could help in enhancing the potential of these sands for pavement applications. [ABSTRACT FROM AUTHOR]

In seasonally frozen regions, concrete pavement is exposed to cycles of freeze-thaw and erosion from de-icing salt, which can lead to unfavorable service conditions and vulnerability to damage. This paper examines the compressive strength, flexural-tensile strength, abrasion resistance, permeability, and spacing factor of concrete, taking into account the impact of various curing conditions, de-icing salt solutions, and mass fractions on the concrete's freeze-thaw resistance. Two test methods, the single-face method and the fast-freezing method, were used to comparatively analyze the freeze-thaw resistance of concrete. The analysis was based on the surface scaling, water absorption rate, mass loss rate, relative dynamic elastic modulus, and relative durability index. The results indicate that the presence of salt solution significantly worsened the degree of concrete damage caused by freeze-thaw cycles. The use of freeze-thaw media, specifically sodium chloride ( N a C l ), calcium chloride ( C a C l 2 ), and potassium acetate ( K A c ) at mass fractions of 5%, 4.74%, and 5%, respectively, had the greatest impact on the surface scaling of concrete. However, their effect on the water absorption rate was inconsistent. When the freeze-thaw medium was water, the concrete's relative dynamic elastic modulus and relative durability index were 9.6% and 75.3% higher, respectively, for concrete cured in 20 °C—95% RH conditions compared to those cured in 0 °C—50% RH conditions. We propose a comprehensive relative durability index ( D F w ) by combining the results of two methods of freeze-thaw tests. The D F w of concrete cured in 0 °C—50% RH conditions was 83.8% lower than that of concrete cured in 20 °C—95% RH conditions when exposed to a freeze-thaw medium of 5% mass fraction N a C l solution. To evaluate the salt freeze-thaw resistance of concrete pavement, it is recommended to use surface scaling and D F w together. [ABSTRACT FROM AUTHOR]

The combination of an absorbing structure and a road is a promising strategy for road deicing using microwaves. In this study, cement mortar (CM) specimens containing a carbon fiber screen (CFS) were prepared to concentrate electromagnetic losses on a road surface. The effect of the size and depth of the CFS on the surface heating efficiency of the microwave was studied and optimized, and a microwave deicing experiment was conducted. The results indicated that the destructive interference produced by the CFS led to the effective surface heating of the CM/CFS specimens. The optimal surface heating rate was 0.83 °C/s when the spacing, depth, and width of the CFS were 5.22, 13.31, and 2.80 mm, respectively. The deicing time was shortened by 21.68% from 83 to 65 s, and the heating rate increased by 17.14% from 0.70 to 0.82 °C/s for the specimen with CFS-1, which was 15 mm depth. Our results demonstrate that CM/CFS composite structures can be effectively applied to increase the capacity and accelerate the development of the microwave deicing of roads. [ABSTRACT FROM AUTHOR]

In the context of ongoing rapid industrialization, the increasing deposition of industrial waste has arisen as a persistent global challenge, necessitating immediate attention and subsequent implementation of sustainable remedies. This study convenes on the efficacy of industrial wastes, namely fly ash and ground granulated blast furnace slag, as geopolymer concrete synthesizers in conjunction with the incorporation of reclaimed asphalt pavement (RAP) aggregates as a replacement for natural coarse aggregates varying over 25% to 100%. Under 7 days of ambient curing, employing 14M NaOH and a 50% RAP replacement, the mix achieved significant strengths of 41.80 MPa in compression and 4.72 MPa in flexure, affirming its suitability for pavement quality concrete (PQC). Through this study, the phenomenon of efflorescence could also be explored, which was particularly significant during the winter seasons. Furthermore, the declining coefficient of determination (R2) with the rise in RAP, observed in the correlation between compressive strength and ultrasonic pulse velocity (USPV), likely signified increased variability in the mixture at higher replacement levels. Assessment of long-term performance in terms of resistance to surface abrasion established the mix as durable, depicting minimal depth of wear (0.081 mm). Furthermore, results of the rapid chloride penetration test (RCPT) demonstrated that the presence of adhered asphalt in RAP aggregates reduces porosity and enhances resistance. Microstructural study was additionally conducted to comprehend the importance of adhered asphalt in impeding crack propagation. ANOVA established a highly significant relationship between the interaction of curing age and RAP fractions with the strength characteristics of the mix. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility and effectiveness of employing waste ceramic (WC) in rigid pavement as a replacement for fine aggregate. WC was integrated into concrete; untreated and treated with a silane compound, where 30 wt.% and 50 wt.% sand was replaced with WC. The workability, compressive strength, water absorption, skid resistance, microstructural analysis, and surface chemistry of mixtures were evaluated. The results illustrated the positive impact of using treated WC on the water absorption of mixtures, where a maximum reduction of 19% was achieved in the mixture with 50% treated WC. Moreover, concrete with 30% treated WC attained a higher compressive strength of 43 MPa than its untreated counterpart, which achieved 29 MPa, when tested at 28 days. The integration of treated and untreated WC in concrete pavement reduced its skid resistance due to the presence of glaze in the untreated mixture and silane in the treated mixture. The morphological and surface chemistry analyses confirmed the development of C–S–H, CaCO3, and SiO2 in high contents in concrete with silane-treated WC. Also, a strong bonded interfacial transition zone was noticed in concrete with silane-treated WC, unlike concrete with untreated WC, which had a poor interfacial transition zone. [ABSTRACT FROM AUTHOR]

As a result of the advantages of the steel fiber reinforced concrete pavement structure, which includes high strength, high stiffness, and high stability, a large number of steel fiber concrete pavements will be used for highway construction in China. As a result, numerous cracks develop, which significantly reduces the life of the road; therefore, the study of the jointing problem is vital. As concrete research on the influence of the load transfer capacity and service life of prefabricated steel fiber reinforced concrete joints on the structural design and use function of the whole and pavement panels, the paper proposes two joint forms, tongue-and-groove and overlap. Using experiments and software, the stress and reflection of prefabricated road panels of the two joint forms are analyzed for different axial loads. The analysis reveals that the maximum tensile stress, shear stress, and deflection of the precast panels of both joint forms increase linearly as the axle load of the vehicle increases, while the service life decreases relatively. The load transfer capacity is independent of the axle load magnitude, and the load transfer capacity difference between the two types of joints is minimal and excellent. [ABSTRACT FROM AUTHOR]

Pavement engineers are paying attention to the stabilization of granular layers in the modern era of sustainable construction. A well-drained pavement can extend the service life to its design life if properly designed and maintained. The water infiltrating into the pavement causes detrimental effects and reduces the service life of the pavement. The open-graded cement-stabilized macadam (OGCSM) can act as a drainage layer in sustainable pavements. Cement cannot be considered as a long-term sustainable material due to its high carbon footprint. This paper investigated the suitability of a supplementary cementitious material, ground granulated blast furnace slag (GGBFS), as a partial replacement of cement in OGCSM, a drainage layer in pavements. The strength and permeability characteristics of the mix were studied using an unconfined compressive strength (UCS) test and specially fabricated permeameters, respectively. OGCSM was optimized at 7% cement content, and cement in the OGCSM was partially substituted with GGBFS at various replacement levels. The mix was optimized at 80% replacement of cement with GGBFS, which satisfied the specified requirements for strength, permeability, and durability. The UCS, coefficient of effective permeability, and water resistance index of the optimized mix were 2.88 MPa, 60.58 m/day and 96.33%, respectively. The morphology and mineralogy characteristics of the optimized mix were determined to justify the strength gain in cementitious mixtures. The porosity of the OGCSM mix was estimated as 25.86% using computed tomography (CT) scanned images. The subsurface drainage design was carried out using drainage requirements in pavements (DRIP 2.0) software, and the quality of drainage was rated as good. [ABSTRACT FROM AUTHOR]

Pavement crack detection is of significant importance in ensuring road safety and smooth traffic flow. However, pavement cracks come in various shapes and forms which exhibit spatial continuity, and algorithms need to adapt to different types of cracks while preserving their continuity. To address these challenges, an innovative crack detection framework, CrackDiff, based on the generative diffusion model, is proposed. It leverages the learning capabilities of the generative diffusion model for the data distribution and latent spatial relationships of cracks across different sample timesteps and generates more accurate and continuous crack segmentation results. CrackDiff uses crack images as guidance for the diffusion model and employs a multi-task UNet architecture to predict mask and noise simultaneously at each sampling step, enhancing the robustness of generations. Compared to other models, CrackDiff generates more accurate and stable results. Through experiments on the Crack500 and DeepCrack pavement datasets, CrackDiff achieves the best performance (F1 = 0.818 and mIoU = 0.841 on Crack500, and F1 = 0.841 and mIoU = 0.862 on DeepCrack). [ABSTRACT FROM AUTHOR]

In order to solve the problem that the skid resistance of concrete pavement in tunnel deteriorates rapidly, which is easy to cause traffic accidents, the anti-skid rapid elevation technology of surface treatment is proposed. Wear tests were used to investigate the effects of concrete surface roughness, properties of modified emulsified asphalt binder and anti-skid fine aggregate type on long-term skid resistance of treated surfaces. The results show that the four coarsening methods of fine milling, milling, grooving and brooming can improve the skid resistance of concrete, and the skid resistance durability of fine milling and milling is better. The adhesive property of modified emulsified asphalt is the best when the content of water-based epoxy resin is 20%. In different aggregates, the anti-skid effect is better when silicon carbide is used as anti-skid aggregate and the particle size is 0.6mm:0.3mm = 2:3. The method of fine milling of concrete surface + spraying epoxy emulsified asphalt + spreading silicon carbide can effectively improve the anti-skid performance of the original concrete pavement, and the feasibility of the scheme is verified by the test road. The research results have a good reference value for improving the skid resistance of tunnel concrete pavement. [ABSTRACT FROM AUTHOR]

Detecting road cracks is essential for inspecting and assessing the integrity of concrete pavement structures. Traditional image-based methods often require complex preprocessing to extract crack features, making them challenging when dealing with noisy concrete surfaces in diverse real-world scenarios, such as autonomous vehicle road detection. This study introduces an image-based crack detection approach that combines a Random Forest machine learning classifier with a deep convolutional neural network (CNN) to address these challenges. Three state-of-the-art models, namely MobileNet, InceptionV3, and Xception, were employed and trained using a dataset of 30,000 images to build an effective CNN. A systematic comparison of validation accuracy across various base learning rates identified a base learning rate of 0.001 as optimal, achieving a maximum validation accuracy of 99.97%. This optimal learning rate was then applied in the subsequent testing phase. The robustness and flexibility of the trained models were evaluated using 6,000 test photos, each with a resolution of 224 × 224 pixels, which were not part of the training or validation sets. The outstanding results, boasting a remarkable 99.95% accuracy, 99.95% precision, 99.94% recall, and a matching 99.94% F1 Score, unequivocally affirm the efficacy of the proposed technique in precisely identifying road fractures in photographs taken on real concrete surfaces. [ABSTRACT FROM AUTHOR]

One of the most significant problems affecting a concrete bridge's safety is cracks. However, detecting concrete bridge cracks is still challenging due to their slender nature, low contrast, and background interference. The existing convolutional methods with square kernels struggle to capture crack features effectively, fail to perceive the long-range dependencies between crack regions, and have weak suppression ability for background noises, leading to low detection precision of bridge cracks. To address this problem, a multi-stage feature aggregation and structure awareness network (MFSA-Net) for pixel-level concrete bridge crack detection is proposed in this paper. Specifically, in the coding stage, a structure-aware convolution block is proposed by combining square convolution with strip convolution to perceive the linear structure of concrete bridge cracks. Square convolution is used to capture detailed local information. In contrast, strip convolution is employed to interact with the local features to establish the long-range dependence relationship between discrete crack regions. Unlike the self-attention mechanism, strip convolution also suppresses background interference near crack regions. Meanwhile, the feature attention fusion block is presented for fusing features from the encoder and decoder at the same stage, which can sharpen the edges of concrete bridge cracks. In order to fully utilize the shallow detail features and deep semantic features, the features from different stages are aggregated to obtain fine-grained segmentation results. The proposed MFSA-Net was trained and evaluated on the publicly available concrete bridge crack dataset and achieved average results of 73.74%, 77.04%, 75.30%, and 60.48% for precision, recall, F1 score, and IoU, respectively, on three typical sub-datasets, thus showing optimal performance in comparison with other existing methods. MFSA-Net also gained optimal performance on two publicly available concrete pavement crack datasets, thereby indicating its adaptability to crack detection across diverse scenarios. [ABSTRACT FROM AUTHOR]

This paper presents an effort to address urgent issues associated with semitruck platooning. The weigh-in-motion data were first examined to determine the characteristics of naturally formed semitruck platoons. A safety-based two-vehicle platoon model was then utilized to determine the critical headways for assessing the safety of semitruck platooning in various driving scenarios. The possibilities for passenger vehicles to cut into semitruck platoons were assessed using actual vehicle headway data. Finally, the potential impacts of semitruck platooning on typical interstate highway pavements were assessed using finite element analysis. Most semitruck platoons consist of two to three vehicles. An optimal platoon gap of 0.94 s was identified for connected and automated semitruck platooning. The potential impacts of truck platooning on concrete pavement were negligible for a platoon gap greater than 0.2 s. The maximum possible impact was less than 4% in terms of the service life reduction for interstate asphalt pavement. [ABSTRACT FROM AUTHOR]

Joints in Roller Compacted Concrete (RCC) pavements are used to distribute traffic loading between adjacent slabs by friction. The Load Transfer Stiffness (LTS) of the joints has critical effects on RCC pavement performance near the joints. Research has shown that LTS can deteriorate over time due to traffic loading or environmental conditions. This study investigates the deterioration of LTS of RCC pavement joints and its effect on the fatigue cracking performance near the joints. To achieve that, first, an innovative experimental programme was designed to measure LTS as a function of number of load repetition, joint width, and RCC mix properties using a cyclic shear test setup. Second, a mathematical model was derived to predict LTS deterioration in joints. This model was validated against the experimental data. Lastly, an RCC pavement design model was developed using the LTS deterioration model. To demonstrate the application of the developed solution, a hypothetical RCC pavement structure consisting of four slabs was considered. The analysis results show that LTS has inverse relationship and direct impact of fatigue life of RCC. In particular, the results demonstrate that fatigue damage over an analysis period of 20 years is negligible if LTS is assumed constant, which is unrealistic, but it can reach 40% if LTS deterioration is considered in the analysis. Accordingly, this study recommends considering the deterioration of RCC joint LTS when design that kind of pavement structures. [ABSTRACT FROM AUTHOR]

Elevated pavement temperature causes the urban heat island (UHI) effect as well as thermal stresses in concrete pavements. Therefore, efforts are being made since the last few decades to reduce the pavement surface temperature. Incorporating phase change materials (PCMs) in pavements to reduce the pavement surface temperature is an emerging field of research. The present study evaluates two commercially available organic mixture (OM)-based PCMs (OM35 and OM42) with an objective to reduce the pavement surface temperature. As direct inclusion of PCM adversely affects the mechanical strength of concrete, encapsulated PCMs were incorporated into the concrete pavement. While most of the earlier studies investigated the short-term thermal behavior of PCM-incorporated pavements, an effort has been made under this study to evaluate its seasonal and long-term performance. The latent heat and phase change temperature of PCM were identified as the crucial factors influencing the cooling potential of the PCM-incorporated pavements. Further, the pavement surface temperature during the night increased only to about half of the reduction in temperature during the daytime due to the slower solidification rate of the PCMs. The statistical analysis indicates that there is a significant and consistent reduction in pavement surface temperature with PCM incorporation in the long term. The maximum temperature reduction reported with PCM incorporation was 4.12 °C with OM42. [ABSTRACT FROM AUTHOR]

To investigate the influence of material factors on the properties of basalt fiber-reinforced pavement concrete (BFRPC), orthogonal test was designed to test the strength, impermeability, and frost resistance of BFRPC. The change trend of properties with various factors was analyzed, and the reasonable dosage ranges were recommended. The results show that the content of basalt fiber and fly ash is the main factor affecting the compressive strength, while the principal elements affecting flexural strength are the content and length of basalt fiber. The electric flux of BFRPC increases 9.6–11.2% with the rise of fiber length, but the impermeability can be improved by adding fly ash. Basalt fiber and superplasticizer are beneficial to improve the frost resistance. Basalt fiber with 12 mm are recommended for use in pavement concrete with a content of 0.06–0.08%, and the dosage of fly ash and superplasticizer is 20 and 0.8–0.9%. [ABSTRACT FROM AUTHOR]

Concrete pavement performance models are evaluated, calibrated, and validated using field data from databases like the Long-Term Pavement Program. Conceptually, performance model predictions should match field data considering a reliability of 50%; that is, there is a 50% probability that the predictions of a certain distress indicator are higher or lower than the field data. However, modern pavements are designed for higher levels of reliability (usually 90% to 95%). Local performance model evaluation for higher levels of reliability requires a high amount of field data that traditional databases lack. Pavement management system (PMS) databases can be a useful resource for high reliability model analysis because of the large amount of data collected locally and regularly. However, when selecting and filtering field databases (of any source), the effect of censored performance data due to rehabilitation, removal from service, or modification of pavement sections is usually ignored. This paper proposes an approach for the use of PMS databases accounting for censored performance data to evaluate the accuracy of performance models' high reliability predictions. The approach is exemplified using a PMS transverse joint faulting database. Results show that by addressing the "survival issue," i.e., accounting for the censored performance data, the resulting PMS-based reliability model improves the faulting model accuracy in matching the field data for high reliability levels. [ABSTRACT FROM AUTHOR]

Semirigid pavements are gaining importance in the pavement design field due to their improved performance in freezing zones. These semirigid pavements are constructed similarly to asphalt pavements, but with a cement-stabilized base layer. However, there is a limited study that quantifies the influence of design factors on the performance of semirigid pavements. Therefore, an attempt was made to investigate the role of subgrade, temperature, moisture, traffic, crack joint spacing, speed, asphalt thickness, cement-treated base (CTB) layer thickness, elastic modulus, and modulus of rupture of CTB layer on semirigid pavement design. Different combinations of factors were formulated using fractional factorial design in the design of the experiment (DoE). All factors influencing the design of semirigid pavements were considered on two levels (low and high). This analysis used data from the Federal Highway Administration's (FHWA's) Long-Term Pavement Performance Program (LTPP). These data were incorporated into the AASHTOWare Pavement ME Design 2.6.1 (MEPDG) software. Design-Expert was used to determine the significance of various factors on the performance indexes. In addition, an optimization technique was used to determine the optimal design thickness for cement-treated base under various subgrade and climatic conditions. The result suggests that the thickness of a CTB layer is greater on fine-grained soil than on coarse-grained soil. [ABSTRACT FROM AUTHOR]

Rigid airport pavements are a critical part of the Australian airport pavement inventory. The thickness design of rigid airport pavements in Australia was previously based on Australian developed charts and a conservative characteristic concrete strength, but in recent years this has changed to reliance on the software FAARFIELD provided by the US. Australian designers have used FAARFIELD in combination with the historical and conservative definition of concrete strength. That conflicts with the intended use of a less conservative Australian concrete strength value for inputting into FAARFIELD. The unintended consequence of this change in Australian practice is an additional 44 to 74 mm of concrete slab thickness, depending on the aircraft type, subgrade support, and concrete strength used. This additional thickness costs an additional AUD 185,000 to AUD 429,000 and 154,000 to 333,000 kg.eCO2 for a modest 100×100-m rigid airport pavement development. This additional financial and environmental burden is not justified, and Australian airport pavement designers should adjust their thickness design calculations to avoid this unintended overdesign in the future. This example also serves as a lesson regarding the potential consequence of mixing elements from different systems for pavement thickness design. [ABSTRACT FROM AUTHOR]

Asphalt overlay is widely used in maintaining and rehabilitating highway system performance. However, explicit calculation methods for the asphalt overlay thickness range is lacking. Taking stone mastic asphalt (SMA) and asphalt concrete (AC) asphalt overlay on cement concrete pavement as examples, the paper proposed a design method for the asphalt overlay thickness range based on the shear performance of the interlayer. Firstly, the shear stress distribution regularities on the asphalt overlay and Portland cement concrete interlayer was calculated with a multilayer elastic theory. Meanwhile, the shear strength was obtained from a series of direct shear tests. The shear characters of the asphalt overlay met with the Mohr–Coulomb criterion, and the shear strength parameters cohesive force c and interface friction angle φ on the interlayer were acquired. Finally, a method for determining the thickness range of double layer asphalt overlay under different traffic conditions was given. The epoxy resin adhesive was recommended for the highway with severe local premature shear failure compared with the modified emulsion asphalt. Therefore, through the above research, the amount of asphalt used is controlled in a reasonable range, thus improving the pavement structure durability and reducing energy consumption. [ABSTRACT FROM AUTHOR]

Alternatives for using end-of-life tyres as a component of concrete are currently being studied. Particularly, granulated rubber and steel fibres from tyres can generate relevant technical benefits in concrete. However, it is not clear what environmental benefits these alternatives can provide. Hence, a study was carried out to evaluate, from an environmental perspective, applications of concrete with recycled materials from tyres. For this purpose, a streamlined life-cycle assessment was developed to compare the impact of the use of concrete with tyre materials and traditional concrete for safety barriers, railway sleepers, pavements and masonry mortar. Furthermore, the analysis was based on energy-thermal simulations, experimental work and collected studies. The results indicated that a safety barrier and a railway sleeper with tyres can reduce the harmful impact by 60 and 50%, respectively. For masonry mortar and concrete pavement applications, the impact reduction was between 4 and 10%. Moreover, one case was observed where, to comply with the technical requirements, it was necessary to incorporate more material into the concrete mix. This had a significant impact on the results, which meant that no environmental benefits were generated. Therefore, the study showed that to ensure the benefits of an application, it was required to consider not only the technical advantages but also the environmental savings that contributed to sustainable construction. [ABSTRACT FROM AUTHOR]

The current standard for evaluating road conditions worldwide relies primarily on the Pavement Condition Index (PCI) and the International Roughness Index (IRI). The IRI can be further calculated to obtain the Riding Quality Index (RQI). To assess pavement damage, various imaging equipment is commonly utilized, providing consistent results that align with actual road conditions. For roughness detection, the Laser Profilometer offers excellent results but may not be suitable for rural roads with poor conditions due to its high inspection cost and the need for a stable environmental setting. Therefore, there is a pressing need to develop cost-effective, rapid, and accurate roughness inspection methods for these roads, which constitute a significant portion of the road network. This study examined the relationship between PCI and RQI using nonlinear regression on 30,088 valid pavement inspection records from various regions in China (totaling 24,624.222 km). Our objective was to estimate RQI solely from PCI data, capitalizing on its broad coverage and superior accuracy. Additionally, we explored how PCI levels impact RQI decay rates. The models in this study were compared to several models published in previous studies at last. Our findings indicate that the model performs best for low-grade roads with low PCI scores, achieving over 90% accuracy for both cement concrete and asphalt concrete pavements. Furthermore, different levels of pavement damage have distinct effects on RQI decay rates, with the most significant impact observed when the pavement is severely damaged. The models in this study outperformed all the other available models in the literature. Consequently, under limited inspection conditions in rural areas, pavement damage inspection results can effectively predict riding quality or roughness, thereby reducing inspection costs. Overall, this study offers valuable insights but has limitations, including limited global generalizability and the model's applicability to high-grade roads. Future research is needed to address these issues and enhance practical applications. [ABSTRACT FROM AUTHOR]

This document discusses the advancements in non-destructive testing (NDT) methods. NDT methods are tests that allow for the detection of external and internal defects in structures without interfering with the structure itself. These methods are used in various industries, including infrastructure, air transportation, rail transportation, and automotive. The document provides a classification of different NDT methods, such as visual, penetrant, magnetic powder, eddy currents, thermographic, vibration, acoustic, ultrasonic, and radiographic methods. It also summarizes various research studies that have been conducted in the field of NDT, covering topics such as measuring grooves on silicon, structural analysis of ordered arrays, air cargo inspection, non-destructive evaluation of aerospace components, detection of defects in marine applications, classification and identification of defects in pipelines, and moisture measurement in building materials, among others. The document concludes by highlighting the popularity and universality of NDT research. [Extracted from the article]

Roller-compacted concrete (RCC) for pavements has experienced problems with its physical-mechanical performance over extended periods due to ambient and in situ curing conditions. Accordingly, this study aimed to present multiple regression equations for calculating the physical-mechanical properties of RCC for pavements under different service and mix conditions. For this purpose, the research included two cement and two water contents, one reduced with admixture, and four combinations of temperature and relative humidity. For model calibration and definition of the equations, cubic and beam samples were fabricated to carry out physical-mechanical tests, such as moisture content, shrinkage, and modulus of rupture. Laboratory-obtained data were studied with the Response Surface Methodology (RSM) to determine the best regression equations. The main findings determined that the behavior of a mixture of RCC at a prolonged ambient exposure time is possible because the surface models and the RSM were consistent with the different service and mix conditions. The models showed an accuracy of 98.99% in detecting shrinkage changes from 12 to 16% cement with 5.65% water in dry to wet ambient conditions. Similarly, moisture content and modulus of rupture had a 98.27 to 98.88% fit. Finally, the drying shrinkage, with mixes of 12% cement and water content variations with water-reducing admixture and superplasticizer effects, had an adjustment of 94.87%. [ABSTRACT FROM AUTHOR]

This research focuses on the behavior of roller-compacted concrete (RCC) used in pavements, which are prone to deterioration affecting their performance. These deteriorations result from various causes, including traffic load, errors during construction, mix design, and ambient conditions. Among these, ambient conditions could lead to a marked variable impact on material behavior and durability depending on the conditions associated with each region. Accordingly, this study aims to deepen the understanding of the effect, which a broader range of ambient conditions and different mix designs have on the physical and mechanical properties of RCC. Measurements such as the amount of water vapor per kilogram of air were used to apply the findings comprehensively. The RCC analysis encompassed experimentation with different compositions, altering the cement water ratio amount, and adding a superplasticizer. The impact of curing on the materials was evaluated before subjecting them to various humidity and temperature conditions. Laboratory tests were conducted to measure performance, including moisture, shrinkage, compressive strength, and the progression of flexural fracture resistance over curing periods of up to 90 days. The results revealed a logarithmic correlation between shrinkage and ambient humidity, which is the most determining factor in performance. Mix optimization through increased cement and reduced water enhanced the tensile strength of the material. Furthermore, the curing process was confirmed to increase resistance to shrinkage, especially in the long term, establishing it as a crucial element for the structural stability of RCC, which is relatively insensitive to variations in ambient conditions. [ABSTRACT FROM AUTHOR]

Nowadays, fiber‐reinforced cement‐based composites (FRCC) can develop ductile behavior with high toughness when the matrix, fibers, and interface are optimally designed. These materials are promising solutions for constructing more resilient structures. In this context, the widespread use in large‐scale applications requires reliable models to predict the performance of FRCC structures. Usually, the studies on numerical modeling of FRCC apply the damage laws developed for quasi‐brittle concrete, making damage increase faster than really occurs in the presence of fibers. Therefore, the present paper proposes a new damage evolution model for FRCC based on energy dissipation concepts. It is assumed that the dissipated energy contributes fully to the evolution of the scalar damage and plastic strain variables, which is a technical advance from the previous works. The damage evolution is obtained with experimental envelopes of uniaxial stress–strain tests and the focal point from loading–unloading cycles. The results showed that the model accurately predicted experimental results using the damage‐plasticity framework. Furthermore, there are no empirical constants in the proposal, which means that it can be applied to any class of FRCC. An application regarding damage evaluation near a load transfer device in jointed plain cementitious pavements is presented. The damage distribution reveals that using FRCC materials has induced smaller damage values when compared with using conventional concrete. Consequently, cracking is reduced in such zones, increasing the structural life of the pavement. [ABSTRACT FROM AUTHOR]

This paper presents research about a mixture design method of pavement concrete coblending rubber and fiber into ordinary concrete. Mechanical-based tests regarding the compressive strength, elastic modulus, splitting tensile strength, flexural strength, and four-point bending stiffness were conducted to evaluate the flexural toughness of concrete, and a slab-based three-point bending test was designed to evaluate the bending toughness improvement of the road pavement concrete slab. The results indicated that with the increase in single rubber content, the compressive strength and elastic modulus of concrete decreased continuously. The rubber concrete specimen remained relatively complete in appearance during destruction, showing the satisfied ductile failure characteristics to pavement usage with the optimal rubber content of 10%. After adding basalt fiber (BF) or polypropylene fiber (PPF), with the increase of fiber content, the bending stiffness of concrete decreased, the corresponding deflection of peak load increased continuously, and the bending deformation capacity of concrete could be significantly enhanced. Compared with the reference group, when the rubber content is 10%, and basalt fiber content is 0.5%–2%, the equivalent initial bending strength of fiber-reinforced rubber concrete is increased by 105.4%–164.4%. In general, BF is better than PPF in improving the toughness of rubber concrete, and the optimal dosage of BF is 1% of concrete volume in this test. When loaded to the limit load, the deflection of the basalt fiber–reinforced rubber concrete slab in the middle of the bottom span was about four times higher than that of the benchmark concrete slab, the bending deformation capacity and toughness of the basalt fiber–reinforced rubber cement concrete slab have been greatly improved. From the test results, the mixture design method of flexible pavement cement concrete based on rubber and fiber coblending was proposed, which contributes to the development of flexible materials for concrete pavement. [ABSTRACT FROM AUTHOR]

Thermally induced stresses can build up in rigid pavements without pressure relief joints. The pressure created becomes a problem for adjacent structures such as bridges. The pressure can cause the pavement to push on the bridge and close the bridge expansion joints. This sets the stage for additional distress if not repaired quickly. This paper presents a case study where excessive pavement pressure damaged a two-span conventional bridge spanning Interstate 35 in Moore, Oklahoma. The bridge was instrumented with vibrating wire sensors to gather information on the behavior of the bridge before and after the repairs. There is a dearth of sensor verified observations of excessive pavement pressure acting on conventional bridges. The sensor data provided in-depth information on the response of the distressed bridge before and after repairs to thermal loading. Prior to the repairs the approach pavement was pushing on the bridge deck and causing the abutment backwalls to tilt toward the bridge. Following the repairs, the approach pavement is no longer pushing on the bridge deck. However, the abutment backwall is now moving in response to thermal changes in the bridge deck, likely due to excessive friction between the deck and the abutment backwall. U-shaped shaped cracking and spalling, previously observed in integral abutment bridges, was observed at this conventional abutment bridge, and the mechanisms causing these cracks and spalling are discussed. Through this study it was found that placement of pavement pressure relief joints relative to the bridge is crucial for reducing the magnitude of stress acting on the bridge. It was also found that the pavement stress acting on a bridge deck can be estimated with vibrating wire strain gauges given a baseline strain response for the approach pavement. [ABSTRACT FROM AUTHOR]

Concrete is now an essential building material for creation of any type of structural elements, including inflexible pavement as well as beams, columns, slabs, bridges, and girders. Cement is the most essential binding component in the manufacture of concrete because, when combined with water, it can bind both coarse aggregate and fine aggregate. The terms brick kiln dust and fly ash, which have certain binding qualities when mixed with water, are waste products, as indicated by the paper's title. The researcher's objective is to show how fly ash and brick kiln dust mixed in the percentages of 0%, 10%, 20%, 30%, and 40% are used to partially substitute ordinary portland cement of 43 grade during the production of M25 grade of concrete mix design and to calculate the flexural strength of plain cement concrete beam in accordance with indian standards. The outcome of this research analysis demonstrates that FA and BKD can be employed in the manufacturing of concrete with the objective of lowering both emissions of greenhouse gases and cement concrete production costs. [ABSTRACT FROM AUTHOR]

Concrete pavements are nowadays winning increasing attention although their use is still limited by the high stiffness or low flexibility of concrete. In addition, worn tires cause environmental problems and also have an inherent ability to absorb energy. Therefore, it is necessary to improve concrete flexibility and energy absorption capacity by adding recycled materials such as crumb rubber. For this study, impact resistance and damping coefficients were investigated as the parameters affecting the energy absorption capacity of pavement concrete as well as the compressive, flexural, modulus of elasticity, and density of rubberized concrete. Crumb rubber 0–5 mm in diameter was replaced in concrete mixes for fine aggregate at volume ratios of 0%–60% (about 25% of total aggregate volume). The numerical models were used for validating laboratory results of damping tests, showing a good agreement between laboratory and numerical model frequencies. Moreover, the influences of geometrical property, as well as crumb rubber content, on the first frequency parameter of the samples were scrutinized by employing the finite-element model. Based on the results obtained, the replacement of 60% crumb rubber led to an increase of about 75% in impact resistance required for the first crack to appear and an increase of about 170% required for the specimen to fail. The damping coefficient of the concrete containing 60% crumb rubber also increased from 2.35% to 4.19%, indicating the significantly enhanced energy absorption capacity of the concrete containing crumb rubber. However, the specimens exhibited reductions of about 32%, 36%, 43%, and 21% in compressive strength, flexural strength, modulus of elasticity, and density of concrete, respectively, as a result of crumb rubber addition. [ABSTRACT FROM AUTHOR]

An investigation was carried out to analyze the flexural fatigue performance of pavement quality concrete (PQC) of M40 and M50 grades, made with conventional materials out of which river sand (RS) was replaced by copper slag (CS) by varying concentrations to the extent of 100% by volume. Experiments were conducted in the laboratory to determine the 90-day flexural strength of PQC samples (100×100×500 mm) under four-point loading. Based on respective flexural strength, repeated loads were applied for the conduct of flexural fatigue tests of PQC specimens at stress levels of 0.7, 0.8, and 0.9, each at 1 Hz frequency. In terms of fatigue life distributions, the flexural fatigue performance of several PQC mixtures has been evaluated. Three methods were used to estimate various parameters for the Weibull distribution. It is observed that the fatigue life distribution of both M40 and M50 grade PQC mixes made with CS can be modeled by a two-parameter Weibull distribution with a correlation coefficient of more than 0.95. The estimation of fatigue life of PQC mixes has also been done at different failure probabilities. The 90-day flexural strength of PQC mixes (both grades) with CS replacing RS, increased compared with conventional PQC. Further, X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) images of PQC mixes confirmed the homogeneity of the concrete. The fatigue performance was also enhanced with CS replacing RS. The goodness-of-fit test also indicated that the present model is valid at the 5% significance level for PQC (both grades) made with CS. [ABSTRACT FROM AUTHOR]

Pavement crack detection in complex scenes presents a significant challenge in achieving precise pixel-level accuracy due to the presence of intricate backgrounds, such as water stains, shadows, and repair grouting, which closely resemble cracks in terms of morphology and colour. Consequently, existing approaches often struggle to differentiate these elements, resulting in misclassification and decreased accuracy in corresponding areas. This paper proposes a novel approach, called the Dual-Stream U-Network (DSU-Net), specifically designed for complex scene crack detection. The DSU-Net model employs a dual-stream framework, enabling improved focus on challenging regions and effectively addressing the issue of low recognition accuracy. To construct a comprehensive dataset, photogrammetry techniques are employed to acquire images of cracks, resulting in a dataset comprising 5000 images. Experimental evaluations demonstrate that the trained DSU-Net model achieves a mean F1 score of 74.17% on a test set, surpassing the performance of the state-of-the-art methods which achieved a score of 68.09%. These findings validate the effectiveness of the proposed algorithm in accurately distinguishing water stains, shadows, repair grouting, and cracks. Additionally, the algorithm successfully performs fine-grained extraction of cracks. The promising results obtained in this study indicate the potential practical applicability of the proposed approach in engineering scenarios. [ABSTRACT FROM AUTHOR]

The structural behaviour and debonding mechanism of continuously reinforced bonded concrete overlay (CRBCO) on deteriorated concrete pavements subjected to environmental loadings are evaluated analytically and experimentally. It is shown that the temperature gradient in concrete significantly affects the debonding potential at the interface between CRBCO and existing continuously reinforced concrete pavements (CRCPs) and that the normal stress at the interface is the dominant cause of debonding failure. The results of factorial experiment show that the debonding potential can be reduced by decreasing the elastic modulus, coefficient of thermal expansion (CTE) and thickness of CRBCO, and by increasing the interfacial bond strength. [ABSTRACT FROM AUTHOR]

Top-down cracking (TDC) is recognized as a significant form of distress in asphalt pavements. While the NCHRP project 1-52 introduced a mechanistic-empirical (ME) predictive model for TDC, this model was found to be less accurate in certain traffic conditions—overpredicting crack initiation in sections with medium to low traffic and underpredicting in high-traffic sections. To enhance the precision of TDC predictions, a new fracture-mechanics-based framework has been developed. This improved framework employs a Hot Mix Asphalt (HMA) fracture mechanics methodology, resulting in a marked enhancement in the accuracy of predicting crack initiation times when compared to the original sub-model from NCHRP 1-52. The new framework also incorporates a novel aging model for the asphalt mixture, ensuring more precise inputs for the crack propagation model. The propagation prediction sub-model has been refined by implementing a J-integral-based Paris' law developed in the NCHRP 1-52 project. The efficacy of this updated framework was rigorously tested on eighteen diverse pavement sections across various geographic locations, with well-documented performance history and material properties. The outcomes indicate that the predicted initiation and propagation of TDC closely align with actual field observations, demonstrating the robustness and improved reliability of the new model. [ABSTRACT FROM AUTHOR]

Over the years, thicknesses of continuously reinforced concrete pavement (CRCP) increased to accommodate rising truck traffic. With a fixed percentage of longitudinal reinforcement relative to the concrete cross-sectional area, thicker slabs necessitate more reinforcement and reduced bar spacing, potentially hindering consolidation. To address this issue, two-mat steel design was implemented in Texas for pavements with thickness of 330 mm (13 in.) or larger. Performance evaluations of thick CRCPs revealed that horizontal cracking developed at the depth of reinforcement where one-mat steel was placed, while no horizontal cracking was observed where two-mat steel was used. Pavement responses with one-mat and two-mat reinforcements with different depths were analysed by three-dimensional modelling with a finite element analysis (FEA) programme for the wide range of environmental loadings. Maximum concrete vertical tensile stresses around longitudinal reinforcement at transverse crack area are a good indicator of horizontal cracking potential; those stresses were evaluated, along with concrete stresses at top of the slab, which are responsible for top-down transverse cracking. The results show that the two-mat design causes higher concrete stresses at the top of the concrete slab and lower concrete stresses around the longitudinal reinforcement, leading to increased transverse cracks and a reduction in horizontal cracking potential. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Dowel bar misalignment causes stress concentration in jointed concrete pavements, and misaligned dowel bars may lose their ability to transfer loads. To examine this problem, a concrete damage plasticity (CDP) model and a method were implemented using ABAQUS to evaluate its parameters. The CDP model simulated the stress–strain relationship for tension and compression in concrete specimens, and was validated through experimental testing. A three-dimensional finite element model of a misaligned dowel in a jointed concrete pavement was developed, and the equivalent stress, plastic strain, and plastic damage under loads for various misalignment conditions were determined. The simulation results of uniaxial tension and compression in a concrete sample were compatible with the experimental results, demonstrating the high accuracy of the CDP model. Under the action of a wheel load, the concrete below a misaligned dowel undergoes plastic damage. The damage extended from the bottom of the dowel to the sides as the misaligned dowel deviated vertically from the alignment with the pavement's longitudinal axis, especially in the case of twin bars misaligned in opposite directions. The plastic damage ratio is close to unity, which indicates complete failure of the concrete below the misaligned dowel. The equivalent stress below the dowel tends to be zero and shifts to the sides of the dowel. Consequently, the concrete below the misaligned dowel failed to support the load, reducing the load-carrying capacity of the dowel. When a fully elastic model was used, the stresses below the dowel exceeded the ultimate strength of the concrete, which contradicts the actual occurence. Therefore, the CDP model is recommended for analyzing the stress in the concrete around a misaligned dowel. [ABSTRACT FROM AUTHOR]

This study aimed to propose a framework for sustainable assessment of pavement by the integration of LCA and LCCA methods. Additionally, a tool was developed that employs a multi-criteria decision-making process to determine the most sustainable pavement design alternative. The developed tool was applied in a case study involving 496 weighing modes to assess the impact of different maintenance intervention levels and the discount and traffic growth rates on the sustainability of design alternatives with varying maintenance treatments. The results of the analysis revealed that asphalt pavement with a stabilised base demonstrated superior sustainability, covering over 87% of the weight modes. Conversely, concrete pavement exhibited lower sustainability, representing only 6.5% of the weight modes. Additionally, among maintenance activities, preventive treatments exhibited heightened sustainability in scenarios with higher discount rates and lower traffic growth. These findings highlighted the importance of selecting the appropriate pavement type for sustainable infrastructure development. [ABSTRACT FROM AUTHOR]

Detection of the tie bars in concrete pavement has been a challenging task. To address the purpose, ground penetrating radar (GPR) was used to acquire a large amount of image data along the longitudinal construction joints of plain concrete pavement in the field. The GPR image data was filtered to construct the dataset, containing 2185 tie bar reflected waves in 670 GPR images. Then, the YOLO series models, as the deep learning algorithms applied in inspecting the tie bars from GPR images, were well trained with the GPR training and validation sets. The comprehensive detection accuracy of the YOLOv4 model outperforms the YOLOv3, YOLOv3-tiny, and YOLOv4-tiny models in the test set. The mAP@0.5 value of the YOLOv4 model can reach 99.74%. All the signatures of tie bars in the testing GPR images, no matter whether they are incomplete, compressed, blurry with missing signal, or strong background noise, can be correctly and completely anchored using the bounding box based on the YOLOv4 model. Meanwhile, the detection speed of the YOLOv4 model for GPR data video is 50.8 frames per second. Therefore, the YOLOv4 model is reliable for automatically detecting the tie bars from GPR data in real-time. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional (3D) finite element model (FEM) consisting of an asphalt concrete (AC) overlay on top of jointed plain Portland cement concrete (PCC) slabs was developed to investigate the mechanism of the crack initiation of traffic-induced reflective cracking. Strain values at the bottom of AC overlay were the primary response obtained from the simulation results to represent the damage induced in the AC layer. Different bonding situations between the two layers, traffic load locations, material properties and thicknesses of the AC layer were taken into consideration. The analysis results show that the dominating strain for damage is dependent on the bonding condition between the AC and PCC layers. When the AC layer is completely bonded with the PCC layer, the damage will initiate firstly at the top of the joint corner between the PCC slabs to deteriorate the bonding, then the AC bottom will be susceptible to bending strain. It was observed that the most critical load location for modeling the case of fully bonded overlays is related to the AC thickness while in the case of partially bonded overlays, the most critical load location is always located on the top of one side of the PCC joint. [ABSTRACT FROM AUTHOR]

This study investigated the behaviour of permeable interlocking concrete pavement (PICP) in terms of water infiltration volume, surface runoff volume, and load resistance, using a specific lab apparatus, designed and manufactured as a rainfall simulator. The connecting pattern of the surface blocks is a stretcher bond pattern with a joint spacing of (5 and 10 mm) between the block pavers to be filled with a small-sized open-graded aggregate to finalise the permeable surface of joints. The adopted pattern has been examined under three rainfall intensities of (20, 40, and 60 l/min), four longitudinal slopes (0, 2, 4, and 6%), and three transverse slopes (0, 2, and 4%). The results showed that at high rainfall intensities (60 l/min), high longitudinal slopes (6%), and high transverse slopes (4%), the stretcher-bonded PICP with 5 mm spacing between the blocks infiltrates less water than the one with 10 mm. Furthermore, PICP with 5 mm spacing has higher surface runoff than PICP with 10 mm spacing at high rainfall intensities (60 l/min), high longitudinal slopes (6%), and all transverse slope percentages (0, 2, and 4%). In addition, the load resistance of stretcher-bonded PICP with 5 mm spacing between the blocks is higher than that of 10 mm at all the subjected loads in the load-deflection test. Despite the shown differences between both types of PICP, they are strongly recommended as an alternative choice for ordinary dense-graded pavement. [ABSTRACT FROM AUTHOR]

The coupling effect of fatigue loads and hydrodynamic pressure has a considerable impact on the durability of pavement concrete. For moderating crack development and improving toughness, basalt fibres (BF) are applied in pavement concrete. The main purpose of this study is to evaluate the performance of using BF in inhibiting cracks and enhancing the toughness of concrete under various coupling conditions. The three-point flexure toughness of basalt fibres-reinforced concretes subjected to the coupled effect of fatigue load and hydrodynamic pressure were carried out, and the strain field of concrete during the bending test was recorded by the digital image correlation (DIC) technique. The cracking behaviours (fractal dimension, tortuosity, surface roughness) during coupling actions and bending tests were characterised by 3D laser instrument and X-ray computed tomography. The experimental results showed that stress level played a decisive role in the deterioration degree of pavement, as stress level increased from 0.5 to 0.7, the bending loads corresponding to the turning point of Df decreased. The hydrodynamic pressure accelerated crack propagation of concrete, especially when loading cycles exceeded 100,000. The addition of BF changed the micro-crack development model of concrete and significantly increased the fracture energy of concrete under coupling actions. [ABSTRACT FROM AUTHOR]

The fourth-generation TSD can provide pavement deflection data at a much higher rate than previous versions. This data is valuable to evaluate the structural health of the transverse joints in concrete pavements. Analysis of TSD measurements from a jointed pavement segment allowed the detection of a mistake in the way the TSD's deflection velocity [vy] data is processed to get deflection slope [S] estimates: We state and prove that the well-known direct relationship between vy and S is only valid in limited scenarios, and particularly invalid nearby the transverse joints. We highlight that vy is made up of two components, one of which is related to S and that at the vicinity of a discontinuity in the pavement structure, the second component of vy gains relevance and explains the discrepancy between vy and S. Also, it is shown that TSD vy measurements gathered near a joint resemble vy signals simulated with a linear elastic model. Thus, this study brings new insight into the contents of a TSD vy measurement and buttresses the TSD's reliability as a vy measurement device. Plus, it suggests that further research should develop TSD data interpretation schemes based on vy instead of deflection slopes and depths. [ABSTRACT FROM AUTHOR]

Part-fill and part-cut subgrade is widely distributed in mountainous highway engineering, and their resilient modulus and settlement exhibit significant transversal non-uniformity, which has an important effect on the performance of cement concrete pavement structure. A numerical model, focusing on a two-slab system on part-fill and part-cut subgrade, was developed by the finite element computer programme taking into account non-uniform settlement (a large range of partial contact) simultaneously with non-uniform modulus. Cement concrete pavement structure responses, including the load stress, vertical displacement and joint load transfer capacity were comprehensively investigated considering the two part-fill and part-cut subgrade characteristics. The results indicate that the non-uniform settlement has a higher impact on the concrete pavement structure than that of the non-uniform modulus in more cases. When the resilient modulus of the fill part is close to that of the cut part, the additional stress (relative stress increment) caused by the combination of the two factors is approximately the sum of the additional stress caused by the two factors individually. [ABSTRACT FROM AUTHOR]