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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]

Our aim is to analyze the function of reinforcement elements (dowel bars) in cement concrete pavement to highlight the influence of these elements on the service life of the pavement as a whole and to find possible alternatives to existing products that are freely available on the Czech market. That is, how these elements in the form of dowel bars should work properly so that the function meets the design assumptions of a rigid pavement. We describe the procedure for inserting dowel bars during paving, which is directly related to the possibilities of using different dowel bars. Finally, we summarize the possibilities of using alternative materials, shapes, or sizes of dowel bars and the possibilities of their use in the Czech Republic. [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]

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]

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]

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]

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]

Structural fibers contribute to the overall performance of concrete pavements by mitigating various distresses. To understand the influence of structural fibers on the pavement structural responses and distresses, the Minnesota Department of Transportation (MnDOT) constructed two ultra-thin (3 and 4 in. thick) and three thin (5 and 6 in. thick) fiber reinforced concrete cells along with one plan concrete control test cell at the Minnesota Road Research (MnROAD) facility in 2017. These test cells have 6 ft x 6 ft concrete slabs and were constructed on the granular base layer. While the structural designs of these cells were intended for roads with low to moderate traffic volume, the cells were subjected to accelerated loading to complete the study in a short period of time. This paper summarizes the design and construction of the six test cells and provides a comprehensive discussion on the joint performance behavior and transverse joint faulting trends, emphasizing the influence of the fibers on the abovementioned. It was found that fibers can improve joint performance and decrease faulting in thin concrete pavements. Regarding the ultra-thin pavements, no conclusion was possible to be drawn on the contribution of the fibers. [ABSTRACT FROM AUTHOR]

The unavoidable transverse non-uniformity of settlement and moduli for part-fill and part-cut subgrade may have some critical impact on concrete pavement structures, hence, some structural optimisations of pavement based on the working conditions of subgrade are essential. In this study, on account of the practical working conditions of part-fill and part-cut subgrade, a finite element model of concrete pavement structure on part-fill and part-cut subgrade developed previously was conducted to analyse the effects of slab thickness, slab concrete modulus of rupture, tie bar diameter and tie bar spacing. Furthermore, improvement methods and strategies were analysed and proposed for the four parameters respectively with fatigue cracking design life under loading as the target and maximum stress at the bottom of slab as the criterion. The results verified the feasibility of incorporating non-uniformity of modulus and settlement into the design phase of concrete pavements on part-fill and part-cut subgrade. Additionally, concrete pavement parameter optimisation priority should be given to concrete modulus of rupture, slab thickness, followed by tie bar diameter and spacing. It can provide a useful reference for designing concrete pavement structures on part-fill and part-cut subgrade. [ABSTRACT FROM AUTHOR]

The unavoidable transverse non-uniformity of settlement and moduli for part-fill and part-cut subgrade may have some critical impact on concrete pavement structures, hence, some structural optimisations of pavement based on the working conditions of subgrade are essential. In this study, on account of the practical working conditions of part-fill and part-cut subgrade, a finite element model of concrete pavement structure on part-fill and part-cut subgrade developed previously was conducted to analyse the effects of slab thickness, slab concrete modulus of rupture, tie bar diameter and tie bar spacing. Furthermore, improvement methods and strategies were analysed and proposed for the four parameters respectively with fatigue cracking design life under loading as the target and maximum stress at the bottom of slab as the criterion. The results verified the feasibility of incorporating non-uniformity of modulus and settlement into the design phase of concrete pavements on part-fill and part-cut subgrade. Additionally, concrete pavement parameter optimisation priority should be given to concrete modulus of rupture, slab thickness, followed by tie bar diameter and spacing. It can provide a useful reference for designing concrete pavement structures on part-fill and part-cut subgrade. [ABSTRACT FROM AUTHOR]

In full-joint concrete roads, as a result of hydropumping under the pavement caused by rain water or drainage water filtered from the joints, cavities are formed after softening in the foundation layer and then the emergence of fine grains to the surface. As a result of the discharges in the foundation layer, cracks that occur in the joint areas during the repeated passage of vehicles can shorten the service life of the concrete pavement. Within the scope of this study, the performance of fiber-added concrete, which has been in demand in the concrete sector in recent years, has been investigated as a solution to these deteriorations in concrete roads. For this purpose, the behavior of plates prepared with fiber-reinforced and plain concrete under cyclic loading was investigated experimentally with dynamic loading, based on the discharge occurring under the pavement. Parameters such as the effect of fibers on cracking in concrete, the amount of load carried in the collapse zone, and displacement performance were investigated. In the light of the results obtained, it has been determined that fiber reinforced concrete is more resistant to cracks in the joint area than plain concrete. [ABSTRACT FROM AUTHOR]

A magnetite mortar microwave-absorbing layer that could be applied to concrete pavement was studied to improve the deicing efficiency of roads in low-temperature conditions. The magnetite cement mortar (MCM) was prepared by using magnetite as the main absorbing material. The microwave absorption ability and heating characteristics of MCM with different magnetite contents were investigated. In addition, the mechanical and durability properties of MCM were studied. Furthermore, a microwave-absorbing layer was prepared and tested for outdoor field deicing. The result showed that adding magnetite effectively improved the mechanical strength and frost resistance of MCM, which could improve its load resistance and service life. Meanwhile, the microwave absorption ability of MCM was also improved with the increase of magnetite content. At the microwave frequency of 2.45 GHz, the average heating rate of MCM with 80% magnetite content was 2.27 times than that of ordinary cement mortar. In addition, the content of magnetite was positively correlated with the heat transfer ability of MCM. Magnetite conversion of microwave energy into heat energy could quickly transfer heat to the whole mortar system. The field deicing test verified the feasibility of efficiently deicing a magnetite mortar microwave-absorbing layer in low temperature conditions. [ABSTRACT FROM AUTHOR]

The falling weight deflectometer (FWD) test is a common non-destructive testing method for evaluating the structural capacity of pavements. At present, data processing of the FWD test mainly focuses on the deflection data, while paying less attention to the deflection-time history. Because a FWD is equipped with impulse loads and geophones, which allow for the generation and capture of surface wave signal propagation, it is hypothesized that Rayleigh wave dispersion theory can be applied to calculate the modulus profile along the pavement depth by analysing the dispersive properties of the deflection signal measured during FWD tests. To test this hypothesis, we develop a new methodology for the FWD test and data analysis, referred to as the FWD dispersion curve method. We first introduce the concept of the new method, followed by an illustration of the procedure and the experimental set-up. Case studies on three concrete pavement segments are then presented to evaluate the effectiveness of the FWD dispersion curve method. Modifications to the existing FWD device are further recommended for the impact loading sources and signal collection process so that the modulus of a much shallower layer, such as the concrete slab and upper asphalt layers, can be obtained. This article is part of the theme issue 'Artificial intelligence in failure analysis of transportation infrastructure and materials'. [ABSTRACT FROM AUTHOR]

With the development in construction technology, dowel bars insertion in the joint plain concrete pavement (JPCP) is practiced using dowel bar inserters (DBI). Although DBI, can reduce the probability of the single dowel bar misalignment, wrong construction practices, gap graded concrete mixtures, inappropriate calibration of DBI may result in the complete assembly of dowel bars being misaligned. Most previous studies investigated the effect of single dowel misalignment, which may not describe the stress-state when entire dowel bars assembly is misaligned. Further, experimental investigations may be expensive to investigate the effect of dowel bars misalignment. In this direction, to understand the impact of uniform misalignment of dowel bars assembly, a 3D finite element model was developed considering vertical and longitudinal translation type of misalignments. The model results indicated that the vertical translation misalignment results in excessive tensile stresses in the concrete at the joint. This may lead to tensile fatigue failure resulting in dowel looseness. Further, the longitudinal translation resulted in higher compressive stresses, which may result in the crushing of the concrete due to repeated application of wheel loads. Both the cases of misalignment resulted in lower load transfer efficiency than no-misalignment cases. The study found that critical stresses in the concrete at the joint are a function of the type of dowel misalignment. [ABSTRACT FROM AUTHOR]

The presented self-developed high-precision contact friction test device conducts experimental research on the friction characteristics of concrete pavement. First, the error analysis of the test device is carried out. The structure shows that the test device meets the test requirements. Subsequently, the device was used to carry out experimental research on the friction performance of concrete pavement under different roughness and temperature changes. The results showed that the friction performance of concrete pavement increased with the increase in surface roughness, and decreased with the increase in temperature. It has a small volume and significant stick-slip properties. Finally, the spring slider model is used to simulate the friction characteristics of the concrete pavement, then the shear modulus and viscous force of the concrete material are adjusted to achieve the calculation of the friction force over time under temperature changes, which is consistent with the experimental structure. [ABSTRACT FROM AUTHOR]

Continuously reinforced concrete pavement (CRCP) is a representative type of concrete pavement constructed with continuous steel bars without intermediate transverse expansions. With reference to pavement conditions, CRCP is an exceptional type of concrete pavement according to the Highway Pavement Condition Index (HPCI) and International Roughness Index (IRI). The two main design methods for CRCP are AASHTO 86/93 and the Mechanistic–Empirical Pavement Design Guide (MEPDG). Because of limitations of the AASHTO 86/93 design method, the MEPDG method is more reliable. While incorporating the interactions among geometrics, pavement structure layers, material properties, subgrade, traffic, and environmental conditions, and the prediction values according to the MEPDG method, it matched the measured results of crack spacing and crack width. The MEPDG punchout, crack width and spacing, and load transfer efficiency (LTE) models were evaluated, and results were compared with the test sections in three European countries consisting of different construction details, which were investigated and recorded between 2019 and 2021. In this sense, a calculation tool was developed to consider the influence of different parameters in design process. In addition, sensitivity analyses were executed for the development of punchout, considering various input parameters. The track surveying and the evaluation of the results indicated that the design process can be improved with consideration of some criteria such as crack formation time or adjustment of the correlation between crack width and crack spacing. Due to the very important function of erosion and resulting pumping in the deterioration of CRCP, it is advisable to include the influence of the base layer and the influence of different shoulder type and heavy traffic volume or effect of deflection in the calculations. [ABSTRACT FROM AUTHOR]

Concrete pavements are subjected to the combination of moisture transport, heat transport and traffic loading. A hygro-mechanical 3D finite element model was created in OOFEM software in order to analyse the stress field and deformed shape from a long-term non-uniform drying. The model uses a staggered approach, solving moisture transfer weakly coupled with MPS viscoelastic model for ageing concrete creep and shrinkage. Moisture transport and mechanical sub-models are calibrated with lab experiments, long-term monitoring on D1 highway and data from 40 year old highway pavement. The slab geometry is 3.5×5.0×0.29 m, resting on elastic Winkler-Pasternak foundation. The validation covers autogenous and drying strain on the slab. The models predict drying-induced tensile stress up to 3.3MPa, inducing additional loading on the slab, uncaptured by current design methods. [ABSTRACT FROM AUTHOR]

Transverse cracking of concrete pavement in Ohio has been a major issue in interstate routes that reduces its service life to approximately ten to fifteen years, costing Ohio department of transportation great deal of maintenance funds. Major factors that aggravate slab failure are slab length, axle spacing and permanent built-in curl which are not directly incorporated in the AASHTO 1993 design procedure. The procedure implies an increasing thickness of concrete will be needed as traffic increases. However, fatigue testing of concrete beams has shown concrete can endure an unlimited number of loads if the stress ratio (SR) is kept below a critical value. Therefore, field and experimental data from Ohio concrete pavements were employed to validate a 3D finite element (FE) model with which critical slab stresses were calculated for several slab geometries. Results from stresses and fatigue damage analyses showed slab thickness of 12 in (305 mm) and slab length of 13 ft (3.9 m) were optimum for concrete pavement in Ohio. Long term pavement performance analysis showed the 12 in (305 mm) thick by 13 ft (3.9 m) long slab exhibited superior performance in terms of IRI, faulting, cracking, and cost over a 50-year design life. [ABSTRACT FROM AUTHOR]

Due to the construction method used, the use of conventional rebar is impractical for roller-compacted concrete (RCC) pavement applications, and the use of discrete fibers seems to be the best alternative to this problem. Among the available types, synthetic fibers are commonly employed in pavement applications, due to their advantages such as ease of handling, cost efficiency, and corrosion-free nature. However, studies that numerically examined the extent of synthetic fiber contribution to the mechanical properties and structural requirements of RCC pavements are very limited. To fill this gap in the literature, an experimental study was conducted to examine the effects of synthetic fibers on the fresh and hardened-state properties of RCC. Then, using the material parameters obtained in this study and retrieved (to cover the effect of different material compositions and synthetic fiber types) from the literature, thickness design for a sample pavement was conducted for plain and fiber-reinforced concrete mixtures, to determine the effect of different material compositions and fiber types on the thickness requirement of RCC pavements. Based on the results of the conducted experiments, the amount of change in the fresh- and hardened-state performance of RCC mixtures due to the addition of synthetic fibers were presented. Thickness design results showed that the contribution of fibers may vary in RCC mixtures depending on the type and amount of fibers used, and the properties of RCC mixture in which they are used. For the type and amount of fibers considered in this study, up to 25% reduction in required thickness was observed for synthetic fiber–reinforced RCC mixtures. [ABSTRACT FROM AUTHOR]

This article aims to outline the established Ground Penetrating Radar (GPR) applications for concrete pavements that are currently under development or not yet commonly applied. GPR is a non-destructive method that detects variations in the electromagnetic properties of materials, primarily the permittivity. The principles of GPR systems operation, including signal processing and data interpretation practices, are summarized in this study to review current and future uses of GPR in concrete pavement detail analysis. The use of different approaches besides GPR, makes pavement evaluation more efficient and provides more details of the material properties. In concrete pavement structure investigations, GPR technology has been utilized to detect layer thickness and rebar properties, and it also determines subsurface defects and assesses base layer conditions. In quality control studies, GPR technology is implemented for thickness and air void content measurements. Future research may include investigating GPR technique in supporting pavement designs and repair strategies. Regardless of the benefits, several limitations are reported that prevent using this technique for pavement investigation on a broader scale. The problems associated with this procedure, such as the accuracy of the method and the difficulties in interpreting recorded signals, are discussed. [ABSTRACT FROM AUTHOR]

The excessive use of cement has caused incremental production of greenhouse gases, one of the consequences of which is the overheating of the planet. These detrimental effects have highlighted the importance of pozzolanic materials and accordingly using alkali-activated concrete pavement instead of cement as a solution. Moreover, using fiber concrete surfaces is a predominant method to repair the concrete pavement due to the high speed of performance and the reduction of thickness. For this purpose, various amounts of sinusoidal steel fibers, kortta embass and kortta twist were added to alkali-activated concrete pavement. The results showed that with an increase in the fiber percentage, compressive strength, flexural strength, energy absorption, splitting tensile strength, impact resistance, skid resistance, resistance against freezing and thawing cycles are enhanced. On the other hand, the thickness of the concrete slab and water penetration into the concrete decreased. However, these cases are somewhat efficient for the sinusoidal steel fibers and then, the process begins to decrease. [ABSTRACT FROM AUTHOR]

Repetitive loads result in increased irrecoverable strain and, consequently, fatigue cracking failure. Fatigue resistance is the prime factor controlling the service life of the concrete pavements. This research study utilized natural rubber latex (NRL) to enhance the mechanical strength and flexural fatigue resistance of normal concrete. The effect of influence factors, such as water to cement (w/c) and dry rubber to cement (r/c) ratios, on the compressive and flexural strengths and flexural fatigue behavior was studied. Normal and NRL concretes were subjected to compressive, flexural, and flexural fatigue tests. At all w/c ratios, a higher r/c ratio resulted in a lower compressive strength but higher flexural strength. The highest flexural strength was found at the optimum r/c ratios of 0.58, 1.16, and 1.73 for w/c=0.3 , 0.4, and 0.5, respectively. Concrete modified by NRL at the r/c ≤ optimum ratio had lower plastic deformation than normal concrete at the same applied flexural stress, hence, higher fatigue life (Nf). As a result, the NRL-concrete pavement at the optimum r/c ratio was found to have a thinner thickness than the normal concrete pavement for the same traffic load conditions at the same service life, which can reduce the operational cost. A cost-effective mix design method of NRL-concrete pavement with the optimized construction (operation and material) cost was also recommended. The outcomes of this research will facilitate the utilization of the NRL additive alternative to synthetic polymer for sustainable NRL-concrete pavement in Thailand and other Southeast Asian and South American countries, which are major global producers of natural rubber. [ABSTRACT FROM AUTHOR]

The aim of this work was to reduce the carbon footprint of cement concrete by using multi-component cement with a high content of blast furnace slag. The analysis consisted of comparing the properties of the concrete mix and the hardened concrete made of the CEM I 42.5 R-NA cement commonly used in Poland and the CEM III cement with a large amount of blast furnace slag. The tests used cement in a constant amount of 380 kg/m3, granite aggregate of 2/8, 8/16, 16/22 mm and sand of 0/2 mm. As part of this project, detailed tests of the concrete mix and hardened concrete were carried out in terms of compressive, bending, fracture and frost resistance after 150 cycles of freezing and thawing, and the pore structure in hardened concrete was assessed according to PN-EN 480-11. The endurance tests were performed after 7, 28 and 90 days. On the basis of the obtained results, it was found that the highest compressive strengths above 70.2 MPa were obtained for concrete with CEM III, 64.5 MPa for concrete with CEM I. Additionally, for concrete with multi-component cement, smaller drops in compressive strength were obtained and a more favorable pore distribution in hardened concrete was obtained. Concrete intended for road surfaces can be made of both CEM I and CEM III cement, as they meet the requirements of the technical specifications for roads with heavy traffic of heavy vehicles. [ABSTRACT FROM AUTHOR]

Freeze–thaw damage is one of the most severe threats to the long-term performance of concrete pavement in cold regions. Currently, the freeze–thaw deterioration mechanism of concrete pavement has not been fully understood. This study summarizes the significant findings of concrete pavement freeze–thaw durability performance, identifies existing knowledge gaps, and proposes future research needs. The concrete material deterioration mechanism under freeze–thaw cycles is first critically reviewed. Current deterioration theories mainly include the hydrostatic pressure hypothesis, osmolarity, and salt crystallization pressure hypothesis. The critical saturation degree has been proposed to depict the influence of internal saturation on freeze–thaw damage development. Meanwhile, the influence of pore solution salinity on freeze–thaw damage level has not been widely investigated. Additionally, the deterioration mechanism of the typical D-cracking that occurs in concrete pavement has not been fully understood. Following this, we investigate the coupling effect between freeze–thaw and other loading or environmental factors. It is found that external loading can accelerate the development of freeze–thaw damage, and the acceleration becomes more evident under higher stress levels. Further, deicing salts can interact with concrete during freeze–thaw cycles, generating internal pores or leading to crystalline expansion pressure. Specifically, freeze–thaw development can be mitigated under relatively low ion concentration due to increased frozen points. The interactive mechanism between external loading, environmental ions, and freeze–thaw cycles has not been fully understood. Finally, the mitigation protocols to enhance frost resistance of concrete pavement are reviewed. Besides the widely used air-entraining process, the freeze–thaw durability of concrete can also be enhanced by using fiber reinforcement, pozzolanic materials, surface strengthening, Super Absorbent Polymers (SAPs), and Phase Change Materials. This study serves as a solid base of information to understand how to enhance the freeze–thaw durability of concrete pavement. [ABSTRACT FROM AUTHOR]

The carbon fiber electrothermal method is an efficient approach for snow melting and deicing of pavements in the cold winter. The heat transfer mechanism needs to be explored for the carbon fiber electrothermal system design, especially how the microstructure affects the thermal behavior of pavement. To do so, a discrete element method (DEM) based heat transfer model considering the pavement microstructure has been established in the current study. The shape and content of coarse-grained aggregates have been represented by using the irregular polygonal aggregate method. The accuracy and feasibility of the proposed model were verified by comparing the numerical results with the measured data. On this basis, the heat transfer characteristics of pavements during snow melting and deicing using the carbon fiber electrothermal method have been investigated. The results show that the ambient temperature and the carbon fiber heating wire (CFHW) temperature are the two primary factors affecting the heating efficiency and the maximum temperature on the pavement surface. The spacing and buried depth of the CFHW also play a crucial role in determining the temperature rise rate and the uniformity of temperature distribution of the road surface layer. Furthermore, the effect of the aggregate content on the overall heating rate is not as significant as that of the specific heat capacity ratio of the aggregate to the mortar, suggesting modifying the thermal conductivity of aggregates to enhance deicing efficiency rather than changing the aggregate contents. The effects of the CFHW design parameters on the temperature distribution of the pavement surface are also investigated. The maximum and minimum temperatures of the pavement layer decrease gradually with the increase of the laying spacing and burial depth of the CFHW, but the temperature difference increases with the increase of the laying spacing of the CFHW and decreases with the increase of the burial depth. The research results can provide a reference for the optimization design of snow melting and deicing of pavements by the CFHW heating method. • A DEM heat transfer model considering the microstructure of concrete pavements was generated. • The accuracy and feasibility of the numerical model were verified. • The ambient temperature is the most significant factor that affects the maximum temperature of pavements. • The effects of design parameters on the heat transfer behavior were investigated. • The heat transfer efficiency and temperature distribution uniformity in the road surface layer under different design conditions were studied. [ABSTRACT FROM AUTHOR]

Loading tests were carried out on the dowel bar-concrete substructure of concrete pavement. Mechanical characteristics of dowel bar-concrete interaction were studied. In the elastic range of concrete, the bearing modulus, which is a crucial parameter but is usually determined by presumption, was calculated using classic Westergaard equations. Its influencing factors were evaluated such as concrete strength, dowel bar thickness, joint width, and anti-cohesive layer. Besides, a theoretical equation for tangential stress at the most dangerous point of concrete was deduced from Westergaard's and Timoshenko's equations. The equation reveals how the tangential stress of the most dangerous point at the dowel bar-concrete interface is affected by influencing factors. Lastly, the deterioration process of concrete around the dowel bar was revealed. The strain gauges' data show that deterioration of concrete develops from the most dangerous point to far away from the dowel bar gradually. Two failure modes were found; one is circular spalling, the other is three main cracks. The initiation of the dowel-bar concrete structure's deterioration is circular spalling, attributed to high radial compressive stress in concrete. The deterioration starts around half the load capacity of the structure. [ABSTRACT FROM AUTHOR]

Accurate monitoring of concrete pavement support condition is critical for pavement maintenance. This paper proposed a novel support condition monitoring method using distributed optical fiber sensing (DOFS) technology. The DOFS-based method can precisely monitor the support condition on a larger scale. Single-mode optical fiber with a particular rubber encapsulation was applied as a compression sensor, measuring the interfacial compression status between the concrete pavement slab and the pavement base through a compression-to-strain transfer mechanism. Finite element analysis (FEA) and laboratory experiments were conducted to compression-to-strain transfer mechanism. It was revealed that the average compression-to-strain transfer efficiency reached over 1900 μϵ/mm. The design parameters of the compression sensor were also provided based on the FEA and experiment results. A quasi-distributed sensing system was developed to capture the two-dimensional support condition by connecting the sensors in a particular path. The sensing system's effectiveness was demonstrated by conducting full-scale tests and using the pressure-sensitive film (PSF) as a comparison. The test results showed a great deal of applicability for support condition monitoring under concrete pavement. [ABSTRACT FROM AUTHOR]

Use of micro-milling and thin dense-graded flame-retardant asphalt overlay in long tunnel concrete pavement is a relatively new technique in China. Earlier research showed that the micro-milling quality control is very important for the service life of overlay treatment. This paper proposed a quality control method, using 3D laser scanning technology, to accurately and efficiently recognise the unacceptable micro-milled area. A validation field test was first designed to verify that the micro-milled surface texture of concrete pavement can be accurately acquired by using 3D line laser technology. On the basis of a modified data processing that was proposed to fix data, the 3D micro-milled texture model was established, and then a micro-milling quality control method was proposed. A field test on a micro-milling rehabilitation project of Highway G75 Jiang Junshi tunnel, Sichuan Province, China, was conducted to assess the feasibility of the proposed method. Results demonstrated the proposed method is promising for providing an automatic, accurate and comprehensive assessment of micro-milled surface and for identifying unacceptable micro-milled areas that need to be re-milled. The developed method is quite valuable for reducing the wait time in the field during micro-milling construction operation, which is important for transportation agencies and public drivers. [ABSTRACT FROM AUTHOR]

The void beneath cement concrete pavement slab (CCPS) is one of the common defects, which can cause the pavement cracking when heavy vehicle load is exerted on the pavement. The void expands when the water trapped inside erodes the inner surfaces of void circularly, bringing more cracks easily. Due to the close relationship with the erosion of the void, the hydrodynamic pressure distribution in saturated void beneath CCPS is investigated in this paper. Firstly, a theoretical expression of the hydrodynamic pressure in saturated void is proposed taking in account the law of mass conservation and the theorem of momentum. Secondly, the deformation patterns of the CCPS and the fluid-structure interaction (FSI) are discussed based on the proposed method. The results show that the hydrodynamic pressure and the water flow velocity in the void are overvalued while the rigid deformation pattern of CCPS is employed and the FSI is ignored. Finally, some influence factors are discussed. It is obtained that, both the maximum hydrodynamic pressure and the average velocity of water increase with the increase of the load amplitude, the vehicle speed and the void dimension. The conclusions are helpful for the prevention and maintenance of void beneath the CCPS. [ABSTRACT FROM AUTHOR]

Stockpiles of discarded tires are a global concern. Since tire incinerating results in severe air pollution, reusing tires as tire rubber particles can reduce environmental pollution. A recycled tire, including rubber and recycled steel fiber, can be introduced in cement concrete. This study aimed to investigate the effects of crumb rubber and recycled steel fiber on the conventional concrete pavement's short- and long-term performance. The impact of crumb rubber (Cr) (0-20%) and recycled steel fiber (F) (0-0.5%) on the compressive, splitting, and flexural strength, as well as abrasion and freezing-thawing resistance of concrete, was evaluated through response surface methodology (RSM). The results indicated that fiber's addition to the concrete mix had a remarkable influence on flexural strength in low content and enhanced post-cracking ductility of rubberized concrete. Furthermore, incorporating crumb rubber as fine aggregate led to a reduction in the abrasion resistance and increased sensitivity to freezing-thawing in the presence of saline solution. According to optimization results, the most appropriate way to benefit from the desirable characteristics of rubberized concrete while minimizing the crumb rubber inclusion's adverse effects is through the addition of fibers into the concrete mixtures. [ABSTRACT FROM AUTHOR]

Since environmental factors at pavement construction sites are usually changed, the behavior of plastic shrinkage cracking, which is a common type of distress in concrete pavement, needs to be assessed to avoid deterioration and apply a more appropriate preventive method. This study evaluates the effects of different ambient temperature (30, 35, and 40 °C), relative humidity of the air (20, 45, and 70%), and wind speed (18, 24, and 30 km/h) on the characteristics of plastic shrinkage cracking distress in concrete pavement that are more practical in terms of inspection. These practical characteristics include temporal characteristics (time of balance of bleeding and evaporation, and time of the start of crackling) and geometric characteristics (mean cracking width, length of cracking, and area of cracking). They were examined in different environmental conditions according to ASTM C1579 standard test method, using an environmental simulator chamber and a digital monitoring approach consisted of digital image analysis. The results showed that practical characteristics are useful in denoting the behavior of plastic shrinkage cracking distress in concrete pavements in different environmental conditions. Each environmental factor has a different significant effect on the behavior of plastic shrinkage cracking distress. The time of balance was the most affected temporal characteristics, which shows higher sensitivity of the bleeding state of concrete pavement to environmental factors. Among geometric characteristics, the area of cracking was changed the most. Different environmental factors also had a more significant effect on the transverse changing of cracking than its longitudinal. The relative humidity had the most effects on the temporal and geometric characteristics, and the effects of temperature and wind speed were close to each other. A significant relationship was observed between the time of balance and the area of cracking, which indicates that the time of balance can be used effectively to predict cracking severity in different environmental conditions. [ABSTRACT FROM AUTHOR]

Road construction is an important engineering process involving two of the most common materials, namely asphalt and concrete, both of which having various environmental effects. This study aims to review documents from 2000 to 2020 using the scientometric analysis method. The documents about carbon footprint of road pavements were obtained from Web of Science (WOS) and analyzed using scientometric analysis tools in terms of citation, the number of published documents and top journals, institutions, authors, countries, and keywords. Finally, the trends of researches on carbon emission from road pavement construction and the building sector were compared in brief. This investigation can provide researchers with the right perspective for future studies in this field. [ABSTRACT FROM AUTHOR]

Proper bonding between different layers of a composite pavement is a major factor in ensuring that the entire structure acts as a monolithic layer under load. This paper studies the bonding between hot mix asphalt (HMA) overlay and Portland cement concrete (PCC) pavement using tack coats. An in-situ pull-off test method was developed for use on project sites on a routine basis to screen and test the quality of bond between asphalt layer and concrete layer. This test replaces the arduous process of coring through often times very thick concrete layer with steel rebars, transporting the core to a lab, trimming the concrete side of the core to fit the shear jig, and finally conducting a shear test. Results show that the in-situ pull-off test method developed in this study is strongly correlated to the laboratory based direct shear test. Limits were also suggested to indicate an adequate bond strength in the PCC–HMA interlayer on the basis of laboratory and field testing. This study also evaluates the influence of various factors on the performance of the interlayer bond in laboratory. These factors include the type of tack coat, application rate, the texture of the concrete pavement surface, the surface cleanliness and the surface moisture. Results indicate that sandblasting and hydro-demolition textures offer the best interlayer bond strength, the influence of application rate is not significant on the interlayer bond strength and the influence of surface moisture and cleanliness are dependent on the type PCC surface texture. • The study develops a pull-off test method to test the HMA–PCC interlayer bond. • This test has a potential to replace the direct shear test performed in laboratory. • This test is performed on-site which requires only 1.5 h to test four replicates. • Pull-off strength strongly correlates with the direct shear strength. [ABSTRACT FROM AUTHOR]

• The inherent process of water permeation across the concrete surface serves to characterize its permeability. • The liquid film sensor is utilized to collect water film data from the concrete surface at a high frequency, enabling extensive data acquisition and rapid permeability detection. • An efficient, real-time, in-situ concrete pavement permeability evaluation method which improves the efficiency and solve the defects of traditional methods. To address the limitations of current concrete permeability evaluation, which can only test cored samples or on specific positions, this study proposed an innovative in-situ approach based on dynamic water film changes for evaluating concrete surface permeability. A porosity prediction model of concrete surface has been developed through ElasticNet regression, based on the data of dynamic water film thickness and concrete surface porosity. Considering different testing environment, the correction factors of temperature, relative humidity, wind speed, solar radiation intensity, and surface slope were determined. Then, we developed a large area in-situ test system based on moving platform for concrete surface permeability evaluation. The result indicates that there is a significant correlation between the water film permeation rate and the porosity, and the porosity prediction model exhibits high accuracy. The large area in-situ test system streamlines the concrete pavement permeability evaluation process, thereby contributes to maintenance and management of concrete pavements. [ABSTRACT FROM AUTHOR]

This investigation was carried out to study the effects of the type and amount of supplementary cementitious materials on mechanical properties and surface durability of Portland cement concrete (PCC) pavement. Three supplementary cementitious materials, two types of fly ash and one ground granulated blast furnace slag, were selected to substitute for a portion of Portland cement with three level contents (5, 15, 25 wt% and 15, 25, 35 wt% for single and compound adding, respectively) in the concrete mixtures. Properties of the concrete were evaluated in laboratory including compressive strength, flexural strength, surface abrasion resistance, surface frost resistance,and microstructure analysis. The results show that the early age strength values of concretes were affected as increasing the replacement contents regardless of fly ash and slag. Effects of both the type and dosage of supplementary cementitious materials on surface abrasion resistance and frost resistance of concrete were remarkable. The concrete with slag had poorer wear resistance than reference concrete and those with fly ash. In addition, general fly ash concrete had worse surface frost resistance than other mixtures, and concrete with slag exhibited better surface frost resistance in saturated sodium chloride solution than reference one and fly ash concrete. [ABSTRACT FROM AUTHOR]

It is universally accepted that curling and warping of jointed plain concrete pavements (JPCP) can influence pavement performance. Recent studies indicated that long-term increases in roughness for pavements could also be largely related to curling and warping changes. The objective of this study is to investigate behaviours of idealised curling profile and resulting values of parameter pseudo-strain gradient (PSG) in the frequency domain from profiles acquired from 30 sections to offer supplementary information on the characteristics of curling profile of interest. Advanced wavelet techniques, including both continuous wavelet transform (CWT) and discrete wavelet transform (DWT), were utilised to decompose profiles into different layers of details in corresponding frequency bands for analysis. A quarter-car (QC) model was applied to simulate each decomposed layer, then frequency-domain changes in PSG and International Roughness Index (IRI) were compared, with results indicating that roughness resulting from curling profile could be strongly correlated to PSG in the frequency domain. The standard deviation for the level of details D 6 from DWT also shows a better correlation to PSG than IRI in the spatial domain. The dominated frequency band for curling profile was identified to be 0.12–1.25 circle/m. Differences between CWT and DWT for profile filtering were also discussed. [ABSTRACT FROM AUTHOR]

The choice between continuously reinforced concrete pavement(CRCP) and jointed concrete pavement(JCP) for different concrete pavement applications has long been controversial. Research on these two types of pavement has been conducted continuously for decades, but existing studies have mostly focused on life cycle costs (LCCs) with numerous assumptions or have predicted life expectancy by using short-term performance results. In this study, comparing CRCP and JCP based on real performance data and actual maintenance and rehabilitation (M&R) cost data collected over 30 years from the Jungbu Expressway in Korea. To assess performance, the service life and pavement conditions of each pavement type were compared. To assess the cost, construction cost and M&R cost data collected over 30 years were compared. In terms of performance, CRCP was superior to JCP based on the 31-year service life of CRCP and the 28-year service life of JCP. In terms of pavement conditions, CRCP was also superior to JCP based on the Highway Pavement Condition Index (HPCI) and International Roughness Index (IRI). Furthermore, in terms of cost, although the construction cost of CRCP was slightly higher than that of JCP, the total cost of CRCP, including the M&R cost, was 8.5% less than that of JCP. [ABSTRACT FROM AUTHOR]

Pavement infrastructures have become vulnerable to damage as they were not designed to withstand the aggressions of extreme weather events such as flooding, induced by climate change. In Ontario, flooding tops the list of climate change hazards having a consequential impact on pavement performance. Rigid pavements are recorded to provide resilience to flood hazard in literature but knowledge about its behavior and response to flood impact is currently scarce. The objective of this study is to investigate flood impact on concrete pavement performance examining case studies of Jointed Plain Concrete Pavement (JPCP) road classes in Ontario. The AASHTOWare Pavement ME was employed to simulate JPCP performance under climate-induced flood scenarios using a conservative Representative Concentration Pathway (RCP) of 4.5W/m2. Typical municipal JPCP collector and arterial road classes were chosen and modelled. While percentage change in faulting performance was considered, overall flood damage was based on relative change in International Roughness Index (IRI) under flood conditions. Results indicated lower damage ratios and pavement life loss in arterial JPCP than collector JPCP. Generally, minor flood damages were observed across RCP 4.5 return periods and event cycles in the collector and arterial case studies when compared to previous flooded concrete pavement investigation. [ABSTRACT FROM AUTHOR]

Due to greater durability and lower maintenance costs, concrete pavements are more competitive than asphalt pavements in areas where rigid pavements are required. To ensure the surface skid resistance of concrete pavement for driving safety, appropriate textures must be created on the concrete pavement surface. Common surface texturing treatments in Germany include exposed aggregate, grinding and grooving, and sealing methods. To investigate the influence of different surface texturing methods on the wearing resistance of concrete pavement, concrete pavement samples with six different surface textures were manufactured in this study. The advanced Aachen Polishing Machine (APM) was used to simulate the different polishing states on the extracted samples with 0, 16, 33, 100, 200, and 300 min of real-tire polishing effect. After each polishing stage, a series of surface characteristic tests was conducted to evaluate the wearing characteristics of pavement samples. The test results showed that different surface textures have different long-term polishing resistances. Of the texturing methods investigated, the exposed aggregate and sealing treatments provide the best long-term polishing resistance for plastic and hardened concrete, respectively. This research provided a comprehensive evaluation of and significant guidance on the selection of surface treatment methods for new construction of cement pavement and surface maintenance of hardened concrete pavement. [ABSTRACT FROM AUTHOR]

Measurement data based load analysis of precast concrete pavements of motorways In Austria, about 40 % and in Germany about 30 % of the motorway and expressway network are concrete pavements. However, very little is known about the stress conditions and temperature loads actually acting in concrete pavements. There is little in‐situ data available, mainly because of the difficulties involved in measuring these conditions in a real paving environment. In the course of a research project, precast slabs were used for the first time to repair concrete pavements in a highway in Austria, and these were also extensively equipped with embedded fiber optic sensors. In an in‐depth analysis of the measurement data of a period of two years, temperature changes, extremes as well as gradients in connection with external weather conditions are evaluated. With regard to the formation of cracks and constraints in the slab, on the one hand measured strains without traffic load are analyzed, on the other hand a statistical analysis of the measured impacting traffic load changes is carried out. In the second section, based on a calibrated nonlinear FE model, a combined analysis of the unsteady stress profile of the slab under dynamic traffic loading with varying temperature‐mechanical loading is performed. After comparison with measured data, the dynamic stress maxima acting in the plate can be determined. [ABSTRACT FROM AUTHOR]

This paper describes a numerical thermo-mechanical model for concrete pavement, implemented in OOFEM software. The thermal part is a heat transfer problem with appropriate initial and boundary conditions (sun irradiation, radiation and convection), calibrated from experimental data. Heat release from cement hydration is also included, calibrated for commonly used cements to demonstrate the difference that can be achieved with the binder selection. The mechanical part of the problem is composed of a 3D elastic concrete slab, subsoil Winkler-Pasternak elements and 1D interface elements, allowing separation in tension. The Winkler-Pasternak constants C1 and C2 were firstly determined from TP170 document and refined later from static load tests on the highway. The model validates well temperature field, static load test and provide several useful insight such as feasible time for summer casting, stress/strain fields and slab separation from the base. [ABSTRACT FROM AUTHOR]

A circular piezoelectric pavement energy acquisition device for road was designed by using the stack mechanism on a piezoelectric ceramic unit. Two different orientations of piezoelectric transducers were compared according to the pavement construction mode, and their conversion performance was evaluated based on the traffic load model. The performance of the transducer was analysed from two aspects, electromechanical conversion effect and structural durability, and its working efficiency was determined. Under a force of 5000 N and loading frequency of 10 Hz, the effective current of the "9-units" transducer was 3 mA, maximum output power was 18.566 mW, and corresponding optimal load was 7 kΩ. The cyclic loading and performance testing of laminated piezoelectric ceramic units demonstrated a voltage between 8 and 12 V under 5000 N and 10 Hz, and the voltage decreased by approximately 2.8% and 9% at loading cycles of 30,000 and 60,000, respectively. The static capacitance remained at approximately 1.1 µF. In addition, among the rubber pads of different materials used as protection for the piezoelectric device, fluorine rubber pad was found to be the most suitable. Compared with the traditional PZT devices, the piezoelectric devices designed for this study show better pavement power generation performance, fatigue resistance, and practical feasibility. [ABSTRACT FROM AUTHOR]

A new 3D hygro-thermo-mechanical model for a single concrete pavement slab is formulated with the objective to capture slab behavior from casting to long-term drying. Strain and temperature data from five-year continuous monitoring system served for calibration and validation. Four simulated scenarios show temperature analysis after concrete casting, cyclic temperature effect and stress/strain response for traffic load and long-term drying. The results show that slab drying leads to the highest principal tensile stress on the surface and induces surface cracking when combined with temperature and traffic effects. • A single concrete slab was analyzed with the hygro-thermo-mechanical model. • The early-age temperature validation was carried out with cement hydration. • Temperature cycles and wheel loading scenarios were analyzed. • Drying led to the highest achieved tensile stress in the slab. • Load combination using the superposition principle leads to crack formation. [ABSTRACT FROM AUTHOR]

Despite excellent service history, concrete pavement faces accelerated deterioration due to water and chemical ingress through micro cracks and surface voids. Surface protection could be an inexpensive way of enhancing the durability of concrete pavement. This research focuses on evaluating the performance of three surface applied hydrophobic materials with different chemistries; fluoropolymer, silicate resin and sodium acetate crystallising material. Tests consisted of a microscopic study to assess the mechanism of treatment, contact angle and pendulum tests to evaluate the hydrophobicity and frictional properties of treatment respectively. Also, surface absorption and water intake tests were conducted to appraise the resistance of treatment to absorb water. It was found that all three materials are capable of developing a hydrophobic effect in concrete, but with different efficacy in reducing water absorption. The rate of water absorption was minimum for sodium acetate compared to fluoropolymer and silicate resin treatments. Scanning Electron Microscope (SEM) analysis revealed different interaction approaches for the three materials with concrete. [ABSTRACT FROM AUTHOR]

In South Korea, the performance of continuously reinforced concrete pavement (CRCP) has been better than that of jointed concrete pavement (JCP). However, most of the Portland cement concrete (PCC) pavements in South Korea have been JCP, primarily due to the difficulty in providing extra space along the edge of the pavement needed for concrete delivery in CRCP construction. In a tube-feeding method (TFM), concrete can be supplied from the front of a paver, which could facilitate CRCP construction without extra space needed. In the present study, efforts were made to improve the capability of TFM in placing longitudinal steel at correct elevations, which resulted in the development of tube feeding equipment (TFE). Field testing results showed that the key to ensuring steel placement at correct elevations was to keep longitudinal steel in adequate tension. The distance from the back of the tubes and the front of the mould, up to 1500 mm, did not have substantial effects on the steel settlement. To evaluate the viability of CRCP construction with TFE, a 400 m long CRCP section with 300 mm slab thickness and 8.2-m width was constructed and performance monitored. [ABSTRACT FROM AUTHOR]

This study presents the results of a laboratory work carried out at to evaluate the properties of roller compacted concrete made with crushed bricks for pavement application. The bricks materials were crushed in order to obtain useable coarse aggregate sizes as specified in relevant standard specifications. The properties investigated were the aggregate impact value, aggregate crushing value, Los Angeles abrasion value, specific gravity and water absorption. The coarse aggregate (crushed granite) was replaced with crushed bricks at 0%, 20%, 40%, 60% and 80% by weight. The concrete mixtures were batched at 1: 3.5: 3 mix ratio of cement, fine aggregate and coarse aggregate. Workability and the density of fresh concrete, and the compressive strength, splitting tensile strength, and flexural strength of hardened concrete were investigated. Compressive strength was measured at 3rd, 7th, 14th, 28th, 56th, and 91st days. The results of the laboratory tests carried out on concrete produced with crushed bricks aggregates were compared with the results of laboratory tests on non-crushed brick concrete specifications and with the specifications of relevant standards and manuals. The results indicate that crushed bricks aggregates can be used as partial replacement of natural coarse aggregates in roller-compacted concrete pavement construction and maintenance. [ABSTRACT FROM AUTHOR]

This study presents the results of a laboratory work carried out at to evaluate the properties of roller compacted concrete made with crushed bricks for pavement application. The bricks materials were crushed in order to obtain useable coarse aggregate sizes as specified in relevant standard specifications. The properties investigated were the aggregate impact value, aggregate crushing value, Los Angeles abrasion value, specific gravity and water absorption. The coarse aggregate (crushed granite) was replaced with crushed bricks at 0%, 20%, 40%, 60% and 80% by weight. The concrete mixtures were batched at 1: 3.5: 3 mix ratio of cement, fine aggregate and coarse aggregate. Workability and the density of fresh concrete, and the compressive strength, splitting tensile strength, and flexural strength of hardened concrete were investigated. Compressive strength was measured at 3rd, 7th, 14th, 28th, 56th, and 91st days. The results of the laboratory tests carried out on concrete produced with crushed bricks aggregates were compared with the results of laboratory tests on non-crushed brick concrete specifications and with the specifications of relevant standards and manuals. The results indicate that crushed bricks aggregates can be used as partial replacement of natural coarse aggregates in roller-compacted concrete pavement construction and maintenance. [ABSTRACT FROM AUTHOR]

Prediction of the temperature development at an early age is a good starting point to assess the development of the restrained thermal stress and thermal cracking in rigid pavements. This paper presents a numerical early age concrete pavement temperature prediction model. It enables to evaluate the effect of various paving conditions, such as paving time, curing method, air temperature, wind speed, and the concrete placement temperature, on the early age concrete pavement performance. A critical review of current heat flux models at the pavement surface covered with a plastic sheet is presented. An extension of existing models to quantify the effect of the plastic sheet curing method is introduced, based on the energy balance method. The numerical implementation procedure for the proposed temperature prediction model is solved by the finite difference method. The temperature prediction model was verified with field measured data of two test sections. The predicted temperature shows a satisfying match with field measured data. Lastly, the effect of plastic sheet curing and its duration on the development of the pavement temperature was analysed by the proposed theoretical model. [ABSTRACT FROM AUTHOR]

Stress occurring in concrete pavement slab changes on daily and annual basis. Daily changes of air temperature in between environments depend on the following: latitude where the structure is located and season. Change of air temperature causes the variable thermal stress of a slab and consequently change of its linear dimensions (slab extension or shortening. "Thermal balance of pavement" prepared for individual structure solutions, should be the basis for construction design and geometric solutions concerning air field structure. This publication refers only to natural changes of temperature conditions of the environment. Other phenomena occurring on concrete airfield pavement under the influence of imposed thermal loads will be the subject of another publication in this regard. [ABSTRACT FROM AUTHOR]