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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]

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 investigates the early-age behaviour of continuously reinforced concrete pavement (CRCP) on the semi-rigid base, including structural behaviour during transverse crack propagation and curling behaviour both in the longitudinal and transverse direction. Field experiments are operated on a CRCP section in Wuhan, China. Vibrating wire strain gauges were installed at mid-slab and slab edge in the longitudinal and transverse direction for concrete strain and temperature measurement. Testing results showed the complexity of early-age behaviour of CRCP on semi-rigid base and curing with wet burlap sheets. An early-age transverse crack may originate from the bottom of the concrete slab due to the water absorption of the dry semi-rigid base. The development of a transverse crack took several cooling cycles. Curling behaviour in the longitudinal direction did not correspond to the temperature gradient after transverse crack occurrence. Typical curling motion in the transverse direction was found in the mid-slab rather than the slab edge. The findings of this study would lead to a better understanding of the early-age structure behaviour of CRCP on semi-rigid base and its impact on later road performance. [ABSTRACT FROM AUTHOR]

Continuously reinforced concrete pavement (CRCP) is frequently used for heavy traffic. In CRCP, early-age cracking can be caused by environmental loading freely and randomly, but only certain crack patterns can affect its long-term performance and induce distress such as punchouts. In this work, we introduce a peridynamic model that includes the time dependency of the environmental loading and material properties to investigate the early-age behaviour of CRCP and predict its cracking. The simulation results match those from field observations in terms of crack patterns, average transverse crack spacing, and crack width. We conduct parametric analyses and find the effects changing environmental conditions and design parameters have on crack patterns. An investigation of active crack control demonstrates that the model can be used to determine optimal pre-notch spacing, for specific environmental conditions, that leads to desirable crack patterns. [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]

Subsidence seriously affects the structural stability and safety of pavements and foundation soils. In heavy-loaded pavements, there is a risk of floor sinking and further construction collapse; hence, there is a need to develop efficient methodologies to detect subsidence earlier. This work proposes the use of ground penetrating radar (GPR) as a solution to non-invasively inspect the subsoil. Furthermore, as the interpretation of the GPR data is arguably subjective and highly dependent on who interprets it, different imaging techniques are herein exploited to improve the interpretability and detection of subsidence and settlement phenomena. The approach was applied to a heavily loaded reinforced concrete pavement servicing a manufacturing facility. Amplitude- and texture-based imaging methods were used to detect subsidence. The interpretation of such imaging was validated with additional geotechnical studies, which show that the proposed methods provide reliable results with good agreement between techniques. [ABSTRACT FROM AUTHOR]

This study mainly examines the slump, mass loss (ML), abrasion loss (AL), residual compressive strength (RCS), and residual splitting tensile strength (RSTS) of concrete reinforced with micro- and macro-polypropylene (PP) fibers after the F–T process. In the blends, micro- and macro-PP fibers were added to the blends at 0.3%, 0.6%, and 1% by volume. In total, 25, 50, 100, and 150 F–T cycles were applied to all samples. The study's results show that micro- and macro-PP fibers negatively affect the blends' slump values. Besides, PP fibers did not contribute to reducing the ML values of the samples after the F–T process. Moreover, the contribution of the PP fibers in prohibiting the decrease in RCS capacities of specimens after the F–T process is valid up to 0.3% volumetric fiber content. Additionally, PP fibers were more efficient in hindering reductions in AL and RSTS capacities after the F–T process of the specimens. Furthermore, using macro-PP fibers in hybrid form with micro-PP fibers reduced AL and improved RCS and RSTS capacities more than single macro-PP fibers. After 150 F–T processes, the reduction in AL of C0 control concrete was 9.41%, while the declines in AL of C1-C6 samples ranged from 7.56% to 8.92%. In addition, after 150 F–T processes, the decrease in RCS and RSTS loss of C0 control concrete is 25.09% and 28.30%. In contrast, the decline in RCS and RSTS loss of C1-C6 samples varies between 22.94–32.97% and 20.10–25.75%, respectively. [ABSTRACT FROM AUTHOR]

Many bridge structural components are subjected to repetitive vehicle load and temperature gradient action. The resulting cyclic tensile stresses within the structures could cause premature fatigue failure of concrete, dramatically impairing structural components' durability and sustainability. Although substantial knowledge of fatigue properties on low-strength pavement concrete and high-strength structural concrete has been obtained, research on the most widely used normal-grade ordinary concrete in bridge engineering is still ongoing. Therefore, a four-point bending fatigue test of 97 C50 concrete specimens under a constant amplitude sinusoidal wave was conducted in the laboratory, the flexural fatigue behavior of plain and reinforced concrete specimens was studied, and the cyclic deformation evolution of concrete under fatigue loading was obtained. The empirical fatigue S-N equations of concrete with a failure probability p of 0.1~0.5 were derived through statistical analysis of the test results. The fatigue life of the tested specimens exhibited a two-parameter Weibull distribution. In addition to the maximum stress level Smax, the stress ratio R is also a key factor affecting the flexural fatigue life of concrete N. The semi-logarithmic and logarithmic equations were almost identical at the tested stress levels, the latter predicting longer fatigue life for Smax < 0.70. The restraining effect from steel reinforcement slightly lengthened the concrete's fatigue cracking initiation life. The insight into concrete flexural fatigue properties from this study not only contributes to a better understanding of structural concrete, but also provides a basis for the practical evaluation of concrete or composite bridge decks. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of hardening accelerator and steel fibre on concrete adhesion strength for the repair of rigid highway and airfield pavements. The concretes were mixed based on CEM II/A-S 42.5 and included MasterGlenium SKY 608 superplasticiser. Experiments with two variable concrete composition factors were carried out. The amount of steel fibre varied from 0 to 100 kg/m3 and the amount of SikaRapid hardening accelerator varied from 0 to 9.6 kg/m3. It was found that modified repair concretes have a sufficiently high adhesion strength to 'old' concrete, from 2.30 MPa when tested by the pull-off method and from 2.05 MPa when tested by the flexural strength test method. Fibre-reinforcement increases the adhesion strength of repaired concrete by 7–15% due to the reduction of shrinkage during hardening. Treating the contact surface of 'old' concrete with a primer additionally increases adhesion strength by 6–10%. The maximum adhesion strength of fibre-reinforced concrete to the base reaches 3 MPa. Due to the high early and design strength, modified steel fibre-reinforced concrete provides the possibility of quick resumption of traffic while ensuring the integrity of the road structure due to the joint work of the repair material with the old concrete repair area. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the dynamic behaviour of continuously reinforced concrete pavement (CRCP) on a multi‐layered transversely isotropic saturated subgrade subjected to a moving load. The stress‐strain relationship of the CRCP is obtained based on classic lamination theory. Then, the differential governing equations of the pavement are established by D'Alembert's principle. Combining the Fourier series expansion and integral transform technique, the displacements of the CRCP in the wavenumber domain are derived. By introducing pavement‐subgrade interface conditions, the solution to the pavement‐subgrade system is acquired with the use of the extended precise integration method (PIM). The solution in the spatial domain is further obtained by the numerical inverse transform. The presented method and the corresponding program are verified. Finally, parametric studies are conducted to determine the effects of the reinforcement ratio and position, the load velocity and the subgrade stiffness. [ABSTRACT FROM AUTHOR]

The abundant availability of natural fibres around the globe seeks researchers' attention on their potential use as construction materials. There is a need to explore the structural integrity of cement concrete reinforced with such natural fibres. To start with, wheat straw is considered. In this study, the structural performance of wheat straw reinforced cement concrete (WSRC) road is evaluated. The properties of plain concrete pavement are taken as a reference. Wheat straw, of approximately 18 mm in length and 1% content (by mass of wet concrete), is considered to make the WSRC road test section. The laying technique of WSRC, at a larger scale, is explained. The laboratory and field investigations are made. The compressive properties, deflection measurements, and cracks progression are determined after the exposure of test sections to vehicular loading for 18 months. Micro-structural analysis of straw–concrete matrix is also done to verdict the uniform dispersion of straw with proper bonding and its failure mechanism. The study is concluded with 34% and 16% more energy absorption capacity and load transfer efficiency, respectively, in the WSRC test section compared to that of the controlled section. Also, the structural performance of the WSRC road test section, with 7% less design thickness than the plain concrete road test section, is comparable for having economical and sustainable concrete roads. [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]

Due to the large-scale use of materials in highways, the sustainability of materials has attracted considerable interest for years. In this respect, significant effort has been spent investigating the use of recycled aggregates in concrete pavements. This study has been carried out to fill the gap in the structural performance of recycled aggregate concrete pavements. First, properties of concrete mixtures, produced with virgin, recycled concrete and recycled brick aggregates were experimentally measured, and the results were compared. Then, finite element analyses were done by following a novel methodology that considers the well-known previous works. Results showed that replacement of coarse aggregates with recycled aggregates decreases the mechanical properties in various amounts. Due to the resulting performances, for the same slab thickness, decreased maximum stress, increased deflection and stress ratio values were found for recycled aggregate mixtures. Additionally, higher thicknesses and material requirements were found for recycled aggregate concrete for a similar life. Despite the decreased performance and increased material requirements, the use of recycled aggregates in pavements can still be a viable alternative for countries with limited natural resources and landfills. Therefore, based on the findings, several important discussions and suggestions were presented for future works. [ABSTRACT FROM AUTHOR]

Airport pavement concrete often suffers from freeze–thawing damage in high latitude and cold areas. In addition, the use of aircraft deicer makes the airport pavement concrete suffer from salt-freezing damage. To improve the durability of airport pavement concrete, modified polyester synthetic fiber (FC), cellulose fiber (CF), and basalt fiber (BF) reinforced concrete were prepared in this paper. The mechanical strength, pore structure, and frost resistance (freeze–thawing and salt freezing) of fiber-reinforced concrete were investigated. The effects of the combined action of fiber (fiber type and content) and surface treatment methods (spraying silane and impregnating silane) on the frost resistance of concrete were investigated. The results show that the flexural strength of concrete is positively correlated with the elastic modulus of fiber, but has little effect on the compressive strength. Fiber can reduce mass loss and dynamic modulus loss of concrete subjected to frost damage. FC more effectively improved the frost resistance of concrete than CF. After 30 cycles of salt freezing, the spalling amount of concrete sprayed or soaked with silane was decreased by 65.5% and 55.5%, respectively. Adding fiber and impregnating silane reduced the spalled concrete by up to 70.5%. Spraying silane treatment is better than impregnating silane treatment in enhancing the frost resistance of concrete because a better silane condensation reaction is achieved with spraying silane. [ABSTRACT FROM AUTHOR]

The construction industry must meet current environmental requirements, mostly those pertaining to the reduction in construction and demolition waste and the consumption of raw materials. The use of recycled concrete aggregates can be part of the solution, but one question that arises is how many times recyclables can be recycled. This unknown involves other related queries regarding the properties and possible uses of repeated recycled concrete aggregates. This research is derived from the precast concrete industry, where multi-recycling is a pressing need. From good-quality parent concretes, three cycles of recycled concrete aggregates were produced and analysed. The final results are promising due to the good quality of the recycled and multi-recycled concrete aggregates obtained. Not only can they be used in low-level applications (backfilling) as usual, but they can also be used for more demanding purposes, such as graded aggregates, cement-treated road bases and concrete pavements. Their use in structural concrete is feasible, but it will be dependent on the water absorption level and the amount of recycled aggregate substitution. This research proves the viability of multi-recycled concrete aggregates with all of the associated environmental benefits. [ABSTRACT FROM AUTHOR]

This study investigates the crack spacing and crack width movement of partially continuous reinforced concrete pavement (PCRCP) under environmental loading. To this end, full-scale field tests were carried out in the highway PCRCP test sections. Measured data were utilized to comprehensively understand the cracking spacing of test sections. The effect of design-related variables on the active crack and passive crack width movement was evaluated by changing the design variables. The results show that the partial continuous steel bars of PCRCP have a significant restraining effect on the shrinkage of pavement slab, and its restraining effect increases with the increase of the partial continuous reinforcement length. With the decrease of active crack spacing, the number of cracks decreases and the crack width decreases. PCRCP, by improving the reinforcement method, reduces the initial construction cost and does not affect its early performance. PCRCP adopts the active crack control method to obtain uniform crack spacing, thereby improving early-age cracking behavior significantly. The crack width prediction model proposed in this study is in good agreement with the field test measured values, and it is more suitable for crack width prediction of PCRCP design variables. Based on the prediction model proposed in this study, the crack width of PCRCP can be predicted so that the early performance of PCRCP can be improved by changing the design variables. • Crack spacing and crack width movement in PCRCP are measured in full-scale field tests. • The cracking spacing of test sections are comprehensively analyzed. • Effect of design-related variables on the crack width movement are investigated. • The partial continuous steel bars of PCRCP have a significant restraining effect. • The crack width prediction model proposed in this study is in good agreement with measurement. [ABSTRACT FROM AUTHOR]

Currently, punchout distress in continuously reinforced concrete pavement (CRCP) frequently occurs even if the reinforcement design strictly adheres to specifications. In this study, a new concept called reinforced concrete pavement with large spacing joints (RCPS) is proposed, and a new isolation layer is applied to the RCPS on the basis of laboratory results. Finally, a test road is constructed to verify the rationality of the structure of RCPS. The results show that reducing the friction and bonding strength between the isolation layer and pavement is the key to implement RCPS. The design method of RCPS not only retains the good bearing capacity of CRCP but also overcomes the problem in which the dry shrinkage and temperature stresses of CRCP cannot be released, which leads to punchouts. [ABSTRACT FROM AUTHOR]

The purpose of the research is to define and describe the performance behaviour during full-scale accelerated loading for a new heavy duty pavement type referred to as Mechanised Cement Bound Macadam (MCBM). MCBM is a cost-effective and reduced carbon footprint alternative to structural asphalt concrete and conventional concrete pavements. Four MCBM test sections were constructed with two key considerations in mind, the influence of layer thicknesses and maximum stone size within the gradation. In addition, defining the fundamental strength behaviour of the pavement, the failure mechanisms and their impact on perpetual pavement design were key objectives for the research. Dynamic and semi-static deflection measurements, strain measurements from strain gauges embedded in the pavement, crack mapping and transverse surface profile were collected at intervals throughout the accelerated loading. Performance testing showed that the stone interlocked structure is unique and undergoes multiple strength phases, enabling excellent shear and rut resistance by upholding vertical load bearing. The accelerated load testing also proved that significant structural strength remains post-bound phase. However, the MCBM design is based on a bound phase criterion and specifies a threshold fatigue stress value less than 30% of the flexural strength (breaking strength under four-point beam testing). Hence, the MCBM is perpetual by design and intended to function in the bound phase, requiring only intermittent resurfacing. [ABSTRACT FROM AUTHOR]

Continuously reinforced concrete pavement has the potential to provide a long term, "zero - maintenance" service life under heavy traffic, provided proper design and quality construction practices are utilized. Concrete mixes containing 0%, 5%, 10%, 15%, 20%, 25%, and 30% of rice husk ash was prepared and cured in portable water. The compressive strengths of concrete specimens were evaluated at the 3rd, 7th, 14th, 28th, 56thand 91st day old. The split tensile strength and the flexural strength were evaluated at the 14th and 28th day. The compressive strength values, split tensile strength values and flexural strength values of the concrete specimens increased with increase in age and also increased with increase in 5% and 10% percentage replacement of cement with rice husk ash. The concrete specimens containing 0% to 25% percentage replacement of cement with rice husk ash satisfied the minimum compressive strength requirements specified in the relevant standard specifications and manuals. The study therefore concluded that up to 25% of rice husk ash should be used as partial replacement of cement in continuously reinforced concrete pavement. [ABSTRACT FROM AUTHOR]

The goal of this research is to evaluate whether it is possible and effective to detect honeycombing of concrete pavement using a ground-penetrating radar (GPR) during construction. The motivation is that identifying honeycombing of concrete during construction would help avoid the spread of consolidation problems in large pavement sections, which are costly and time consuming to repair. GPR has been used as a tool for concrete quality control and detection of delamination in reinforced concrete elements since the 1980s, but it has not been used for the early detection of relatively small air voids. In this project, first, preliminary field testing was conducted to determine the possibility of detecting honeycombs in existing concrete pavement. Then, air voids of different sizes, shapes, and depths were artificially created using spray-foam in several laboratory specimens and detected using a high-frequency GPR antenna at different times after concrete placement. Cores were extracted to validate GPR readings and determine the capability of this technique. Another field testing was conducted to evaluate the efficiency and economy of using GPR as a nondestructive quality control tool. Field and lab test results indicated that GPR could be efficiently used to detect air voids as small as 32 mm (1.25 in.) and as deep as 102 mm (4 in.) from the surface of the concrete pavement as early as the initial set of concrete. These findings suggest that GPR is an effective, efficient, and economic quality control tool for this application. [ABSTRACT FROM AUTHOR]

Experiences around world using continuously reinforced concrete pavements (CRCPs) in tropical hot-wet climates were not relevant to further characterise peculiar technical issues like crack width along seasons as well as bars rust potential due to typical rainfall conditions. This study purposes to assess the cracking pattern developed in a CRCP bus lane employing four different concrete mixes as well as the effects of steel type (black and galvanized) on crack width and load transfer efficiency (LTE). The central sections have presented the largest number of cracks since they are anchored by the ending sections and their average crack spacing is consistent with former studies on temperate climate. Crack width surveys shown the cracks are tighter than what traditionally came across in temperate climate and the average LTE at crack results is higher than 90% for both galvanized and black steel. [ABSTRACT FROM AUTHOR]

[Display omitted] • The damage and responses of two asphalt pavements under blast loads are simulated. • The proposed simulation methodology is validated based on a real blast test. • A reinforced concrete layer is added to improve the anti-blasting performance. • The proposed anti-blasting pavement structure reduces the damage area by up to 20%. The explosion accidents are threatening the service functionality of pavement structures, which puts forward new requirements such as multi-hazard resistance and resilience. Although the widely used asphalt pavement structure is vulnerable to blast loads, its dynamic behaviors under blast loads are still unclear. This research mainly focused on the damage and responses of two asphalt pavement structures, one of which was conventional asphalt pavement, and the other was the anti-blasting asphalt pavement structure with the reinforced concrete layer. The numerical simulation method, which was validated based on a real blast test, was proposed using Abaqus code with appropriate material models and simulation procedures. The finite element models of two pavement structures were built. Under various blast loads, the damage contours and dynamic responses of different pavement structure components were investigated. It was found that the total damage areas of two asphalt pavement structures were grew by 2.26 and 3.19 times, respectively, as the blast loads increased from 100 kg TNT to 2000 kg TNT. The slope of pavement structure was extremely sensitive to the changes in blast load. The proposed anti-blasting pavement structure could reduce the damage area by up to 20 %, but it would be invalidated under particularly destructive blast loads. These findings could be helpful for the further design of an anti-blasting pavement structure. [ABSTRACT FROM AUTHOR]

• Polyoxymethylene fibres added as reinforcement in cement-based concrete. • Polyoxymethylene fibres increase the crack resistance of airport-pavement concrete. • Strain-rate sensitivity of fracture behaviour reduced with increasing fibre content. • Results provide insights for using such reinforced concrete in airport pavements. Polyoxymethylene (POM), a novel type of fibre, can be incorporated into airport-pavement concrete as a reinforcing fibre. Airport pavements are thin-plate concrete structures continuously subjected to various complex random loads. Thus, understanding the fracture behaviour of POM-fibre-reinforced concrete under various strain rates is essential. In this study, ordinary airport-pavement concrete and POM-fibre-reinforced airport-pavement concrete were subjected to three-point bending fracture tests at five strain rates (10−6, 10−5, 10−4, 10−3 and 10−2 s−1), and the effects of fibre content and strain rate on the fracture performance of these concrete were systematically investigated. The results showed that POM fibres could enhance the crack resistance of concrete used in airport pavements; for a POM fibre concentration of > 1.2 vol%, the fracture toughness increased by ∼ 50 %. The analysed critical crack propagation rates demonstrated the ability of POM fibres to inhibit fracture propagation. Although PFAPC showed distinct strain-rate-dependent fracture characteristics, this dependency weakened as the fibre concentration increased. Finally, statistical analyses of the fractured surface were performed to assess the fracture behaviour of PFAPC under various stresses and quantify the contribution of POM. These results provide a critical foundation for the practical application of PFAPC in airport pavements. [ABSTRACT FROM AUTHOR]

Continuously reinforced concrete pavement (CRCP) is a widely used alternative for heavy traffic highways due to good performance and low maintenance needs. Recently, the use of short length CRCP (50-m long slabs) has been proposed for bus stops and terminals. This paper examines the structural behaviour of cracks in short CRCP. This includes analysis of the Falling Weight Deflectometer (FWD) deflections and strain gauge measurements obtained from the full-scale test sections as well as structural modelling of the pavement. An evaluation of the influence of cracks on the FWD deflection basins collected on the experimental short CRCP pavement along with FWD data collected under the Long-Term Pavement Performance programme for conventional CRCP resulted in similar behaviour between the short and conventional CRCP. Therefore, the effects of the short CRCP transverse cracks on stresses were investigated. Three ISLAB2000 models differed by the concrete base or crack model were developed and their stress predictions were compared with field stresses. An applicability of the conventional aggregate interlock model for describing the behaviour of short CRCP was evaluated as only the continuous slab (no cracks) model was able to match the field stresses. A need for re-appraisal of the PavementME structural model is also discussed. [ABSTRACT FROM AUTHOR]

Necessity of protective runway pavement is important to reduce the maintenance cost and avoid disruption. The study started with conducting few impact drop weight tests on small specimens of normal concrete runway pavement and a proposed fibre reinforced concrete runway pavement. The performance of the proposed fibre reinforced runway pavement specimen was proved much better than the normal concrete runway pavement specimen. A three-dimensional finite element model of this fibre reinforced runway pavement specimen was then validated using ABAQUS software. Furthermore, the performance of this improved fibre reinforced concrete runway pavement was studied in large scale under the single and multiple impact of Airbus 380. A rigorous parametric study was also carried out to explore the effects of type of aircraft, impact duration, compressive strength, tensile strength and boundary condition of runway fibre reinforced concrete pavement in changing the surface deflection. [ABSTRACT FROM AUTHOR]

Pavement is an important part of a road structure. Selection of road pavement type is one of the important challenges of decision making by highway administrators. The life-cycle cost analysis is one of the common tools to select the pavement type which considers economic criteria such as costs of construction, maintenance and rehabilitation, and user costs; however, noneconomic criteria are neglected. The inadequate selection of road pavement type tends to increase the pavement life-cycle cost and impacts both environmental and social parameters. In this study, a three-step hybrid model is proposed to solve this problem. Initially, the causal relationships of main criteria affecting the pavement type selection are determined using decision making trial and evaluation laboratory. Then, the weight and importance of criteria and sub-criteria are determined using fuzzy analytic network process. Finally, the ranking of pavement alternatives is carried out using a fuzzy technique for order preference by similarity to ideal solution. A real case study consisting of five different types of pavements including hot mix asphalt, stone mastic asphalt, jointed plain concrete pavement, roller compacted concrete pavement with hot mix asphalt overlay and continuous reinforced concrete pavement is used to show the validity of the proposed model. [ABSTRACT FROM AUTHOR]

Repair of concrete traffic areas with slim carbon reinforced concrete layers Concrete pavements are exposed to high loads from existing traffic volumes and extreme weather conditions. In order to prevent wild cracking caused by the resulting constraining stresses, transverse joints are usually installed. However, these are also weak points in the concrete pavement, so that continuous maintenance and upkeeping is necessary. An ecologically and economically viable alternative to renewing the entire concrete slab is to rehabilitate the concrete runway with the aid of a jointless as well as thin top layer of carbon reinforced concrete. By separating the bond between the old concrete layer and the carbon concrete layer in the area of the transverse joint, a distribution of cracks is ensured and the crack width of the individual cracks in the carbon reinforced concrete pavement is reduced by multiple crack formation. Liquids can therefore penetrate less deeply into the concrete and damage neither the old concrete layer nor the corrosion‐resistant carbon reinforcement. [ABSTRACT FROM AUTHOR]

The restricted use of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) motivates the use of RAP in portland cement concrete (PCC) as an aggregate replacement. The addition of RAP causes significant changes in PCC's properties, but little research has been done to investigate the impact of these changes on pavement performances. In this study, punchout performances of continuously reinforced concrete pavement (CRCP) made with PCC containing RAP (RAP-PCC) slabs were extensively assessed using existing models in the Pavement ME. Based on the results, the major drawback for using RAP in CRCP is the RAP-PCC's reduced modulus of rupture (MOR); the reduced MOR causes higher stress to strength ratio in the slab, which can lead to higher chances of fatigue. However, the RAP-PCC slab is anticipated to have tighter transverse cracks due to the reduction in modulus of elasticity. A decrease in crack width could potentially yield a higher transverse crack load transfer efficiency (LTE). The Pavement ME simulations indicate that the CRCP made with RAP-PCC, which has tighter cracks, can maintain a higher LTE for a much longer time and ultimately leads to a longer pavement service life compared to the plain CRCP. [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]

Use of fibre reinforced concrete (FRC) for pavements is advocated since the higher crack resistance could lead to lower slab thickness and higher joint spacing. The post-cracking capacity of FRC allows pavements to be designed and analysed considering the response beyond the elastic regime. The current paper presents possible failure patterns in FRC pavement slabs, which are governed by the slab dimensions, loading type and boundary conditions, and the appropriateness of inelastic design methodologies for these failure patterns. Subsequently, a mechanistic-empirical design methodology developed for FRC pavements, based on yield line analysis incorporating fatigue in the moment calculation, is discussed. The proposed design methodology gives specific checks for the different failure patterns and the consequent design strategy to be adopted. The method incorporates material parameters, such as the first crack and post crack flexural strengths, and fatigue correction factors for the evaluation of the moment carrying capacity. Cumulative fatigue damage analysis is also done as a serviceability check. The final design solution satisfies both the inelastic moment capacity requirement and fatigue life required without excessive damage accumulation. [ABSTRACT FROM AUTHOR]

Challenges of uniform production of road concretes and possibilities of rheology‐based mixing process control The German road infrastructure comprises around 13 000 km of federal motorways and 39 000 km of federal highways. Large parts of the existing road network require rehabilitation and reconstruction. Then concrete pavement is increasingly being used for federal motorways. Accordingly, this article is dedicated to one aspect of the joint research project "Betonfahrbahn 4.0" [1], funded by the Federal Ministry of Transport and Digital Infrastructure, which focuses on the process‐reliable production of concrete roadways. In this project, partners from the construction machinery manufacturing industry, the construction industry and two university research institutes have the common goal of developing and implementing targeted improvement and innovative measures and components for the construction of concrete pavement. Finally all targeted improvement measures will be applied and tested under real conditions of the construction site. The project receives expert advice by the Federal Highway Research Institute and administrative advice by TÜV Rheinland. The present article concentrates on the unerring construcion of roadway concretes. A new approach of mixing process is presented which enables the slipform paver to meet the high consistency requirements for paving fresh concrete. The joint research project offers the IWB, the Otto‐Graf‐Institut and thus the MPA University of Stuttgart links to the research activities of Prof. Dr.‐Ing. E. h. mult. Otto Maximilian Graf on concrete road construction, who researched the use of concrete and reinforced concrete in road pavement back in the 1920s [2]. Also Prof. Dr.‐Ing. Prof. h.c. Dr.‐Ing. E.h. Hans‐Wolf Reinhardt, who headed the IWB and the Otto‐Graf‐Institut from 1990 to 2006, dedicates his research to various problems of concrete pavement in road construction [3]. In his honour, the potentials of a "mix design" adapted to the raw material situation and a rheology‐based mixing process management adapted to the composition of the concrete mixture will be shown in the following. [ABSTRACT FROM AUTHOR]

• Flexible SFRRuC can be constructed using waste tyre materials. • Mechanical and fatigue performance of SFRRuC are presented. • Three probabilistic models are used to derive the (P f -S-N) relationships. • SFRRuC pavements can accommodate large subgrade settlements. Recycled rubber particles and steel fibres from end-of-life tyres have the potential to enhance the flexibility and ductility of concrete pavements and produce more sustainable pavement solutions. However, the fatigue behaviour of such pavements is not fully understood. This article investigates the mechanical and fatigue performance of steel fibre reinforced concrete (SFRC) and steel fibre reinforced rubberised concrete (SFRRuC). Specimens tested were cast using rubber particles as replacement of natural aggregates (0%, 30% and 60% by volume), and using a blend of manufactured and recycled tyre steel fibres (40 kg/m3). Prisms were subjected to four-point flexural cyclic load (f = 15 Hz) at stress ratios of 0.5, 0.7, 0.8 and 0.9. The results show that, compared to plain concrete, the addition of steel fibres alone improves the fatigue stress resistance of concrete by 11% (at 25% probability of failure). The replacement of natural aggregates with rubber particles improves the flexibility of SFRRuC (from 51 GPa elastic modules for plain concrete to 13 GPa for SFRRuC), but reduces its fatigue stress resistance by 42% (at 25% probability of failure). However, a probabilistic analysis of the fatigue life data and overall design considerations show that the flexible SFRRuC can be used for pavements. To account for the effect of fatigue load, the Concrete Society approach included in TR34 is modified to account for SFRRuC pavements. Finite element analyses show that flexible SFRRuC pavements can accommodate large subgrade movements and settlements and result in much smaller cracks (up to 24 times) compared to SFRC pavements. [ABSTRACT FROM AUTHOR]

Field evaluation of distresses in continuously reinforced concrete pavement (CRCP) indicated punch-out distress associated with horizontal cracking at the depth of the longitudinal steel is the most severe performance problem in CRCP. The developed 3-D model was used to perform a parametric analysis to determine the effects of critical loading location, concrete properties, and longitudinal steel design on horizontal cracking potential. The maximum vertical tensile stresses in the concrete were slightly affected by the coefficient of thermal expansion of the concrete. The critical tensile stresses in the concrete were observed to decrease as the base modulus, slab–base friction, slab thickness, and transverse crack spacing increase. The vertical tensile stresses significantly decreased when the longitudinal steel spacing decreased. The use of varying longitudinal steel spacing and reducing the depth of steel may be one of the ways to reduce the horizontal cracking potential without changing the steel ratio of the slab. [ABSTRACT FROM AUTHOR]

The accelerations of sandwich-type composite pavements consisting of cross-tensioned concrete pavement (CTCP), asphalt sand (AS) stress-absorbing layer, and continuously reinforced concrete pavement (CRCP) layers from the top to the bottom were measured un der different traffic loads. First, the acceleration spectra of double plates of composite pavements were measured under axle loads of 100, 200, and 300 kN using an embedded accelerometer. The universal mean of the acceleration ratio of CTCP to CRCP was defined as the stress-absorbing ratio of the AS layer as obtained through statistical analysis of the test data. A frequency spectrum was obtained for the pavement under each vehicle load by using Fourier transf ormation. Test results show that the maximum acceleration of CTCP and CRCP in composite pavements was 0.022, 0.039, and 0.059 ms-2 and 0.01, 0.015, and 0.025 ms-2 under vehicle loads of 100, 200, and 300 kN, respectively. The corresponding mean stress-absorbing ratio of the AS layers was 3.38, 3.15, and 3.46. The results suggest that the proposed composite pavement is suitable for roads with heavy traffic because its stress-absorbing layer can effectively reduce the pounding caused by heavy loads on the pavement. [ABSTRACT FROM AUTHOR]

• The crack propagation in fiber reinforced concrete (FRC) and Engineered Cementitious Composites (ECC) beams is studied from a probabilistic perspective. • An experimental program was devised to investigate crack formation and propagation in FRC and ECC beams. • The probabilistic model is then used to study the behavior of crack paths in the presence of discrete fibers considering different scenarios. • Examples of inferences and numerical simulations are presented to showcase the potential uses and applications of the proposed probabilistic approach for the design and scheduling of inspection visits and maintenance/rehabilitation strategies of concrete pavements and surfaces. Concrete possesses good resistance to compressive stresses; however, it remains weak in resisting tensile stresses, making the formation of cracks in concrete members inevitable. The concrete's durability is directly affected by the development of cracks, which are a direct pathway for deterioration agents that damage the concrete elements. Consequently, the reinforced concrete can experience corrosion, spalling, loss of strength, or progressive disintegration. One way to avoid such problems is to incorporate discrete fibers into the concrete matrix. The fibers act by bridging the gaps formed by cracks, thus, slowing down the crack-opening and propagation process. Studying the crack formation and propagation in the presence of material and geometric uncertainties is impossible using deterministic approaches. In the present paper, the crack propagation in fiber reinforced concrete (FRC) beams is studied from a probabilistic perspective considering the formation and propagation of cracks as a stochastic process. A multinomial Random Walk model is developed based on experimental data on steel fiber reinforced concrete beams. The model is then used to investigate the behavior of crack paths in the presence of discrete fibers considering different scenarios. Inferences are made based on the simulations done through the proposed model to establish a framework to determine the probability of failure of FRC beams. The findings of this study are useful to engineers inspecting existing members and in the design of new members by considering the probability of failure due to crack propagation as the design objective. [ABSTRACT FROM AUTHOR]

Plant fibers (especially, wheat straw) are available surplus to requirements in sub-tropical regions. Many researchers have studied these fibers for non-structural applications. However, for civil engineering structural applications, in depth behavior of wheat straw reinforced concrete (WSRC) with steel rebars is not known. For this purpose, WSRC needs to be explored in detail for load bearing structures. This paper presents the contribution of plant fibers (i.e. wheat straw) in improving the behavior and capacity of reinforced concrete for structural applications. Reinforced concrete beam-lets with varying flexure and shear rebars, without and with inclusion of wheat straw, are experimentally investigated for studying the altered behavior due to fibers. In addition, to start with the practical implications, concrete pavements are considered. The study is concluded with an increase in flexural strength (up to 7.5%), energy absorption (up to 30.4%), and toughness indices (up to 11.1%) along with better crack arresting mechanism by incorporation of wheat straw in reinforced concrete. Also, concrete pavement containing wheat straw has comparable design with likely more durable and sustainable structure. [ABSTRACT FROM AUTHOR]

In some configuration cases for concrete pavements, such as at the intersection of two road pavements or the connection of a road pavement to a bridge abutment, the pavement can be considered to be semi-infinite with one end adjoining a rigid structure. In addition, continuously reinforced concrete pavements may weaken over time as a result of corrosion, erosion, shrinkage, fatigue cracking or the like, and in these instances the weakened pavement can also be considered as being semi-infinite with a joint. This rotational joint constrains the end of the pavement, which has an effect on the potential upheaval buckling of the pavement when subjected to heatwaves. This paper presents an analytical solution for thermal-induced upheaval buckling of such a semiinfinite continuously reinforced concrete pavement when constrained by a rigid medium with a quantifiable rotational stiffness. The method of minimum total potential energy is invoked to derive the differential equations for the post-buckling response, and the equilibrium equations with variable parameters that govern the behaviour are solved analytically by considering both the deformation of the pavement and the rotational and translational restraints. Parametric investigations are conducted on the buckling response of the pavement when constrained at one end; the parameters considered being the rotational stiffness of the joint, the thickness of the pavement, the properties of the pavement subgrade base and the effective weight of the pavement. It is found that the constraint affects the buckling temperature considerably, and the so-called safe temperature increases with the rotational stiffness of the constraint the end of the pavement. [ABSTRACT FROM AUTHOR]

• A rigid pavement structure called partially continuous reinforced concrete pavement (PCRCP) is proposed. • The early-age shrinkage cracking behavior of PCRCP is analyzed through experiment and numerical analysis. • The early-age behavior of PCRCP is improved than CRCP and ARCP. • There is a coupling relationship between temperature and humidity. • Active crack induction of PCRCP improves early-age cracking behavior significantly. As a form of durable pavement structure commonly used in the world, continuously reinforced concrete pavement (CRCP) has prominent problems caused by irregular crack distribution in the early stage. According to the characteristics of the discontinuous distribution of CRCP longitudinal steel bar stress and active crack control method, a rigid pavement structure called partially continuous reinforced concrete pavement (PCRCP) was proposed to simultaneously optimize the crack distribution pattern and reduce the longitudinal steel ratio in this paper. Since early-age shrinkage cracking behavior is a key factor affecting its durability. This paper purposes to assess the early-age shrinkage cracking behavior of PCRCP by comparing different reinforcement methods in laboratory experiments. Research results indicated that the early-age shrinkage behavior of PCRCP is basically the same as that of CRCP. The early-age shrinkage behavior of PCRCP is significantly improved than the advanced reinforced concrete pavement (ARCP). Restricted by the boundary and longitudinal steel bars system, the concrete beam produces a top-down nonlinear temperature and humidity gradient, resulting in various degrees of shrinkage deformation at different depths inside. The active crack control method can control the early-age concrete slab to form uniform crack pattern with straight lines or fewer bending cracks, which improves early-age cracking behavior significantly. This paper is to further deepen and develop the theory of CRCP early-age cracking behavior and provide basic theory support for the subsequent experimental section studies of PCRCP. [ABSTRACT FROM AUTHOR]

• An analytical model with bilinear slab-base friction relationship was developed. • A process considering real-time property for crack width prediction was proposed. • Two CRCB test sections were constructed for field verification of the proposed model. • Reinforcement and concrete drying shrinkage significantly affected crack properties. Transverse crack properties (crack spacing and crack width) are important indicators of service life performance of continuously reinforced concrete pavements (CRCP). Crack properties are related to concrete material properties, reinforcement ratio, interface friction between both the concrete-base layer and concrete-steel, and the local climatic conditions. An improved analytical model with a bilinear concrete-base friction relationship is presented to predict crack spacing and crack width from concrete drying shrinkage and temperature contraction. The proposed 1D model was validated with test section data from a continuously reinforced concrete beam resting on asphalt base layer, which contained two reinforcement ratios, a standard paving concrete, and a lightweight aggregate concrete. A sensitivity study of model determined the bond stiffness coefficient between the concrete and reinforcement, bar spacing and diameter, elastic modulus of the reinforcement, and concrete drying shrinkage had the greatest impact on both crack spacing and crack width. [ABSTRACT FROM AUTHOR]

Over the years, the design of thin and ultra-thin concrete overlays (TWT and UTW) has improved. The performance of TWT and UTW sections built with various designs in Texas has been evaluated, with the goal of further improving design standards and construction specifications. Distresses observed in TWT and UTW sections built prior to 2005 were associated with (1) panel size and layout, (2) transition areas, (3) sliding of slab panels, and (4) defects in existing HMA. Design improvements were made in 2011 to mitigate those distresses, which included placing joints away from wheel paths and the use of continuously reinforced concrete pavement (CRCP) or thickened slabs at transition areas. Regardless of the slab thicknesses used, the panel layout should be 1.83- × 1.83-m (6- × 6-ft). The goal is to have saw-cut joints away from the wheel paths, and thus reducing wheel load stresses in concrete slabs. The increase in curling stresses due to the use of this slab size compared with smaller size slabs appears to be offset more by reduced wheel load stresses. Comprehensive characterization of the existing HMA condition should be made to identify and address hidden defects before the TWT or UTW overlays. Even with some distresses, TWT and UTW sections in Texas have performed satisfactorily with oldest sections having been in service for more than 14 years with minimal repairs required. No distresses have been observed in two TWT projects built in 2011 and 2012 with the improved design practices. [ABSTRACT FROM AUTHOR]

The objective of this study is to understand the confining effect of two base types on the longitudinal displacements of the continuously reinforced concrete pavement (CRCP) subjected to short- and long-term temperature loadings. To this end, a series of full field experiments was carried out at two highway CRCP sections in Korea: one section with asphalt bond breaker beneath the concrete slab and the other with lean concrete beneath the concrete slab. Each section was instrumented with linear variable differential transformers and thermocouples to monitor the longitudinal displacements (expansions and contractions) of the concrete slab at different longitudinal locations as the temperature changed throughout the year. Results showed that the lean concrete base was more effective at confining the daily maximum expansions than the asphalt bond breaker especially in the region between the free end and 10 m away from the free end. In addition, the free-end expansion gradients (expansion per unit temperature change) were developed based on the test data to estimate the annual maximum expansions along with the daily maximum expansions of the terminals. Finally, the optimum expansion joint widths were proposed for CRCP with varying construction and design conditions, such as base type, slab length, and construction season. [ABSTRACT FROM AUTHOR]

The results showed that the crack pattern of the recycled coarse aggregate beams was similar to that of the natural coarse aggregate beams; however, the recycled coarse aggregate beams exhibited smaller crack spacing than the natural coarse aggregate beams. Z. Yao et al. analyse the static and dynamic mechanical characteristics of the coal gangue concrete used to replace coarse and fine aggregates in concrete, in mine support structures. Moreover, the dynamic strength of concrete was improved with the addition of coal gangue fine or coarse aggregate; the incorporation of coal gangue coarse aggregate made the concrete shear surface smooth; and the given impacting pressure of the concrete with coal gangue coarse aggregate has greater particle breakage. [Extracted from the article]