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Since the mid-2000 s, longitudinal tinning has been applied to concrete pavements of expressways to improve the comfort and safety of road vehicle users. However, in certain longitudinal tinning sections, lateral vibrations occur during driving, which poses a safety hazard. This paper analyzes the cause behind this problem and proposes a longitudinal texturing specification that can minimize lateral vibration. To perform this analysis, the accelerations of driving vehicles and the degree of lateral vibration transmitted to panels in the vehicles were evaluated for each longitudinal texture applied in South Korea. Structural analysis was also conducted for the lateral force and moment according to the tire tread profile and longitudinal texturing specifications using the finite element method. In addition, field investigation, indoor drivability evaluation, and field application were performed to evaluate the optimal longitudinal texturing specification. The results indicate that the texture designated as 2 × 3 × 19 mm is the optimal longitudinal texture on hardened concrete pavement. However, because this specification is difficult to apply to fresh concrete, 3 × 3 × 16 mm is proposed as the optimal longitudinal texture owing to its excellent performance in the panel survey and in structural analysis. [ABSTRACT FROM AUTHOR]

When spalling occurs at a concrete pavement joint, partial depth repair (PDR) is implemented by removing the damaged part of a slab and filling the space with repair materials. However, re-repair is frequently also required because additional distress develops at the boundary of the repaired area due to improper PDR size in addition to poor quality of materials and construction methods. For the sustainability of pavement structures, it is necessary to study the PDR size based on the mechanical theory. Therefore, in this study, the PDR size for spalling was suggested based on the results of laboratory and field tests conducted using the impact echo (IE) method. The dynamic modulus estimated in the laboratory using the IE and forced resonance methods were compared for concrete specimens subjected to repetitive freeze–thaw cycles. In addition, the correlations of the dynamic modulus estimated by the methods with the compressive strength and absorption coefficient were analyzed. As a result, the IE method, for which vibration could be estimated on the same side of the specimen where impaction was applied, was selected for use on the pavement surface. Furthermore, the short-time Fourier transform technique was used instead of the fast Fourier transform, which has been commonly used for nondestructive methods, to minimize the noise in the field and, consequently, to estimate the dynamic modulus more accurately. The dynamic modulus was estimated according to the distance from the spalling end using the IE method at the Korea Expressway Corporation test road to identify the damaged range in the slab based on the severity of spalling. The dynamic modulus, compressive strength, and absorption coefficient tests were conducted in the laboratory for specimens cored from the concrete slab where the field test was performed. Finally, the PDR size was suggested according to the severity of spalling based on the damaged range in the slab, as determined by the field test and laboratory test results. [ABSTRACT FROM AUTHOR]

Reflective crack has been a major problem of asphalt overlay on existing concrete pavements. Joint or crack movements of concrete slab induce the concentrated stress in asphalt layer; thus producing this distress. Rainwater can then infiltrate into subgrade through this crack opening and the loss support is expected. In addition, the cohesive zone model has been steadily utilised to investigate the fracture behaviour of pavement materials. This method can characterise the crack propagation to the real-life phenomenon. Further, current prediction models of reflective crack have adopted the concept of uniform crack propagation to simplify their analysis. This assumption may misinterpret the crack estimation since nonuniformly propagation occurs over the cross-sectional area of asphalt overlay. Therefore, this study aimed to develop a cohesive-zone-based prediction model that can reasonably compute the amount of reflective cracks with the consideration of nonuniform crack propagation. Available data from LTPP database were also collected for reflective crack modelling and calibration. In addition, traffic- and thermal-induced reflective crack was evaluated by 3D finite element method and cohesive zone model. The mechanistic results were afterward correlated with measured the amount of reflective crack to form the prediction formulation. This model consequently generated the acceptable results with measured reflective crack. [ABSTRACT FROM AUTHOR]

Blowup refers to concrete pavement distress resulting from compressive failure at joints or cracks when excessive concrete expansion occurs, compressive forces are generated, and the horizontal movement of the pavement is constrained. Blowup occurs because of many reasons including heatwaves caused by abnormal climatic conditions, improper installation spacing between expansion joints, pavement expansion due to an alkali-aggregate reaction, concrete pavement aging, and contraction joint failure. In the summer of 2018, the Korean peninsula experienced the worst heatwave ever recorded, and hence, the possibility of blowup increased. Consequently, the Korea Expressway Corporation established a draft policy for installing pressure relief joints (PRJs) to prevent blowup. In this draft, three installation classes were specified for installing PRJs on in-service roads, and the installation priority for each class was set such that the limited budget could be used efficiently. In addition, the draft presented specific guidelines for installing each class of PRJs and suggested PRJ cross sections that could ensure structural stability. However, the draft lacks systematic research on the causes of blowup and the development of countermeasures and does not provide an engineering basis for the suggested technological solutions to prevent blowup. Therefore, this study aimed to reexamine and complement the suitability of the existing PRJ installation standards through field studies, laboratory experiments, and analytical techniques. [ABSTRACT FROM AUTHOR]

Since the mid-2000 s, longitudinal tinning has been applied to concrete pavements of expressways to improve the comfort and safety of road vehicle users. However, in certain longitudinal tinning sections, lateral vibrations occur during driving, which poses a safety hazard. This paper analyzes the cause behind this problem and proposes a longitudinal texturing specification that can minimize lateral vibration. To perform this analysis, the accelerations of driving vehicles and the degree of lateral vibration transmitted to panels in the vehicles were evaluated for each longitudinal texture applied in South Korea. Structural analysis was also conducted for the lateral force and moment according to the tire tread profile and longitudinal texturing specifications using the finite element method. In addition, field investigation, indoor drivability evaluation, and field application were performed to evaluate the optimal longitudinal texturing specification. The results indicate that the texture designated as 2 × 3 × 19 mm is the optimal longitudinal texture on hardened concrete pavement. However, because this specification is difficult to apply to fresh concrete, 3 × 3 × 16 mm is proposed as the optimal longitudinal texture owing to its excellent performance in the panel survey and in structural analysis.

Because traffic and environmental loadings cause concrete pavement failure, a large budget is allocated for maintenance. Through understanding the effect of traffic and temperature loadings on pavement behavior or performance, concrete pavement design can be improved. Hence, this study focuses on the behavior of jointed concrete pavement (JCP) with traffic and temperature loadings by analyzing data from a test road in Korea. Strain gauges, displacement sensors, temperature sensors, and demec gauges were used to evaluate JCP behavior. Static loading, temperature loading, and falling weight deflectometer tests were also conducted. Strain, stress, vertical movement, and joint movement were evaluated based on different slab thicknesses, measurement locations, and substructures. Overall, temperature loading was a governing factor in JCP movement. Measurement location, thickness, substructure, and depth also affect JCP behavior. In the future, the behavior of JCP will be clearer with more acquired data, which will be used in the design of Korean concrete pavement. [ABSTRACT FROM AUTHOR]

The effects of dowel and key joints in the rigid airfield pavements on the stress distribution in the concrete slab and on the Load Transfer Efficiency (LTE) at joints were investigated in this study. Numerical analysis models including dowel and key joints of the rigid airfield pavements were developed to analyze behaviors under environmental and aircraft gear loads. The analysis results showed that under gear loads both the dowel and key joint pavement slabs had very similar stress distributions when the joint gap did not exist, but the key joint pavement slab had larger stresses than dowel joint one when the joint gap existed and the loads were applied near the joint. The LTEs at joints were excellent at both pavement slabs without a joint gap, but the LTE decreased significantly in the key joint pavement as the joint gap became larger. Under environmental loads, the stresses at both the dowel and key joint pavement slabs were almost the same and those increased slightly when there was a joint gap. When the rigid airfield pavement had only the dowel joints along both the longitudinal and transverse joints, there was no stress concentration in the slabs and the stresses were smaller and the LTEs were higher than the pavement that had the dowel joints along one direction and the key joints along the other direction, which was the current airfield pavement joint design in Korea. Keywords: rigid airfield pavement, dowel joint, environmental load, gear load, jointed concrete [ABSTRACT FROM AUTHOR]

A cost-effective strategy is needed to remedy the decaying jointed concrete pavements (JCP). The distress problems continue to cause poor ride quality and continued expense and delay to the traveling public. To explore the bonded concrete overlay (BCO), a half mile section was constructed with a 178 mm continuously reinforced concrete (CRC) overlay. Two other nearby sections were monitored along with the CRC BCO section, over the following 3 years. Over the 3 year period, the CRC BCO section was far less expensive to maintain than the other sections that continued to receive conventional full-depth repair (FDR). The ride quality of the CRC BCO section is also improved by approximately 60-100 inches/mile over conventionally FDR sections. It is believed that the CRC BCO offers a cost advantage over the conventional FDR strategy, and should be considered for future JCP rehabilitation projects. [ABSTRACT FROM AUTHOR]

Highlights: [•] An innovative FDR technique with two layers of steel reinforcements and tie/dowel bars was established. [•] The technique has been implemented with success to repair areas with recurring failures. [•] DCP was utilized to determine the depth of concrete slab thickness. [•] FWD was utilized to determine and monitor the changes of LTEs. [Copyright &y& Elsevier]

Longitudinal cracking at transverse joints in the Jointed Concrete Pavement (JCP) was investigated and causes were discovered by performing field observation and numerical analyses. Finite element models of JCP were developed considering very detailed modeling of dowel bars and their contact characteristic to concrete. Using the models, transverse stresses at joints that could induce longitudinal cracking were comprehensively analyzed. The results showed that primary causes of longitudinal cracks at joints were found to be related to the vertical translation of dowel bar and the curling of the JCP slab due to environmental loading. Other factors affecting those cracks included concrete elastic modulus, concrete thermal expansion coefficient, foundation stiffness, vertical temperature gradient, and bond characteristic between concrete and dowel bar. To mitigate longitudinal cracking at joints, dowel bars should be installed at the mid-depth of the slab and cares must be taken when installing dowel bars to prevent their vertical translation. [ABSTRACT FROM AUTHOR]

Transportation authorities need tools to characterize the structural conditions of jointed concrete pavements (JCPs) to minimize or, in the best case, prevent premature failures of rehabilitated JCPs. Applications of the rolling dynamic deflectometer (RDD) and ground penetrating radar (GPR) in pavement forensic studies and rehabilitation investigations are presented. The continuous RDD deflection profiles allow the evaluation of mid-slab behavior and load transfer conditions of joints/cracks, while GPR surveys assist in detecting adverse subsurface conditions such as voids and increased moisture. In this paper, the patterns in RDD deflection profiles that represent the four different structural conditions in JCPs are presented and discussed. Then, the results from combined RDD and GPR surveys on two rehabilitation projects are presented. In the first project, the problematic slabs with poor load transfer and high vertical differential deflections are identified in the RDD profile. The GPR survey is used to identify the cause of the high differential deflections, voids filled with water under the slabs. The recommendation is to fill the existing voids by using under-sealing techniques and install dowel-bar retrofit prior to a new overlay. In the Grogans Mill project, the RDD profile shows that the southbound lane has a significant number of slabs with a strong potential for reflective cracking. The GPR data indicated that there is moisture beneath the deteriorated slabs. A reconstruction of the southbound lane is recommended. On the other hand, the northbound lane consists of three subsections that require different rehabilitations: Slab replacement, asphalt overlay, and reconstruction. The success of rehabilitation generally depends on the selection of appropriate treatments. By providing 100 % coverage, both RDD and GPR are effective tools in evaluating existing conditions, and the combination of these tools significantly assists in selecting the optimum rehabilitation treatment. [ABSTRACT FROM AUTHOR]

Abstract: In the last 10years, TxDOT has utilized Dowel Bar Retrofit (DBR) in five projects. International Roughness Index (IRI), Falling Weight Deflectometer (FWD), Rolling Dynamic Deflectometer (RDD), and coring were employed to evaluate DBR effectiveness in those five projects. Different versions of special specifications were utilized for each DBR project. The main variables in different versions of the specifications are grout material and slot width requirements. Out of the five projects, four projects (SH73, SH73/SH87, US69, and US287) have performed to the designers’ satisfaction. Those four projects demonstrated that DBR was able to improve Load Transfer Efficiency (LTE) and minimize reflective cracking on an AC overlay. The US69 project reveals that after DBR, Diamond Grinding (DG) should be applied to restore the ride quality. Faulting of greater than 25mm has been successfully corrected by DBR and DG on the US287 project, which still provides good ride quality after 6years of service. The experiences from these four projects suggest that DBR with either DG or an AC overlay can be used effectively to extend pavement life and restore the ride if it is done properly. However, on the US59 project, the DBR performance is unsatisfactory. Visible faulting of 6.4mm–9.4mm developed in less than 2years. It was found that the primary cause for the unsatisfactory performance was excessive voids under the dowel bar, which prevented proper load transfer at the joint. X-ray tomography results indicate that approximately 50% of the area under the dowel was void. The following four main variables were investigated in the laboratory for potential causes for voids around dowels: (1) time of placement after grout mixing, (2) vibration time of grout, (3) slot width, and (4) maximum aggregate size. It was found that maximum aggregate size, in the range of 9.5mm–12.7mm was not a critical factor for the consolidation of the grout. Although slot width above 63.5mm may be beneficial, it was not a critical factor for grout consolidation either. The factors that had significant effects on consolidation of the grout were time of placement after mixing and vibration time. Delayed placement of the grout without vibration led to substantial voids. These two factors might be the causes for the voids under dowels that led to poor performance of DBR on US59. The most significant factor for the consolidation of grout materials is vibration. Although vibration has been included in the current Texas Department of Transportation (TxDOT) special specifications for DBR, it should be properly enforced to ensure optimum consolidation. Based on the test results, 20s of vibration is recommended for each slot. In addition, it is preferable to place grout into the slots before the initial set takes place, or within the manufacturers’ recommended working time. [Copyright &y& Elsevier]

The article evaluates the coefficient of thermal expansion (CTE,PCC) test protocol and its impact on jointed concrete pavement performance. A laboratory experiment is conducted using the method of CTE,PCC of concrete paving mixtures made from different sources in Michigan. Coarse aggregates used include limestone, dolomite, gravel and trap rock. Result show that aggregate geology, specimen age, and the number of heating-and-cooling cycles have a significant impact on the magnitude of CTE,PCC.

A forensic study was performed using a rolling dynamic deflectometer (RDD) and overlay tester (OT) to investigate the reflective cracks on SH87. Comparative tests were performed on the BU90 that has no cracks. The test results show that BU90 has lower density and lower asphalt content than SH87. This means the hot-mix asphalt (HMA) on BU90 has less resistance to reflective cracking than SH87. The OT confirmed that the cycles to failure are less for BU90 than for SH87. Thus, in terms of individual layer properties, the wearing surface and crack-retarding layer on SH87 has a greater crack resistance than that on BU90 and the asphalt mixes were not the principal reason for the cracking. The three main contributing factors for the reflective cracking on SH87 are: (1) thinner HMA, (2) higher joint movements, and (3) poor bonding between layers. Based on the reliability concept, at 90 % confidence level, the threshold W1-W3 deflection values were found to be 4.4 mils and it is much less than 6.5 mils developed from the IH20 project that has 100 mm of HMA as opposed to 64 mm for the SH87 project. It reaffirms that thicker HMA takes longer to have reflective cracking and it also needs a higher threshold W1-W3 deflection value. Thus, the thicker HMA overlay on BU90 (183 ram) would delay the reflective cracks. The methodology presented demonstrates RDD and OT's abilities to characterize the reflective cracking potential and the proposed threshold value provides a good foundation for further refinement when additional data are available. [ABSTRACT FROM AUTHOR]

Most distresses in composite pavement structures, such as Portland cement concrete (PCC) overlays on PCC slabs-on-grade, form when their layers delaminate. To predict the delamination potential of bonded concrete overlays (BCOs) on slab-on-grade pavements at early ages, a mechanistic delamination model was developed in this study. To calibrate the model, an experimental BCO on jointed concrete pavement (JCP) section was constructed, and its behavior was monitored for the first 72 h after construction when subject to climatic loading, i.e. changes in temperature and moisture. Two- and three-dimensional finite element models of the BCO system were developed and calibrated. Theoretical equations to predict the corner stresses at the interface were formulated using the interfacial stresses predicted by the two-dimensional model as input. These equations yield stresses that match the results from the three-dimensional model well. A sensitivity analysis reveals the influence of overlay and JCP parameters, such as elastic modulus, slab length, thickness, and coefficient of thermal expansion, on the interfacial shear and normal stresses. This mechanistic delamination model has been incorporated into the HIPERBOND software developed for the Federal Highway Administration. [Copyright &y& Elsevier]