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Concrete block pavement is used as a modern pavement type owing to its economic benefits. The physical properties, mechanical properties, and functional characteristics of bedding sand and joint sand, the main components of concrete block pavements, should be accurately understood. Owing to the discontinuous structure of these pavements, load transfer efficiency (LTE) is the most important index from the perspective of performance. The factors that affect LTE are bedding sand (type, grading, and thickness), joint sand (type and grading), and concrete block (shape and pattern). Therefore, the optimal design for concrete block pavements can be achieved by analyzing each factor. In this study, three types of sand (river, quartz, and manufactured) were selected to examine the mechanical properties via direct transfer experiments. It was observed that the shear strength of river sand was the highest. It was also found that the difference between the shear strength and the internal friction angle (according to the content of 0.6 mm in the grading of bedding sand) was not large, and the shear strength and the friction angle increased as the content increased to 0.075 mm. In addition, the load transfer characteristics of the joint and rotational interlocking of the block were evaluated through a non-destructive test using the degree of joint filling, block shape, and construction pattern as variables. As a result, the degree of joint filling had the greatest effect on the load transfer characteristics of the joint and rotational interlocking of the block. The effect of the block shape was larger than that of the construction pattern. When a heavy load is applied, the LTE between blocks must be maintained at 50% or more, and the rotation of blocks at 0.6° or less, if 75% or more of the joint must be filled for preventing excessive vertical deformation. [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]

Concrete block pavement (CBP) is distinct from typical concrete or asphalt pavements. It is built by using individual blocks with unique construction patterns forming a discrete surface layer to bear traffic loadings. The surface structure of CBP varies depending on the block shapes and construction patterns, so it is hard to apply a general equivalent elastic modulus estimation method to define the surface structural strength. In this study, FEM analysis and dynamic loading test were carried out to develop a deflection prediction model for CBP considering the block shapes and construction patterns. Based on the analysis results, it was found that block shapes did not have much effect on load distribution, whereas construction patterns did. By applying the deflection prediction model to the rutting model for CBP proposed by Sun, the herringbone bond pattern showed the best performance comparing with stretcher bond or basket weave bond pattern. As the load repetition increased to 1.2 million, the rutting depth of CBP constructed by herringbone bond pattern was 2 mm smaller than those constructed by the other two patterns. [ABSTRACT FROM AUTHOR]

The performance of a joint in airport rigid pavements can be evaluated using load transfer efficiency (LTE). Various existing methods to calculate LTE using different parameters were reviewed in this paper, illustrating how the performance of a joint that performs well is underestimated. To address this concern, a new parameter obtained from the deflection time history output of HWD (Heavy Weight Deflectometer) is being proposed to calculate LTE. Field measurements and FEM (Finite Element Method) modeling were employed to validate the proposed calculation in comparison with the conventional calculations of LTE. Based on the statistical analysis, the proposed method shows low variance and error compared to the conventional calculation of LTE in airport pavements. Moreover, core samples were collected along the tested joints to verify if the calculated values manifest the internal condition of the joints. The calculated results from the proposed LTE show a good agreement not only with the surface condition of the joints, but also with the collected core samples. [ABSTRACT FROM AUTHOR]

• Innovative Pavement Distress Detection: This study introduces a pioneering approach utilizing an RGB-D camera and instance segmentation algorithm to detect and quantify pavement distress, offering a unique solution to a critical infrastructure challenge. • Accurate 3D Point Cloud Analysis: The method efficiently converts pixel data into 3D point clouds, enabling precise assessment of distress area and severity, enhancing reliability in pavement condition evaluation. • Optimized Data Acquisition Strategy: Through rigorous testing and simulation using high-density polystyrene foam, the study identifies an optimal data acquisition scheme, ensuring dependable results even under varying experimental conditions. • Severity-Dependent Error Reduction: Findings demonstrate that error rates in area and volume measurements decrease as distress severity increases, highlighting the method's capacity to provide more accurate assessments for severe pavement issues. • Cost-effective Maintenance Solution: This approach offers a low-cost, high-precision solution for pavement distress detection and maintenance, presenting significant potential benefits for infrastructure management and maintenance planning. This study presents an innovative and cost-effective approach for pavement distress detection and quantification using an RGB-D camera in conjunction with an instance segmentation algorithm. The proposed method employs the instance segmentation algorithm to acquire 2D coordinate information pertaining to the affected pixels and integrates the internal reference matrix and depth data from the depth camera to transform the 2D images of the distressed areas into 3D point cloud data, consequently enabling distress quantification. To assess the dependability of the proposed approach, high-density polystyrene foam was used to simulate potholes and cracks of the pavement. Data collection was conducted under varying experimental conditions to identify the optimal data collection scheme. Using the approach, potholes and cracks of varying severity were collected from both asphalt and cement concrete pavements. The outcomes of the study demonstrate that the proposed methodology is capable of accurately detecting and quantifying potholes on the pavement. Furthermore, the errors associated with both the calculated area and volume exhibit a gradual decrease with an increase in the severity of pavement distress. However, for cracks, the method yields a larger error in results, primarily due to the instance segmentation algorithm's imprecise segmentation of crack edge pixels, despite superior restoration of the planar contour of cracks. [ABSTRACT FROM AUTHOR]

For partial depth repair of airport concrete pavement, the thickness and physical properties of the materials used in the repair project are the prerequisite for the success of the repairing works. While under most actual constructions, these two factors are always regarded as the focus of the project, which leads to the re-damage of the repaired section once again. The repaired concrete pavement can be easily re-failed due to the incompatibility between the repair materials and the matrix concrete for their different characteristics in the aspect of thermal expansion and drying shrinkage. In general, the mechanistic model is used to calculate the interface stress by drying shrinkage and thermal expansion. However, the interface stiffness cannot be figured out by this way. In this study, the interface stress was calculated by the volume change of three kinds of repair materials which were Styrene Butadiene Rubber Concrete (SBR), Polymer Concrete (PC) and Coarse Aggregate Polymer Concrete (CPC). Besides, the characteristics of the interface behavior was also analyzed from the aspect of the interface slip and the shear stress. In the end, the calculation method for the interface stiffness was proposed. The procedure can be used in design. The slip range of these three sorts of repair materials is indicated by the test results of this study as follows, 900–1500 μm for SBR, 3000–9000 μm for PC and 6000–15,000 μm for CPC, and the interface stiffness of each material is 110.44 N/mm 3 , 45.65 N/mm 3 and 10.58 N/mm 3 respectively. [ABSTRACT FROM AUTHOR]

Few studies have been conducted on horizontal shifting prediction models that consider block shapes and laying patterns for block pavements. To develop a prediction model, a combination of different block shapes and laying patterns was evaluated by computer modeling and laboratory tests. The relationship between the force and displacement was recorded via a photogrammetric method using a friction tester. In order to quantify the recorded video results, rigid body analysis was performed. The results of laboratory experiments and the rigid body analysis offered a good match. A displacement vector was used to express the movement of the block with time, according to the start and end position information of each block. Also, a concept of Specific D-Moment (SDM) was proposed to describe the relationship between the movement of the individual blocks and the entire movement. A horizontal shifting mechanistic-empirical prediction model of concrete block pavement is proposed based on regression analysis of the existing performance data. According to the prediction model, higher SDM values give lower cumulative amounts of horizontal shifting due to traffic. [ABSTRACT FROM AUTHOR]

Highlights: [•] We proposed a joint spalling mechanism under traffic and thermal loadings in JPCP. [•] Finite element method was applied to evaluate the principal shear stresses at joints. [•] Field spalling exponentially grows with the accumulated principal shear stress. [•] A mechanistic-empirical spalling prediction model was developed based on LTPP data. [Copyright &y& Elsevier]

Abstract: Various preformed joint sealants (PJS) can be used for joint concrete pavement (JCP) to prevent the JCP from distresses such as pumping and faulting. Even though PJS have an important role in concrete pavement structures, most of the test methods that assess PJS focus on evaluating their basic mechanical and chemical properties rather than performance-related properties. In this study, a tester for PJS is developed and utilized to determine the resistant stiffness, which is considered to be a performance-related parameter, of PJS in transverse joints. The resistant stiffness is determined by dividing the peak force by the displacement; and the normalized value, which is used to simplify the relationship between the joint width and the sealant width, is determined by dividing the joint width by the sealant width. From laboratory tests performed on the developed tester, it is found that the resistant stiffness and normalized value are representative parameters that can be used to recommend the proper width of the joint, regardless of the joint width and joint type. Also, the relationship between the slip-down distress and the joint width, which is obtained from field survey results, can be utilized to recommend a minimum width for PJS. [ABSTRACT FROM AUTHOR]