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An ultrathin seal serves as a preventive maintenance technology. The design method predominantly relies on engineering experience and lacks a theoretical foundation. In order to investigate the impact of aggregate size, spreading mass, and original pavement texture depth on the formation of an ultrathin seal, a compaction model was developed using the discrete element method (DEM). Different aggregate sizes and spreading masses were analyzed to examine the particle structure and thickness. The three-dimensional (3D) Weierstrass–Mandelbrot (WM) function was used to reconstruct random rough surfaces to assess the effect of the original pavement texture depth (1, 2, 3, and 4 mm) on voids and dosage of filling asphalt. Results showed that the dynamic compaction led to a rapid increase in collision velocity and then declined sharply by 0.02 s, eventually reaching zero by 0.3 s. Particle contacts steadily increased to 365 by 0.3 s and kept stable after the plateau, indicating the formation of an interlocking structure. Coordination numbers and contact vectors varied with particle size and spreading mass, which were more pronounced for small particles. However, the smaller particles (<4.5 mm) had negligible compaction effects, suggesting that the optimal aggregate size should be 3–5 mm. Excessive spreading mass resulted in a multilayered structure incompatible with the single thickness requirement and the recommended range was 9–12 kg/m2. Furthermore, greater texture depth led to higher void content at the bottom of the seal, requiring more filling asphalt. Therefore, when designing asphalt dosage, both the compaction and the variation in voids due to the original pavement texture depth should be considered to ensure sufficient contacts. [ABSTRACT FROM AUTHOR]

In cold climates, early-age cementitious material is easily threatened by frost damage, causing deterioration of material properties. To investigate the hazard and failure mechanism of cement paste due to early frost damage, the cement hydration process was divided into five stages via the electrical resistivity method, and then fresh cement pastes were frozen in five stages and two different temperatures, respectively. Furthermore, mechanical tests and X-ray computed tomography scanning were carried out to characterize the development of frost-related damage. The results indicated that the effect of initial frost time on strength growth is greater than that of freezing temperature, and the cement matrix can be considered completely damaged when frost-related damage occurs before the initial setting. The frost-related texture develops from outside to inside and the porosity of the sample frozen at the first three stages was higher than that of samples frozen at the last two stages. Finally, the frost-related damage could be divided into three types: flow extrusion damage, freezing expansion cracking damage, and flow extrusion-freezing expansion cracking combined damage. [ABSTRACT FROM AUTHOR]

Precise documentation of as-is status of transportation infrastructures is an essential task for several public transportation agencies. To tackle this task, such agencies have adopted various advanced technologies, such as light detection and ranging (LiDAR), for three-dimensional (3D) reconstruction and as-built documentation purposes. In this research, we study the feasibility of an alternative 3D reconstruction method, photogrammetry, which has the advantage of being inexpensive and easy to operate compared to LiDAR. To assess the proposed alternative method in transportation asset-inventory collection, this paper evaluates the feasibility of using photogrammetry in providing an acceptable 3D point cloud model of two important categories of transportation assets: roadway assets and pedestrian access ramps. The analysis of the data quality and associated cost attests to the feasibility of using close-range photogrammetry in pedestrian access ramps inventory, while using this technology as a complementary tool with LiDAR in the mobile setting holds the promise for a feasible roadway asset data collection. [ABSTRACT FROM AUTHOR]

To further facilitate the automation and computational efficiency in asphalt mixture micromechanical simulation using finiteelement methods, this paper develops a three-dimensional (3D) microstructural modeling method for asphalt mixture to automatically generate the adaptive 3D finite-element mesh. The methodology contains three main steps, as follows: (1) two-dimensional (2D) enclosed outlines in every X-ray computed tomography (CT) image of the specimens are detected with shape features of outlines and grayscale discrepancy between each two different phase pixels; (2) for each independent geometric solid such as aggregate particle and air void in a specimen, the mapping between the solid and its outlines on various layers is established, so that the 3D model of each solid is constructed; and (3) models of the same phase are assembled into a specific substructure model. The specimen microstructure model is finally obtained with appropriate Boolean operations towards specific substructure models. Experiment results indicate that the specimen microstructure model not only has an excellent accuracy in modeling and simulation, but also supports adaptive meshing toward each specific substructure model, which significantly reduces the computational cost and can be applied to asphalt mixture numerical simulation. [ABSTRACT FROM AUTHOR]

The global scale of point cloud data (PCD) generated through monocular photography and videogrammetry is unknown and can be calculated using at least one known dimension of the scene. Measuring one or more dimensions for this purpose induces a manual step in the three-dimensional reconstruction process; this increases the effort and reduces the speed of reconstructing scenes, and induces substantial human error in the process due to the high level of measurement accuracy needed. Other ways of measuring such dimensions are based on acquiring additional information by either using extra sensors or specific classes of objects existing in the scene; it was found that these solutions are not simple, cost effective, or general enough to be considered practical for reconstructing both indoor and outdoor built infrastructure scenes. To address the issue, this paper proposes a novel method for automatically calculating the absolute scale of built infrastructure PCD. A premeasured cube for outdoor scenes and a sheet of paper for indoor environments are used as the calibration patterns. Assuming that the dimensions of these objects are known, the proposed method extracts the objects' corner points in two-dimensional video frames using a novel algorithm. The extracted corner points are then matched between the consecutive frames. Finally, the corresponding corner points are reconstructed along with other features of the scenes to determine the real-world scale. To evaluate the performance of the method, 10 indoor and 10 outdoor cases were selected and the absolute-scale PCD for each case was computed. Results illustrated the proposed algorithm is able to reconstruct the predefined objects with a high success rate, while the generated absolute-scale PCD is sufficiently accurate. [ABSTRACT FROM AUTHOR]

This work provides an analysis of the applicability of two image-based three-dimensional (3D) reconstruction techniques-(1) four-dimensional augmented reality () 3D reconstruction software and (2) phototourism applications-for remote site construction project planning. Remote sites present uncertainty to construction project planning through access, material and resource availability, potential lack of technical expertise on site, and environmental considerations. Both and phototourism have the potential to minimize remote site uncertainty by using available camera technology to digitally capture existing site conditions for the development of accurate 3D modeling for construction project planning. For this study, the researchers (1) analyzed the applicability of 3D reconstruction and phototourism software applications to remote construction planning; (2) determined the appropriateness and robustness of various levels of camera technology for capturing existing conditions on remote sites; and (3) evaluated the impact of image resolution and the method of capture on 3D image-based software-all key facets to usability and access. The researchers used three cameras of various performance capabilities, i.e., a 35-mm disposable box camera, a 5.7-17.1-mm (35 mm equivalent: 37-111 mm) low-level digital camera, and a high-level digital single-lens reflex camera. The following paper outlines a methodology for testing these camera technologies and discusses their appropriateness for reducing barriers to the application of image-based reconstruction techniques for remote site construction planning. This work offers the conclusion that ordinary camera technology is an appropriate option for capturing existing conditions in remote sites (usability), while more advanced camera technology offers better total system benefits (access) of the image-based 3D reconstruction platform. offers a more robust system for modeling remote sites; however, both and phototourism have the potential to generate useful computer models using catalogs of digital images to enable better planning and execution of construction projects in remote areas. [ABSTRACT FROM AUTHOR]