Blow-ups refer to concrete pavement distress resulting from compressive failure at joints or cracks when excessive concrete pavement expansion occurs. The main cause of concrete pavement blow-up is the accumulation of axial compressive forces that are attributable to the expansion of concrete pavement. Several blow-up models have been proposed in previous research; it was practically impossible to validate the blow-up model because obtaining blow-up field data from pavements in service was not feasible. In other words, the period and location of their occurrence could not easily be predicted. Therefore, this study investigated the axial compressive forces and compressive stresses at the failure of blow-ups in concrete pavement slabs using large-scale blow-up tests. Two concrete slabs were brought into contact, and horizontal compressive loads were applied to the ends of the slabs to determine when compressive failure occurred. An initial geometric imperfection range of 5–50 mm was set as the experimental condition. The test results showed that increasing initial geometric imperfections significantly reduced the compressive stress that caused compressive failure. Compressive failure occurred at approximately 53.0 % of the compressive strength when an initial geometric imperfection of 5 mm, which is the typical value attributable to curling and warping for concrete pavements, was observed. It was determined that the blow-up prediction could be improved based on the large-scale blow-up tests.

The purpose of this study is to evaluate the pressurized titanium dioxide (TiO₂) fixation method and its application to hardened vertical structures nearby the road. The usefulness of pressurized TiO₂ fixation method for the application of vertical concrete road structures such as side ditches, barriers, and retaining walls was evaluated based on conditions of experiment taking cognizance of pressurization time and pressure. To confirm the TiO₂ distribution characteristics, penetration depth and mass ratio of TiO₂ particles in the concrerte specimens were measured after pressurezed fixation. Additionally, the removal efficiencies of nitrogen oxides (NOx) were evaluated using the NOx analyzing system. The penetration depth and surface mass ratio of TiO₂ increased as increasing pressure and pressurization time. To achieve the efficiency of NOx removal more than 40%, a pressure 0.2 MPa and higher than 0.3 MPa with a pressurization time at least 10 seconds and 5 seconds were required, respectively. The finding demonstrated that the pressured TiO₂ fixing method was effective, indicating that the suggested NOx removal technology is adequately appropriate to existing vertical concrete road constructions.

Pavement surface friction significantly impacts road safety and is predominantly influenced by pavement texture characteristics. Traditionally, mean texture depth (MTD) has been widely used as a primary indicator for friction prediction. However, reliance solely on MTD neglects crucial surface texture variables such as exposed aggregate number (EAN) and aggregate shape, potentially limiting prediction accuracy. This study evaluates the field applicability of a pavement surface friction prediction model previously developed using 3-D–printed specimens, incorporating MTD, EAN, and aggregate shape as key predictors. Field data from 184 pavement sites, including exposed aggregate concrete pavement, dense graded asphalt concrete, and open graded asphalt concrete, were analyzed. Measurements of surface texture (MTD, EAN) and friction British pendulum number were collected, and the aggregate shape index was optimized for real pavement conditions. The application of the 3-D–printed specimen-based prediction model to actual pavement surfaces yielded an R2 of 51 % with a P value of 0.00, demonstrating moderate predictive capability. The analysis identified an optimal aggregate shape index (S = 2.75), indicating that aggregate shapes between spherical and pyramidal significantly influence pavement friction. Moreover, the study confirmed a nonlinear relationship between EAN and friction, with an optimal EAN around 30 for maximum friction. These findings highlight the importance of incorporating additional texture variables beyond MTD for improved accuracy in pavement friction prediction. This research provides a foundation for more comprehensive and effective models, contributing to enhanced pavement safety management.

Protective coverings are an effective means of preventing direct fire exposure and delaying the charring of cross-laminated timber (CLT). This study evaluated the effects of practical covering configurations on the fire behavior and charring characteristics of four Korean larch CLT wall assemblies through 120-min fire resistance tests. The specimens varied in fire-resistant gypsum board thickness, joint arrangement, fastening details, and insulation conditions. Fire-induced damage, internal temperatures, and post-fire charring characteristics were evaluated. Specimens with non-staggered gypsum board joints exhibited cracking and detachment of the protective covering, resulting in localized flame penetration, with a maximum measured localized charring depth of 80 mm in CW-WS-G-1 and a measured localized charring depth of 73 mm in CW-WS-G-2. In contrast, specimens with staggered joints and improved fastening details largely maintained covering integrity. Only minor surface charring was observed in CW-WS-G-3, while no distinct charring occurred in CW-WS-W-1. The highest temperature recorded by the installed thermocouples was 225.2 °C in CW-WS-G-1, whereas the highest recorded temperatures in all other specimens remained below 100 °C. Nevertheless, localized charring occurred in CW-WS-G-2 despite its low internal temperature, indicating that temperature measurements alone may not adequately capture localized fire damage. These results indicate that, within the tested configurations, covering integrity associated with the combined joint arrangement and fastening details played an important role in limiting localized flame penetration and charring.