Concrete structures that employed general and multicomponent blended binders were constructed using a low-carbon, ecofriendly microwave heat curing technology with the aim of accelerating the concrete’s curing process. In this study, a field-cast concrete tunnel lining that employed a general binder (portland cement) and a precast box culvert that employed a multicomponent blended binder were constructed using the microwave heat curing technology. In the precast concrete box culvert, portland cement was partially replaced by ground granulated blast furnace (GGBF) slag and fly ash, and rapid-cooled steelmaking slag was used as an alternative to fine aggregates. Through a series of evaluations, it was found that the proposed curing technology was able to fully complete the curing process with the use of electric power alone, reduce the time required to cure the concrete in the field-cast concrete tunnel lining and permit form removal to 4 h, and potentially lower the cost of curing by about 70% compared with conventional steam curing.

This study addresses the significant concern of contaminated soil resulting from oil leakage and explores the influence of indirect heated microwave thermal desorption technology on geotechnical properties. Geotechnical engineers increasingly worry about the repercussions of hydrocarbon-induced soil pollution on infrastructure stability. This research aims to fill a gap by investigating how the thermal treatment process affects soil characteristics and functions. Soil samples from a railway subgrade construction site were subjected to varying temperature conditions (300, 450, and 600 °C) and treatment durations (5, 15, and 30 min) to remediate diesel-contaminated soil with a 10% TPH (Total Petroleum Hydrocarbons) concentration. The findings encompass changes in particle-size distribution (PSD), shear strength parameters (cohesion and internal friction angle), maximum dry density (MDD), and the California bearing ratio (CBR) for natural, diesel-contaminated, and thermally treated silty sand (SM). Significantly, the results underscore the effectiveness of precise control of heat exposure duration in minimizing soil degradation during oil-contaminated soil remediation. In conclusion, this study provides invaluable insights into the geotechnical properties of railway subgrade soil when treated with indirect heated microwave thermal desorption technology, offering a highly promising approach to effectively address oil-contaminated soil issues and safeguard infrastructure stability.

As train failures from icicles annually recur in old railway tunnels in cold weather, fundamental measures to prevent the formation of icicles within the tunnels are necessary for the safe operation of trains and efficient maintenance of old tunnels. This study develops and tests a thawing-guided drainage system for old railway tunnels. The proposed system consists of heating panels, supporting stands, and the drainageways for discharging leaked water. A heating panel is composed of a film heater, thermal insulator, and a steel plate. The heater installed on a steel plate supplies the heat source to prevent icicle formation. This system uses a low-power module lining structure, which fundamentally prevents the formation of icicles from cracks in old railway tunnels and induces the drainage of thermally melted icicles to the outside of the track. A prototype system was installed in the Seungbu tunnel (a railway tunnel) and monitored over 3 weeks in winter from 22 December 2021 to 12 January 2022. The icicle prevention and guided drainage performances were verified at an ambient temperature of about −10 °C, with an internal temperature for maintaining the system above 0 °C over the whole test period. The proposed system is judged by the fact that the applicability of the developed system has been verified in consideration of the following three aspects: usability in the operational railway line, effectiveness through icicle prevention performance, and operational safety which does not interfere with train operations.