Infrastructures

Non-destructive testing (NDT) methods are widely used to evaluate the performance of concrete, but their accuracy can be influenced by external factors such as curing temperature. Temperature not only modifies hydration kinetics and strength development but may also change the correlation between NDT measurements and compressive strength. However, no prior research has systematically examined how different curing temperatures influence the reliability of various NDT techniques. This study evaluates three curing temperatures and their effect on the correlation between NDTs and compressive strength at various ages (1, 3, 7, 28, and 90 days). Both simple regression analysis and artificial neural networks (ANNs) were employed to predict strength from NDT measurements. Results show that NDT sensitivity to curing temperature is most pronounced at early ages, and that linear regression models cannot adequately capture the complexity of these relationships. In contrast, ANNs demonstrated superior predictive capability, though initial training with limited data led to overfitting and instability. By applying Gaussian Noise Augmentation (GNA), model accuracy and generalization improved substantially, achieving R2 values above 0.95 across training, validation, and test sets. These findings highlight the potential of non-linear models, supported by data augmentation, to improve prediction reliability, lower experimental costs, and more accurately capture the role of curing temperature in NDT–strength correlations for concrete.

The multimodal North Sea–Baltic corridor, consisting of 6934 km of road, is an integral part of the EU’s trans-European transport network. However, an unsatisfied level of development of alternative fuels infrastructure for road transport is considered one of the obstacles to connecting northern Member States and North-East countries. A “what-if” scenario was employed to obtain useful insights into how a given situation might be handled, and a comparison of several paths forward to make better decisions was analysed. Environmental insights for transportation sector scenarios in 2030–2035 were explored and analysed using the COPERT v5.5.1 software program. In this study, the installation of natural gas infrastructures of various station sizes and with varying capacities and types of natural gas (LNG, CNG, bio-methane) dispensed was evaluated in detail. Replacement of the existing HDV fleet (heavy-duty vehicles) with LNG-powered trucks would result in the following investment to upgrade the existing network and build new stations to meet rising LNG demand: from €21.47 to €32.3 million (the scenario of 10% market share for HDVs running on LNG), €42.94 to €64.6 (20%), and €64.4 to €96.9 (30%). The dual-fuel 10–diesel fuel 90% scenario seems to be the safest option for a large-scale investment until 2035 which may lead to moderate emission savings of 84.6 kton CO₂ eq. compared to 2022 levels.

Cement-based construction in cold regions faces severe challenges due to the dramatic retardation of hydration and strength development under sub-zero temperatures. Joule curing as a novel curing method showed certain advantages in solving this problem, while the curing efficiency was low for Joule curing under severely cold temperatures. This study systematically investigates the performance of graphene nanoplatelet (GNP)-modified electrically conductive cementitious composites under sub-zero temperature curing conditions. Joule curing method was employed to ensure a high-quality curing at ambient temperatures of −20 °C, −40 °C, and −60 °C. The results demonstrate that GNP incorporation significantly enhances electro-thermal performance. For the electrical conductivity of the specimens, the specimens containing 0.5 wt% GNP showed a much stable electric resistance development under severely cold environment, illustrating the value of 1169 Ω after 1 day Joule curing at the environmental temperature of −60 °C, which was 36% lower than the Ref. group. As for the curing temperature, the specimen with 0.5 wt% GNP effectively maintained the internal temperature within 50–60 °C during the 24 h curing period, even under extreme conditions. Mechanical tests reveal that the GNP-modified specimens exhibit remarkable strength retention, with the 0.5% GNP composite maintaining 86.3% of its compressive strength and 95.9% of its flexural strength at −60 °C compared to standard curing values. Microstructural characterization through XRD and TG analyses confirms that while the crystalline phase composition remains unchanged across different curing regimes, the hydration degree directly correlates with the mechanical performance, explaining the observed strength variations. MIP analysis further proved the advantage of Joule curing on refining the microstructure for the specimens. The findings establish that GNP modification, combined with Joule curing, presents an effective strategy for winter concrete construction, ensuring adequate strength development through enhanced electrical conductivity and controlled internal curing temperature, without altering the fundamental hydration chemistry.