Navigating circular economy in key construction materials – Part 1: general regulations and reuse, recycling, and circular practices for steel and timber

Construction and demolition waste represents one of the largest waste streams worldwide and plays a central role in achieving circular economy objectives in the built environment. This study aims to systematize and synthesize recent knowledge on the potential for reuse and recycling of key construction materials - steel, timber, concrete, and bricks and blocks - at the end of their service life. The research is structured in two papers: Part 1 focuses on regulatory frameworks, recycling rates, and reuse and recycling practices for steel and timber, while Part 2 addresses concrete and bricks and blocks. The objective was to identify opportunities for reuse and higher-value recycling as more effective circular solutions. The results indicate that, although the European regulatory framework for C&DW is well developed and aligned with circular economy principles, significant gaps remain, particularly the lack of harmonized end-of-waste criteria and quality standards for most material fractions. Consequently, high reported recovery rates often conceal downcycling practices and limited material circularity. Steel exhibits consistently high recycling rates, driven by strong market demand and established regulatory criteria, while direct reuse remains marginal. In contrast, timber recovery is dominated by energy recovery, with material recycling and reuse constrained by heterogeneous material quality, limited classification systems, and insufficient policy suppor

H-posets induced by graph-associated polytopes

H-posets induced by graph-associated polytope

Behaviour and design resistance of long bolts in shear

The European standard EN 1993-1-8 lacks specific design provisions for bolted connections incorporating long bolts, despite their increasing use in innovative joint configurations. Long bolts are defined as structural bolts that are manufactured from circular steel, fully or partially, threaded rods instead of a steel coil and are not subjected to heat treatment. In contrast to standard structural bolts, they do not present a bolt head. They are assembled with standard washers and nuts at both ends and feature an extended length compared to standard bolts, offering unique advantages in addressing challenges that conventional bolts cannot resolve. Within the framework of the RFCS CONNECT4C project, which focuses on promoting circular economy principles in steel construction, adaptable and reusable steel joints are being developed, with long bolts playing a key structural role. As part of this initiative, the present study explores the mechanical performance of long bolts subject to shear through an extensive experimental campaign involving 60 tests. The aim is to characterise their behaviour and assess the applicability of the existing EN 1993-1-8 formulations for shear resistance and stiffness to this specific bolt type. Finally, a reliability assessment is conducted to establish a suitable partial factor (γM2) for connections utilising long bolts, confirming that the values for standard bolts are appropriate for long bolts in shear. The outcomes provide direct guidance for incorporating long bolts into future CEN product standards and extend the current design provisions of EN 1993-1-8 to long bolts

3D voksel litološko modeliranje u GIS okruženju: uticaj obima i prostornog rasporeda istražnih bušotina

Tokom poslednjih decenija, sa razvojem digitalnih alata i tehnologija, geotehnička praksa beleži pomak sa tradicionalnog modeliranja tla/stena na 3D modele bogate podacima i sa mogućnošću realnijeg prikaza geološko‐geotehničke kompleksnosti. Temelj ovakvih modela čine podaci iz terenskih istražnih radova. S tim u vezi, ključno pitanje ostaje otvoreno: koliko istražnih radova je potrebno i kako ih optimalno rasporediti u prostoru, kako bi se unapredila pouzdanost prediktivnih modela i iskoristila informativna vrednost postojećih podataka? U ovom radu primenjen je empirijski bajesov kriging u GIS okruženju za generisanje 3D voksel litoloških modela. Analizirani su podskupovi od 10 do 70 istražnih bušotina, grupisani u različite prostorne rasporede. Tačnost predviđanja litologije analizirana je pomoću nezavisnog seta validacionih bušotina i u odnosu na kvazi‐referentni model baziran na svih 94 bušotina. Standardna greška predviđanja korišćena je kao indikator nepouzdanosti uz pristup zasnovan na graničnoj vrednosti. Rezultati pokazuju porast tačnosti predviđanja i smanjenje nepouzdanosti sa rastom broja bušotina i sa njihovim optimalnim prostornim rasporedom,posebno u domenu modela sa ograničenom gustinom istraživanja

Hydrological climate change impact assessment in high latitudes: are bucket-type models up to the task?

Accurate future flow projections necessitate hydrological models suitable for such a purpose. However, there are no formal guidelines on model selection. We here evaluate the suitability of 29 commonly used bucket-type models for climate change impact studies across 50 high-latitude catchments. Model performance is represented by various indicators and the percentage of catchments with well-reproduced hydrological signatures. Models are grouped according to their structural attributes, and performance among the groups is compared to identify key features. Models generally reproduce well mean flows, 30-day maxima and runoff seasonality, but perform less reliably under low-flow conditions. Best-performing models feature balanced complexity with non-linear soil- and routing parameterisations and a limited number of parameters. Complexity of the snow routine does not noticeably influence overall model performance, as opposed to the efficiency in low flows. These findings contribute to good modelling practice by supporting systematic model selection for climate change impact studies in high latitudes

Beam–to–column joint solutions for reusable moment-resisting steel frames

This paper advances reusable building practices by introducing an innovative beam–to–column joint for moment-resisting steel frames. The proposed joint, featuring T-stubs and cleats, is fully demountable, employing bolted connections instead of welds. Moreover, it is designed to accommodate reclaimed steel, incorporating an adaptable link that extends the service length of existing members and adjusts them to the required span of a new structure. Experimental testing was conducted on three test specimens to evaluate joint performance and identify failure modes, moment resistance, rotation capacity and stiffness. Two joint configurations were tested, varying the T-stub section and number of bolts on the T-stub web–to–beam flange connection. Additionally, the influence of material origin, reclaimed versus new steel, was investigated through two specimens with identical configurations. Testing revealed two failure modes: bearing deformation at bolt holes in the T-stub web and failure of the first bolt row on the column flange. Results also highlighted the critical role of bolt slip resistance on the T-stub web–to–beam flange connection in governing the rotational stiffness. Finite element models were developed and validated against the experimental results to simulate the mechanical behaviour of the joints. A parametric numerical study explored key design variables, including link length, bolt diameter, and number of bolts. The findings contributed to improving the joint structural performance by increasing its resistance and delaying the stiffness degradation. Results indicated that increasing the link length from 100 to 150 mm does not have a negative effect on the joint performance

Lessons learned in institutional preparedness and response during the 2022 European drought

Droughts in Europe are becoming increasingly frequent and severe, with the 2022 drought surpassing previous records and causing widespread socio-economic impacts. Using a Europe-wide survey (n = 481 across 30 countries) combined with hydroclimatic data (i.e., Standardized Precipitation Evapotranspiration Index; SPEI), we quantify how forecasting systems and Drought Management Plans (DMPs) affected response timing and perceived effectiveness. It specifically assesses the role of forecasting systems and Drought Management Plans (DMPs) in improving preparedness and in facilitating more effective and timely responses. Our findings show that organisations with forecasting systems or DMPs in place implemented drought response measures on average two and one months earlier respectively than those without, and rated their effectiveness higher. Additionally, the study investigates how drought management practices and awareness have evolved as a consequence of the 2018 European drought and how recent experiences shape water managers' perceptions, with 35 % of the respondents indicating introducing or updating their DMPs after the 2018 drought. The findings emphasize the necessity of a standardized, continent-wide drought risk management coordination to address the multifaceted nature of drought risk by integrating climatic and societal factors, and advocates for a Drought Directive as a means to achieve this. This research aims to inform policy development towards sustainable and holistic drought risk management, highlighting the crucial roles of preparedness, awareness, and adaptive strategies in mitigating future drought impacts.This study and its companion paper The 2022 drought needs to be a turning point for European drought risk management are the result of a study carried out by the Drought in the Anthropocene (DitA) network, an IAHS initiative

Evaluation of bouguer gravity anomalies using global geopotential models: comparison with terrestrial data

The Earth's gravitational field is a key physical parameter in geodesy, geophysics, and geodynamics, as it enables the study of the Earth's crust and its internal structure. Spatial variations in gravity are used to identify geological structures, determine the geoid, and establish vertical reference systems. In this context, the Bouguer anomaly is significant because it removes the effects of topography and surface masses, isolating contributions from deeper lithospheric structures. Modern gravimetric analyses increasingly rely on global geopotential models, which are mathematical approximations of the gravitational field derived from satellite missions, terrestrial measurements, and digital terrain models. In this study, terrestrial gravimetric measurements were compared with values of gravitational acceleration and Bouguer anomalies derived from the global geopotential models EIGEN-6C4 (European Improved Gravity model of the Earth by New techniques 6C4), XGM2019e (combined global Earth gravity field model 2019e), and EGM2008 (Earth Gravitational Model 2008). The analysis compares modeled Bouguer anomalies with data from a detailed gravimetric survey of the test area. Based on statistical parameters and the spatial distribution of anomalies, the quality of the evaluated models and their suitability for regional gravimetric studies were assessed

Lessons learnt in creating and operating the RECONECT nature-based solutions massive open online course

Massive open online courses (MOOCs) have emerged as powerful educational tools for disseminating complex scientific knowledge. This study examines the RECONECT MOOC, an innovative online learning platform designed to educate stakeholders about nature-based solutions (NbS) for hydrometeorological risk reduction. Developed by a multidisciplinary team of international experts, the course drew on diverse professional and geographical perspectives, across a range of national and sectoral contexts. Its primary aim to bridge the knowledge gap in climate adaptation strategies across diverse professional sectors. The research investigated the effectiveness of interactive, multimedia-based learning approaches in communicating advanced NbS concepts. Using the Sharable Content Object Reference Model (SCORM) framework, the course integrated multiple learning methods, including reading, listening, inquiry-based learning, discussion forums and practical application exercises. The MOOC was divided into six modules and targeted local authorities, policymakers, academics, postgraduate students and other stakeholders interested in climate resilience. Findings revealed that 90% of participants gained additional NbS knowledge, 69% reported a shift in perception and 62% felt confident applying what they learned. Participants valued the interactive resources and flexible, self-paced format. Overall, the study demonstrates that MOOCs can effectively support scientific knowledge dissemination and strengthen understanding of complex environmental solutions