The damage rating index (DRI) is a microscopy tool that captures the extent of internal swelling reaction-induced deterioration (ISR). Although engineering practitioners more widely use mechanical tests, confirming the presence of ISR products through microscopy is required and standard practice. A more detailed evaluation can be achieved by combining mechanical and microscopy techniques, including the DRI, which has proven reliable in diagnosing the extent of ISR-induced deterioration. However, there is currently a lack of practical guidelines and standards in the literature explaining how to perform the DRI, raising concerns about the tool's use, particularly regarding operator variability and subjectivity. This work aims to create practical guidelines for conducting the DRI analysis methodology on concrete affected by alkali-silica reaction (ASR) originating from either reactive coarse or fine aggregates at various degrees of damage (i.e., 0.05%, 0.12%, 0.20%, and 0.30% expansion). Ranges of expected values were established to serve as autonomous training for new operators using the same reactive aggregates and mixtures.

Magneto-rheology control, an advanced active rheology control (ARC) technique, is achieved by applying an external magnetic field to a cementitious mixture with responsive additives. It is a promising method to address the contradicting rheological requirements of cementitious materials during the placing process, enabling the development of smart and reliable concrete structures. This article reviews recent advances in magneto-rheology control for cementitious materials. The fundamental principles of magnetic particle movement and cluster formation in cementitious suspensions are first examined. Afterwards, the typical magneto-rheological responses and the key factors influencing the responsive behaviors are discussed. Finally, the potential applications and challenges of this technology in modern construction practices, including smart casting process, 3D/4D concrete printing, and the development of sustainable and multifunctional concrete, are provided.

The cement and concrete industries are currently facing the urgent and arduous challenge of decarbonisation and material circularisation for improved resource efficiency. The pursuit of new raw materials and binders that will improve sustainability is urgent, especially as end-of-pipe carbon capture and storage (CCS) technologies have not yet been scaled up economically even after five decades of research and large investments. On the other hand, society is facing the colossal issue of managing mineral wastes which are produced in several Gts per year globally, posing a massive environmental and societal liability. Many of these mineral wastes have elemental and mineralogical profiles that make them good candidates for use as clinker raw feed or supplementary cementitious materials. Although the published research on the topic is extensive, it is not organised, lacking a systematic comprehensive approach, making valorisation challenging. RILEM TC UMW was developed to address this gap and create a framework for realising the potential of upcycling mineral wastes focusing on using powders as either clinker raw feed or other binder applications while excluding discussion on calcined clays and mineral carbonation.

The RILEM Technical Committee (TC) 281-CCC, on carbonation of concrete with supplementary cementitious materials (SCMs) was active from 2018 to 2024, bringing together over 120 members from different continents. The objective of the TC was to understand the mechanisms leading to carbonation and identify best practices for the assessment of carbonation resistance of blended cement concrete. The activities of the committee were carried out in five different working groups (WGs) centring on (i) effect of SCMs on natural and accelerated carbonation of blended cementitious materials, (ii) modelling of carbonation, (iii) effects of the combined action of load and carbonation, (iv) carbonation induced corrosion, and (v) carbonation of alkali-activated materials. These topics covered all critical aspects to reveal the connections between the mechanisms and factors leading to carbonation of binders and concrete with SCMs, the impact of carbonation in concrete performance and corrosion, and the suitability of existing testing methodologies for its evaluation. The scientific activities of the TC members led to the publication of a topical collection with nine articles in Materials and Structures and one article in RILEM Technical Letters. This included three critical review papers, six original research papers and one recommendation. In this Letter we provide an overview of the key findings linked to the WGs activities and present remaining research needs on the topic of carbonation of concrete with SCMs.

This technical letter investigates mechanical wave propagation (MWP) methods to characterize the stiffness of bituminous mixtures (BM), particularly using ultrasonic testing (UT) and impact resonance testing (IRT), as innovative alternatives to traditional quasi-static techniques. Recognizing the complexity of BM’s viscoelastic behavior influenced by temperature and frequency, the paper presents critical scientific and technological challenges to the newly started RILEM Technical Committee on MWP to characterize BM. By addressing the need for standardized testing procedures and data interpretation guidelines, the anticipated impact includes enhanced quality control and characterization capabilities that promote cost-effective pavement design. Furthermore, with this first effort on laboratory procedures, it is expected to facilitate future integration of non-destructive assessment methods into field practices, thus advancing the state-of-the-art in pavement engineering. This work aims to provide a robust framework for future research and practical applications in the characterization of bituminous materials.

For more than a century, the corrosion of steel in concrete has prevailed as a complex and yet poorly understood phenomenon, with many durability design approaches relying on phenomenological or semi-empirical service life models. The increasing societal demand to maintain aging infrastructure, the development of new cementitious binders and the push towards an environmentally more benign and circular concrete economy exacerbate the need for a more comprehensive scientific understanding of the underlying physicochemical processes, particularly in the absence of long-term empirical data. This manuscript retraces the history of thermodynamic modeling in cement and concrete research, examining early concepts, the barriers to adoption, and the pivotal role of modern Gibbs free energy minimisation solvers towards its broad level of acceptance within the scientific community. We further examine the current use of thermodynamic modeling techniques in corrosion science, emphasizing the limitations of classical potential-pH stability diagrams and addressing the widespread misconception that thermodynamics and kinetics are opposing concepts. Finally, we explore the opportunity to leverage the recent developments in the field of cement science and adopt thermodynamic modeling techniques in corrosion research, thereby addressing open questions related to the corrosion of steel in concrete.

This Opening Letter outlines the objectives and scope of the newly developed RILEM Technical Committee QPA "Quality and Performance Assurance of Additively Manufactured Cementitious Composites by Advanced Non-Invasive Techniques". The letter also provides quick overview of the current stateof- the-art on 3D concrete printing (3DCP) technology, and highlight key issues with regards to sustaining quality of the additive manufacturing process and the corresponding performance of the printed materials and structures. These are followed by discussion on prospect of developing and rationalising suitable non-destructive testing and evaluation methodologies to improve efficiency and quality of 3DCP through review of some previous studies. The letter also identifies potential achievements that can be obtained, and discusses key challenges and strategies in running the TC.

Corrosion of steel in concrete is one of the major deterioration mechanisms for reinforced concrete (RC) structures such as floaters of floating offshore wind turbines (FOWTs). As these are vital components of FOWTs, addressing corrosion is critical to ensure their durability with minimal maintenance. The existing literature indicates that RC in the tidal zone can experience premature corrosion. To mitigate this, galvanic cathodic protection (CP) is a well-known approach for protecting RC structures. Therefore, a field experiment in the tidal zone was conducted to study the behaviour of aluminum anode CP for RC with CEM I and CEM V cement types across two concrete surface textures, smooth and rough. The half-cell potentials (HCP) (for specimens without CP), mixed potentials and protection current (for specimens with CP) were monitored continuously. Furthermore, the effect of water levels and biofilm on corrosion characteristics of steel in concrete and the efficiency of CP was assessed. The findings highlighted that the biofilm on the concrete surface acts as a physical barrier, limiting the diffusion of oxygen – affecting the corrosion characteristics of steel embedded in concrete. This influence was distinctly observed in both protected and non-protected categories. In the protected category, the average protection current was found to increase upon biofilm removal for CEM I concrete - indicating that the CP is efficient/or working with or without biofilm on the concrete surface. Finally, this paper highlights the importance of understanding how the presence of biofilm on concrete surfaces can affect the corrosion characteristics of steel embedded in concrete.

The early-age viscoelasticity of alkali-activated slag concrete (AASC) is critical for its early-age cracking proneness and long-term performance, particularly regarding creep and internal stress development. This study employs an innovative approach to quantify the early-age viscoelastic behavior of AASC, utilizing a Temperature Stress Testing Machine to conduct compressive, repeated and minutes-long creep tests, covering the curing age from 6 h till 28 days. This study is based on the linear theory of viscoelasticity and the Boltzmann superposition principle. A double power law function is employed to model creep and to further predict the internal stress of restrained AASC. It is demonstrated that the double power law function accurately captures the short-term creep of AASC, enabling reliable predictions of early-age stress accumulation and relaxation. Overall, this study highlights the pronounced viscoelasticity of AASC and the effectiveness of the experimental and modelling approaches used to quantify it.

Digital fabrication with concrete has the potential to contribute to sustainability as a resource-efficient construction method. However, the absence of standardized testing, processing and approval procedures hinders the widespread adoption of 3D printing in concrete construction. The need for uniform testing procedures and processing requirements is crucial to overcome the complexities, lengthiness, and costliness of current construction processes, ultimately promoting the quality and reliability of 3D printed structures. This paper examines the current state of development, identifies gaps in existing standards, and proposes initial steps towards European-level standardization.