This study investigates early‐age carbonate mineralization in cementitious systems using in situ Raman microspectroscopy. In the presence of dissolved CO 2 , clinker phases undergo accelerated dissolution, decomposing to form various calcium carbonate polymorphs and a transient amorphous silica gel network. Once the available CO 2 is consumed, clinker hydration resumes, leading to delayed calcium–silicate–hydrate (C–S–H) and portlandite (Ca(OH) 2 ) formation. The precipitation of portlandite through the pore network triggers a localized pozzolanic reaction at the silica gel–portlandite interface, yielding a distinct calcium–silicate–hydrate (C–S–H*). This templated mechanism produces a homogeneous and highly polymerized binder, leading to improved 24‐h compressive strength compared to reference samples. Correlation function analysis confirms that the evolution of silica gel, portlandite, and C–S–H follows a three‐stage sequence— mineralization , transition , and stabilization— quantitatively demonstrating a strong spatial anticorrelation between silica gel dissolution and portlandite precipitation. These findings establish a new chemomechanical framework for CO 2 mineralization in cement, highlighting transient silica gel as a critical intermediate for engineering sustainable, high‐performance concrete.

Recent excavations at Pompeii’s Regio IX have uncovered an intact ancient construction site, offering insights into Roman building techniques at the time of the eruption of Mount Vesuvius in 79 CE. Microstructural and chemical analysis of materials collected from previously constructed walls, walls under construction, and adjacent dry, raw material piles show unequivocally how quicklime was pre-mixed with dry pozzolan before adding water in the creation of Roman concrete. This construction method, also known as hot mixing, results in an exothermic reaction within the mortar and the formation of lime clasts, key contributors to the self-healing and post-pozzolanic reactivity of hydraulic mortars. The analysis of reaction rims around volcanic aggregates demonstrate aggregate/matrix interfacial remodeling, where calcium ions originating from the dissolution of lime clasts diffuse and remineralize, producing amorphous phases and various polymorphs of calcium carbonate (including calcite and aragonite). Furthermore, the parallel discovery of masonry materials and tools permits elucidation of the entire construction workflow, including the steps required to process binding mortars and larger aggregates (caementa). These findings advance our understanding of ancient Roman construction and long-term material evolution, providing a scientific basis for developing more durable and sustainable concretes and restoration materials inspired by ancient practices. Here the authors combine microstructural and chemical analysis of building materials collected from an active construction site in Pompeii prior to the eruption of Mount Vesuvius in 79 CE. Through these analyses, they identify the key raw materials and processes used in the production of Roman concrete.

Significance As the world transitions from fossil fuels to a renewable energy-based economy, scalable, safe, and sustainable energy storage becomes essential to balance intermittent supply and demand. To address these needs, electron-conducting carbon concrete (ecˆ3) has emerged as a promising multifunctional material that unites structural performance with electrochemical energy storage, but its application has remained limited by low voltage and scalability challenges. Through nanoscale 3D imaging, electrolyte optimization, and multicell stacking, we demonstrate the production of high-voltage, energy-storing concrete components capable of powering devices and supporting mechanical loads. Our approach bridges architecture and energy systems, advancing ecˆ3 as a transformative material system for decarbonizing construction and enabling resilient infrastructure in the era of clean energy.

Sewage sludge, a biosolid product of wastewater processing, is an often-overlooked source of rich organic waste. Hydrothermal processing has shown promise in converting sewage sludge into valorized materials with potential application in biofuels, asphalt binders, and bioplastics. Here we characterize the physicochemical properties of hydrochar, the carbonaceous solid phase product of hydrothermal processing, and investigate its use as bio-based filler in additive manufacturing. We find that the presence of metallic and metalloid dopants in sewage sludge, which are not typically found in biomass wastes, yields unusual results in organic material processing such as decreased graphitic ordering after thermal activation. We further find that addition of hydrochar generally decreases mechanical performance of additive manufacturing composites, however, some properties such as toughness can be recovered with nature-inspired architecting into gyroid microstructures. These findings demonstrate that more investigation is required to optimally valorize sewage sludge and similarly disordered waste streams. Sabrina Shen, Markus Buehler, and colleagues valorize hydrothermally processed sewage sludge as fillers for 3D printing. They study physicochemical and mechanical properties, finding that hydrochar-filled composites reduce consumption for more sustainable waste management

The possibility to use light in the visible spectrum to induce near-infrared luminescence in some materials, particularly Egyptian blue and related pigments, offers a significant advantage in terms of their detection. Since 2008, this property has been exploited to reveal the presence of those pigments even in tiny amounts on ancient and decayed surfaces, using a technical-photography method. This paper presents a new type of imaging device that enables real-time, easy, and inexpensive identification and mapping of Egyptian blue and related materials. The potential of the new tool is demonstrated by its effectiveness in detecting Egyptian blue within some prestigious sites: (a) Egyptian findings at Museo Egizio, Turin; (b) underground Roman frescoes at Domus Aurea, Rome; and (c) Renaissance frescoes by Raphael, Triumph of Galatea and Loggia of Cupid and Psyche, at Villa Farnesina, Rome. The device is based on night vision technology and allows an unprecedented fast, versatile, and user-friendly approach. It is employable by professionals including archeologists, conservators, and conservation scientists, as well as by untrained individuals such as students or tourists at museums and sites. The overall aim is not to replace existing photographic techniques but to develop a tool that enables rapid preliminary recognition, useful for planning the work to be carried out with conventional methods. The ability to immediately track Egyptian blue and related pigments, through real-time vision, photos, and videos, also provides a new kind of immersive experience (Blue Vision) and can foster the modern use of these materials in innovative applications and future technologies.

Sewage sludge, a biosolid product of wastewater processing, is an often-overlooked source of rich organic waste. Hydrothermal processing (HTP), which uses heat and pressure to convert biomass into various solid, liquid, and gaseous products, has shown promise in converting sewage sludge into new materials with potential application in biofuels, asphalt binders, and bioplastics. In this study we focus on hydrochar, the carbonaceous HTP solid phase, and investigate its use as a bio-based filler in additive manufacturing technologies. We explore the impact of HTP and subsequent thermal activation on chemical and structural properties of sewage sludge and discuss the role of atypical metallic and metalloid dopants in organic material processing. In additive manufacturing composites, although the addition of hydrochar generally decreases mechanical performance, we show that toughness and strain can be recovered with hierarchical microstructures, much like biological materials that achieve outstanding properties by architecting relatively weak building blocks.

Significance The extent and pace of the transition from our current fossil fuel-based economy to one based on renewable energy will strongly depend on the availability of bulk energy storage solutions. Herein, we investigate one such candidate technology, using chemical precursors which are inexpensive, abundant, and widely available, specifically cement, water, and carbon black. The energy storage capacity of these carbon-cement supercapacitors is shown to be an intensive quantity, and their high rate capability exhibits self-similarity. These properties point to the opportunity for employing these structural concrete-like supercapacitors for bulk energy storage in both residential and industrial applications ranging from energy autarkic shelters and self-charging roads for electric vehicles, to intermittent energy storage for wind turbines.