The nucleation of C-S-H via prenucleation clusters.

The nucleation and growth of calcium-silicate-hydrate (C-S-H) is of fundamental importance for the strength development and durability of the concrete. However, the nucleation process of C-S-H is still not fully understood. The present work investigates how C-S-H nucleates by analyzing the aqueous phase of hydrating tricalcium silicate (CS) by applying inductively coupled plasma-optical emission spectroscopy as well as analytical ultracentrifugation.

The influence of AGEs and enzymatic cross-links on the mechanical properties of collagen fibrils.

Cross-links are considered to be a key component of collagen fibrils as they can change the fibrillar behavior in various ways. Advanced-Glycation Endproducts (AGEs), one particular type of cross-links, have been shown to accumulate and impair the mechanical properties of collageneous tissues, whereas enzymatic cross-links (ECLs) are known for stabilizing the structure of the fibril. However, the reasons for whether a given type of cross-link improves or impairs the material properties remain unknown.

Learning physics-consistent particle interactions.

Interacting particle systems play a key role in science and engineering. Access to the governing particle interaction law is fundamental for a complete understanding of such systems. However, the inherent system complexity keeps the particle interaction hidden in many cases.

A collection of three-dimensional datasets of hydrating cement paste.

This dataset contains a collection of digitized three-dimensional hardened cement paste microstructures obtained from X-ray micro-computed tomography. Four sets of ordinary Portland cement-based pastes were produced and X-ray screened, varying in the initial water-to-cement ratio (wcr=0.35 and 0.

Adhesives free bark panels: An alternative application for a waste material.

The proportion of bark in tree trunks is in the range of ~ 10-20%. This large amount of material is currently mainly considered as a by- or even waste-product by the timber processing industry. Recently, efforts towards the use of bark have been made, e.

Overcoming Environmental Stress Cracking of FDM 3D Printed Formwork for Counter-Pressure Casting of Concrete.

The rapid growth of interest toward concrete digital fabrication reflects the current aspiration for better, smarter, faster, and greener construction means. Among a broad variety of techniques developed by our community, digital casting presents clear advantages regarding dimensional precision, geometrical freedom, and surface finish of the produced elements. In contrast to robotic slip forming, the usage of digitally fabricated formworks requires simpler equipment.

Eco-Friendly, Set-on-Demand Digital Concrete.

Digital fabrication with concrete is considered to potentially revolutionize the construction sector and is often presented as a means to reduce its environmental footprint. However, at least in the case of concrete, it encounters significant challenges in terms of material design, since high paste volumes and Portland cement contents are normally used due to process requirements. In this article, the application to layered extrusion of a recently developed low clinker cement containing 50% Portland cement and 50% supplementary cementitious materials, such as limestone, burnt oil shale, and fly ash, is presented.

Sustainability in Wood Products: A New Perspective for Handling Natural Diversity.

Wood is a renewable resource with excellent qualities and the potential to become a key element of a future bioeconomy. The increasing environmental awareness and drive to achieve sustainability is leading to a resurgence of research on wood materials. Nevertheless, the global climate changes and associated consequences will soon challenge the wood-value chains in several regions (e.

Atomic-Level Structure of Zinc-Modified Cementitious Calcium Silicate Hydrate.

It has recently been demonstrated that the addition of zinc can enhance the mechanical strength of tricalcium silicates (CS) upon hydration, but the structure of the main hydration product of cement, calcium silicate hydrate (C-S-H), in zinc-modified formulations remains unresolved. Here, we combine Si DNP-enhanced solid-state nuclear magnetic resonance (NMR), density functional theory (DFT)-based chemical shift computations, and molecular dynamics (MD) modeling to determine the atomic-level structure of zinc-modified C-S-H. The structure contains two main new silicon species (Q and Q) where zinc substitutes Q silicon species in dimers and bridging Q silicon sites, respectively.

Passive climate regulation with transpiring wood for buildings with increased energy efficiency.

Buildings are significant end-users of global energy. About 20% of the energy consumption worldwide is used for maintaining a comfortable indoor climate. Therefore, passive systems for indoor temperature and humidity regulation that can respond to environmental changes are very promising to reduce buildings' energy consumption.

Creep fronts and complexity in laboratory earthquake sequences illuminate delayed earthquake triggering.

Earthquakes occur in clusters or sequences that arise from complex triggering mechanisms, but direct measurement of the slow subsurface slip responsible for delayed triggering is rarely possible. We investigate the origins of complexity and its relationship to heterogeneity using an experimental fault with two dominant seismic asperities. The fault is composed of quartz powder, a material common to natural faults, sandwiched between 760 mm long polymer blocks that deform the way 10 meters of rock would behave.

Formation of Iron (Hydr)Oxide Nanoparticles with a pH-Clock.

We demonstrate the autonomous synthesis of iron (hydr)oxide (green rust, magnetite, and lepidocrocite) nanoparticles by precipitating iron(II) ions using hydroxide ions generated in situ with the methylene glycol-sulfite (MGS) reaction, a pH-clock. We show that the nature of the products can be predetermined by tuning the initial iron(II) concentration.

Emerging Engineered Wood for Building Applications.

The building sector, including building operations and materials, was responsible for the emission of ∼11.9 gigatons of global energy-related CO in 2020, accounting for 37% of the total CO emissions, the largest share among different sectors. Lowering the carbon footprint of buildings requires the development of carbon-storage materials as well as novel designs that could enable multifunctional components to achieve widespread applications.

Functionalized Cellulose Nanocrystals as Active Reinforcements for Light-Actuated 3D-Printed Structures.

Conventional manufacturing techniques allow the production of photoresponsive cellulose nanocrystals (CNC)-based composites that can reversibly modify their optical, mechanical, or chemical properties upon light irradiation. However, such materials are often limited to 2D films or simple shapes and do not benefit from spatial tailoring of mechanical properties resulting from CNC alignment. Herein, we propose the direct ink writing (DIW) of 3D complex structures that combine CNC reinforcement effects with photoinduced responses.

A method for the mix design of low carbon concrete towards industrial production.

Unlabelled: The introduction of newly developed blended cements into the mass market is essential to ensure an effective reduction of the carbon footprint related to cement production. To facilitate this process, formulating mix proportions using pastes and/or mortars rather than concrete can be a great advantage. However, for the upscaling towards industrial concrete it is then essential to maintain the target rheological and mechanical properties, something that is all too often challenging.

Cellulose lattice strains and stress transfer in native and delignified wood.

Small specimens of spruce wood with different degrees of delignification were studied using in-situ tensile tests and simultaneous synchrotron X-ray diffraction to reveal the effect of delignification and densification on their tensile properties at relative humidities of 70-80 %. In addition to mechanical properties, these analyses yield the ratio of strains in the cellulose crystals and in the bulk, which reflects the stress-transfer to crystalline cellulose. While the specific modulus of elasticity slightly increases from native wood by partial or complete delignification, the lattice strain ratio does not show a significant change.

Intercellular Matrix Infiltration Improves the Wet Strength of Delignified Wood Composites.

Delignified wood (DW) represents a promising bio-based fibrous material as a reinforcing component in high-performance composites. These cellulose composites possess excellent strength and stiffness in the dry state, which are significantly higher than for natural wood. However, in the wet state, a penetrating water layer enters the intercellular regions and disrupts the stress transfer mechanisms between cell fibers in fully DW.

Sustainable wood electronics by iron-catalyzed laser-induced graphitization for large-scale applications.

Ecologically friendly wood electronics will help alleviating the shortcomings of state-of-art cellulose-based "green electronics". Here we introduce iron-catalyzed laser-induced graphitization (IC-LIG) as an innovative approach for engraving large-scale electrically conductive structures on wood with very high quality and efficiency, overcoming the limitations of conventional LIG including high ablation, thermal damages, need for multiple lasing steps, use of fire retardants and inert atmospheres. An aqueous bio-based coating, inspired by historical iron-gall ink, protects wood from laser ablation and thermal damage while promoting efficient graphitization and smoothening substrate irregularities.

Review on design strategies and applications of metal-organic framework-cellulose composites.

Metal-organic frameworks (MOFs) are among the most attractive functional porous materials. However, their processability and handling remains a substantial challenge because MOFs generally occur in powder form due to their crystalline nature. Combining MOFs and cellulose substrates to fabricate engineered materials offers an ideal solution to broaden their utilization as functional materials.

Additive Digital Casting: From Lab to Industry.

Concrete construction harms our environment, making it urgent to develop new methods for building with less materials. Structurally efficient shapes are, however, often expensive to produce, because they require non-standard formworks, thus, standard structures, which use more material than is often needed, remain cheaper. Digital fabrication has the potential to change this paradigm.

Thermoresponsive Smart Gating Wood Membranes.

Smart membranes that can open and/or close their pores in a controlled manner by external stimuli possess potential in various applications, such as water flow manipulation, indoor climate regulation, and sensing. The design of smart gating membranes with high flux, immediate response, and mechanical robustness is still an open challenge, limiting their versatility and practical applicability. Inspired by the controlled opening and closure of plant stomata, we have developed a smart gating wood membrane, taking advantage of the unique wood scaffold with its hierarchical porous structure to carry thermoresponsive hydrogel gates.

Photoresponsive Movement in 3D Printed Cellulose Nanocomposites.

Photoresponsive soft liquid crystalline elastomers (LCEs) transform light's energy into dynamic shape changes and are considered promising candidates for production of soft robotic or muscle-like devices. 3D printing allows access to elaborated geometries as well as control of the photoactuated movements; however, this development is still in its infancy and only a limited choice of LCE is yet available. Herein, we propose to introduce biocompatible and sustainable cellulose nanocrystals (CNC) into an LCE in order to facilitate the printing process by direct ink writing (DIW) and to benefit from the anisotropic mechanical properties resulting from the extrusion-induced alignment of such nanoparticles.

A multi-technique study of corrosion products at the steel-concrete interface under two exposure conditions.

Steel corrosion can cause serious damage to reinforced concrete structures. This study employed multiple techniques, including SEM/BSE, EDX and Raman spectroscopy, to analyse the distribution and mineral composition of corrosion products (rusts) in corroded reinforced cementitious materials under two conditions, namely, chloride-induced corrosion and accelerated corrosion in carbonated mortar. Results showed that corrosion products tend to precipitate in large pore spaces close to the steel bar, such as the bleed water zones and voids.

Earthquake breakdown energy scaling despite constant fracture energy.

In the quest to determine fault weakening processes that govern earthquake mechanics, it is common to infer the earthquake breakdown energy from seismological measurements. Breakdown energy is observed to scale with slip, which is often attributed to enhanced fault weakening with continued slip or at high slip rates, possibly caused by flash heating and thermal pressurization. However, seismologically inferred breakdown energy varies by more than six orders of magnitude and is frequently found to be negative-valued.

Dissolution of Zinc Oxide Nanoparticles in the Presence of Slow Acid Generators.

We describe a preliminary investigation of the dissolution dynamics of zinc oxide nanoparticles in the presence of cyclic esters (δ-gluconolactone and propanesultone) as slow acid generators. The particles dissolution is monitored by means of turbidimetry and correlated with the evolution of pH over time. The results could be of interest for the design of chemically programmable colloidal systems.