Traditional Construction Materials Research Articles

Load bearing geopolymer from agro-waste and its energy-environmental- economic (E3) performance: Application through building information modeling

Agro-waste geopolymers are being significantly researched as sustainable substitutes to traditional construction materials for structural performance. However, a thorough assessment of their energy, environment, and economic (E3) performance is still questioned to facilitate in-situ building applications. This study first opts for a novel method of pressure catalysis for rice husk ash (RHA)-based geopolymers to enhance physico-mechanical performance with a low alkali activator dose. Afterward, the thermal conductivity of the optimized specimen was evaluated experimentally. Then, to assess its practical application, an E3 performance investigation was conducted on masonry brick/blocks as a pioneering approach for geopolymers. Distinct wall scenarios were simulated using Building Information Modeling (BIM) in a digital residential building. The experimental results showed that geopolymers with 50 % RHA, catalyzed under 20 MPa pressure, achieved 26.8 MPa compressive strength, lower density (1510 kg/m3), reduced water absorption (6.8 %), and 0.552 W/(m·K) thermal conductivity, outperforming traditional fired-clay brick and concrete block. The BIM analysis revealed that walls with RHA material had 53 % lower energy consumption and 30 − 41 % lesser CO2 emissions, respectively. Despite the higher cost, the RHA block has advantages as a masonry unit due to a high economic index. The significant energy and environmental gains suggest the potential for optimizing the production process of RHA-based geopolymer to enhance cost-effectiveness and amplify benefits.

Assessing the Sustainability and Performance of Hempcrete

Aim: Traditional construction materials like cement, concrete, glass, asphalt, and steel require more energy in the manufacturing process, which results in high GHG emissions. Therefore, researchers from all over the world are focusing on solutions to tackle carbon emissions, with hempcrete emerging as a less polluting construction material. Hempcrete is a bio-composite comprising a woody core of hemp stem and hydrated lime. The objective of the study is to find out the physical and mechanical properties of hemp-lime concrete. Study Design: The present research paper is part of the ongoing study on hempcrete at G.B. Pant University of Agriculture & Technology, Pantnagar, Uttarakhand, India. The present study chose an experimental research design. Methodology: The study presents its results in two parts: performance and sustainability. The first part investigates the performance of hempcrete in terms of its physical and mechanical characteristics. The researcher conducted numerous trials to fix mix designs, focusing on their workability. Cubes of size 10 cm were cast manually for five distinct mix designs. The second part of the paper examines the sustainability aspect of hemp-lime concrete via a relevant literature review. Results: During the specified time intervals of 28, 56, 84, and 112 days, the cubes exhibited a range in weight density from 506 to 674 kg/m3. In parallel, the compression test results demonstrated varying values, spanning from 0.510 Mpa to 0.810 Mpa across the same time points. Results show that there is a negative correlation between density and compressive strength and a positive correlation between density and water absorption rate. Conclusion: The results pertaining to weight density highlight the lightweight nature of hempcrete, to the extent that the cubes have the propensity to float in water. Due to its relatively low compressive strength values, hempcrete is deemed suitable for non-load-bearing applications within building construction.

Multifunctional cementitious composite: Conductive and auxetic behavior

This research focused on developing an innovative multifunctional cementitious material with both conductive and auxetic properties simultaneously. This novel cement-based metamaterial has different applications, ranging from piezoresistivity to structural energy dissipation. The cementitious composite (CC) with an auxetic structure were produced using additive manufacturing techniques. The study involved analyzing different cementitious compositions, including Ultra High-Performance Concrete (UHPC) formulation tailored for both high strength and workability, and flexible mortar. Both types of composites were combined with two types of fibers: recycled carbon and Polyvinyl Alcohol (PVA). Uniaxial compression tests, conductivity, piezoresistivity by load cycles, and Digital Image Correlation (DIC) analysis were carried out on the auxetic cementitious composite (ACC). Among these tested cementitious composites (UHPC and flexible mortar) reinforced with PVA and recycled carbon fibers, only the flexible mortar with carbon fibers achieved the desired multifunctional properties. This success with flexible mortar and carbon fibers suggests promise for this combination. Conversely, UHPC composites with PVA fibers, with or without additional carbon fibers, failed to achieve the targeted functionality. As a result, both piezoresistivity and auxetic properties were achieved. From the auxetic behavior results, the Poisson’s ratio reached -67.5%. This implies that if compressed longitudinally, the specimen is shortened transversely (auxetic behavior) by up to 67.5%. This finding stands out compared to traditional construction materials like concrete and steel, which typically exhibit much lower strain recoveries (15–30%). On the other hand, the specific deformation energy absorption of the auxetic specimen reached 0.076 Jcm3. Moreover, the resistivity reached the small magnitude of 0.15 Ωm at 50 Hz, proving to be a conductive composite. The gauge factor of 4.26 indicates that it can be used as a self-sensing concrete. This innovative cementitious composite opens new possibilities for future applications that require materials with conductive and auxetic behaviors.

Flexural Behavior of Cross-Laminated Timber Panels with Environmentally Friendly Timber Edge Connections

As a sustainable construction material, timber is more promoted than steel, concrete, and aluminum nowadays. The building industry benefits from using timber based on several perspectives, including decarbonization, improved energy efficiency, and easier recycling and disposal processes. The cross-laminated timber (CLT) panel is one of the widely utilized engineered wood products in construction for floors, which is an ideal alternative option for replacing reinforced concrete. One single CLT panel has an outstanding flexural behavior. However, CLT cannot be extended independently without external connections, which are normally made of steel. This article proposes two innovative adhesive-free edge connections made of timber, the double surface (DS) and half-lapped (HL) connections. These connections were designed to connect two CLT panels along their weak direction. Parametric studies consisting of twenty models were conducted on the proposed edge connections to investigate the effects of different factors and the flexural behavior of CLT panels with these edge connections under a four-point bending test. Numerical simulations of all the models were done in the current study by using ABAQUS 2022. Furthermore, the employed material properties and other relevant inputs (VUSDFLD subroutines, time steps, meshes, etc.) of the numerical models were validated through existing experiments. The results demonstrated that the maximum and minimum load capacities among the studied models were 6.23 kN and 0.35 kN, respectively. The load–displacement responses, strain, stress, and defection distributions were collected and analyzed, as well as their failure modes. It was revealed that the CLT panels’ load capacity was distinctly improved due to the increment of the connectors’ number (55.05%) and horizontal length (80.81%), which also reinforced the stability. Based on the findings, it was indicated that adhesive-free timber connections could be used for CLT panels in buildings and replace traditional construction materials, having profound potential for improving buildings’ sustainability and energy efficiency.

Fungal mycelium-based biofoam composite: A review in growth, properties and application

Recent years have shown a surge in interest in incorporating living systems into materials research to synthesize functional materials using biological resources. Among these, mycelium-based materials, notably biofoam, have emerged as innovative solutions for repurposing organic wastes that were previously considered unusable. The growth of mycelium, vital for the synthesis of biofoam, is influenced by a multuple of factors including substrate composition, moisture content, temperature, nutrient availability, pH levels, oxygen concentration, and measures for contamination control. Additionally, physical stimulation techniques have been explored to enhance mycelium growth, ranging from cold stress-induced adaptations to electrical shock-induced modifications and optimization of sound treatments and light exposure. This review highlights the growing interest in biofoam composite materials, a novel class of environmentally friendly and cost-effective materials that are gaining popularity, for advancing sustainable construction practices. Biofoam composites use organic fungal growth as a low-energy bio-fabrication process to transform abundant agricultural byproducts and waste into viable alternatives to energy-intensive manufactured building materials. Their versatility in composition and manufacturing methods allows them to be used in a wide range of applications, including insulation and door cores, panelling, flooring, and furniture components. Notably, biofoams outperform synthetic foams and engineered wood in terms of thermal insulation, sound absorption, and fire resistance, making them highly promising for construction industry. Besides, due to its customizable composition and production method, biofoam can be used in the replacement of foams, leather, wood, and plastics in a variety of applications such as water treatment and filtration, medical supplies and healthcare applications. However, despite their remarkable properties, biofoam typically serve as non- or semi-structural supplements to traditional construction materials due to inherent limitations. Nevertheless, the useful material properties of these materials, combined with their low cost, ease of manufacture, and environmental sustainability, imply that they will have an important part to play in the development of environmentally friendly materials in the future.

Sustainable construction materials for low-cost housing: Thermal insulation potential of expanded SBR composites with leather waste

In recent years, there has been a growing interest in improving energy efficiency and thermal comfort in low-income housing, especially in regions prone to extreme climatic conditions. Conventional construction materials such as bricks and concrete exhibit shortcomings in energy efficiency, resulting in high indoor temperatures. This scenario not only impacts residents' well-being but also increases energy consumption, especially for air conditioning systems, potentially straining the electrical infrastructure in hot climate areas, leading to power outages and adverse consequences for the community and local industry. This study proposes an innovative and sustainable solution: the use of expanded styrene-butadiene rubber (SBR) with micronized leather shavings, possessing thermal insulation properties. The thermal insulation capacity of the composites was evaluated using heat flow methods, hot/cold plate heat flow analysis, and impedance tube acoustic method. The SBR/Leather waste composite at 20 phr emerges as a viable, promising, and sustainable alternative, exhibiting significant thermal insulation capacity with a thermal conductivity of 0.073 Wm-1.K−1 and temperature attenuation close to 15 °C, potentially enhancing comfort and quality of life in urban areas. The thermal insulation results of the other composites also surpassed traditional construction materials such as building boards, plywood, fiberglass, asphalt roofing, and cement tiles. The study demonstrates the feasibility of reusing leather as a reinforcing filler in rubber-based foams to produce thermal insulation materials, offering a sustainable solution to mitigate urban heating and improve quality of life in cities.

VERNACULAR ARCHITECTURE OF JODHPUR: A RESILIENT APPROACH TO SUSTAINABLE ENVIRONMENT

Sustainable architecture is the application of principles that contribute in the evolution of building designs and processes that reduce the negative environmental effects of construction. When contemplating Jodhpur's vernacular architecture, it becomes clear that traditional construction methods correspond to basic green design principles such as using energy-efficient locally available materials and resources. Many traditional aspects of Jodhpur architecture can be easily incorporated into contemporary environments to provide a sustainable atmosphere and natural accompaniment. This study presents the scope of eco-friendly development of the city by using traditional construction techniques and materials, built forms, and fabric with a thorough analysis of the hot and dry climate of the area. It also encompasses the use of this local architecture to help create an energy- efficient thermal comfort zone in similar climatic conditions in any part of the world. This work is an attempt to reclaim the ideals about good architecture towards this setting, in not only terms of identifying the hot and arid climate but also in terms of producing a design philosophy relevant to the manner of living in a conventional city.

From Textile to Structure: Advancing Sustainability in Construction Practices

The construction industry, with its significant environmental footprint, is increasingly turning towards sustainable practices to mitigate its impacts. This article explores the potential of integrating textile materials into construction processes to enhance sustainability. Textiles offer versatility, lightweight properties, and potential for recycling, making them a promising alternative to traditional construction materials. Through a review of current research and innovative case studies, this paper examines the application of textiles in various construction contexts, including structural components, insulation, and façade systems. Additionally, it investigates the environmental benefits associated with utilizing textiles in construction, such as reduced carbon emissions, energy consumption, and waste generation. Furthermore, challenges and opportunities in implementing textile-based construction methods are discussed, including material durability, cost-effectiveness, and regulatory considerations. By highlighting the advancements and possibilities in textile-based construction practices, this article contributes to the discourse on sustainable construction methodologies, providing insights for practitioners, researchers, and policymakers seeking to foster greener approaches within the built environment.

Effect Of Quarry Dust On Mechanical Properties Of Rice Husk Ash-Based Concrete For Sustainable Environment

As the global population has continued to grow, the costs and environmental issues associated with traditional construction materials like cement and river sand have become increasingly problematic. This research aimed to explore an alternative and eco-friendly approach to traditional building materials. The researchers conducted an experimental program to assess the mechanical properties of the rice husk ash-based concrete at different curing ages 7, 14, 21, and 28 days. Following the mix design, the concrete was produced using water to binder ratio of 0.5. A series of experiments were conducted on both fresh and hardened states to investigate the impact of quarry dust on rice husk ash-based concrete. It was observed from the experimental results that when 40% of the quarry dust was used as a replacement for fine aggregates, the concrete exhibited the highest strength. After 28 days of curing, the compressive strength showed a 0.65% improvement, while the splitting tensile strength displayed a 1.77% enhancement compared to the reference mix. To ensure the reliability of the experimental findings, a statistical analysis was conducted. The study concluded that certain factors, such as quarry dust, curing duration, and rice husk ash, interacted synergistically to influence the compressive and splitting tensile strengths of the concrete. The researchers also proposed equations to predict these strengths based on the aforementioned parameters.

Review on Advancements in the Production of Artificial Aggregates from Industrial Byproducts: A Sustainable Solution for Infrastructure Development

This review paper explores the burgeoning interest in artificial aggregates as sustainable alternatives to traditional construction materials, driven by concerns over resource depletion and environmental degradation. It comprehensively examines recent advancements, challenges, and future prospects in this field. Beginning with an overview of the imperative for alternative aggregates in construction, the paper discusses various types of artificial aggregates sourced from industrial by-products, recycled materials, and innovative manufacturing processes. It delves into their mechanical, physical, and environmental properties, contrasting them with natural aggregates, and evaluates the impact of production techniques like sintering, foaming, and chemical activation on their performance. Environmental sustainability aspects, including carbon footprint reduction and waste management, are rigorously analyzed, underscoring the potential of artificial aggregates to mitigate ecological impacts associated with conventional extraction and processing methods. Addressing hurdles to widespread adoption, such as technological barriers and economic viability, the review proposes strategies for overcoming these challenges and outlines future research directions to optimize artificial aggregates' properties and applications. In conclusion, this review offers valuable insights into the state-of-the-art developments in artificial aggregate technology, highlighting their pivotal role in advancing sustainability and resilience within the construction sector. Key Word: Artificial aggregates, Sustainable construction materials, Environmental impact, Recycling, Waste utilization.

Mechanical Properties of Concrete Containing Coconut Shell as Coarse Aggregate Replacement

The increase in the price of traditional construction materials is a serious issue. Concrete, which is made of cement, sand, coarse aggregate, and water, is widely used as a building material. However, an increase in concrete production has certain negative consequences for the environment, such as the extraction of natural resources such as aggregate. Therefore, innovation in concrete materials without neglecting strength can always be done. Coconut shells are one of the recycled materials that can be used as a replacement for conventional construction materials such as aggregate. The aim of this research is to investigate the properties of concrete by using coconut shell as a partial replacement for coarse aggregate. A total of 60 samples with 0%, 10%, 20% and 30% of coconut shells as coarse aggregate for concrete replacement were cast. The properties of fresh and hardened concrete with coconut shell as coarse aggregate replacement were determined at 7, 14, and 28 days of curing ages. The results showed that concrete with coconut shell as a coarse aggregate replacement had a positive impact on workability, porosity, density, and UPV but not on compressive and tensile strength. However, the concrete made from coconut shell aggregates satisfied the minimum requirements of normal concrete, resulting in the acceptable strength required for M30 grade concrete. It can be used as lightweight concrete. Using coconut shell as a replacement for aggregate is not only cost-effective and environmentally friendly, but it also helps solve the problem of conventional material shortages, such as coarse aggregate. It can also help to solve the problem of waste disposal.

Antimicrobial fibres derived from aryl-diazonium conjugation of chitosan with Harakeke (Phormium tenax) and Hemp (Cannabis sativa) Hurd

Surface functionalisation of natural materials to develop sustainable and environmentally friendly antimicrobial fibres has received great research interest in recent years. Herein, chitosan covalent conjugation via aryl-diazonium based chemistry onto Phormium tenax fibres (PTF) and hemp hurds (HH) was investigated. PTF are fibres derived from Harakeke/New Zealand flax, an indigenous and abundant plant source of leaf fibres, which served as an important 19th century export commodity of New Zealand. HH are obtained as a by-product from the hemp (Cannabis sativa) industry and find applications as traditional construction material, animal bedding, chemical absorbent, insulation, fireboard etc. This study reports aryl-diazonium covalent attachment of chitosan and PD13 (6-O-(3-(2-(N,N-dimethylamino)ethylamino)-2-hydroxypropyl)chitosan), a chitosan derivative with improved antibacterial activity, on to PTF and HH. The modification was confirmed using FTIR, XPS, SEM and water contact angle studies. Comparison of aryl-diazonium versus the use of succinic anhydride bridging for chitosan attachment was also investigated, with the diazonium method giving improved results. The treated PTF and HH fibres had good antibacterial activity against Staphylococcus aureus and this study contributes to the development of sustainable antibacterial fibres using bio-based materials.

Investigation of Multi layered Mitigation Systems for Protection from 120mm Mortar HE Top Attacks

This paper investigates the protection of reinforced concrete (RC) structures from the Mortar 120mm HE (high explosive) top attacks. Two multi-layered mitigation systems are proposed to be added on RC structures' roofs to achieve full protection against the Mortar 120mm destroying effects (i.e. ballistic penetration and explosion effects). The proposed mitigation systems combine relatively high-strength materials, to stop or slow down the projectile, with lightweight porous materials, to attenuate the explosion shock wave. Another function of the porous materials is to increase the thickness of the proposed mitigation systems and hence increasing the explosion stand-off distance. Traditional construction materials, steel and RC, were used as cheap high-strength materials, whereas commercial rigid polyurethane foam and light-weight brick were examined as shock wave absorbers. Two firing tests of the 120mm bomb from cannon barrels against one-story RC structures strengthened with the proposed protection systems were executed. A numerical simulation of the real firing tests was performed via Autodyn hydrocode to further analyze the performance of the constituting components in alleviating the round effects. The current study demonstrated that the proposed mitigation systems, which are based on the multi-layering concept, are efficient and have their merits in defeating the Mortar 120mm HE attacks.

Mechanical, fracture, and environmental performance of greener polymer composites containing low to high micro fillers with recycled and byproduct origins

AbstractPolymer adhesives have considerable mechanical and environmental privileges; however, their high price makes them uncommercial for common uses. This study investigates the incorporation of recycled or byproduct fillers in epoxy resin‐based composites to assess their mechanical properties, environmental impacts, and cost efficiency. The fillers examined include fly ash, glass powder, slag, silica powder, and limestone powder. Tensile, compressive, and fracture tests were conducted on composites with various filler proportions (0%–80% by weight). From microstructure observations, round (fly ash, glass powder) and rough (slag, silica, and limestone powder) morphologies are seen. Also, it is seen that all the fillers are well distributed in the matrix; with the increase of filler content, the air voids increase. The tensile and compressive results indicate that adding fillers improves the composite's strengths, with up to a 20% increase compared to neat epoxy resin. However, when filler contents exceed 40%, the strengths decrease. Fracture toughness values also decrease with increasing filler content. Comparing the results with those of other studies indicates the similarity of trends. Cost‐strength and CO2eq‐strength curves were evaluated to assess the financial and environmental aspects. The composites show potential for cost efficiency but may have some environmental drawbacks compared to traditional construction materials like cement concrete.Highlights The incorporation of recycled or byproduct fillers in epoxy resin composites. Examined fillers include fly ash, glass, slag, silica, and limestone powder. Tensile, compressive, flexural, and fracture tests were conducted. SEM and failure patterns were analyzed, and similar studies were compared. Cost‐strength and CO2eq‐strength data evaluated.

Durability and micromechanical properties of biochar in biochar-cement composites under marine environment

Integrating biochar into traditional construction materials presents a promising avenue to reduce carbon emissions from the construction industry. While recent research has focused on the performance of biochar-cement materials, limited attention is given to the durability of biochar in cementitious materials. This study investigated the alterations in the structural, chemical, and mechanical properties of biochar in the cementitious system and marine environment. The results showed an increased pore size in the biochar and a potential collapse of its structure after long-term exposure of biochar to an alkaline cement environment. The decline of the aromaticity, 23.8% increase in matrix defectiveness, and formation of organometallic complexes between Ca2+ and oxygen-containing functional groups of biochar indicated that its interactions with hydrated cement would lead to the changes in its chemical properties. The exposure of biochar to the simulated cement solution reduced its Young’s modulus from 3.81 GPa to 1.55 GPa and hardness from 0.70 GPa to 0.13 GPa possibly due to the collapse of the pore structure. The saponification reaction might disrupt the cross-linking network structure constructed by COOC and C–O–C in the biochar and release the fulvic-acid organics, causing a decrease in the short- and long-term rebound ratios by 5.6–25.6% and 5–17%, respectively. Biochar exposed to the simulated harsh environment (seawater) exhibited an increase in Young’s modulus and hardness by ∼40% compared to virgin biochar. The long-term rebound ratio reached 96.6–99.2% due to brucite, NaCl, and KCl deposition and filling, implying the potential advantage of biochar-cement composites for long-term durability in the marine environment. These findings contribute new insights to the assessment of mechanical performance and durability of biochar-cement composites in diverse environmental conditions.

Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada

Over the years, structural engineering codes and specifications in Canada and elsewhere have moved from an allowable stress design (ASD) approach to a load and resistance factor design (LRFD) philosophy. LRFD methodology takes better account of the inherent variability in both loading and resistance by providing different factors of safety for loads of distinct natures with regard to their probability of overload, frequency of occurrences and changes in point of application. The method also results in safer structures because it considers the behavior at collapse. While resistance factors for traditional construction materials based on LRFD in the National Building Code (NBC) of Canada are available, they cannot be used for non-conventional ones. This is because the resistance of such materials due to various load effects has unique bias factors (λR) and coefficients of variation (VR), which greatly impact their reliability index (β). In this study, relationships between the resistance factor ϕ and critical load effects from the NBC load combinations at ultimate limit states are developed for a wide range of resistance bias factors and coefficients of variation. The relationships are presented in the form of charts that are useful for researchers and code-writing professionals who have expertise in the various fields of structural engineering but lack proper background in reliability theory. The developed spectra showed that for the same ϕ, β increases with an increase in the live-to-dead load (L/D) ratio until it reaches 1; thereafter, the shape of the relationship will depend on the statistics of the resistance as well as on the magnitude of ϕ. For a small ϕ and VR, β will keep increasing with an increase in the L/D ratio from 1 until 3, albeit at a lesser rate. For L/D > 3, the relationship between the critical β and applied load is just about constant. This finding is also true for load combinations involving snow and wind. Application of the method is illustrated by a practical example involving the shear strength of a corrugated web steel beam.

Analysis of the Influence of Fiber Orientations in Carbon Fiber Reinforced Composites on their Structural Properties Based on Eddy Current Measurements

Fiber-reinforced plastics (FRP) are a type of composite material consisting of a reinforcing structure and a plastic matrix. When compared to traditional construction materials, FRP has higher strength and stiffness due to the high mechanical properties of reinforcing fibers such as carbon or glass. However, the properties of FRP are dependent on the alignment of fibers within the composite, with deviations leading to reduced strength and stiffness. Eddy current testing is a non-destructive technique used to visualize carbon fibers in the composite and assess the impact of local fiber orientation on the structural properties of FRP. This study aims to understand the influence of local fiber orientation on tensile strength and elastic modulus by producing composites with defined fiber orientations, analyzing them with eddy current testing, and assessing their mechanical properties through tensile tests. The measured fiber orientations are then used to validate a finite element model, in which the actual, measured fiber orientation is applied to the simulation and correlated with the mechanical properties. In contrast to previous published studies measured fiber orientation is used, which as shown in this work, differs from the theoretically implemented fiber orientation.

Application of various microscopy techniques to study early-age and longer-term behaviour of super sulphated cement microstructure.

Super sulphated cement (SSC) is a very promising substitute for traditional construction materials (i.e. Portland cement), due to its enhanced durability and particularly low environmental impact. This paper explores the microstructure and certain properties of SSC, focusing on the particular complexities of its microstructure and the difficulties of microanalysis of its hydrates. To do so, SSC paste samples were first cast to identify hydration products using X-ray diffraction, then observed at early age using confocal laser scanning microscopy (CLSM) and at early and late age using scanning electron microscopy. In addition, concrete cores impregnated with fluorescein in order to highlight porosity, cracking and aggregates debonding were observed under UV light using optical microscopy (OM), showing a complete absence of cracking and aggregate debonding. Both microscopy techniques (CLSM and UV light OM) have been applied to this type of binder for the first time. The results show that SSC microstructure is characterised by a sophisticated intergrowth of various phases, including ettringite and amorphous calcium-(alumina)-silicate hydrate gels. Finally, Monte-Carlo simulation of electron-matter has been provided for a better understanding of EDS analysis.

Self-sensing properties of cementless ultra-high performance concrete (UHPC) with slag aggregates

This research addresses the environmental impact of traditional cement-based construction materials and explores sustainable alternatives. The study aims to explore the mechanical properties, flowability, setting time, and self-sensing performance of cementless ultra-high performance concrete (UHPC) by utilizing the electrical properties of electric arc furnace slag (EAF slag) as a replacement for natural aggregates, along with alkali-activated slag as the binding material. Comparative analyses are conducted between cementless UHPC with EAF slag and silica sands, as well as the impact of incorporating carbon fiber. The study reveals that cementless UHPC with EAF slag exhibits improved fluidity and slightly increased setting time compared to UHPC with silica sands, attributed to the spherical shape and ball bearing effect of EAF slag. While the compressive and tensile strength of cementless UHPC with EAF slag is slightly lower than that of UHPC with silica sands, it still meets UHPC standards with strengths of 150 MPa and 8 MPa, respectively. Nonlinear curve fitting accurately quantifies the self-sensing performance, yielding precise simulation results. Importantly, EAF slag-based UHPC exhibits superior self-sensing capabilities, outperforming carbon fiber incorporation. Unlike UHPC with silica sands, which generates substantial noise even with carbon fiber, EAF slag-based UHPC demonstrates effective self-sensing with minimal noise, even in the absence of carbon fiber. This study expands the understanding of self-sensing performance in cementless UHPC by effectively utilizing EAF slag as a replacement for natural aggregates. The results suggest that the valorization of EAF slag has the potential to enhance sustainability and the self-sensing capabilities of cementless UHPC.

Prefab Light Clay-Timber Elements for Net Zero Whole-Life Carbon Buildings

"Net zero whole life carbon" is an ambitious climate target that refers to neutralizing and offsetting the entire LCA-based carbon footprint of a building, including both operational and embodied greenhouse gas emissions. Especially in the Northern climate, viable building envelope structures must, therefore, provide good thermal insulation and low embodied emissions. Carbon offset is typically based on excess on-site renewable energy or purchased carbon offsets disconnected from the building and the site. Viable strategies for carbon neutrality start by minimizing material-related and energy-related CO2e emissions. As a result, new kinds of building envelope structures have been recently introduced in the academic literature and experimental building projects. Traditional construction materials, such as timber and clay, have been sourced locally and processed manually, providing good results for the embodied emissions in life cycle assessment. Recent studies on clay-based construction materials have concluded that more research on clay as a construction material is needed, in particular considering its environmental performance. One specific concern in the Northern climate is that the weather conditions limit clay construction outdoors and prevent industrial-scale application of these solutions. The methods of prefabrication can address these issues. This study introduces the critical technical and environmental properties of a new prefabricated wall element based on a combination of light timber frame and light clay. In a hybrid light clay-timber structure, a mixture of clay and hemp shives is cast between the timber studs. On the one hand, the novelty of this wall structure is the prefabrication that enables industrial applications and upscaling without the limitations of weather conditions. On the other hand, the study assesses the climate impact of a light clay-timber wall element : cradle-to-gate emissions, thermal insulation, and the climate benefits outside the system boundary (carbon handprint) reported in the D-module of the LCA framework. The study also shows that natural materials require a different approach than synthetic materials from industrial processes. There may be variations in the properties of hemp and clay, especially when local sourcing is prioritized for better environmental performance. Moreover, the mixing and installation processes have a significant impact on the final properties and the performance. We show that constructing a light clay wall is a knowledge-intensive process that may result in very different technical properties.