The well-known tradeoff between strength and ductility is a key issue in the large-scale engineering application of steel materials to resist fatigue due to earthquakes and other vibrational excitations. The steel production industry provides a vast range of technologies to achieve the desired performances. Through experimental research, it was found that FeCrNi-based high-ductility steel (HD-S) can demonstrate remarkable hysteresis behavior due to extensive deformation capacity of strain-hardening until the ultimate fracture, compared to industrially manufactured high-strength steel (HS-S) with the level of 1 GPa in yield strength. The balance between strength and ductility can be realized by slightly adding the percentage of Ni by 5% to achieve a ductile hysteresis behavior. Moreover, the HD-S specimens exhibit greater resistance to low-cycle fatigue with large plastic amplitude. By developing a new damage evolution law based on instantaneous damage differential during nonstationary fatigue history, the fatigue life of materials is extended into the inelastic hinges of flexural beams/origami components. The proposed approach enables the fatigue design of steel structural components with desirable disaster-prevention capacities for complex steel structures.

The Portland cement (PC) production industry is a key contributor of CO₂ emission. The demand of cement is mounting day by day due to the rapid infrastructure development in the world. Consequently, CO₂ discharge from the construction sector is continuously increasing and accounts for about 8% of the total CO₂ emission, which becomes a global concern nowadays. Wide applications of eco-friendly cements can significantly reduce the CO₂ release. Therefore, use of magnesium cements (MCs) might be a promising solution to ease such concern. As a rapid hardening cement, MCs can be characterized as low-carbon due to their lower embodied energy and carbon storage ability during the service. This review mainly summarizes the findings of previous studies related to the carbonation performances of PC blended with magnesia and MCs products, and particularly, the influence of Accelerated carbonation curing (ACC) process on the properties of MCs and corresponding CO₂ sequestration performance. The effects of ACC on mechanical strength, hydration and mineral carbonation mechanisms, pore structures, pore solution pH and thermal properties are discussed. The limitations of existing research are also discussed, which may provide the directions for future research and development of MC material products.

The construction and demolition industry generates a significant quantity of concrete waste, presenting an environmental challenge. The concrete waste generated can be processed to produce Recycled Aggregates (RA) of various sizes. Utilization of Recycled Aggregates (RA) as a substitute to conventional aggregates in concrete has captured considerable attention in the past few years, owing to its promising environmental and economic advantages. However, the combined utilization of recycled fine and coarse aggregate in the production of concrete for low-strength application has not been adequately explored. In this article, an attempt is made to investigate the characteristics of concrete blocks made with RA and polypropylene fiber (PF) are investigated for different cement content. Cement and PF content varied from 8 to 12% and 0% to 2% respectively in production of concrete blocks using Recycled Fine Aggregates (RFA) and Recycled Coarse Aggregates (RCA) at different replacement intervals. Water absorption of blocks manufactured across all replacement intervals of RA was less than 10%. Blocks containing 75% RFA and 25% RCA resulted in improved compressive strength of the order more than 3.8 MPa. Rate of improvement in compressive strength of block was 11% to 20% and 6.5% to 8.2% when the fiber dosage was increased from 0.5% to 1% and 1% to 2% respectively. The optimal fiber dosage was found to be 1%, beyond which no notable improvement in mechanical properties of blocks was observed. Use of RA in concrete blocks reduced embodied energy by 19% to 24% for varying cement content from 8 – 12%. Cost of blocks was found to be reduced by 10 – 15% when made with PF dosage of 0 to 2% with 8% cement content.

Recycled concrete powder (RCP) has a large amount of calcium carbonate, which suggests that it can be used to make limestone - calcined clay (CC) cement (LC³) system by replacing limestone powder. So that it can promote the recycling of construction demolition waste and reduce the requirement of the natural resource for LC³. In this study, the fresh and hardened properties of CC-RCP cement system were comprehensively characterized by varying the CC/RCP ratio and dosage, including rheological, mechanical properties, hydration products and pore structure. The results indicate that the addition of CC prolong the setting time, but the effect could be mitigated by the recombination of RCP. By comparing with RCP, CC had a less obvious effect on increasing viscosity, but it could improve the shear thickening behavior of paste. In the case of less total content of CC and RCP, a ratio of 1:1 CC/RCP was better for the development of long-term strength. Whereas, with the increasing of substitution, the mixtures with CC alone or blending with RCP in a 2:1 ratio achieved higher strength. The incorporating of CC and RCP could make the conversion of C₄AH₁₃ into hemicarboaluminate (Hc) and monocarboaluminate (Mc), and it resulted in a denser structure with more medium capillary pores and gel pores than that mixtures with CC only.

Seismic metastructures are able to effectively attenuate or convert elastic surface waves, attracting increasing attention in different areas such as civil engineering. However, the effects of the source depth and layered characteristics of viscous soil on metastructures for elastic surface wave reduction with Bragg bandgap mechanism remain challenging, which are the key issues for practical applications. In this work, we calculate the dispersion and transmission of metastructures in layered soil and confirm that the metastructures can effectively attenuate the elastic surface waves within the bandgaps. Then, the influence of the embedded depth of the metastructures, the depth of the vibrating source, layered characteristics of viscous soil on the surface vibration reduction are further discussed. It is found that surface vibration attenuation is enhanced by increasing the embedded depth of the metastructures and the density of the first layer. The width of the bandgap increases with the introduction of soil viscosity. On the contrary, the surface vibration attenuation decreases if the vibrating source is placed at a certain depth which requires the bandgap of bulk waves of the metastructures. This study of the seismic metastructures in layered soil provides a guidance in surface vibration reduction in practice.

In order to comply with the trend of global climate change, countries are gradually promoting energy conservation and emission reduction, and prefabricated buildings have become one of the main paths for the construction industry to develop towards carbon peaking and carbon neutrality goals. This paper takes the box-shaped column flange connection achieved by plug welding-core sleeve in the dormitory building of Tongzhou Campus of the Affiliated High School of Capital Normal University in China as the research object. Based on the consumption quota of prefabricated construction projects and the actual project quantity, the carbon emissions of steel structure column connection joints at different phases are calculated by the emission factor method, and it is proposed that the production consumption of building materials plays a key role in energy conservation and emission reduction. This paper concludes that the box-shaped column flange connection achieved by plug welding-core sleeve in the construction phase of an assembled steel building emits 49.5% less carbon dioxide than a conventional full fusion-welded joint. And the reason for the high carbon emissions of the latter is mainly from the amount of materials and machinery required for full penetration welding. It further affirms the green and environmental protection effect of the assembled steel structure plug welding-core sleeve flange connection joint in actual projects, and provides a reference for related research.

In light of the paramount considerations of environmental sustainability and the protection of both life and property, a significant number of existing reinforced concrete (RC) buildings fall short of meeting contemporary standards in terms of their structural and energy performances. In response to these pressing concerns, there is an imperative need for comprehensive building retrofitting processes that integrate both structural and energy considerations. One such approach, the addition of RC walls, is commonly employed as a structural retrofitting technique. However, its potential to enhance overall building efficiency has been relatively underexplored in previous research. In this study, we focus on a representative RC building and utilize two key performance indices: structural residual life and energy consumption, to comprehensively evaluate the impact of RC wall retrofitting on both structural and energy performance. Our investigation considers retrofitting on both the exterior and interior sides of the building. It is observed that the structural performance exhibits notable improvement with the addition of RC walls on either side, and this improvement becomes even more pronounced when complemented by local retrofits to adjacent beams. While the RC walls added on the interior side have negligible impact on the building energy efficiency, those installed on the exterior side could obviously reduce the energy consumption of the HVAC system by 7.9%. Hence, the outcomes of this study indicate that employing the RC wall retrofitting on the exterior side of the existing building is an efficient way to reach structural and energy performance targets simultaneously.

The Trombe wall is a passive solar building exterior wall system proposed by Professor Felix Trombe in France, which can collect solar energy to heat buildings without additional energy consumption, making it a focal point of research in building energy conservation. However, its effectiveness is constrained by the low density of solar radiation in winter and the potential for overheating in summer. This study introduces a novel Trombe wall designed to address these issues through a focused strategy, enabling automatic transition between heating during winter and shading during summer. The thermal performance parameters of the novel Trombe walls in both winter and summer seasons are examined, and their energy consumption is assessed using experimental research methodologies. Findings indicate that the novel Trombe wall facilitates greater energy savings in both winter and summer. When compared with traditional Trombe walls, the novel Trombe wall achieves a significant reduction in energy consumption, with up to 55 W/m² in heating load during winter and 47 W/m² in cooling load during summer. The introduction of this new system holds substantial potential for the realization of zero-energy buildings.

In recent years, extensive research has focused on applying machine learning (ML) techniques to predict the properties of engineered cementitious composites (ECCs). ECCs exhibit crucial characteristics such as compressive strength (CS), tensile strength (TS), and tensile strain (TSt). Accurate forecasting of these critical properties can reduce material waste, lower construction expenses, and expedite project timelines for engineers and designers. This study investigates mixture design components and corresponding strengths of ECCs based on only polyethylene fiber drawing from existing literatures. Artificial neural network (ANN) models are developed to predict CS, TS, and TSt using a dataset of 339 experimental results with twelve input variables. The ANN models, implemented in MATLAB, consider various hidden layers and neurons to optimize accuracy and validation metrics demonstrate the model's high accuracy. Sensitivity analysis explores individual parameter impacts. Drawing inspiration from this study, it would be advantageous to enhance the predictive modeling toolkit by leveraging the progress made in existing technologies, thereby driving the green and low-carbon development of civil engineering. This approach not only improves the efficiency and sustainability of construction practices but also aligns with global environmental goals by reducing the carbon footprint associated with civil engineering projects.

Porous concrete plays a crucial role in addressing various environmental challenges and mitigating the impacts of climate change. It proves effective in reducing issues such as flooding, heat phenomena in the earth, and groundwater decline. Typically devoid of sand content, porous concrete’s key attributes lie in its permeability and compressive strength. Accurate prediction of these properties is essential for cost and time savings, ensuring precise proportions of materials in the concrete mixture. This article explores different models, including the linear model (LR), nonlinear model (NLR), and Artificial Neural Network (ANN), to predict and estimate permeability and compressive strength in porous concrete. The analysis incorporates 139 samples from various papers and experimental studies, utilizing significant parameters and variables like water-to-cement ratio, coarse aggregate content, cement content, porosity, and curing time as input variables. Statistical assessments, such as Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and coefficient of determination (R²), are employed to assess model performance. The results reveal that the ANN model outperforms other models in forecasting permeability and compressive strength of porous concrete. The SI and OBJ value of the ANN model are lower than those of all other models, indicating superior performance. The robust performance of the ANN model has significant implications for construction applications, ensuring precise material proportions and contributing to the durability of porous concrete structures. The success of the ANN model suggests avenues for refinement, including architecture adjustments and dataset expansion. These findings offer valuable insights into the ongoing efforts to optimize simulation techniques for predicting key properties of construction materials. On the other hand, the use of these models to optimize concrete mix design not only enhances efficiency but also significantly conserves raw materials and reduces energy consumption. These advancements contribute to lowering carbon emissions and promoting sustainable practices in the construction industry.

This study integrates previous experimental data and employs machine learning (ML) methods, including Random Forest (RF), Support Vector Machine (SVM), Artificial Neural Network (ANN), and eXtreme Gradient Boosting (XGBoost), to predict the compressive strength (CS) and tensile strength (TS) of engineered cementitious composites (ECC). XGBoost emerged as the superior model among the four ML models, providing an interpretable and highly accurate predictive framework. To optimize the model performance, hyperparameter tuning using a fivefold cross-validation approach with the data divided into 80% training and 20% testing subsets. The Shapley Additive Explanations (SHAP) algorithm was also employed to reveal the impact of important features, such as the water/binder ratio, fly ash content, and water reducer dosage, on the model’s predictions and their interrelationships. The XGBoost demonstrates the most exemplary performance, as reflected in the R² values of 0.92 and 0.97 for CS and TS testing, respectively. The SHAP analysis provided insights into the impact of individual features on CS and TS, shedding light on how specific characteristics influence the predictive accuracy of these properties. This highly accurate prediction model uncovers insights into correlated features, aids in creating new mix designs of ECC, and supports global efforts toward a low-carbon future in the construction industry by reducing carbon emissions.

Wood ash, a byproduct of wood combustion, poses environmental challenges when disposed of in landfills. This study explores a sustainable alternative by investigating the carbonation of wood ash, a process converting CO₂ into stable carbonate minerals. With increasing concerns about waste management, this research aims to identify optimal carbonation conditions by varying relative humidity, liquid-to-solid ratio (L/S), and temperature. Results demonstrate that the ideal conditions for wood ash carbonation involve a moderate relative humidity of 55%, room temperature at 25 °C, and a lower L/S ratio. Thermogravimetric analysis (TGA) indicates that extended curing times increase CaCO₃ formation. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirm the presence of carbonate phases. Mechanical strength tests reveal that samples with lower porosity and higher carbonation products exhibit superior strength. This study contributes to the understanding of wood ash carbonation but also emphasizes its potential practical applications in construction materials as light aggregates in cement concrete. The research explores the implications for sustainable waste management, offering insights into environmentally and economically viable solutions for wood ash recycling.

The parietodynamic wall, a type of dynamic insulation, has been recognized as an effective technology to reduce energy loss in buildings by recovering heat energy through forced convection. However, current research on the thermal performance of parietodynamic walls has overlooked the influence of thermal radiation, a crucial factor in energy transfer within the air layers of these walls. To bridge this gap, an innovative simulation model was developed and experimentally validated. Employing simulation methods, we investigated the impact of thermal radiation on the thermal behavior of parietodynamic walls under various influencing factors. Our findings reveal that thermal radiation markedly increases heat loss. Specifically, at an emissivity of 1, thermal radiation contributes up to 80.7% to the heat transfer coefficient (HTC) of the parietodynamic wall. Moreover, for a parietodynamic wall without insulation, the HTC of this wall will increase by more than 268% when thermal radiation is taken into account, compared to when it is not considered. These revelations deepen our comprehension of the role of thermal radiation in parietodynamic walls and offer valuable guidance for the development of more energy-efficient buildings.

Recycled aggregate concrete (RAC) is recognized as an environmentally friendly construction material derived from reclaimed concrete components. This paper aims to conduct a comprehensive scientometric analysis of RAC research published between 2000 and 2023 in the Web of Science core database. The study includes analyses of publication trends over time, contributions and collaborations among authors, productivity of institutions and countries, co-citation networks, and keyword co-occurrence patterns. Additionally, the research identifies emerging frontiers in RAC studies. The results are visually presented to provide a holistic overview of the current state of RAC research and future developmental trajectories. The study analyzes publication trends over time, with over 80% of the papers published after 2017, reflecting the growing interest in sustainable construction. Key trends identified include the increasing focus on improving the mechanical properties and durability of RAC, microstructural analysis, and innovative manufacturing techniques. While the field has advanced significantly, challenges remain in areas such as the integration of nanoparticles, biomineralization techniques, carbon capture and utilization, and 3D printing technologies. These challenges underscore the need for continued innovation and exploration. With these advancements, RAC has the potential to play a pivotal role in promoting sustainable construction practices in the future.

The impact of carbon emission and other pollution generated by the construction industry on the natural environment and ecosystems is immeasurable. Wood, as a renewable building material with excellent performance, is a practical solution for future low-carbon buildings. Current screwed wood connections have good ductility, but the initial stiffness is relatively low. In this paper, composite wood connections with screw and adhesive were proposed and investigated. Static loading tests were conducted to screwed connections and composite connection specimens. The failure modes of different connection types, as well as the effects of adhesive type and adhesive connection area on the joint bearing capacity are discussed. The results show that the yield load and ultimate load of the composite joint made with the existing adhesive increased by up to 169% and 222%, respectively, compared with the screw connection. At the same time, the influence of curing time and bonding should also be taken into consideration. This study provides a foundation for wood joint design and promotes the sustainable development of the building industry.

An efficient double-layer formwork curing method using an “inner supporting formwork + outer insulation formwork” was proposed in this study to address the early cracking of precast concrete components in high altitude regions. Steel and plywood formwork were designed as inner support formwork, while polystyrene (PS) and polyurethane (PU) were used as outer insulation formwork. Indoor experiments and two finite element methods (The complete simulation method focuses on computational accuracy, and the equivalent simulation method emphasizes computational efficiency) were employed to analyze the evolution of the concrete temperature field under different double-layer formwork curing methods throughout the curing period, combined with compressive strength and pore structures testing. The results show that steel + 5-mm-thick PU insulation formwork curing method can significantly mitigate the impact of large diurnal temperature variations on the internal temperature of concrete. Unlike traditional steam-curing, this method does not deteriorate the pore structure or compressive strength of the concrete. This study is of great significance in addressing the problem of early cracking of precast concrete components exposed to large diurnal temperature vriations in high altitude regions.

The objective of this study is to explore the physical and mechanical behaviour of concretes comprising four different ratios of recycled fine (RF), namely (5%, 10%, 15% and 20%) along with that of a reference concrete (Cref-0%), under three different heating–cooling cycles (200 °C, 400 °C and 600 °C). The thermal properties of concrete during heating and cooling (20 °C – 600 °C – 20 °C) were also investigated. It was determined that the physical properties (mass loss and ethanol porosity) of recycled concrete (RC) with 5% of recycled fine (RC-5%) were similar to those of Cref-0%. At ambient temperatures, the higher the ratio of recycled fines, the lower the residual compressive strength and residual elastic modulus of the recycled concrete. After thermal loading at 600 °C, the residual mechanical properties of all types of concrete were equivalent, regardless of the content recycled fine.

Volcanic ash (VA) reactivity is typically low and requires activation or modification to expand its applicability. This study focuses on modifying the VA reactivity by introducing optimal mixing proportions of amorphous materials (AM) and by developing a reliable reactivity measurement technique based on the standard Ca(OH)₂-reactivity test (CRT). CRT was used as a reference test to quantify the reactivity of four VAs. Optimal AM addition was used to increase the reaction rate and to take advantage of synergistic effects on the strength of mortars. Replacing VA with 15 wt.% silica fume (SF), 30 wt.% slag (SL), or 25 wt.% metakaolin (MK) to form modified-VA (MVA) significantly improved the strength and reactivity. The standard CRT was modified by utilizing a constant w/b ratio of 0.484 and by changing the curing regime where the ambient temperature was set to 43℃ for up to 91 days. This revised CRT is referred to as the “modified-Ca(OH)₂-reactivity test” (MCRT). A relationship between the strength and the heat was used as a foundation to develop a classification that determines the level of reactivity of VA/MVA. The results indicate that three of the four VAs evaluated were found to be reactive. The synergistic actions within MVA mixtures significantly improved the reactivity at early ages. Results show that MVA mortar mix with 70% volcanic ash and 30% slag can achieve 25.6 MPa compressive strength at 91 days. By substituting 15% SF, 30% SL, or 25% MK for VA to form MVA, the mixes provide promising results for an alternative concrete mixture for future industrial applications.

This study explores the use of Electric Arc Furnace (EAF) slag as a sustainable alternative raw material in cement clinker production. The research demonstrates the synthesis of ferrite-rich clinker using EAF slag, achieving a clinker composition of 47% alite, 32% ferrite, and 20% belite while replacing 20% of clinker raw materials i.e. limestone, iron and silica source. The hydration behavior and influence of carbonation curing on the reactivity of the ferrite phase were assessed. Results show that the addition of 5% gypsum to the clinker enhanced the hydration rate of alite and ferrite phases, promoting the formation of portlandite, C-S-H and ettringite as the major hydration phases. Typical of ferrite-rich cement, Fe/Al-rich siliceous hydrogarnet was also identified as secondary hydration products of the ferrite phase, formed as a result of the reaction of katoite (formed from ferrite dissolution) with dissolved silica. However, prolonged carbonation exposure led to a decrease in the formation of the hydrogarnet and the decomposition of ettringite, but the mortar’s strength increased with increasing calcium carbonate formation.

Applying 3D concrete printing (3DCP) technology to design and manufacturing can create a diverse configuration of the marine landscape. However, this combination of 3D technology and artificial coral products is still in the initial stage of research and application. Therefore, this study introduces a novel design shape model, bridging theory and experimental models. Two innovative design models have been presented, and one has been manufactured and assembled based on the optimal assembling process. The paper aims to propose a design shape model for artificial coral reefs that employs innovative 3D concrete printing technology to create rough surfaces with openings and cavities similar to those found in natural rocks. The proposed design shape for artificial coral reefs, successfully trialed in this research, can be used as a reference model. The procedure for essential works, including drawing, printing, assembling, and some techniques, is helpful for understanding and implementing the works presented in the study. The application of 3D concrete printing technology to an artificial reef fulfills an identified need and plays a crucial role in marine ecosystem restoration and protecting endangered habitats, thereby making a significant social impact while promoting sustainable development in construction. This paper fulfills an identified need to apply 3D concrete printing technology to manufacturing artificial coral reefs.

This research explores the utilization of wheat straw ash (WSA), an agricultural by-product enriched with amorphous silica, as a partial cement replacement in concrete production. The WSA content ranged from 4% to 16% by mass, with water-to-cement (w/c) ratios varying between 0.4 and 0.6. Using response surface methodology (RSM) combined with central composite design, this study optimized mix designs and developed predictive models for key performance indicators, including workability and mechanical properties of concrete. The results demonstrate that an optimal balance of the WSA and a reduced w/c ratio significantly enhance both the workability and mechanical performance of concrete. The pozzolanic reaction between WSA and calcium hydroxide promotes the formation of calcium silicate hydrate (C-S-H) gel. The optimal mix composition, comprising 10.12% w(WSA) with a w/c ratio of 0.45, achieved a desirability score of 71.83%. This ground-breaking research underscores the viability of WSA as a supplementary cementitious material, offering a sustainable solution for concrete production while simultaneously enhancing its workability and mechanical properties.