Search Results (55)

The global construction industry faces pressing challenges in enhancing building energy efficiency standards. To address this critical issue, facilitate worldwide green and low-carbon transformation in construction practices and improve the thermal performance of building wall panels to achieve optimal levels, a novel polypropylene fiber-reinforced concrete wall panel has been developed and investigated. A three-dimensional steady-state heat transfer finite element model of the wall panel was established to simulate its thermal performance. Key parameters, including the thickness of the inner and outer concrete layers, insulation layer thickness, connector spacing, and connector arrangement patterns, were analyzed to evaluate the thermal performance of the fiber-reinforced concrete composite sandwich wall panel. The results indicate that the heat transfer coefficients of the G-FCSP and FCSP wall panels were 0.768 W/m² · K and 0.767 W/m² · K, respectively, suggesting that the glass fiber grid had a negligible impact on the thermal performance of the panels. The embedded insulation layer was crucial for enhancing the thermal insulation performance of the wall panel, effectively preventing heat exchange between the two sides. Increasing the thickness of the concrete layers had a very limited effect on reducing the heat transfer coefficient. Reducing the spacing of the connectors improved the load-bearing capacity of the composite wall panel to some extent but had minimal influence on the heat transfer coefficient; to achieve optimal performance by balancing structural load distribution and thermal damage resistance, a connector spacing ranging from 200 mm to 500 mm is recommended. The variation in heat transfer coefficients among the four different connector arrangement patterns demonstrated that reducing the thermal conduction media within the wall panel should be prioritized while ensuring mechanical performance. It is also recommended that the connectors are arranged in a continuous layout. Full article

Straw as a building material alternative is in line with sustainable development goals. To make effective use of straw resources such as rice and corn stalks in rural areas, a kind of steel wire mesh-reinforced straw concrete sandwich panel (SCSP) was developed. The SCSP was composed of cold-drawn low-carbon steel-wire mesh (SWM), fine gravel concrete (FGC), and straw. The used type of FGC was shotcrete. A cold-drawn low-carbon SWM was arranged on the upper and lower sides of the SCSP, and a vertical wire tie was arranged between the upper and lower cold-drawn low-carbon SWMs. The FGC was sprayed on the SWM to make the SCSP layer work together. The loading process of the SCSP could be divided into three stages: elastic working state, cracking state, and failure state. The results of the four-point loading test show that the maximum flexural moment of the SCSP can be up to 7.5 kN·m in the elastic range. The ultimate bearing capacity of SCSP reaches 10.9 kN·m, and the maximum crack width can reach 3~4 mm. At the same time, based on the assumption of the flexural section of SCSP, two simplified calculation models of SCSP bearing capacity were established. The average error was 2.99% and 9.41%, respectively, by comparing the experimental values with the two calculated values. The results obtained by using the two models were in good agreement with the experimental results. Full article

Concrete sandwich wall panels (CSWPs) have been constructed since the early 1900s using various wythe connectors, panel geometries, and construction methods to create a structurally and thermally efficient system. Initially, thermal bridging hindered thermal efficiency due to the concrete connections and steel bars used to transfer interface forces between the concrete wythes. This issue was mitigated with the advent of polymer connectors, now widely used in the precast and tilt-up industries. As a result, CSWPs now offer buildings an efficient envelope, aiding in energy savings and reducing the need for additional construction materials and therefore contributing to the construction industry’s sustainability goals. This paper examines the current state of the practice in CSWP construction, focusing on CSWP’s construction methods, sustainability, material selection, and design processes. This manuscript delves into the history of CSWPs and showcases projects ranging from housing to industrial applications. Moreover, the materials and hardware popularly used in their construction are reviewed from the practicing engineer and researcher’s point of view and other aspects, such as environmental, architectural, and structural design, are presented. The most popular construction methods and approaches when precasting these panels on- or off-site and their associated challenges are also presented. Lastly, current deficiencies in CSWP design and construction are outlined and future directions for research and practice are suggested to advance this field further. Full article

The development of sustainable and energy-efficient construction materials is crucial for mitigating the growing environmental impact of the building sector. This study introduces a new lightweight sandwich panel, featuring a core made of lightweight concrete with rice husk bio-aggregate (RHB) and faces constructed from foamed cementitious composites. The innovative design aims to promote sustainability by utilizing agro-industrial waste while maintaining satisfactory mechanical performance. Composites were produced with 4% short sisal fibers and matrices containing 15%, 20%, and 30% foaming agent. These composites were evaluated for density, direct compression, and four-point bending. It was found that the mixture with 20% foam volume demonstrated the highest efficiency for use in the production of sandwich panels. Concrete mixtures containing 50%, 60%, and 70% rice husk bio-aggregates were tested for density and compressive strength and used in the production of lightweight sandwich panels with densities ranging from 670 to 1000 kg/m³. Mechanical evaluation under flexion and shear indicated that the presence of fibers inhibited crack propagation in the face, enabling the creation of lightweight sandwich panels with deflection-hardening behavior. On the other hand, the increase in RHB content led to a reduction in the ultimate stress on the face, the core shear ultimate stress, and the toughness of the sandwich panels. Full article

This study investigates the shear-bending performance of GFRP (Glass Fiber Reinforced Polymer) connectors in sandwich insulation composite wall panels following tension–compression fatigue damage. A total of 24 specimens, divided into 11 groups, were prepared for experimental analysis. Three distinct load amplitudes (5.4 kN, 4.0 kN, 2.7 kN) and three fatigue loading cycles (30,000, 50,000, 80,000) were established as loading conditions. The experimental protocol included out-of-plane tension–compression fatigue tests followed by post-fatigue shear-bending tests. The influence of varying load amplitudes and fatigue loading cycles on failure modes, load–displacement relationships, and bearing capacity alterations was systematically examined. A two-factor analysis of variance (ANOVA) was utilized to evaluate the statistical significance of these factors. The findings reveal that the predominant shear-bending failure modes post-fatigue damage are connector fracture and concrete crushing in the anchorage zone. Specifically, under a load amplitude of 2.7 kN and 30,000 cycles, the shear-bending capacity of the specimens exhibited a minimal reduction of 1.82% compared to the ultimate capacity of undamaged specimens. Conversely, at a load amplitude of 5.4 kN and 80,000 cycles, the shear-bending capacity experienced a substantial decline of 37.11%. Both load amplitude and fatigue loading cycles were found to significantly impact the shear-bending capacity, with fatigue loading cycles demonstrating a more pronounced effect. This research provides critical insights for the design and assessment of sandwich insulation composite wall panels, particularly in the context of long-term fatigue damage and its implications on structural performance, thereby contributing valuable theoretical and practical knowledge to the field. Full article

Given the current need to improve the thermal and energy performance of buildings, special attention has been given to the building envelope and materials. Concrete sandwich panels (CSPs) are versatile composite construction elements whose popularity is increasing given their properties, e.g., good thermal and acoustic insulation, durability, and fire resistance. Nevertheless, besides their properties, it is important to evaluate the sustainability of composite panels under development. This work aims to assess the eco-efficiency of six CSPs with distinct insulation materials: lightweight concrete (LWC), cork, glass wool, and expanded polystyrene (EPS). Coupling both life cycle assessment (LCA) and life cycle costing (LCC) analysis, this study derives eco-efficiency indicators to inform decisions regarding CSP environmental and economic performances. The results of the LCA and LCC showed that the high-performance concrete (HPC) layer was the main hotspot of the CSPs in all scenarios. Moreover, the best scenario changed when different environmental impact categories were considered. Thus, using multiple environmental indicators is recommended to avoid problem-shifting. Considering the final cost, the CSP with cork is the most expensive panel to produce, with the other five options having very similar manufacturing prices. On average, raw material inputs, labour, and material delivery account for 62.9%, 18.1%, and 17.1% of the total costs, respectively. Regarding the eco-efficiency results, the most eco-efficient scenario changed with the environmental indicator used. Cork seems to be the best option when considering the carbon footprint of the panels, whereas when considering other environmental indicators, the recycled EPS scenario has the best eco-efficiency and the CSP with cork the worst. Full article

Sandwich panels, consisting of two concrete wythes that encase an insulating core, are designed to improve energy efficiency and reduce the weight of construction applications. This research examines the thermal and flexural properties of a novel sandwich panel that incorporates ultra-high-performance fiber-reinforced concrete (UHPFRC) and cellular lightweight concrete (CLC) as its core material. Seven sandwich panel specimens were tested for their thermo-flexural performance using four-point bending tests. The experimental parameters included variations in UHPFRC thickness (20 mm and 30 mm) and different shear connector types (shear keys, steel bars, and post-tension steel bars). The study also assessed the effects of adding steel mesh reinforcement to the UHPFRC layer and evaluated the performance of UHPFRC box sections without a CLC core. The analysis concentrated on several critical factors, such as initial, ultimate, and serviceability loads, load–deflection relationships, load–end slip, load–strain relationships, composite action ratios, crack patterns, and failure modes. The thermal properties of the UHPFRC and CLC were evaluated using a transient plane source technique. The results demonstrated that panels using post-tension steel bars as shear connectors achieved flexural performance, and the most favorable composite action ratios reached 68.8%. Conversely, the box section exhibited a brittle failure mode when compared to the other sandwich panels tested. To effectively evaluate mechanical and thermal properties, it is important to design panels that have adequate load-bearing capacity while maintaining low thermal conductivity. This study introduced a thermo-mechanical performance coefficient to evaluate both the thermal and mechanical performance of the panels. The findings indicated that sandwich panels with post-tension steel bars achieved the highest thermo-mechanical performance, while those with steel connectors had the lowest performance. Full article

Objectives: Low-grade metabolic inflammation is associated with several chronic metabolic disorders, including obesity. However, no concrete evidence that supports obesity as a direct cause of chronic inflammation. This study aims to identify the association of inflammation with obesity in apparently healthy adults. Methods: In this study, 162 seemingly healthy volunteers, aged between 20 and 40 years, of comparable sex ratio, were recruited and categorized based on their body mass index (BMI) into four obesity scales: normal (N), overweight (OW), obese (OB), and severely obese (SOB). After clinical examination, fasting blood samples were collected from the study subjects for glycemic (fasting blood glucose—FBG, and HbA1c) and lipid (total cholesterol, LDL-C, HDL-C, and triacyl glycerides -TAG) profile analysis. In addition, plasma levels of a panel of diverse inflammatory biomarkers, IL6, IL8, procalcitonin (PCT), TREM1, and uPAR were analyzed by sandwich ELISA. Results: The results showed that LDLC, TAG, FBG, and HbA1c were significantly higher in the obese (OB and SOB) group, compared to the non-obese (N and OW) group, while HDLc was significantly lower. The biomarker levels were not correlated with age or significantly differed between males and females. Importantly, levels of all assessed inflammatory biomarkers were comparable between the obesity classes. Moreover, the assessed biomarkers in subjects with dyslipidemia or dysglycemia were comparable to those with normal profiles. Finally, the biomarker levels were not correlated with the obesity, glycemic, or lipidemic parameters. Conclusions: After correction for age and co-morbidities, our results deny the association of discrete obesity, probably dyslipidemia, and dysglycemia with systemic chronic inflammation. Further studies of local and systemic inflammation in non-elderly, healthy obese subjects are needed. Full article

The construction field is one of the largest sectors and industries worldwide. This industry is the main industry accused of contributing to greenhouse gases and increasing the effects of climate change. However, the construction industry is indispensable, accordingly in an attempt to decrease the greenhouse gas effects of construction this research presents the manuscript for building a one-story building with all components including waste products. The building model used a strip foundation with a concrete mix design incorporating recycled concrete as a partial replacement for aggregates, cement hollow blocks containing granite waste instead of conventional cement blocks, and sandwiched insulated panels made of wood-plastic composites for the roof. The structural soundness of the system was tested by loading it with a load surpassing its design load in addition to measuring the deflection and checking its abidance to the code limitations. The thermal efficiency was tested by measuring the temperatures in comparison with the outside of the building for a span of 7 days with data recorded every 1 h. Analysis of both the short-term and long-term costs and carbon emissions was performed by acquiring the carbon emissions per unit of material from literature and multiplying it by the quantities of the materials used within the different building alternatives. That study showed that the roofs made of Structural Insulated Panels (SIPs) using Wood-Plastic Composite (WPC) facings when used with hollow-block cement block walls have shown enduring cost efficiency and improved thermal insulation, leading to diminished energy usage, life-cycle expenses, and carbon emissions. Furthermore, the proposed system is more environmentally friendly than conventional reinforced concrete technologies due to their lower costs and emissions in addition to improving sustainability through utilizing recycled materials. Full article

In the article, the authors attempted to analyze the impact of such materials factors as surface emissivity, surface roughness, air gap thickness, and type of concrete on heat transport in the microstructure of vertical multilayer building walls. The surface analysis conducted using three-dimensional modeling tools provided information about the formation of its microstructure before and after the application of a reflection-smoothing coating, which has a direct impact on the emissivity of the surface and was reduced from 0.93 to 0.29. Thermal analyses demonstrated that after applying the reflective coating, thermal resistance increased significantly in the air gap, by approximately 86%, which resulted in a 28% improvement of the evaluated walls samples. The studies have shown that increasing the gap thickness between concrete and thermal insulation results in a thermal resistance increase. It is feasible to enhance the thermal insulation of walls while simultaneously reducing their thickness, a development that holds significant potential for application in the production of prefabricated sandwich panels. The statistical analyzes performed showed significant differences between the analyzed configurations. Full article

This paper aims to explore the impact of different arrangements of new steel-glass FRP composite connectors (SGCCs) on the bending and composite performance of sandwich wall panels. Through monotonic loading bending tests on six full-size specimens, aspects such as their failure modes, load-deflection curves, load-strain relationships, slip between the thermal insulation layer and concrete, and composite action were analyzed. The results show that all sandwich wall panels experienced bending and ductile failure, and exhibit partial composite performance, with P4 having the best composite performance and P1 the worst. The degree of composite action is positively correlated with the flexural bearing capacity. The bending capacity mainly depends on the layout rather than the total number of SGCCs. Arranging connectors along the short side of the panel has a more significant impact, and the number of connectors at the panel’s ends has a greater influence on the composite performance. Except for P1, the theoretical value of the composite degree of the other sandwich wall panels exceeds 70%, and P4 reaches 85%. The theoretical calculations are in good agreement with the experimental results. This study provides theoretical and data support for the rational configuration of connectors in sandwich wall panels and is of great significance for building engineering applications. Meanwhile, suggestions for configuring connectors in actual engineering are also given. Full article

One of the important findings of the recent decades in the construction industry is composite sandwich panels (CSPs), which have benefits of being lightweight, providing thermal insulation, and aiding the economy; they are transforming continuously through many add-ons as needed by the industry. With the demand for sustainability in the field, CSPs need structural and sustainable enhancement. In the present study, an approach for the same has been attempted with geopolymer concrete (GPC) and novel nylon fibre to improve the sustainability and structural benefits, respectively. With various material combinations including GPC reinforced with fibres, six CSPs were cast and studied. The inherent limitations of GPC have been addressed by the nylon fibre reinforcement instead of using steel fibres, which have a similar strength, considering the aim of maintaining the density of the wythe material. A comparison of the flexural behaviour of the CSPs through the parameters of load–deflection, ductility, and toughness was made using the four-point loading test. The results of the test specify that the fibres enhance the performance of the CSPs under flexural loading. Full article

Precast concrete sandwich panels consist of two outer layers connected by a central connector and an inner insulating layer that enhances thermal and acoustic performance. A key challenge with these panels is eliminating thermal bridges caused by metallic connectors, which reduce energy efficiency. PERFOFRP connectors, made from perforated glass fiber-reinforced polymer (GFRP) sheets, have been proposed to address this issue. These connectors feature holes that allow concrete to pass through, creating anchoring pins that enhance shear resistance and prevent the separation of the concrete layers. This research aimed to evaluate the effect of the diameter and number of holes on the mechanical strength of PERFOFRP connectors. Three diameters not previously reported in the literature were selected: 12.70 mm, 15.88 mm, and 19.05 mm. A total of 18 specimens, encompassing 6 different configurations with varying numbers of holes, underwent push-out tests. The most significant resistance increase was a 15% gain over non-perforated connectors, observed in the configuration featuring three holes of 19.05 mm. The connections exhibited rigid and nearly linear behavior until failure. Full article

To study the lateral performance of a cold-formed steel–concrete insulation sandwich panel composite wall, two full-scale specimens with different arrangements were designed. The specimens underwent cyclic loading tests to examine the failure characteristics of the composite wall, and lateral performance aspects such as the experimental hysteresis curve, skeleton curve, and characteristic value of the whole loading process were acquired. The experimental results indicate that the failure of the composite wall system was primarily caused by the failure of the connection; the overall lateral performance of composite walls with one wall panel at the bottom and two wall panels at the top (W1) was superior to that of composite walls with two wall panels at the bottom and one wall panel at the top (W2). When loaded to an inter-story drift ratio of 1/300, the composite wall did not exhibit any significant damage. A finite element (FE) model was developed and validated by the experiments. Factors affecting the shear bearing capacity were analyzed based on the FE model, including the yield strength of diagonal braces, the thickness of the diagonal braces, the arrangement pattern of the wall panels, the dimensions of the wall panels, and the strength of the connection of the L-shaped connector and the flat connector. The FE results show that all these factors can influence the lateral performance of the composite wall. Full article

Traditional concrete buildings exhibit low energy consumption and high heat loss, which results in a larger environmental problem. Precast insulation walls are proposed for strengthening thermal insulation efficiency and mitigating heat loss. Numerous studies have investigated the thermal performance of insulation walls over the past decades. However, gaps remain in practical engineering applications. This study aims to bridge these gaps by providing practical design recommendations based on experimental research. Nine different types of precast insulation walls were tested to examine the thermal performance, and the parameters of the insulation material, insulation form, insulation layer thickness, and concrete rib width were investigated. Then, numerical models of these walls were developed for simulating the thermal performance of the tested specimens. Finally, a six-story student apartment model using designed walls was developed to assess energy consumption in two distinct climate zones: the hot summer and cold winter zone of Changsha City, and the cold zone of Harbin City. The results indicate that the precast insulation wall with external insulation form shows better thermal performance than the sandwich insulation form. It is recommended to use precast insulation walls with 50 mm extruded polystyrene (XPS) external thermal insulation form in Changsha City and 80 mm XPS external thermal insulation form in Harbin City. Furthermore, buildings using precast insulation walls can significantly reduce energy consumption by 49.25% in Changsha and 49.38% in Harbin compared to traditional concrete wall buildings. Based on these findings, suitable design suggestions for this precast concrete wall panel building composed of insulation walls are given. Full article