Lightweight Building Research Articles

Dynamic properties of alkali residue-based foamed concrete under dry-wet cycles

Alkali residue-based foamed concrete (A-FC) is a lightweight and sustainable building material made from cement, alkali residue, blast furnace slag and foam. The dynamic properties under dry-wet cycles and confining pressure are essential considerations for the engineering application of A-FC. Dynamic triaxial tests were used in this study to explore the influence of dry-wet cycles and confining pressure on the backbone curves, damping ratio, and dynamic elastic modulus of A-FC. A calculation model was established to illustrate the combined effects of confining pressure and dry-wet cycles on the maximum dynamic elastic modulus. Test results indicate that during dry-wet cycles, the coupling effects of temperature, expansion force, and osmotic pressure cause vulnerable pore walls to rupture, pores to become rougher, and microcracks to develop. The backbone curves demonstrate elastoplastic deformation, with no significant change in shape caused by the dry-wet cycles. As the number of dry-wet cycles increases, internal damage accumulates, resulting in a weakening of dynamic deformation ability and a decline in the dynamic elastic modulus. The damping ratio rises with the number of dry-wet cycles once the axial dynamic strain surpasses the transitional strain. Increasing confining pressure can mitigate the adverse impacts of dry-wet cycles on dynamic performance. A-FC demonstrates remarkable durability and favorable dynamic performance, supporting its widespread application in diverse environments.

Exploitation of extruded polystyrene (XPS) waste for lightweight, thermal insulation and rehabilitation building applications

The present article investigates the possibility of Extruded Polystyrene (XPS) waste to be used as a lightweight aggregate in cement-based materials for structural applications. The developed material offers a promising solution for rehabilitation and energy efficiency upgrades of existing civil infrastructures, providing thermal insulation without adding excessive weight to reinforced concrete structures. Through a comprehensive experimental approach, this contribution evaluates the mechanical and thermal performance of cement-based composites with varying XPS content (up to 100 %) as sand replacement. Results demonstrate a balance between enhanced thermal insulation and maintained mechanical robustness, with optimal XPS content ranges identified for specific application needs. The incorporation of XPS waste into construction materials supports sustainability by repurposing non-biodegradable materials, while meeting the dual requirements of structural performance and energy efficiency. This research supports the exploitation of XPS-modified cement-based materials in structural rehabilitation of existing structures and innovative construction applications, promoting greener and more efficient building materials that could be utilized in ground structures, such as buildings.

StarchCrete: A starch-based biocomposite concrete for lightweight building material applications

StarchCrete is a novel composite material that utilizes starch as a biobased binder, replacing traditional inorganic binders. The composite was prepared using varying hemp shives ratios (from 0−1) at constant sand: corn starch: water ratio (5:1:1). The mixture was manually compacted into a mold and heated under microwave radiation. The effect of different starches on a composite’s compressive strength was investigated. The result reveals that high-viscosity starch leads to strong compressive strength. Increasing the hemp shives ratio significantly reduced thermal conductivity (from 0.52 to 0.15 W/(m·K)) and thermal diffusivity (from 0.85 to 0.35 mm2/s). With its strong compressive strength (2.8 MPa), low density (887 kg/m3), and low thermal conductivity (0.18 W/(m·K)), the hemp shives ratio of 0.5 was deemed appropriate. Furthermore, coating the material with paraffin wax improved its water resistance, extending its durability from 7 to 16 days, making it suitable for industrial applications.

Autoclaved aerated concrete reinforced by polymeric pins

Autoclaved Aerated Concrete (AAC) is a lightweight and sustainable building material known for its thermal insulation and acoustic properties. However, its relatively low mechanical strength limits its use in load-bearing applications. This paper introduces the concept of incorporating unsaturated polyester resin (UPR) pins into AAC blocks to improve compressive and flexural strength of the material. Pin diameters of 4, 6, 8 and 10 mm were studied, oriented at 90° and 45° in relation to the AAC main plane. The effects of the UPR/AAC interface were analyzed through microscopy. The results point to a substantial increase in mechanical strength of the reinforced AAC, wherein smaller pins with orientation of 45° and 90° presented the best behavior under flexural (up to 298%) and compressive loading (up to 183%), respectively.

Application of a decision tree approach to predict energy consumption in lightweight buildings under subtropical climate

PurposeLightweight building systems have emerged as alternatives to reduce the high environmental impact of conventional masonry. However, in subtropical climates, the low thermal inertia of lightweight envelopes negatively affects energy performance. The purpose of this paper is to investigate the thermophysical parameters that influence heating and cooling energy consumption in lightweight residential buildings under subtropical climates and develop a model to predict these parameters using statistical and machine learning tools.Design/methodology/approachA database was created with computer simulation data on the energy performance of 2048 building conditions generated by factorial combination of 10 parameters. Sensitivity analysis was performed to identify which parameters contribute most to energy performance indicators. Subsequently, decision trees were created using a classification and regression tree (CART) algorithm to visualize parameters and improve energy performance indicators, particularly cooling energy consumption.FindingsLow thermal transmittance and ground contact are interesting strategies for low thermal capacity buildings. Furthermore, the findings showed that relying only on the most influential properties does not ensure good energy performance; rather, it is the adequate combination of envelope properties that leads to good energy efficiency. The tree developed by CART can be used as a guide to assist designers and researchers in the initial selection of building envelopes, demonstrating the impact of each choice on electrical energy consumption for indoor climate control.Originality/valueBy adopting a global approach to assess the thermal performance of lightweight buildings, this study makes a significant contribution to synthesizing the results of a complex and time-consuming methodology into a guide for optimizing envelope design decisions and directing efforts and resources toward efficient strategies.

Moment capacity of cold-formed steel trusses with Howick Rivet Connectors: Tests, modelling and design

Cold-formed steel (CFS) trusses are increasingly used in lightweight building construction. A new type of pin-jointed connector, known as the Howick Rivet Connectors (HRCs), has been developed for CFS trusses. Previous studies focused on testing T-stub connections and shear strengths of CFS trusses with HRCs, providing insights into their structural performance and shear capacity. This paper extends the research by testing ten new CFS trusses with HRCs to determine their moment capacity. The study involved two different cross-sections: lipped channel sections and hat sections, used as truss chords. Variations in the number and locations of lateral supports were introduced to simulate different boundary conditions. A parametric study explored the effects of span-height ratio and variability in lateral support locations on truss strength and failure modes. Finally, the trusses with lipped section chords were designed according to the American Iron and Steel Institute (AISI 2016) and Australia/New Zealand standards (AS/NZS 2018), achieving an average test-to-design strength ratio of 0.86.

Experimental analysis of the influence of PCM on the thermal behavior of lightweight buildings in different natural environments

Phase-change materials (PCM) can effectively improve the thermal performance of lightweight buildings, but their heat storage and release capacity are highly dependent on the heat exchange between the wall surface and the ambient environments. However, the current research mostly focuses on numerical simulation in a specific climate environment, and the effectiveness of PCM on the thermal regulation of lightweight buildings under a long-period natural environment is insufficient. Therefore, two experimental rooms (with and without PCM) of the same size were built and conducted in this paper to compare the changing rules of wall surface temperature, heat flux, and indoor temperature in different seasons without mechanical equipment. The results show that: (1) The effect of PCM on the thermal performance of lightweight buildings is highly correlated with seasons, and its contribution efficiency varies in different seasons; (2) The attenuation rate of the internal surface temperature in different seasons can be reduced by 18.08%–42.90 %, the delay time can be improved to 2.67–4 h compared with the reference wall; (3) PCM can effectively inhibit the fluctuation and rise of indoor temperature, which can reduce the maximum indoor temperature by 4.9–12.0 °C, increase the minimum temperature by 1.1–2.8 °C, and the thermal comfort hours added by 2–5 h; (4) Lightweight buildings incorporating PCM can saves 18.69 % and 49.63 % for the peak cooling in summer and transition seasons, and 15.9 % for the heating in winter. The research results can provide the theoretical basis and experimental support for the efficient application of PCM in lightweight buildings.

Scenario analysis of supply‐ and demand‐side solutions for circular economy and climate change mitigation in the global building sector

AbstractResidential and non‐residential buildings are a major contributor to human well‐being. At the same time, buildings cause 30% of final energy use, 18% of greenhouse gas emissions (GHGE), and about 65% of material accumulation globally. With electrification and higher energy efficiency of buildings, material‐related emissions gain relevance. The circular economy (CE) strategies, narrow, slow, and close, together with wooden buildings, can reduce material‐related emissions. We provide a comprehensive set of building stock transformation scenarios for 10 world regions until 2060, using the resource efficiency climate change model of the stock–flow–service nexus and including the full CE spectrum plus wood‐intensive buildings. The 2020–2050 global cumulative new construction ranges from 150 to 280 billion m2 for residential and 70‐120 billion m2 for non‐residential buildings. Ambitious CE reduces cumulative 2020–2050 primary material demand from 80 to 30 gigatons (Gt) for cement and from 35 to 15 Gt for steel. Lowering floor space demand by 1 m2 per capita leads to global savings of 800‐2500 megatons (Mt) of cement, 300‐1000 Mt of steel, and 3‐10 Gt CO2‐eq, depending on industry decarbonization and CE roll‐out. Each additional Mt of structural timber leads to savings of 0.4‐0.55 Mt of cement, 0.6‐0.85 Mt of steel, and 0.8‐1.8 Mt CO2‐eq of system‐wide GHGE. CE reduces 2020–2050 cumulative GHGE by up to 44%, where the highest contribution comes from the narrow CE strategies, that is, lower floorspace and lightweight buildings. Very low carbon emission trajectories are possible only when combining supply‐ and demand‐side strategies. This article met the requirements for a gold‐gold JIE data openness badge described at http://jie.click/badges.

Assessment of Physico-Chemical Behavior and Sorptivity-Diatomaceous Earth as Support for Paraffinic Phase-Change Materials.

Diatomite's most common application is its use as a sorbent for petroleum substances. Since paraffin is a petroleum derivative, this paper investigates the sorption capacity of diatomite to absorb it. In this paper, the physical and chemical properties were studied for 4 different fractions of diatomite (0-0.063 mm; 0-2 mm; 0.5-3 mm; and 2-5 mm) in the crude and calcined states, and the sorption capacity of diatomite earth for absorbing paraffinic phase-change substances was determined. The physical and chemical studies of the material included conducting an oxide chemical composition analysis using XRF, examining the composition of the mineral phases using X-ray diffraction, and determining the particle size, porosity, and thermal conductivity of the diatomite. Morphology images were also taken for all 8 diatomite variants using scanning electron microscopy. Each fraction was subjected to static calcination at 850 °C for 24 h. The results showed that the calcination of the diatomite increased the porosity of the material and reduced the thermal conductivity coefficient, and most importantly, the sorption capacity to absorb paraffins. The highest sorption capacity was characterized by calcined diatomite powder, that is, diatomite with the smallest particle size. Absorption of paraffinic substances by diatomite exceeding 200 wt.% is possible. Thus, diatomite is one of the feasible candidates for an economical and lightweight building material for making PCM composites for thermal energy storage in buildings.

Petrography and geomechanical properties of some mine waste rocks from the Tarkwaian Group in Ghana: implications for their use as aggregates in general engineering works

This research investigated some mine waste rocks from the southwestern part of the Tarkwaian Group in Ghana to check their suitability for general engineering works using petrography and geomechanical characteristics of the rocks. The rocks were subjected to a total of ten (10) tests, including Aggregate impact value (AIV), Aggregate crushing value (ACV), Loss Angeles abrasion (LAA), Specific gravity (SG), and Water absorption (WA), as well as flakiness and elongation index, slake durability (SD), chloride test (CT), sulphate test (ST), and ten percent fines (TPF). The tests were carried out per the American Society for Testing and Materials guidelines (ASTM). The following average test results were obtained: AIV (7.12%), ACV (15.60%), LAA (23.16%), TPF (269.7 kN), sulphate (0.0215%), chloride (0.00123%), flakiness (39.5%) and elongation (39.4%). The mine waste rocks are dominated by quartz and sericite, according to the petrographic examination and thus, can be classified as quartzites. Except for the flakiness and elongation index tests, all the results were consistent with the ASTM standards. The analysis carried out on the selected mine waste rocks from the southwestern part of the Tarkwaian Group could be catastrophic for heavy engineering works such as roads, bridges, and heavy buildings but can be used for pavements, lightweight buildings, monuments, and decoratives due to the percentage of quartz present to compensate for the weakness posed by the sericite.

Wood ash-based binders for lightweight building materials: Evaluating the influence of hydraulic lime and cement on the setting and mechanical properties of wood ash pastes

The shift from fossil fuels to bioenergy has led to increased wood ash output. Since a large proportion of this waste ends up in landfills, recycling wood ash in construction materials is one of sustainable approaches of managing this by-product. However, the amount of biomass ashes currently recycled in building materials is still limited. This study therefore explored the feasibility of valorising four different types of wood ashes in large quantities in the production of lightweight building materials. Thirty pastes with different levels (80, 90, 95 and 100 wt%) of wood ash and (0, 5, 10 and 20 wt%) of natural hydraulic lime (NHL) or ordinary Portland cement (PC) were developed. Partial replacement of wood ash (WA) by NHL or PC accelerated the setting and improved the mechanical properties of blended pastes. The initial and final setting times decreased with increasing NHL or PC content in the mixes. The strength of the pastes increased with increasing NHL or PC levels and curing time. However, wood bottom ash (WBA) mixes were controversial because their mechanical properties gradually weakened over time. For WA-NHL blends, the 28-day flexural and compressive strength ranged from 0.02 to 1.12 MPa and from 0.05 to 2.59 MPa, respectively. On the other hand, for WA-PC pastes, the flexural and compressive strengths at 28 days varied from 0.07 to 2.72 MPa and from 0.13 to 5.49 MPa, simultaneously. These results prove that wood ash can be used effectively as a main component of binding matrices for lightweight building materials.

An Improved YOLOv5s Model for Building Detection

With the continuous advancement of autonomous vehicle technology, the recognition of buildings becomes increasingly crucial. It enables autonomous vehicles to better comprehend their surrounding environment, facilitating safer navigation and decision-making processes. Therefore, it is significant to improve detection efficiency on edge devices. However, building recognition faces problems such as severe occlusion and large size of detection models that cannot be deployed on edge devices. To solve these problems, a lightweight building recognition model based on YOLOv5s is proposed in this study. We first collected a building dataset from real scenes and the internet, and applied an improved GridMask data augmentation method to expand the dataset and reduce the impact of occlusion. To make the model lightweight, we pruned the model by the channel pruning method, which decreases the computational costs of the model. Furthermore, we used Mish as the activation function to help the model converge better in sparse training. Finally, comparing it to YOLOv5s (baseline), the experiments show that the improved model reduces the model size by 9.595 MB, and the mAP@0.5 reaches 82.3%. This study will offer insights into lightweight building detection, demonstrating its significance in environmental perception, monitoring, and detection, particularly in the field of autonomous driving.

Contour Extraction of UAV Point Cloud Based on Neighborhood Geometric Features of Multi-Level Growth Plane

The extraction of UAV building point cloud contour points is the basis for the expression of a three-dimensional lightweight building outline. Previous unmanned aerial vehicle (UAV) building point cloud contour extraction methods have mainly focused on the expression of the roof contour, but did not extract the wall contour. In view of this, an algorithm based on the geometric features of the neighborhood points of the region-growing clustering fusion surface is proposed to extract the boundary points of the UAV building point cloud. Firstly, the region growth plane is fused to obtain a more accurate segmentation plane. Then, the neighboring points are projected onto the neighborhood plane and a vector between the object point and neighborhood point is constructed. Finally, the azimuth of each vector is calculated, and the boundary points of each segmented plane are extracted according to the difference in adjacent azimuths. Experiment results show that the best boundary points can be extracted when the number of adjacent points is 24 and the difference in adjacent azimuths is 120. The proposed method is superior to other methods in the contour extraction of UAV buildings point clouds. Moreover, it can extract not only the building roof contour points, but also the wall contour points, including the window contour points.

Preparation of egg-structured ceramsites from molybdenum tailings with improved properties

Conversion of solid waste tailings into building materials is an effective way to turn waste into resources as well as resolve the problems of their accumulation and pollution. Herein, in this paper, light-weight and high strength molybdenum tailings ceramsites (LHMCs) were prepared using molybdenum tailings as the main raw material supplemented with fly ash, sludge, steel slag and other solid wastes by egg-structure (three-layer structure) design and high-temperature sintering. The effects of raw material ratio, amount of carbon powder agent, sintering temperature, and sintering time on the properties of LHMCs were investigated, and the optimal preparation process was proposed to be preheating at 400 °C for 60 min and sintering at 1150 °C for 40 min. The results of the physicochemical properties, morphology, and component analysis of LHMCs show that the LHMCs with egg-structure including porous core, reinforced middle layer, and dense outer layer can significantly increase the strength of the ceramsites under the premise of ensuring the low density of the ceramsites. Meanwhile, the doping of molybdenum tailings improves the physical properties of the ceramsites and achieves the reuse of waste tailings. Importantly, the optimized LHMCs can meet the performance requirements of 900-grade ceramsites. This paper proposes a strategy for the preparation of tailings-doped light-weight and high-strength ceramic building materials, which provides a new idea for the recycling of solid waste.

Diminishing benefits of thermal mass in Iranian climate: Present and future scenarios

Thermal mass, a pivotal element in a building's performance, functions as an indoor thermal buffer. While literature underscores its advantages, the enduring impact of thermal mass amid climate change remains uncertain. This study methodically assesses thermal mass effects in 21 Iranian cities across contemporary and future climates, juxtaposing heavyweight and lightweight constructions. The EPSAP algorithm, a generative building design method, created a dataset of two-story single-family houses. Cooling and heating demands were evaluated in EnergyPlus, accounting for current and future system design efficiencies. Future climates were simulated using EC-Earth3 model estimations for the SSP5-8.5 scenario in 2050 and 2080 timeframes. The findings reveal that the energy efficiency advantage of heavyweight over lightweight buildings will diminish by up to 0.60 kW·h·m−2 in 2050 (40 % less than the present-day climate difference between constructions) and 0.93 kW·h·m−2 in 2080 (63 %) for cities in central and southern regions. The performance differences between constructions will sometimes be null, making thermal mass negligible. Conversely, only three cities in Northern Iran exhibit an opposing trend for mid to very-high thermal transmittances. Regarding building geometry, heavyweight construction correlates strongly with indexes related to building compactness, while lightweight construction aligns more with glazing-related indexes. However, as climates warm or we move towards warmer regions, discernible differences between lightweight and heavyweight constructions vanish for both shape- and glazing-related indexes. In conclusion, although the use of thermal mass will be less effective, building design professionals will have greater latitude for innovative construction and design solutions.

Preparation of Hydrophilic and Fire-Resistant Phytic Acid/Chitosan/Polydopamine-Coated Expanded Polystyrene Particles by Using Coating Method

Expanded polystyrene (EPS) particles are commonly used for thermal insulation in lightweight building materials due to their low density, low thermal conductivity, and affordability. However, shortcomings such as hydrophobicity and poor fire safety limit the application of EPS. Bio-based flame retardants have been developed for use in polymer composites due to their renewable, environmentally friendly, and non-toxic properties. In this study, to improve the hydrophilicity and fire resistance of EPS particles, phytic acid (PA)/chitosan (CS)–polydopamine (PDA)@EPS particles (PA/CS-PDA@EPS) with a bio-based coating were prepared by using a simple coating method based on PDA@EPS particles using PDA as an adhesive and PA and CS as bio-based flame retardants. The results showed that the modified EPS particles had good hydrophilicity, the residual carbon yield of the 10PA/3CS-PDA@EPS samples was increased to 24 wt%, and the maximum loss rate was reduced by 69% compared with unmodified EPS. In flammability tests, the 10PA/3CS-PDA@EPS samples also demonstrated low flame spread and some fire resistance. Furthermore, the modified EPS particles exhibited fire resistance even after multiple washings. The hydrophilic and fire-resistant modified EPS particles are anticipated to offer a novel approach to the advancement of EPS-based lightweight building materials.

Review on Aerated Lightweight Concrete Challenges and Application

This study explores the use of environmentally friendly Aerated Lightweight Concrete (ALC) in constructions, focusing on its versatility and adaptability to various densities. The growing demand for lightweight building materials with excellent strength-to-weight ratios has led to an expansion in the use of ALC over the past decade. The focus is on creating customized ALC for specific uses, rather than introducing novel materials. The article analyzes the primary variables affecting ALC use, such as raw materials, manufacturing processes, and anticipated density-based features. The review aims to demonstrate how ALC's physical and mechanical properties can be altered for building applications using new and alternative raw materials.

Biomimetic versatile wood hybrids with gradient structure towards lightweight, high strength, fire-retardant, and deterioration-resistant materials

The development of versatile wood-based biomaterials with integrated low density, high surface hardness, high strength, fire-resistance, anti-decay, and termite-resistance is highly desirable, yet challenging to skillfully fabricate. Inspired by the ubiquity of gradient biostructures in nature, we achieve biomimetic gradient densification structures by controlling the distribution of thermal-moisture fields within the wood, and combine this with in-situ curing of polyacrylic acid/borate supramolecular resins within the wood cells to transform bulk natural wood into lightweight, high strength, and multifunctional materials. The optimally gradient-densified hybrid wood, with a slight increase in density, demonstrates markedly improved mechanical properties (≈2.4 × increase in surface hardness, ≈52 % increase in flexural strength), excellent dimensional stability, and leaching resistance. In addition, the collaboration of the gradient-densified structure and the in-situ cured acrylic resin/borate supramolecular network provides the biomimetic wood hybrids with excellent fire resistance (V-0 rating in fire retardant grade, 74 % reduction in total smoke release, ≈2.5 × increase in fire performance index), decay and mildew resistance (mass loss of less than 10 %), as well as termite resistance (100 % protection efficiency and termite kill rate) properties. It is the first report to combine gradient densification with in-situ curing of supramolecular resins in the structural design and functionalization of wood-based composites. This new design principle provides guidance for fabricating advanced all-in-one wood materials with applications in lightweight, strong, fire-resistant, deterioration-resistant, and scalable building and furniture materials.

Influence of the shading nets on indoor thermal environment and air-conditioning energy consumption in lightweight buildings

Lightweight envelopes are increasingly utilized in temporary relief and shelter buildings, due to their cost-effectiveness and efficient construction process. However, these envelopes often result in inadequate indoor thermal conditions during the summer months, which can negatively impact the physical and psychological well-being of occupants, particularly victims and patients in disaster or epidemic situations. Addressing this challenge necessitates the use of simple yet effective materials and technologies to improve indoor thermal environments even with limited resources. This study explores the potential of shading nets to enhance indoor thermal conditions in lightweight buildings by mitigating solar radiation gain during the summer period. A comparative experiment was conducted on two lightweight buildings, one of which was equipped with standard six-needle black shading nets, to assess the impact of shading nets on the indoor thermal environment and air-conditioning energy consumption. The findings reveal that shading nets can reduce solar radiation intensity by approximately 57.86%, resulting in a significant decrease in peak indoor air temperatures by 2.3°C to 3.4°C under natural ventilation and a reduction in air-conditioning energy consumption by up to 23% under air-conditioned conditions. These findings demonstrate that shading nets are effective in improving indoor comfort and reducing energy usage, providing a practical solution for enhancing living conditions in lightweight structures during hot weather.

A lightweight building change detection network with coordinate attention and multiscale fusion

A lightweight building change detection network with coordinate attention and multiscale fusion