Search Results (625)

This article concerns the issue of contactless estimation of the complex electrical permittivity of masonry materials by means of a microwave technique in the frequency domain. The main aim of the study was to develop a method enabling the determination of the real part of relative permittivity and the electrical conductivity of ceramic building materials using microwave reflection measurements, as well as to assess the applicability of the proposed approach for moisture diagnostics in porous media. The research was performed using a reflection-mode measuring setup comprising a vector network analyser and a broadband horn antenna, while measurements were carried out in the frequency range from 1 to 6 GHz on samples of solid ceramic brick with six gravimetric moisture levels. A one-dimensional model of electromagnetic wave propagation in the material was developed, considering complex permittivity, impedance transformation, and a calibration procedure compensating for the influence of the antenna and free-space propagation. Based on the fitting of the magnitude and phase characteristics of the reflection coefficient, the electrical parameters of the tested samples were estimated. The results obtained showed an increase in both permittivity and conductivity with increasing moisture content and revealed very good agreement with the reference values determined using the time-domain method. It can be concluded that the frequency-domain microwave approach may be effectively applied for contactless and non-destructive diagnostics and estimation of the dielectric properties and moisture content in ceramic materials. Full article

Using solid waste as supplementary cementitious materials (SCMs) is an effective strategy for promoting low-carbon construction development. However, single or binary systems often exhibit mismatched reaction kinetics, thereby limiting their performance at high cement replacement rates. This study focuses on a novel low-carbon concrete designed based on reaction sequence coordination, containing recycled brick powder (RBP), ground granulated blast-furnace slag (GGBS), and self-combusting coal gangue (SCCG). The effects of RBP, GGBS, and SCCG on the hydration process and microstructure of the novel low-carbon concrete with different replacement levels have been studied by testing compressive strength, workability, and durability and observing microstructural changes. The results showed that an optimized ternary composition with an RBP:GGBS:SCCG ratio of 4:3:1 achieves a cement replacement level of 30% while exhibiting a 28-day compressive strength of 38.26 MPa, representing a 14.2% increase compared with plain cement mortar. Microstructural analyses indicate that this enhanced performance results from a time-dependent reaction sequence, in which GGBS contributes predominantly at early ages by supplying calcium, whereas RBP and SCCG mainly participate through delayed pozzolanic reactions and pore refinement at later ages. Consequently, the optimized ternary mortar exhibits a water absorption of 11.12% and a 27.2% reduction in electrical flux. This study aims to provide practical strategies for enhancing the performance of low-carbon cementitious materials through a reaction sequence coordination design approach, thereby improving the utilization efficiency of solid waste in the production of low-carbon building materials. Full article

Aging populations have intensified the demand for thermally comfortable and energy-efficient housing, particularly for elderly residents whose diminished thermoregulatory capacity renders them disproportionately vulnerable to indoor temperature fluctuations. Existing senior apartments in cold-climate regions frequently fail to meet age-specific thermal comfort standards, yet systematic retrofit optimization frameworks explicitly tailored to elderly occupants remain scarce. This study presents a data-driven multi-objective optimization framework for building envelope retrofitting, which is validated using on-site temperature measurements from a representative 1980s brick–concrete senior apartment building in Beijing. The framework integrates Latin Hypercube Sampling (LHS) for design space exploration, a Long Short-Term Memory (LSTM) surrogate model for simultaneous prediction of three performance objectives, and Non-dominated Sorting Genetic Algorithm II (NSGA-II) for Pareto-optimal solution generation, with final selection performed via a weighted Mahalanobis distance-based Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS). Optimization targets—annual energy consumption, indoor thermal discomfort hours, and retrofit cost—are parameterized using the age-sensitive comfort thresholds specified in GB 50340-2016. The LSTM surrogate achieved R² values of 0.91–0.93 across all objectives with training–testing differences below 0.02. The optimal retrofit package—Polyvinyl Chloride (PVC) Low Emissivity (Low-E) double-glazed windows (5 + 6A + 5), glass fiber roof insulation (65.25 mm), and Extruded Polystyrene (XPS) external wall insulation (65.39 mm)—reduces annual energy consumption by 47.1% (from 40,867 to 21,626 kWh) and annual thermal discomfort hours by 62.4% (from 2454 °C·h to 923 °C·h). SHapley Additive exPlanations (SHAP)-based sensitivity analysis further identifies wall U-value and roof thickness as the dominant performance drivers. A reproducible and computationally efficient pathway is provided by the proposed framework for evidence-based envelope retrofit decision-making in existing senior residential buildings. Full article

The sustainable renovation of ageing industrial buildings presents both a challenge and an opportunity to enhance energy efficiency while preserving architectural and structural integrity. This study develops an integrated methodological framework for assessing and optimising multilayer wall systems in such conversions, combining thermal, environmental, and durability analyses. Six composite wall configurations were designed and numerically evaluated using steady-state 2D heat conduction and vapour-diffusion models. The results reveal substantial thermal improvement compared to the reference uninsulated brick wall (U = 1.41 W/m²·K). The proposed systems achieved U-values between 0.351 and 0.172 W/m²·K, meeting or surpassing European energy standards. The BP–EPS wall exhibited the lowest U-value (0.172 W/m²·K), while the FC–EPSR configuration achieved superior corner performance with a 2D surface temperature (Tsi) of 17.99 °C and the highest surface temperature factor (fRsi = 0.943), along with a reduced condensation risk, indicating more balanced overall performance. Weight and thickness reductions of up to 80.5% and 52%, respectively, were observed, enhancing retrofit feasibility and space efficiency. Life Cycle Assessment results indicated that optimised wall configurations reduced embodied carbon (A1–A3) by up to 78% and total life cycle emissions (A1–A3 + B6) by over 86% relative to the reference case. Vapour-diffusion analysis confirmed the FC–EPSR wall’s lowest condensation fraction, indicating excellent hygrothermal durability. Multi-criteria evaluation using the simple additive weighting method and Monte Carlo robustness analysis verified FC–EPSR as the most balanced and reliable system. Overall, the findings present a validated and replicable pathway for the sustainable renovation of industrial buildings, supporting the goals of European carbon neutrality and the circular economy. Full article

Global land use is changing rapidly, particularly in the tropics, where human populations have had relatively high growth rates in recent decades. This has resulted in wildlife increasingly living in or using anthropogenic environments, which often have different thermal properties in comparison to natural habitats. For example, materials used for buildings, such as concrete and brick, typically absorb, retain and radiate more heat than vegetated surfaces. The mosaic of man-made and natural areas formed when anthropogenic environments expand is therefore likely to generate microhabitats with different thermal properties. Here, we investigated the association between microhabitats and the body surface temperature of wild banded mongooses (Mungos mungo), a social mammal living in equatorial Uganda. After controlling for the significant effects of air temperature, humidity, time of day and body contact, we found that mongooses had the highest body surface temperatures when present on anthropogenic substrates, such as discarded roofing straw and refuse, while mongooses present on building materials, dead vegetation and bare soil had intermediate body surface temperatures. In contrast, mongooses had the lowest body surface temperatures when present in more natural, vegetated habitats. Although our study is relatively small scale and limited in scope, our results indicate that anthropogenic modifications to natural environments may result in hotter microhabitats, which may in turn impact space use, movement and thermoregulation in wildlife. We hope that our study encourages further research into this understudied but emerging topic. Full article

Global interest in sustainable building materials is increasing due to growing concerns regarding the environmental impacts of conventional construction materials, particularly fired clay bricks. Compressed Stabilized Earth Blocks (CSEBs) have emerged as a viable, cost-effective, and environmentally sustainable alternative for building construction. The incorporation of waste-derived additives in CSEBs not only addresses waste management challenges but also enhances the functional performance of earthen materials. This study presents a comprehensive synthesis of existing research on the influence of fibers, binders, stabilizers, and production processes on the performance characteristics of CSEBs. A systematic literature review was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 guidelines, resulting in the identification and analysis of 256 relevant studies. The selected literature was synthesized using the Theories, Contexts, Characteristics, and Methodologies (TCCM) framework to map research trends and methodological approaches. The review indicates that fiber reinforcement primarily improves flexural strength and thermal performance, while binders significantly enhance compressive strength and erosion resistance. The findings also demonstrate that selected waste materials can partially replace natural soil, provided minimum material and performance standards are satisfied. The study highlights the need for standardized manufacturing guidelines and testing protocols to improve the reliability, scalability, and wider adoption of CSEBs in sustainable building applications. Full article

This study introduces a hybrid framework that integrates transient numerical simulations with artificial neural networks (ANNs) to analyze and predict heat transfer in building walls. The framework is applied to ten different material–insulation combinations. Using the Leapfrog–Hopscotch (LH) finite difference scheme, we evaluated dynamic heat transfer and identified optimal insulation thicknesses for buildings in the cold continental climate of Bukhara. An ANN model was trained and validated on a dataset generated from 410 simulated wall configurations. The model achieved high predictive accuracy, with a mean squared error below 0.005. The thickness of the outer material layer ranged from 20 cm to 35 cm, while the inner layer thickness varied from 1 cm to 3 cm. Among the materials analyzed, glass wool + steel and gypsum + brick demonstrated superior insulation performance by minimizing heat loss most effectively, with values as low as 361,234 J/m² and 4,983,441 J/m², respectively, at 35 cm wall thickness. These findings underscore the potential of combining ANN-based predictions with physics-based simulations to design energy-efficient building envelopes in cold climates. Full article

This paper presents a new ceramic building material produced by the cold sintering process (CSP), as a greener and cleaner technology compared to conventional ones. The ceramic composites were made from recycled clay bricks (RCBs), a byproduct resulting from construction and demolition and waterglass (WG) as a liquid solvent, pressed at 400 MPa and sintered at a temperature of 150–200 °C. After the samples were produced, their structure and physical and mechanical properties were investigated. The internal morphology of samples shows a homogeneous structure with a low porosity (up to 3%). The compressive strength of ceramic building material produced by the CSP was up to 211 MPa, considerably higher than the reference sample whose value was 45 Mpa. This high strength is due to the internal structure of the ceramic composed of a tough amorphous phase that acts like a binder holding together the powder particles and closing most of the porosity inside the material. Full article

Masonry buildings have shaped construction history since about 6500 BCE. They offer durability, strength, and cost effectiveness, especially in developing countries. Yet assessing compressive strength during construction remains challenging due to the constituent materials soil, cement, and stone, complicating standardization worldwide. In the present study, an innovative model based on a machine learning algorithm is put forth to predict the compressive strengths of prisms. Some important factors considered as input to the algorithm based on traditional methods are the brick and mortar strengths, prism geometry, mortar bed thickness, and empirically derived height-to-thickness (t) (h/t) ratios. Three different ANN algorithms are coded and trained on the input data, and they are based on the Levenberg–Marquardt algorithm, the resilient backpropagation algorithm, and the conjugate gradient algorithm. The optimal ANN model trained using the conjugate gradient Polak–Ribière algorithm (traincgp) achieves superior performance, with R² = 0.9881, R² = 0.9927, RMSE = 0.9914 MPa, MAE = 0.6039 MPa, MAPE = 20.9141%, VAF = 0.9881, and WI = 0.9970. Sensitivity analysis shows the height-to-thickness (h/t) ratio is the dominant influence on compressive strength, consistent with structural mechanics. The primary contributions are the systematically curated, richly parameterized dataset and its use to produce robust, physically interpretable predictions with established ANN methods. Full article

This study evaluates the mechanical and thermal properties of bricks made from polylactic acid (PLA) and recycled polyethylene terephthalate (rPET). A filament-based 3D printer was used with process parameters specific to PLA, while rPET—also known as recycled plastic—was obtained by grinding and compacting products. Brick samples of various dimensions were manufactured to conduct flexural, compressive, and tensile tests. Several samples were used for each test. On the other hand, a thermal conductivity analysis was performed to determine the internal temperature of dwellings, such as a house or a building. Thermal conductivity influences energy efficiency and the thermal comfort of occupants. The macrostructures observed in the NIKON microscope were examined, where the direction of the fibers and their compaction, which significantly influences thermal conductivity, can be seen. A 53.4% reduction in thermal conductivity was determined for the PLA brick compared to the commercial brick, while the rPET brick showed a 6.4% decrease. The evaluation of the tests carried out on the universal testing machine indicates that the brick made from rPET exhibits a higher maximum load and stress compared to the brick made from PLA in all tests. These results suggest that both the manufacturing process and the composition of the material have a significant impact on the mechanical and thermal properties of plastic bricks. In the flexural test, the recycled plastic brick withstood a maximum stress of 16 MPa and a maximum load of 5784 N. Similarly, in the compression test, the recycled plastic brick withstood a maximum load of 9471 N and a maximum stress of 5.83 MPa. During the tensile test, the rPET brick demonstrated a maximum load of 9203.92 N and a maximum stress of 5.64 MPa. These results show that bricks made from recycled plastic have better mechanical properties compared to polylactic acid bricks in the tests carried out and can therefore be considered for use in the construction industry. Full article

In order to realize the large-scale resource utilization of solid waste in building materials, geopolymer mortar was prepared by alkali excitation technology with municipal solid waste incineration fly ash (MSWIFA), waste glass powder (WGP) and metakaolin (MK) as raw materials. After 28 days of curing, compressive strength and heavy metal leaching concentration of MSWIFA-WGP-MK geopolymer mortar were measured. The microstructure and phase composition of geopolymer samples were examined using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis. The results demonstrated that the compressive strength of mortar increased as the MSWIFA content decreased and the alkali activator (AA) content increased. The mortar containing 30% MSWIFA and 35% AA achieved the highest 28-day compressive strength of 70.9 MPa. The high compressive strength was strongly associated with the compact microstructure, as revealed through scanning electron microscopy. The heavy metals in MSWIFA were solidified well in geopolymer matrix, and the leaching concentrations of heavy metals were below the regulatory thresholds. Based on the test results of mortars, concrete pavement bricks were produced. The performance of the optimized concrete paving brick satisfied requirements of the specification. The results indicated that the MSWIFA and WGP can be utilized in building materials. Full article

The chemical and mineral composition, physical and mechanical properties, and pozzolanic activity of ancient bricks from Hubei Province, China were investigated in this study. X-ray diffraction (XRD), thermogravimetric analysis (TG-DSC), X-ray fluorescence analysis (XRF) and scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS) were adopted to characterize the chemical composition, crystalline minerals and microstructure of the ancient bricks. The results show that quartz is the dominant component in most ancient bricks, with a content exceeding 70% in samples BB-2, BB-5, BB-6 and BB-7. Some bricks contain minor non-clay minerals such as calcite, dolomite and albite. On some points in the SEM image, substances such as gypsum, calcite, and quartz can be clearly seen. The calcining temperature of the ancient bricks from Yupan Village, Xiantao City (sample BB-1), does not exceed 600 °C, while that of other samples ranges from 800 to 1100 °C. The compressive strength of most ancient bricks is around 10 MPa, with the highest value of 14.3 MPa (BB-6) and the lowest of 1.2 MPa (BB-3). The apparent density of all samples is approximately 2.2 g/cm³, and the water absorption rate ranges from 6.5% to 23.1%. The pozzolanic activity index of some samples reaches 76% at 28 days, with the 150-year-old sample BB-7 showing the best activity. This study provides a reliable experimental basis for analyzing the weathering resistance and deterioration mechanism of ancient bricks in Hubei Province, offers technical support for the restoration of local ancient buildings, and lays a foundation for the development of antique-style brick craftsmanship. Full article

Building materials have become a predominant source of indoor radon in mid- to high-rise buildings, making in situ measurement of radon exhalation rates from building surfaces essential for identifying radon sources and assessing associated risks. Based on practical survey requirements—addressing sealing leakage at chamber edges and ensuring device portability—this study developed an improved in situ measurement method integrated with leakage compensation through theoretical analysis and experimental validation. The method employs an acrylic accumulation chamber and a portable passive radon detector, adopts a 24 h continuous measurement duration, and processes radon concentration data using an exponential fitting approach. Comparative experiments with the activated carbon method demonstrated good consistency between the two methods. Furthermore, small-scale in situ measurements were conducted in the Beijing area, covering diverse building materials (concrete, brick), surface treatments (cement plaster, coating, wallpaper), and structural components (walls, floors). The results, which varied widely from 0.13 ± 0.11 to 28.00 ± 4.87 Bq/m²·h, confirm the reliability and applicability of the method for in situ determination of radon exhalation rates from interior building surfaces. Full article

In many densely populated towns and semi-urban areas, masonry buildings often stand close to busy roads, exposing them to blasts from improvised explosives or other localized sources. Such structures are rarely designed to resist sudden explosive forces, making severe damage or even progressive collapse likely. Even moderate-intensity blasts can weaken walls, endanger occupants, and cause significant property loss. Unlike reinforced concrete, masonry is highly susceptible to explosive impact. Therefore, understanding how these buildings behave under blast loads and developing affordable protection methods is crucial. Low-rise unreinforced masonry (URM) structures, usually up to about 13 m in height (roughly 2–4 stories), common in villages, semi-urban regions, and conflict-prone zones, are particularly at risk. In many areas, these poorly constructed buildings lack proper engineering design and are therefore highly vulnerable to blast damage. Non-load-bearing internal dividers and perimeter enclosures are especially prone to lateral displacement, which can initiate instability and, in severe cases, lead to overall structural failure. This research focuses on reducing catastrophic damage in URM walls when exposed to close-proximity blast forces using concrete-based protective coatings, both with and without embedded steel-welded wire mesh. The study references a previously tested laterally supported clay brick wall built with cement–sand mortar as the baseline model, with its behavior validated against experimental findings from existing literature. Two blast cases were considered corresponding to scaled stand-off distances of 2.19 m/kg^1/3 and 1.83 m/kg^1/3, representing moderate flexural-shear cracking and full structural failure, respectively. To replicate the observed behavior, a comprehensive 3D numerical simulation was developed using the ABAQUS/Explicit 2020 solver. The model’s predictions were benchmarked and verified through comparison with reported test data. While both blast intensities were used to confirm computational accuracy, the effectiveness of UHPC and UHPFRC protective coatings with and without embedded wire mesh was specifically evaluated under the more severe collapse scenario (Z = 1.83 m/kg^1/3). Results indicated that at a scaled distance of 1.83 m/kg^1/3, the uncoated URM wall could not withstand the blast because of poor tensile and bending capacity. In contrast, the UHPC- and UHPFRC-coatings provided improved confinement and better stress distribution. When welded wire mesh was embedded, crack control improved further, the interface bond strengthened, and a larger portion of blast energy was absorbed and dissipated. Full article

Central business district (CBD) hospitals must sustain reliable pressure relationships in critical rooms while reducing whole-facility carbon under tight space and disruption constraints. We developed an ontology-grounded semantic digital twin that normalizes building automation system (BAS) and building management system (BMS) telemetry into a unified semantic store consistent with Brick Schema, enabling portable asset discovery via query and thereby supporting forecasting, anomaly detection, and multi-objective optimization without dependence on vendor point naming conventions. Whole-facility impacts were verified using International Performance Measurement and Verification Protocol Option C–style measurement and verification with an S0-calibrated baseline model and residual-based savings attribution. Relative to the baseline (S0), the intervention (S3) produced a step increase in the critical-room pressure-compliance pass rate, tighter room-to-corridor differential-pressure (ΔP) control across airborne infection isolation and open room strata, and intent-aligned ventilation delivery (air changes per hour ratio distribution concentrated near unity; p < 0.05 where letter groups differ). Operational-state discrimination improved (AUC 0.649→0.696) and issue-resolution times shortened (left-shifted cumulative distribution function), indicating reduced service burden. Option C verification showed energy residuals shifting negative under S3, consistent with net savings versus baseline expectations. Across progressive maturity (S0→S3), time-to-value and burden fractions decreased, carbon intensity (tCO₂e m⁻²) decreased, long-tail exposure compressed (log-scale horizon), and composite performance indices increased (p < 0.05). These results demonstrate a verifiable pathway to pressure-reliable, decarbonized hospital operations at the whole-facility boundary while making the semantic layer’s utility explicit through query-driven, ontology-grounded asset discovery. We present an IPMVP Option-C–verifiable semantic digital-twin governance framework that links audited operational evidence (telemetry → actions → verification) to whole-facility energy and carbon outcomes while maintaining critical-room pressure-relationship reliability. Optimization benchmarking (including quantum annealing) is used as supporting decision-support evaluation, rather than as the central contribution. Full article