Search Results (1,738)

This study experimentally and numerically examines the structural and seismic performance of recycled solid-brick masonry infills and load-bearing walls constructed from demolition materials. Solid bricks recovered from demolished structures were reused as infill in reinforced concrete (RC) frames and as standalone walls. Five full-scale panels, bare, 50% infilled, and 100% infilled frames, were tested under diagonal compression in accordance with ASTM E519-17, simulating in-plane seismic loading. Results showed that fully infilled frames exhibited a 149% increase in diagonal shear strength but a 40% reduction in ductility relative to the bare frame, indicating a trade-off between stiffness and deformation capacity. Finite element simulations using the Concrete Damaged Plasticity (CDP) model reproduced the experimental load–displacement curves with close agreement (within 6–8% in peak load) and captured the main failure patterns. Reusing cleaned demolition bricks reduces the demand for new fired bricks and helps divert construction waste from landfill, contributing to sustainable and circular construction. The findings confirm the potential of recycled masonry for low-carbon and seismic-resilient construction, provided that ductility limitations are appropriately addressed in design. Full article

The aim of this study was to rigorously quantify and analyse the concentrations of atmospheric pollutants (PM₁₀, PM_2.5, SO₂, NO₂, CO, H₂S, and O₃) emitted by artisanal brick kilns in Juliaca City, Peru. The AERMOD dispersion model and a network of low-cost sensors (LCSs) were employed to characterise air quality at specific receptor sites. A georeferenced inventory of kiln operations was created to determine their parameters and operational intensity, providing a foundation for estimating emission factors and rates. Data were obtained from the United States Environmental Protection Agency (EPA) and supplemented with locally gathered meteorological records, which were processed for integration into the AERMOD model. The findings revealed that brick kilns are a principal source of atmospheric pollution in the region, with carbon monoxide (CO) emissions being especially pronounced. The LCSs facilitated the identification of pollutant concentrations at various locations and enabled the quantification of the specific contribution of brick production to ambient aerosol levels. Comparative assessments determined that these sources account for approximately 85% of CO emissions within the study area, underscoring a significant adverse impact on air quality and public health. Background pollutant levels, emission rates, spatial distributions, and concentration patterns were analysed within the assessment zones, resulting in solid model performance. These results provide a sound scientific basis for the formulation and implementation of targeted environmental mitigation policies in urban areas and the outskirts of Juliaca. Full article

Amphibians face a global conservation crisis, driven largely by habitat degradation. Effective and practical strategies for habitat restoration are urgently needed, particularly for Critically Endangered species in human-impacted ecosystems. Telmatobius philippii is a species classified as Critically Endangered by the IUCN. Its habitat is restricted to a few thermal springs in the Ascotán salt flat in Chile. A significant portion of one of these springs, V11, dried up in 2005 due to industrial groundwater withdrawals, leading to the loss of natural refuges and population decline. As part of a recovery plan for this spring we implemented a habitat improvement program by installing artificial refuges (clay tiles, bricks, and rock piles) and monitored their use over a two-year period. The results indicated that the refuges, particularly the clay tiles, were utilized by T. philippii at all life stages (larvae, juveniles, and adults). Refuge occupancy increased over time, reaching 75% by the end of the study, and the presence of eggs and early-stage larvae confirmed successful breeding associated with the artificial structures. This demonstrates the positive effect of artificial refuges as a practical tool for the recovery of Telmatobius populations. To our knowledge, this study provides the first documented case of successful habitat enhancement for this threatened group of high Andean amphibians, offering a replicable strategy for conservation in fragile ecosystems. Full article

The construction industry’s growth is causing a surge in CO₂ emissions, driven by increased demand for concrete and other building materials. There is a growing demand for more sustainable building materials, including alkali-activated materials. This study investigates the impact of varying ratios of Na₂SiO₃ and NaOH on the mechanical properties and microstructure of metakaolin (MKW) and ceramic brick waste (CBW) based geopolymer binder. Geopolymer binder precursors were made of three main CBW/MKW ratios: 100/0%wt. (C100), 50/50%wt. (C50M50), and 0/100%wt. (M100). Alkaline activator solutions had three different Na₂SiO₃/NaOH ratios: 0.5, 1.0, and 2.0. The investigation into the geopolymer binder mechanical properties was conducted using a range of analytical methods, including compressive strength, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The findings of the study indicate that the Na₂SiO₃/NaOH ratio alone is inadequate for evaluating geopolymer mechanical properties when different AS/P ratios are employed, given its influence on other parameters, such as the W/S ratio and the total Na₂O content. CBW-based geopolymer binders demonstrate limited capacity to attain substantial compressive strengths because they contain high amounts of unreacted CBW particles, as shown by XRD analysis. The incorporation of MKW precursor resulted in enhanced reactivity and intensified geopolymerization reaction. After the evaluation of all essential ratios, the most favorable Na₂SiO₃/NaOH ratio is 1.0. This determination was based on the highest strengths observed in designs that contained ≥50% of MKW precursor, attributed to predominance of goosecreekite and N-A-S-H gels, as evidenced by XRD and FT-IR analysis. Full article

In the production of modern nongxiangxing daqu, mechanical stamping is utilized to compact raw materials into daqu bricks. Nevertheless, variations in stamping frequencies may modify the initial physicochemical properties of daqu, which in turn influence its physicochemical and biochemical parameters, and ultimately affect the quality of baijiu. This study systematically evaluated daqu samples prepared with different stamping frequencies (2 to 5 cycles) in terms of (1) physicochemical and biochemical parameters, (2) volatile compound profiles, (3) microbial community dynamics, and (4) interspecific interactions. The results showed that with the increase in stamping frequency, the moisture content, fermentative power, esterifying power, and liquefying power of daqu were all enhanced, with respective increases of 20.11%, 67.16%, 12.24-fold, and 36.27%. Specifically, the relative abundances of Weissella, Lactobacillus, Aspergillus, and Rasamsonia in daqu exhibited a significant increase with the elevation of pressing cycles. With the reduction in stamping frequency, the primary producers of flavor compounds shifted gradually from bacteria to fungi. These findings verify that stamping frequency exert a substantial regulatory impact on the physicochemical and biochemical parameters, microbial community dynamics, accumulation of flavor substances, and abundance of functional enzymes in daqu. Through a systematic elucidation of the mechanistic links between stamping parameters and daqu functionalities, this research offers actionable insights for optimizing industrial pressing processes and establishes a scientific basis for modern daqu production. Full article

The increasing demand for sustainable construction materials has prompted the recycling of construction and demolition waste in concrete manufacturing. This study investigates the feasibility of utilizing porcelain and brick waste as partial substitutes for natural sand in concrete with the objective of improving sustainability and preserving mechanical and durability characteristics. The experimental program was conducted in three consecutive phases. During the initial phase, natural sand was partially substituted with porcelain waste powder (PWP) and brick waste powder (BWP) in proportions of 25%, 50%, and 75% of the weight of the fine aggregate. During the second phase, polypropylene fibers were mixed at a dosage of 0.5% by volume fraction to enhance tensile and flexural properties. During the third phase, zinc oxide nanoparticles (ZnO-NPs) were utilized as a partial substitute for cement at concentrations of 0.5% and 1% to improve microstructure and strength progression. Concrete samples were tested at curing durations of 7, 28, and 91 days. The assessed qualities encompassed workability, density, water absorption, porosity, compressive strength, flexural strength, and splitting tensile strength. Microstructural characterization was conducted utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The findings indicated that porcelain waste powder markedly surpassed brick waste powder in all mechanical and durability-related characteristics, particularly at 25% and 50% sand replacement ratios. The integration of polypropylene fibers enhanced fracture resistance and ductility. Moreover, the incorporation of zinc oxide nanoparticles improved hydration, optimized the pore structure, and resulted in significant enhancements in compressive and tensile strength throughout prolonged curing durations. The best results were obtained with a mix of 50% porcelain sand aggregate, 1% zinc oxide nanoparticles as cement replacement, and 0.5% polypropylene fibers, for which the improvements in compressive strength, flexural strength, and splitting tensile strength were 39.5%, 46.2%, and 60%, respectively, at 28 days. The results confirm the feasibility of using porcelain and brick waste as sand replacements in concrete, as well as polypropylene fiber-reinforced concrete and polypropylene fiber-reinforced concrete mixed with zinc oxide nanoparticles as a sustainable option for construction purposes. Full article

Summer–autumn green tea (SAGT) is a high-yield green tea often compromised by pronounced bitterness, astringency and a weak aroma, which severely limit its consumer acceptability and economic value. To enhance its quality, this study employed solid-state fermentation with Eurotium cristatum, the core probiotic fungus in Fu brick tea (FBT), to investigate its effects on the physicochemical, sensory, and volatile profiles of SAGT. The findings showed that after fermentation, the tea leaves developed a golden-yellow color, and the tea infusion turned brown. Moreover, the contents of flavonoids, tea polyphenols, soluble sugars, catechins, and free amino acids showed decreases of 3%, 33%, 38%, 41%, and 48%, respectively, when compared to SAGT. At the same time, the astringency and bitterness levels of the infusions significantly diminished (p < 0.05) post-fermentation, and the 8-day fermented tea sample was the most preferred by the sensory panel. During fermentation, E-nose, GC-MS, and GC-IMS analyses revealed a substantial transformation of the volatile profile, with a total of 104 and 129 volatile organic compounds (VOCs) were identified using GC-MS and GC-IMS techniques, respectively. The ROAV analysis highlighted 22 aroma-active compounds, particularly linalool and methyl salicylate, whose values increased significantly (p < 0.05), reaching values of 19,561.95 and 109.56, respectively, making them key contributors to the prominent floral and minty fragrance in the fermented tea. Additionally, PLS-DA analysis revealed 22 and 33 differential VOCs in the GC-MS and GC-IMS methods, respectively, with the majority stemming from the PAL and MEP metabolic pathways. This study provides theoretical insights aimed at enhancing the flavor quality of SAGT. Full article

A pilot-scale reactor prototype was designed to produce hydrocarbons through the catalytic pyrolysis process of low-density polyethylene, thereby extending its life cycle and contributing to energy efficiency and sustainability. The reactor consists of a stainless-steel tank encased in a ceramic jacket with refractory cement and clay bricks. The tank, made of 304 stainless steel, ensures mechanical strength and efficient heat transfer to the reactor core. A spiral condenser was incorporated into a water tank to cool the vapors and recover the liquid oil. The insulating materials, ceramic, refractory cement and clay brick, demonstrated a high combined thermal resistance of 0.159 m²·K/W. Simulations and energy flow calculations demonstrated that heat is efficiently directed to the reactor core, reaching 350 °C with only 3000–3800 W, while the outside of the jacket remained close to 32 °C. These results confirm that the proposed design improves thermal efficiency and optimizes energy use for catalytic pyrolysis. The novelty of this design lies in its energy-efficient configuration, which can be replicated in rural regions worldwide due to the accessibility of its construction materials. This reactor was developed based on a smaller-scale model that previously yielded excellent results. Full article

Pakistan’s housing sector faces a significant shortfall alongside growing climate risks. This study assesses climate-smart construction options autoclaved aerated concrete (AAC) blocks, interlocking bricks, and rat-trap bond masonry through energy simulations, cost modeling, and expert consultations. A 10-Marla residential unit in Islamabad was used as the reference case. Results indicate AAC reduces cooling energy by 22%, interlocking bricks reduce construction costs by 26.6%, and rat-trap masonry lowers electricity use by 12–16%. Despite technical viability, adoption remains limited due to financing and regulatory barriers. The study proposes a phased policy roadmap to integrate low-carbon materials into Pakistan’s housing and climate adaptation strategies. Full article

Brick tea is a type of post-fermented food that involves microorganisms. Long-term consumption of brick tea exposes consumers to high fluoride levels, which can adversely affect their health. This study explored the feasibility of selective defluorination of Qingzhuan brick tea through membrane separation technology, and pilot production was conducted to produce defluorinated instant brick tea. The concentration of tea polyphenols increased by more than 10 times after nanofiltration, demonstrating the high selectivity of nanofiltration membranes toward fluoride. Defluorination trends were studied at different initial material concentrations (0.5–4%) and operating pressures (0.1–0.5 MPa) under cyclic defluorination. Defluorinated instant brick tea products were also industrially prepared using 300- (DF-300) and 1000-Da (DF-1000) membranes, followed by vacuum freeze-drying. The DF-1000 and DF-300 products exhibited a defluorination rate of 51.46% and 67.96%, respectively. The products have excellent characteristics in terms of color, aroma, and flavor quality, as well as solubility. Gas chromatography–mass spectrometry indicated that the volatile components in the defluorinated instant brick tea were slightly different from those in the original tea, but the key aroma and flavor characteristics of the defluorinated brick tea remained unchanged. Membrane separation provides technical support for the large-scale production of low-fluoride post-fermented tea. Full article

Wearable, rectifiable aerosol photometers (WRAPs), instruments with combined nephelometer and on-board filter-based sampling capabilities, generally show strong correlations with reference instruments across a range of ambient and household PM_2.5 concentrations. However, limited data exist on their performance when challenged by mixed aerosol exposures, such as those found in dusty occupational environments. Understanding how these instruments perform across a spectrum of environments is critical, as they are increasingly used in human health studies, including those in which concurrent PM_2.5 and coarse dust exposures occur simultaneously. The authors collected co-located, ~24 h. breathing zone gravimetric and nephelometer PM_2.5 measures using the MicroPEM v3.2A (RTI International) and the UPAS v2.1 PLUS (Access Sensor Technologies). Samples were collected from adult brick workers (n = 93) in Nepal during work and non-work activities. Median gravimetric/arithmetic mean (AM) PM_2.5 concentrations for the MicroPEM and UPAS were 207.06 (interquartile range [IQR]: 216.24) and 737.74 (IQR: 1399.98) µg/m³, respectively (p < 0.0001), with a concordance correlation coefficient (CCC) of 0.26. The median stabilized inverse probability-weighted nephelometer PM_2.5 concentrations, after gravimetric correction, for the MicroPEM and UPAS were 169.16 (IQR: 204.98) and 594.08 (IQR: 1001.00) µg/m³, respectively (p-value < 0.0001), with a CCC of 0.31. Digital microscope photos and electron micrographs of filters confirmed large particle breakthrough for both instruments. A possible explanation is that the miniaturized pre-separators were overwhelmed by high dust exposures. This study was unique in that it evaluated personal PM_2.5 monitors in a high dust occupational environment using both gravimetric and nephelometer-based measures. Our findings suggest that WRAPs may substantially overestimate personal PM_2.5 exposures in environments with concurrently high PM_2.5 and coarse dust levels, likely due to large particle breakthrough. This overestimation may obscure associations between exposures and health outcomes. For personal PM_2.5 monitoring in dusty environments, the authors recommend traditional pump and cyclone or impaction-based sampling methods in the interim while miniaturized pre-separators for WRAPs are designed and validated for use in high dust environments. Full article

Identification of the strength characteristics of mortars in brick or stone masonry is crucial in the structural analysis of heritage buildings and selecting materials for their repairs and reconstruction. Non-destructive, minimally destructive, and minor-destructive tests have been developed to establish the strength of mortar in existing masonry. This paper presents strength tests on mortar samples extracted from bed joints of heritage buildings erected in the historic center of Cracow during the 19th and 20th centuries. The mortar samples were tested using the double-punch method, a minor-destructive technique especially useful for heritage structures where cutting out large masonry specimens is not possible due to conservation reasons. The impact of sample thickness and type of capping materials on the test results were analyzed in detail. Practical recommendations are also proposed for the procedure of the double-punch method in relation to historical mortars. Full article

The construction industry is among the most resource-intensive sectors, generating nearly 40% of global CO₂ emissions and over two billion tonnes of construction and demolition waste (CDW) annually. This study investigates the sustainable reuse of CDW in developing binder-free alkali-activated paste (AAP) using sodium hydroxide (NaOH) as an activator. Eleven formulations were prepared by varying the brick-to-total waste ratio (BW/TW: 0–1), NaOH concentrations (0–10%), and curing durations (7, 28, and 60 days). The mixes were evaluated for unconfined compressive strength (UCS), shear modulus (G_o), durability (wet–dry and freeze–thaw cycles), and microstructural evolution. Results showed significant improvements in mechanical and durability properties with increased NaOH content, BW/TW ratios up to 0.9, and longer curing times. The optimal mix (10% NaOH, BW/TW = 0.9, 60 days of curing) achieved a UCS of 28.7 MPa and a G_o of 30 GPa, while exhibiting minimal mass loss (<2% freeze–thaw; <3% wet–dry). Microstructural analyses revealed densified matrices and enhanced gel formation. A dimensional analysis using the Buckingham π theorem yielded a scalable predictive model that correlates material composition, alkaline activation, and curing with mechanical performance. The study underscores the feasibility of transforming CDW into durable, high-performance AAPs for sustainable infrastructure development. Full article

The circular economy in construction requires the valorization of gypsum waste from construction and demolition. Waste from gypsum plasterboards is considerable, yet it is still viewed more as a problem than as a mineral resource. This study investigates the potential for utilizing recycled gypsum (RG) from waste plasterboards in the production of blended green binders. Four gypsum–cement–pozzolanic binders are designed with two pozzolanic additives (natural zeolite and recycled brick powder) in two ratios to cement—0.6 and 1.0. The structural mineral compounds of the binders are analyzed by XRD and DTA/TG, while the performance of both fresh and hardened paste is evaluated by standardized methods for binders to determine possible construction applications of these green binders. Results show that RG can be used to produce blended fast-setting binders with a gypsum content of above 40%. Systems with natural zeolite achieve higher strength (up to 30 MPa at 90 days) and sufficient water resistance, thus suitable even as substitutes for cement binders. The developed blended binders with recycled brick powder can be used in low-moisture environments only as substitutes for gypsum binders in plasters, masonry units, and lightweight composites. Full article

In response to escalating environmental concerns, the construction industry is under growing pressure to adopt sustainable practices. As a major consumer of natural resources and a significant emitter of greenhouse gases, it paradoxically holds the potential to become a leader in green transformation. This study investigates the development of innovative, fire-resistant, and alkali-activated hybrid binder foams incorporating recycled materials: fly ash, coal slag, and ground brick waste, as sustainable alternatives to traditional building materials. The fire resistance performance at a technical scale and the thermal behavior of fiber-reinforced, alkali-activated hybrid binder foams synthesized from recycled aluminosilicate precursors were determined. The properties of unreinforced composite were compared with the composites reinforced with merino wool, basalt fibers, polypropylene fibers, and coconut fiber. Small-scale fire-resistance tests revealed that merino wool-reinforced composites exhibited the best thermal insulation performance, maintaining structural integrity, that is, retaining shape and continuity without delamination or collapse for 83 min under fire exposure. Analyses combining chemical characterization (X-ray fluorescence) with microstructural methods (computed tomography and colorimetry) confirmed that fire performance is strongly influenced not only by fiber type but also by pore distribution, phase composition, and oxide migration under thermal loading. These findings demonstrate the potential of fiber-reinforced foamed, alkali-activated hybrid binder as eco-efficient, printable materials for fire-safe and thermally demanding construction applications. Full article