Journal of building engineering最新文献_第2页

Plant-based composite foam as insulating material: Foaming agent effect

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110685

{"title":"Plant-based composite foam as insulating material: Foaming agent effect","authors":"","doi":"10.1016/j.jobe.2024.110685","DOIUrl":"10.1016/j.jobe.2024.110685","url":null,"abstract":"<div><p>Foams or vegetable composites can represent solutions to reduce the environmental impact in the building sector by decreasing the use of non-renewable materials. Some composite foams are employed as insulating material due to their low porosity which can be induced using surfactants allowing the foaming during the mixing step. Generally, the composition of foams includes exclusively mineral resources without vegetable part. This study aims to investigate the influence of two surfactants, the petrosourced foaming agent (PFA) Betomouss® and the biobased decyl α/β D-xylose ether (C<sub>10</sub>Xyl), on the foaming, stability, consistency, mechanical and thermal performances of a plant-based composite foam made of gypsum, earth and flax shives. The petrosourced surfactant decreases from 10 to 21 % more the dry density of the composite than the biosourced. This last generates larger air void bubbles than the petrosourced. The results have also shown that the addition of surfactant (biosourced or petrosourced) improves the fluidity of the plant-based composite in increasing the spreading diameter from 34.8 up to 50.8 % according to the surfactant concentration. The air void concentration is doubled inducing a thermal conductivity from 0.078 to 0.097 W m<sup>−1</sup> K<sup>−1</sup> in place of 0.147 W m<sup>−1</sup> K<sup>−1</sup> for the mix without foaming agent and a good thermal inertia with a time lag around 12 h and a decrement factor around 0.045, in considering a 240 mm depth material.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimal high-pressure correlation for transcritical CO2 cycle in direct expansion solar assisted heat pumps

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110616

{"title":"Optimal high-pressure correlation for transcritical CO2 cycle in direct expansion solar assisted heat pumps","authors":"","doi":"10.1016/j.jobe.2024.110616","DOIUrl":"10.1016/j.jobe.2024.110616","url":null,"abstract":"<div><p>Heat demand may be met sustainably by a solar-assisted heat pump that CO<sub>2</sub> as a refrigerant. This is made possible by the employment of an ecologically benign refrigerant and a renewable energy source that enhances system performance. At the ideal high pressure, the CO<sub>2</sub> heat pump running in a transcritical cycle will function at its highest coefficient of performance (COP). In that way, this study aims to present correlations for calculating the optimum high pressure in a CO<sub>2</sub> direct expansion solar assisted heat pump (DX-SAHP). In this study a mathematical model for compressor, solar evaporator and gas cooler was developed and validated experimentally. The mean difference between the mathematical model and experimental results are −3.9%. Two new equations are proposed to calculate the optimum high pressure in a CO<sub>2</sub> DX-SAHP. The first one considered environment temperature, water outlet temperature and evaporating temperature, which are easy to measure. These facilities the use of correlation to control the heat pump. The second one considered environment temperature, water outlet temperature and solar radiation, which are more suitable for designing CO<sub>2</sub> DX-SAHP. A data base with 100 optimum points was used to curve fitting. Another data base with 50 optimum points was used to compare the results obtained from curve fitting and correlations for the optimum high pressure available in the literature. The proposed correlations shown a maximum error lower than 10.2% despite of the correlations available in the literature from which the errors are about 30%.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigating the dynamic thermal performance of a novel PCM to earth-air heat exchanger: Developing numerical model and comparing thermal performance

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110718

{"title":"Investigating the dynamic thermal performance of a novel PCM to earth-air heat exchanger: Developing numerical model and comparing thermal performance","authors":"","doi":"10.1016/j.jobe.2024.110718","DOIUrl":"10.1016/j.jobe.2024.110718","url":null,"abstract":"<div><p>Integrating phase change materials (PCMs) into earth-air heat exchangers (EAHE) to form PCM-EAHE systems effectively enhances the efficiency of natural energy utilization. This study proposes a novel PCM-EAHE configuration for the first time, incorporating multiple annular PCM layers and a single cylindrical PCM layer within the duct. Mathematical models for four distinct scenarios were developed and validated against experimental data. The findings indicate that the proposed system outperforms existing PCM-EAHE systems in terms of temperature drop, cooling capacity, average coefficient of performance, and temperature drop factor. Furthermore, positioning multiple annular PCM units along the centerline of the pipe (detached from the pipe wall) enhances the cooling and heating performance of the system, while placing a layer of PCM units on the inner wall of the pipe mitigates heat buildup in the soil surrounding the buried pipe. At the same outlet air temperature, this innovative structural design increases the fresh air handling volume and reduces the length of buried ducts by 44 %–54.5 % compared to existing systems. Over five months of continuous operation in Chongqing, the system demonstrated a maximum temperature drop of 6.91 °C, with the maximum liquid fraction reaching 0.34 and a maximum cooling capacity of 5795.14 W. This research contributes to the advancement of natural energy resource exploitation.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A mechanism study of thermal resistance formation and post-fire strength recovery in cement paste with carbon nanotubes and nanosilica via focused ion beam/scanning electron microscopy tomography

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110750

{"title":"A mechanism study of thermal resistance formation and post-fire strength recovery in cement paste with carbon nanotubes and nanosilica via focused ion beam/scanning electron microscopy tomography","authors":"","doi":"10.1016/j.jobe.2024.110750","DOIUrl":"10.1016/j.jobe.2024.110750","url":null,"abstract":"<div><p>Although carbon nanotubes (CNT) and nanosilica (NS) have shown substantial potential for enhancing the thermal resistance and post-fire mechanical recovery of cementitious composites, their combined synergistic effects remain unclear. This study aimed to elucidate the influence of CNT and NS double-hybrids on the physicochemical properties of cementitious composites under different heating temperatures (200, 500, and 800 °C) and re-curing conditions (25 °C/65 % RH and water immersion). We assessed the changes in the compressive and tensile strengths, bulk density, surface morphology, hydration products, and pore characteristics using focused ion beam scanning electron microscopy to visualize the evolving nanoscale pore structures. Our findings reveal a remarkable synergistic effect on the thermal resistance and strength recovery properties of the CNT/NS hybrid samples, owing to the stable matrix observed after heating to 800 <sup>°</sup>C. Following exposure to 800 °C, the tensile strength exhibited a remarkable 69.6 % increase compared to its pre-heating state, without any indication of crack formation. The CNT served as nucleation sites, expediting the pozzolanic reaction of NS during heating and resulting in a homogenized pore structure with interconnected hydrates. The CNT/NS hybrid samples exhibited uniform shrinkage of hydrates without creating nanoscale rod-like pores typical in ordinary cement paste, while the increase in pore volume was predominantly attributed to the expansion of existing pores and the formation of nearby new pores.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corrigendum to “Utilizing bio-based and industrial waste aggregates to improve mechanical properties and thermal insulation in lightweight foamed macro polypropylene fibre-reinforced concrete” [J. Build. Eng. 91 (2024) 109588] 利用生物基和工业废料骨料改善轻质发泡大聚丙烯纤维增强混凝土的机械性能和隔热性能》[J. Build. Eng. 91 (2024) 109588]勘误表

IF 6.4 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110756

Zi Cong Yong, Ming Kun Yew, Ming Chian Yew, Jing Han Beh, Foo Wei Lee, Siong Kang Lim, Lip Huat Saw

引用次数: 0

Drying shrinkage and crack width prediction using machine learning in mortars containing different types of industrial by-product fine aggregates 在含有不同类型工业副产品细集料的砂浆中利用机器学习预测干燥收缩率和裂缝宽度

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110737

{"title":"Drying shrinkage and crack width prediction using machine learning in mortars containing different types of industrial by-product fine aggregates","authors":"","doi":"10.1016/j.jobe.2024.110737","DOIUrl":"10.1016/j.jobe.2024.110737","url":null,"abstract":"<div><p>Concrete is a material that loses water and changes shape while hardening due to its structure. Over time, this water loss results in some shrinkage of the hardened concrete, referred to as drying shrinkage. In addition, water loss of concrete also causes the formation of various cracks. The aggregate used in concrete plays an important role in the shrinkage and cracking of concrete. The focus of this study is to accurately estimate the amount of crack width and drying shrinkage over time after the substitution of fine aggregates with other types of aggregates (consisting of various industrial by-products or wastes at different percentages) in the concrete mortar. For this purpose, various experimental results of the ‘substituted fine aggregate concrete mortars’ were converted into a data set. Following this a model was developed to predict the drying shrinkage and crack width of concrete mortars. The machine learning model was trained with the measurement results of 60-day drying shrinkage and crack widths of concrete mortars with different proportions of bottom ash (BA), granulated blast furnace slag (GBFS), fly ash (FA), and crushed tiles (CT). To enhance the detection/prediction capability of the model, the model hyperparameters were optimized. It is observed that the developed model was able to detect the drying shrinkage and crack width with an accuracy exceeding 99.6 %. In addition, the physical properties such as grain shape (angular or round) of components like fine aggregates may be effective for improved performance of the machine learning models in predictions of the drying shrinkage values or drying shrinkage cracking widths.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of hybrid lead-PVA fibers on microstructure and radiation shielding properties of high-performance concrete

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110705

{"title":"Effect of hybrid lead-PVA fibers on microstructure and radiation shielding properties of high-performance concrete","authors":"","doi":"10.1016/j.jobe.2024.110705","DOIUrl":"10.1016/j.jobe.2024.110705","url":null,"abstract":"<div><p>With the widespread application of nuclear technology in the medical and energy fields, the demand for efficient radiation shielding materials is increasing. Employing only lead or polyvinyl alcohol (PVA) fiber reinforcement cannot achieve improvements in the brittleness of high-performance concrete (HPC) while also enhancing radiation shielding efficiency and mechanical properties. This study develops a novel HPC for radiation attenuation, incorporating magnetite as the aggregate and reinforced with hybrid lead-PVA fibers (RSHPC). The synergistic effects of various proportions of hybrid lead-PVA fibers on the mechanical properties, three-dimensional microstructure, pore structure, and interfacial transition zone (ITZ) were investigated. In addition, the radiation attenuation capacities of RSHPC with different hybrid lead-PVA fiber proportions were evaluated through experimental and simulation analysis. The results show that hybrid lead-PVA fibers notably improve the air-void structure of RSHPC. The incorporation of PVA fibers, by improving the ITZ of matrix, effectively mitigates the negative impact of lead fibers on mechanical performance. The refinement of pore structure and the introduction of light and heavy nuclides lead to a significant enhancement in the gamma-ray and neutron radiation attenuation capabilities of RSHPC. Utilizing X-ray computed tomography (X-CT) for three-dimensional reconstruction further indicates the optimization impact of hybrid lead-PVA fibers on the microstructure, notably in the improvement of pore distribution and fiber dispersion, thus enhancing the overall properties and radiation attenuation performance of RSHPC.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Study of the inhibitory effect of tetracycline hydrochloride on mild steel in HCl, HNO3, H2SO4 and NaCl solutions 盐酸四环素在 HCl、HNO3、H2SO4 和 NaCl 溶液中对低碳钢的抑制作用研究

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110708

{"title":"Study of the inhibitory effect of tetracycline hydrochloride on mild steel in HCl, HNO3, H2SO4 and NaCl solutions","authors":"","doi":"10.1016/j.jobe.2024.110708","DOIUrl":"10.1016/j.jobe.2024.110708","url":null,"abstract":"<div><p>This study investigates the potential of tetracycline hydrochloride as a corrosion inhibitor for mild steel in various corrosive environments, including 1 M H<sub>2</sub>SO<sub>4</sub>, 1 M HCl, 1 M HNO<sub>3</sub>, and 0.05 M NaCl. The inhibition efficiency of tetracycline hydrochloride was evaluated using electrochemical impedance spectroscopy (EIS), metallographic analysis with optical microscope, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and weight loss measurements. The results indicate a maximum inhibition efficiency of 74.10 % in the sample with 500 ppm of tetracycline hydrochloride in HCl, while efficiencies of 41.16 %, 59.76 %, and 72.58 % were observed for H<sub>2</sub>SO<sub>4</sub> (500 ppm), HNO<sub>3</sub> (100 ppm), and NaCl (100 ppm), respectively. For the EIS analysis, the measurements were performed in a frequency range from 10 kHz to 0.01 Hz, with an amplitude of 0.01 V. This study suggests that tetracycline hydrochloride has promising potential as a corrosion inhibitor in various industries, offering a sustainable alternative for the reuse of expired medications.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142232746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Influence of synthetic fibers on the performance of ultra-high performance concrete (UHPC) at elevated temperatures

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110735

{"title":"Influence of synthetic fibers on the performance of ultra-high performance concrete (UHPC) at elevated temperatures","authors":"","doi":"10.1016/j.jobe.2024.110735","DOIUrl":"10.1016/j.jobe.2024.110735","url":null,"abstract":"<div><p>Adding synthetic fibers to ultra-high performance concrete (UHPC) is an effective method for improving its resistance to high temperatures. This study examined the impact of different synthetic fibers on high-temperature spalling and corresponding residual mechanical performance of UHPC, including compressive strength, elastic modulus, and flexural strength. This study conducted high-temperature tests on UHPC with different synthetic fibers (PET, PP, NY, PVA, PAN fibers) and analyzed their microscopic morphology after exposure to 200 °C using scanning electron microscopy (SEM). The findings revealed that conventional steel fiber UHPC (without synthetic fibers) experienced severe spalling only after 400 °C. To some degree, synthetic fibers enhanced the resistance of UHPC to high-temperature spalling, but significant differences were observed among the different fibers. PP fibers provided the most significant improvement in high-temperature resistance, followed by NY fibers, while other fibers were less effective. Although the contributions of different synthetic fibers to high-temperature resistance varied, the differences in compressive strength and elastic modulus of UHPC with different synthetic fibers after high-temperature exposure were not substantial. NY fibers, despite being slightly less effective than PP fibers, provided superior flexural performance at both room and high temperatures compared to PP fibers. Both PP fibers and NY fibers inhibited high-temperature spalling of UHPC and maintained its mechanical performance. Even at 1050 °C, UHPC that did not spall retained residual mechanical performance, with compressive strength, elastic modulus, and flexural strength after exposure to 1050 °C being 24.4 %, 29 %, and 26.8 % of their respective values at room temperature.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Identification of the damage location for the structural sealant based on deep learning

IF 6.7 2区工程技术

Journal of building engineering Pub Date : 2024-09-13 DOI: 10.1016/j.jobe.2024.110689

{"title":"Identification of the damage location for the structural sealant based on deep learning","authors":"","doi":"10.1016/j.jobe.2024.110689","DOIUrl":"10.1016/j.jobe.2024.110689","url":null,"abstract":"<div><p>Structural sealants are essential to maintain the safety of panel units of hidden frame glass curtain wall. Damage localization of the concealed structural sealant is still difficult because of the unknown baseline model. In this paper, a convolutional neural network-based identification method is proposed to localize the damage of structural sealants without the baseline model. The method develops a novel input of the convolutional neural network (CNN), multi-symmetry-point images (MSPI), which is encoded by the response of four symmetrical points to impulse excitations. The CNN would identify the damage location by discerning differences among four images. Then, a dataset with 28803 samples, which considers the effect of the multiple damages and noise, was used to train the CNN. Three types of transformed images and four CNN models were compared to optimize the input signals and the configuration of the CNN. A series of numerical examples indicated that the Gram angle difference field is the optimal image transformation method, and improved-DenseNet121 is the optimal CNN for damage localization in structural sealants. Then, several laboratory experiments validate the effectiveness of the optimized image input and CNN with an accuracy rate of 92 % in the identification of damage location.</p></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0