Journal of building engineering最新文献

{"title":"Mechanical properties and hydration mechanism of nano-silica modified alkali-activated thermally activated recycled cement","authors":"","doi":"10.1016/j.jobe.2024.110998","DOIUrl":"10.1016/j.jobe.2024.110998","url":null,"abstract":"<div><div>The recycling and reuse of waste concrete are crucial for reducing environmental pollution, minimizing resource waste, and lowering carbon emissions. However, current efforts to improve the performance of recycled cement (RC) using the synergistic effects of alkali activation and thermal activation have been suboptimal. Therefore, this study explores the influence of nano-silica (NS) incorporation on the mechanical properties and hydration mechanism of alkali-activated and thermally activated RC. The research focuses on cement mortar with a thermal activation temperature of 750 °C, an RC replacement rate of 30 %, and an alkali content of 6 %. Various analytical techniques, including thermogravimetric analysis (TG-DTG), X-ray diffraction (XRD), and scanning electron microscopy (SEM), were used to evaluate the impact of different NS dosages (1 %, 2 %, 3 %, and 5 %) on the mechanical properties and hydration characteristics of nano-modified alkali-activated and thermally activated RC mortar. The study reveals the mechanism by which NS enhances the microstructure of alkali-activated and thermally activated RC. The experimental results show that as the NS content increases, the compressive and flexural strengths of RC initially increase and then decrease. The optimal strength was achieved with a 2 % NS content, with a 31.5 % increase in compressive strength compared to RC without NS. At this dosage, RC exhibited a higher hydration rate during the acceleration period of hydration. Additionally, the initial hydration heat release rate of RC increased with rising NS content. While NS incorporation did not alter the phase composition of RC, it activated the pozzolanic effect of RC, causing free active substances such as CaO and gypsum in the components to dissolve and react to form Aft at the start of the hydration reaction. The unsaturated bonds (≡Si-O- and ≡ Si-) on the surface of NS absorbed Ca²⁺ and OH⁻ from the RC, promoting the hydration of C₂S and C₃S. However, excessive NS content (greater than 3 %) led to a decline in RC strength and the formation of more cracks. This is primarily due to the excess NS particles not contributing to an increase in effective nucleation sites, causing agglomeration, an increase in large pores, and a reduction in transition and gel pores, which negatively affected the microstructure and thus reduced the mechanical properties of the RC. Our findings enhance the understanding of the role of nanomaterials in alkali-activated RC and provide valuable insights for further research into high-performance recycled cement materials.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535102","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}

{"title":"Multi-objective optimal scheduling of electricity consumption in smart building based on resident classification","authors":"","doi":"10.1016/j.jobe.2024.111085","DOIUrl":"10.1016/j.jobe.2024.111085","url":null,"abstract":"<div><div>By the end of 2021, the urbanization rate of China had reached 64.72 %. Increasing urbanization rates have led to an 80 percent share of carbon emissions in urban areas. Therefore, a load optimal scheduling model of smart buildings is proposed in this paper, which takes into account the cost of carbon emissions. The model aims to minimize the electric cost for building residents and maximize the utilization of distributed energy. The research focuses on the load optimal scheduling for two types of residents, i.e., the working residents and the retired ones, based on their electricity usage patterns and habits. To address the challenges of uneven load distribution, nonlinear behavior, and uncertainties introduced by electric vehicles and photovoltaic energy, the multi-objective beluga whale optimization algorithm with hybrid reverse learning competitive strategies (RCMBWO) is introduced. It utilizes the energy storage and discharge capabilities of electric vehicles to mitigate the uncertainties of photovoltaic energy generation. The simulation results show that load optimal scheduling for both types of residents can lead to significant cost savings for a smart building with 100 households, approximately 29,554 RMB per year. Furthermore, the optimized results can guide the determination of the appropriate size for the photovoltaic energy storage system, reducing energy waste resulting from insufficient energy consumption capability of smart buildings. The research on targeted load optimal scheduling for classified residents presents a viable solution for enhancing the cost-effectiveness and environmental benefits of smart buildings.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535149","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}

{"title":"Precision detection and identification method for apparent damage in timber components of historic buildings based on portable LiDAR equipment","authors":"","doi":"10.1016/j.jobe.2024.111050","DOIUrl":"10.1016/j.jobe.2024.111050","url":null,"abstract":"<div><div>For the purpose of preservation and restoration of historic timber buildings, it is critical that damage to timber components must be detected and identified accurately since proper detection and identification lay the foundation for scientific utilization and preservation of cultural heritage. Portable smart devices with integrated LiDAR sensor technology have significantly advanced, enabling them to be major pedestals for damage detection. An iPhone Pro based technique is therefore suggested for the precise detection and diagnosis of apparent damage to the timber components. The study consists of three major procedures. First, an apparent data collection of the timber components was conducted. A high-resolution triangular mesh model was utilized for precision detection and identification. Point cloud and texture data were the main constituents of this data collection. Second, a technique for image processing and apparent damage analysis was proposed for crack detection in historic timber buildings. This approach can be used to identify, recognize,and assess damage to timber components such as cracks, rotting, and knots. Finally, actual measurements of the timber components in Datong, Shanxi Province, at the Great Temple Corner, proved the effectiveness of the iPhone 12 Pro as a substitute approach to the conventional inspection equipment. The findings indicate that the iPhone 12 Pro, which has a built-in LiDAR sensor, performs exceptionally well in terms of effectiveness, accuracy, and graphical interpretation when identifying apparent damage to historic timber components. Moreover, it has the potential to substitute traditional measurement, 3D scanning, and other detection and identification techniques. Even though damage detection and identification of historical timber buildings has reached a mature stage in terms of portable, refined, and digital transformation, such technique can serve as a compatible addition as a safe, affordable, and paradigm shifting technical solution for detection and identification of historic building components.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446896","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}

{"title":"Study on non-destructive visualization identification of concrete internal cracks based on SH array ultrasound","authors":"","doi":"10.1016/j.jobe.2024.111076","DOIUrl":"10.1016/j.jobe.2024.111076","url":null,"abstract":"<div><div>Ultrasonic nondestructive testing (NDT) technology was one of the most frequently used and fastest-developing NDT techniques in detection field. This method had high detection sensitivity, more accurate defect localization, and was harmless to the human body. With the development of ultrasonic testing technology, modern ultrasonic imaging technology generally had automatic data acquisition and processing functions, which allowed for intuitive and clear recognition of internal defects by the human eyes. The overall purpose of this study was to visualize the cracks in concrete by synthetic aperture focusing technique (SAFT) and full-waveform inversion (FWI) algorithms on the basis of ultrasonic nondestructive testing technology. At present, there have been studies on the use of ultrasonic instruments to detect the internal defects of concrete. However, the accuracy and authenticity of this method have not been compared in previous studies. Therefore, in this experiment, four concrete specimens with different buried depths, angles, shapes, and thicknesses of cracks were designed. Based on SH ultrasonic wave NDT technology, two types of operations were performed on the collected ultrasonic wave data: one was the application of SAFT method, and the other was the first application of FWI method for detecting internal cracks in concrete. The study found that both algorithms were most accurate in determining the burial depth of cracks, with error results not exceeding 10 %. They also showed good recognition effects for the angle, shape, and thickness of the buried cracks. This proved that both identification methods had the capability to recognize internal cracks. The Introview software bundled with the ultrasonic instrument could identify cracks using SAFT directly and quickly. When FWI was used with MATLAB computation, the results were more precise and intuitive. The overall purpose of this study was to detect cracks in concrete by SAFT and FWI algorithms on the basis of ultrasonic nondestructive testing technology. Combining the two crack identification techniques could be of great significance for ensuring the long-term safety and stability of concrete structures, providing strong support for structural maintenance and reinforcement.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446903","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}

{"title":"Interpretable reduced-order optimization research for improving indoor environmental quality in buildings based on dimensional analysis and surrogate-based optimization","authors":"","doi":"10.1016/j.jobe.2024.111083","DOIUrl":"10.1016/j.jobe.2024.111083","url":null,"abstract":"<div><div>Implementing large-scale optimization designs and identifying optimal design variables in fields such as architectural engineering is crucial for improving indoor environmental quality. However, the high-dimensional nonlinear characteristics complicate the understanding of the optimization process and increase the difficulty of finding optimal solutions. This study proposes an interpretable reduced-order optimization (ROO) method based on dimensional analysis, which integrates numerous variables into a single reduced-order coefficient through a power form. The goal is to develop a reduced-order and approximately one-dimensional nonlinear relationship during the optimization process and to reveal the mechanisms of single-objective and multi-objective optimization, thereby enhancing the interpretability of the optimization process. The reliability of the ROO is validated through single-objective optimization of building thermal bridges and multi-objective optimization of squirrel cage fans. The study shows that the power in the reduced-order coefficient can be used to determine the sensitivity and impact of design variables on optimization targets. The nonlinear relationship between the composite structural parameters of the building thermal bridge and the total heat flux can be reduced to an approximately one-dimensional linear relationship, significantly reducing the total heat flux of the thermal bridge by 10.3 %. The ROO accurately describes the aerodynamic performance of the fan and its high-dimensional nonlinear relationship with eight design variables, eliminating optimization conflicts among multiple operating conditions and significantly enhancing the aerodynamic performance. The ROO method proposed in this study offers a new approach to making the optimization process more interpretable, playing a crucial role in optimization design and revealing optimization mechanisms in engineering applications.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535162","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}

{"title":"Evaluation method for uniformity of steel slag concrete aggregate based on improved YOLOv8","authors":"","doi":"10.1016/j.jobe.2024.111046","DOIUrl":"10.1016/j.jobe.2024.111046","url":null,"abstract":"<div><div>The use of steel slag as a replacement for natural aggregates in concrete effectively alleviates the issue of natural resource scarcity. The uniformity of aggregates in steel slag concrete directly affects its performance and durability. Therefore, precise segmentation of aggregates in sedimentation images is crucial for evaluating their uniformity. This paper not only proposes an improved instance segmentation model for accurate segmentation of steel slag concrete aggregates but also introduces a new method for assessing the uniformity of aggregates when steel slag replaces natural aggregates. This method quantitatively analyses the area, replacement rate, and spatial distribution of the aggregates and conducts a comprehensive quantitative analysis using the comprehensive uniformity evaluation coefficient, K. This approach allows for the evaluation of the uniformity of aggregates in sedimentation images of steel slag concrete. Experimental results show that the proposed improved model achieved an mAP₅₀ of 98.3 %. Furthermore, the aggregate uniformity assessment method based on the improved model can objectively and accurately evaluate the uniformity of steel slag concrete aggregates.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535163","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}

{"title":"Synchronous vacuum hot pressing ultra-high performance geopolymer: Ultrafast polymerization and early strength development","authors":"","doi":"10.1016/j.jobe.2024.111071","DOIUrl":"10.1016/j.jobe.2024.111071","url":null,"abstract":"<div><div>To overcome the application bottleneck of geopolymer in high-end industries, this study aims to develop ultra-high performance geopolymer products. By employing Synchronous Vacuum Hot Pressing, we have significantly enhanced the rate of polymerization and mechanical properties of Geopolymer based on Metakaolin-Fly Ash. The influence of Si/Al ratio, alkali equivalent, and molding time on the geopolymerization process, mechanical properties, and microstructure of geopolymers was investigated, while elucidating the underlying mechanisms. The compressive strength of SVHP-MFG reaches 90.92 MPa when the Si/Al ratio is 2, alkali equivalent is 8 %, and molding time is 30 min, owing to increased production of aluminosilicate gels and matrix structure densification. The ongoing reaction of unreacted particles and the subsequent transformation from \"alumina-rich gel\" to \"silica-rich gel\" in later stages further enhance the mechanical properties of the material. Additionally, the mean pore diameter of Synchronous vacuum hot pressing of metakaolin-fly ash geopolymer measures below 13.24 nm, thereby significantly enhancing the pore structure of the geopolymer. The synchronous vacuum hot pressing metakaolin fly ash-based geopolymers synthesized in this study represents a novel category of ultra-high performance ceramic-like geopolymers, exhibiting exceptional early strength and early stability. The research aims to promote the application of geopolymer in high-end industry and provide technical and theoretical support for the development of ultra-high performance geopolymer based products.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535268","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}

{"title":"A review on the influence of particle packing theory and materials on characteristics of ECC","authors":"","doi":"10.1016/j.jobe.2024.111079","DOIUrl":"10.1016/j.jobe.2024.111079","url":null,"abstract":"<div><div>Engineered Cementitious Composites (ECC) play a vital role in the construction industry due to their high strain-hardening capability, superior strength, and durability. The micromechanics of ECC, particularly the closely packed particle arrangement within the matrix, which is minimize the porosity and enhances performance, This paper reviews a comprehensive analysis of performance-based fibre-reinforced ECC, which substitutes conventional concrete in structural applications. The homogeneity of the ECC was achieved through not only cement but also the major role played by fine materials such as fly ash, silica fume, GGBS, etc., namely supplementary cementitious materials (SCMs), which enhance the packing density and reduce the pore structure of the ECC. The results obtained from existing studies show that the inclusion of the SCMs combinations and fibres with ECC enhances the mechanical properties. The superior performance of ECC was achieved through the proper optimized mix proportion by the Particle Packing Model (PPM). Based on previous studies, the fundamental principles of PPM can be effectively utilized to achieve the proper mix proportions of ECC. Additionally, it discusses how the water-to-cement (W/C) ratio and type of fiber influence ECC's fresh and mechanical behaviour. The conclusions recommend selecting specific combinations of SCMs and fibers to achieve better mechanical properties and strain hardening in ECC.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535178","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}

{"title":"Pyrolysis modelling of insulation material in coupled fire-structure simulations","authors":"","doi":"10.1016/j.jobe.2024.110969","DOIUrl":"10.1016/j.jobe.2024.110969","url":null,"abstract":"<div><div>This paper presents a modelling approach to predict the thermodynamical and thermomechanical behaviour of structures with a layer of insulation material under fire, which takes into account the pyrolysis of the insulation and its effects on the structure. First, an existing 1D pyrolysis model is implemented and verified by theoretical and validated by experimental results. Then the model’s 1D setup is integrated into 3D Heat Transfer (HT) analyses of structures. The obtained thermodynamical results, i.e. temperatures as a function of time and the pyrolysis process, are transferred to a thermomechanical Structural Response (SR) analysis. Mechanical results are then obtained via temperature and pyrolysis-dependent material properties. The resulting HT and SR analyses are demonstrated in fire-structure simulations of facades made of sandwich panels, including their supporting frames with steel sections, and bolt and screw connections, modelled by non-linear spring elements. It is shown that in a short time window of 100 s, pyrolysis is limited to certain zones of the panel and for limited depths. Nevertheless, due to the endothermic process, it reduces expansion and bending of the panels, and consequently results in smaller displacements, and delayed failure of the connections. For longer periods, with connection failures neglected, significant pyrolysis takes place, which influences the temperature distribution in the complete interior of the sandwich panel. However, this has only a marginal effect on the structural behaviour. In conclusion, pyrolysis effects are relevant, can be modelled, and may somewhat reduce fire risks in structures. Future research can combine pyrolysis with advanced modelling of bolt and screw connections, using a two-scale method. As such, all relevant details of structures can be modelled and investigated for different fire scenarios, including fire-structure effects, all still to be validated by experiments.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inducing pitting in low carbon steel via chloride contamination: Electrochemical noise analysis in concrete gel pore solutions","authors":"","doi":"10.1016/j.jobe.2024.111056","DOIUrl":"10.1016/j.jobe.2024.111056","url":null,"abstract":"<div><div>This study explores an alternative approach to examining the corrosion of reinforced concrete, a persistent and challenging issue. The research utilizes an agar-based gel as a synthetic pore solution to simulate the environment of reinforcing steel, with the goal of confining pitting corrosion induced by chlorides to specific areas of the steel. By employing this innovative approach, metastable and stable pits were successfully induced according to the <span><math><mrow><mfrac><msup><mrow><mi>C</mi><mi>l</mi></mrow><mo>−</mo></msup><msup><mrow><mi>O</mi><mi>H</mi></mrow><mo>−</mo></msup></mfrac></mrow></math></span> ratio at pre-selected locations on the steel surface. The presence of metastable pits was determined in the range of 31.6 &gt; <span><math><mrow><mfrac><msup><mrow><mi>C</mi><mi>l</mi></mrow><mo>−</mo></msup><msup><mrow><mi>O</mi><mi>H</mi></mrow><mo>−</mo></msup></mfrac></mrow></math></span> &gt; 3.2, as indicated by electrochemical noise analysis. The findings support the efficacy of this experimental procedure for enabling precise manipulation and contamination of localized regions with chloride ions.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}