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Enhanced Internal Curing for Ultra-High Performance Concrete Using a Reactive Curing Solution

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SSRN 2024年

作者： Wang, Jialai Chen, Peiyuan Pei, Chunning Fang, Yi Tan, Weibo Li, Jin Qian, Xin School of Civil Engineering and Architecture Anhui University of Science and Technology Anhui Huainan232001 China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and Technology Anhui Huainan232001 China Hong Kong Polytechnic University Hong Kong Key Laboratory of Infrastructure Durability and Operation Safety in Airfield CAAC Tongji University Shanghai201804 China Department of Civil Construction and Environmental Engineering The University of Alabama TuscaloosaAL35487 United States

Autogenous shrinkage in ultra-high performance concrete (UHPC), due to its low water-to-cement ratios and dense particle packing, poses a critical challenge to the material. Internal curing can mitigate this, but UHPC often requires more internal curing water than high performance concrete. To tackle this issue, this study proposes an enhanced internal curing technology that significantly reduces autogenous shrinkage without necessitating additional internal curing water or compromising mechanical properties. This is achieved by utilizing perforated cenospheres (PCs) as the internal curing agent and replacing internal curing water with a carbamide solution, which reacts with portlandite upon release into the cement paste to produce CaCO3. Consequently, chemical shrinkage of the cement paste is reduced, and the stiffness of the paste is enhanced. As a result, this technology achieves over 90% reduction in autogenous shrinkage with a 3% carbamide solution, compared to less than 50% with water alone. © 2024, The Authors. All rights reserved.

关键词： Calcite

Urban Environmental Influences on Ride-Hailing Safety: An Interpretable Machine Learning Approach for Predicting Accident-Prone Areas Using Crowdsourced Accident Datasets

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SSRN 2023年

作者： Liu, Jianxiao Yu, Yue Liu, Zhewei Jian, Yi Yao, Yepeng Department of Real Estate and Construction Faculty of Architecture The University of Hong Kong Hong Kong Department of Land Surveying and Geo-informatics The Hong Kong Polytechnic University Hung Hom Hong Kong UrbanResilience.AI Lab Zachry Department of Civil and Environmental Engineering Texas A&M University College StationTX United States Department of Social Sciences and Policy Studies The Education University of Hong Kong Hong Kong The Planning Department The Government of the Hong Kong SAR 999077 Hong Kong

Accurate identification of accident-prone areas and understanding the influential urban environmental factors for ride-hailing vehicles are of paramount importance for ensuring road safety. While past research has predominantly focused on the influences of ride-hailing drivers’ behaviors on road accidents, the role of various urban environmental factors has long been understudied. To address this gap, this work presents an interpretable machine learning approach to predict accident-prone areas for ride-hailing vehicles, based on intertwined urban environmental features. The task of identifying accident-prone areas is formulated as a binary classification problem. The accident-prone areas in the cities are predicted with two ensemble decision trees models, and the crowdsourced accident datasets from two major Chinese cities are used for model validation. The results demonstrate that the models can achieve good accuracy (over 0.7) in identifying accident-prone/non-prone areas. Notably, our methodology excels in delivering a high true positive rate (0.74) coupled with a low miss rate, attesting to the model's practicality for accurately predicting accident-prone areas. The model interpretation results pinpoint topographical features such as elevation and slope, as critical influencers of ride-hailing road accidents. The crossregion transferability analysis reveals that the feature importance and model transferability vary among cities, which suggests that the urban environmental determinants for ride-hailing accidents are not uniform, necessitating localized model adjustments for accurate accident-prone area prediction. The datadriven machine learning models presented provides a useful tool for predicting accident-prone areas and, the findings reveal novel insights on intertwined urban features’ influence on ride-hailing accident, facilitating integrated urban design towards road safety improvement and risk mitigation. © 2023, The Authors. All rights reserved.

关键词： Machine learning

Influence of FE modelling approaches on vulnerabilities of RC school buildings and proposal of a CFRP retrofitting intervention

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Open Construction and Building Technology Journal 2019年 13卷 269-287页

作者： Gazzani, Valentina Poiani, Marina Clementi, Francesco Pace, Giuseppe Lenci, Stefano Department of Civil and Building Engineering and Architecture (DICEA) Polytechnic University of Marche Ancona Ancona Italy

Background: The vulnerability assessment of existing school buildings against earthquakes represents a priority concern for society. In recent years, several countries promote seismic rehabilitation projects of school buildings, including the allocation of funds to regions with high seismic ***: This research aims to highlight some key role aspects related to difficulties encountered in the numerical modelling of RC structures hosting school activities. This work evaluates the seismic vulnerability of school buildings located in the municipality of Trecastelli (Marche, Central Italy) to quantify the effective influence of typical and specific seismic vulnerabilities detected on the global seismic behaviour of each building. The effectiveness of a possible Carbon Fibre Reinforced Polymer (CFRP) local strengthening intervention, for the case study, aimed to confine unconfined beam-column joints is also considered. Methods: Three different numerical models of a Reinforced Concrete (RC) school building are implemented with the lumped plasticity, the distributed plasticity (fibre) and the 3D Continuum Finite Element (FE) approaches. Nonlinear static (pushover) analyses are performed to assess the global seismic behaviour of the structure, and the limitations to represent the reality with different approaches. After the seismic vulnerability assessment of the case study, a CFRP retrofitting intervention is proposed to confine external beam-column joints. Results: The comparison of the numerical results of three models shows that the fibre model is the least suitable means to represent shear problems, while the lumped plasticity model is closer to reality than the previous one even if it does not take into account the concomitance of bending, shear and axial force and the interaction between them in the inelastic response. Of course, the 3D Continuum model is the most accurate representation to describe the complex and combined mechanisms developed in the join

关键词： 3D Continuum FE model Beam-column joints CFRP intervention Distributed plasticity model Nonlinear static analyses School building

Seismic investigation and retrofit of Villa Vannucchi in the Vesuvius area

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AIP Conference Proceedings 2025年第1期3269卷

作者： Giovanna Longobardi Francesco Fabbrocino Antonio Formisano Department of Structures for Engineering and Architecture School of Polytechnic and Basic Sciences University of Naples “Federico II” P.le V. Tecchio 80 80125 Naples Italy Department of Engineering Pegaso Telematic University Naples Italy

The seismic safety evaluation, together with adequate retrofitting operations, constitute useful and necessary tools to ensure the conservation and protection of the artistic and architectural heritage. Starting from these premises, the current paper deals with the seismic vulnerability assessment of an ancient mansion, Villa Vannucchi, placed in San Giorgio a Cremano, in the district of Naples. The study of the behaviour of the construction, covered by the bond of Superintendence of Cultural Heritage, has been pursued following the instructions of Italian Guidelines on Cultural Heritage (IGCH), which proposed three evaluation levels having an increasing detail degree. After collecting the main historical, geometrical and structural features regarding the Villa, firstly a qualitative analysis (EL1) has been performed obtaining two indices representative of the “health” of the building. Subsequently, via EL2, local mechanisms have been investigated. The vulnerability assessment has been completed through a global verification (EL3) by modeling the building on a computer software, which gives back the seismic safety facto α, defined as the ratio between capacity and demand acceleration. Based on the achieved results, a consolidation plan, including different compatible operations, has been hypothesized to reduce the seismic of the vulnerability of the Villa. Finally, the effectiveness of the interventions has been demonstrated by static non-linear analyses, which have shown an improvement of the α index.

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3D change detection for cultural heritage monitoring: Two case studies of underground sculptural reliefs

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Digital Applications in Archaeology and Cultural Heritage 2024年 33卷

作者： López-Armenta, María Fernanda Nespeca, Romina Universidad Autónoma Metropolitana (México) PhD student at División de Ciencias y Artes para el Diseño Unidad Xochimilco Calzada del Hueso 1100 Col. Villa Quietud Coyoacán Ciudad de México 04960 Mexico Polytechnic University of Marche Department of Civil Engineering and Architecture Ancona Italy

The preservation of underground cultural heritage is a challenging goal. Difficult acquisition conditions, the need for uniformity of temporal data and the speed at which surfaces change are some of the issues to consider. Also, quantifiable three-dimensional data are often unavailable when assessing changes on sculptural reliefs because traditional records are two-dimensional. In this paper, we present a workflow to easily detect and measure 3D superficial changes in sculptural reliefs using the deviation analysis technique. We compared multitemporal surveys, testing a quantitative, replicable, and verifiable procedure in two case studies: the reliefs of Pakal's Tomb at Palenque, Mexico, and those of the Osimo Caves in Italy. Both are located underground and show similar superficial alterations such as material disaggregation, efflorescence, salt crusts, and biological colonization. The reliefs showed visible and quantifiable changes on the deviation maps. The procedure to detect changes can be implemented with models generated by structured light scanning as well as photogrammetry. © 2024 Elsevier Ltd

关键词： 3D digitization Change detection Cultural heritage monitoring Multitemporal survey Sculptural reliefs

Performance and Environmental Impact Assessment of a Novel Zeolite Modified Cement Stabilized Calcareous Sand Material for Island Eco-Construction

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SSRN 2024年

作者： Cao, Liang Cao, Peng Wang, Ziyu Tan, Zhifei Zhou, Changjun Zhang, Guizhu Zhang, Shaojie Wang, Jianru Faculty of Architecture Civil and Transportation Engineering Beijing University of Technology Beijing100124 China Yazhou Bay Innovation Institute Hainan Tropical Ocean University Sanya572025 China College of Marine Science and Technology Hainan Tropical Ocean University Sanya572022 China Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hong Kong School of Infrastructure Engineering Dalian University of Technology Dalian116024 China Yancheng Maolei Information Science & Technology Co. Ltd Yancheng224001 China Academy of Aerospace Solid Propulsion Technology Xi'An710025 China

Adaptive use of local resources of remote islands as well as reducing carbon emissions and neutralizing heavy metal ions in the road construction and operation of the islands are important for protecting island ecosystems and human health. This study innovatively developed a novel zeolite modified cement stabilized calcareous sand (Z-CSCS) material. The physicochemical properties of the Z-CSCS material were investigated using various experimental tests. Furthermore, the environmental impact of the Z-CSCS material was evaluated in terms of both Pb2+ adsorption performance and a prospective life cycle assessment. The macroscopic test results demonstrated that zeolite could maintain its activity in Z-CSCS material under the designed mixing ratios of raw materials. The strength and porosity of Z-CSCS at 56 days decreased by 40.51% and 82.75%, while Pb2+ removal increased by 91.74% at 50% dosage of activated zeolite powder. Microscopic tests indicated the exchange of Ca2+ by zeolite inhibited the generation of calcium silicate hydrate (C-S-H), which weakened the connections between the components. The adsorption mechanisms of Z-CSCS on Pb2+ included cation exchange effect of zeolite and physical adsorption and chemical binding of C-SH. Additionally, the use of Z-CSCS could significantly reduce carbon emissions and energy consumption during the construction of island subgrade. Overall, the above results demonstrated the extraordinary potential of applying the Z-CSCS material in the eco-construction of islands. © 2024, The Authors. All rights reserved.

关键词： Life cycle

Chemical Upcycling of Waste Pet into Sustainable Asphalt Pavement Containing Recycled Concrete Aggregates: Insight into Moisture-Induced Damage

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SSRN 2022年

作者： Xu, Xiong Chen, Guofu Wu, Qiaoyun Leng, Zhen Chen, Xuyong Zhai, Yanfa Tu, Yanping Peng, Chao School of Civil Engineering and Architecture Wuhan Institute of Technology Wuhan430073 China Hubei Provincial Engineering Research Center for Green Civil Engineering Materials and Structures Wuhan430073 China Department of Civil and Environmental Engineering The Hong Kong Polytechnic University 999077 Hong Kong Henan Investment Group Company Limited Zhengzhou450000 China Faculty of Engineering China University of Geosciences Wuhan430074 China

Waste polyethylene terephthalate (PET) plastic and construction and demolition waste (C&DW) are main municipal solid wastes. If they are not properly disposed of, they will cause continuous damage to the ecological environment. Previous studies have shown that recycled concrete aggregate (RCA) can be successfully adopted to replace natural aggregate (NA) for asphalt pavement construction. However, the moisture-induced damage, as one of the pavement engineering performances, is very prominent for asphalt concrete containing RCA (RCA-AC), due to the high absorption of RCA. Given this, PET additive, derived from waste bottle bodies, is considered to improve the resistance of RCA-AC to moisture-induced damage in this study, which has been previously identified effective to enhance the anti-stripping characteristics of asphalt mixtures containing NA. To achieve this goal, this study applied a series of tests including contact angle, image recognition, boiling water test, immersed Marshall test, freeze-thaw (F-T) splitting test, wheel tracking test, and field emission scanning electron microscope (FESEM) to evaluate the moisture-induced damage of RCA-AC containing PET additive. The results showed that PET additive has significant ability to improve the bonding strength and adhesion of asphalt binder to RCA and reduce the stripping percentage and moisture-induced susceptibility of RCA-AC, especially under the F-T cycles. In addition, the 60 °C rut deformation resistance of RCA-AC after immersion can be improved as the PET additive is used. Furthermore, the interfacial bonding layers (IBL) of PET additive modified asphalt binder between RCA particles are still existent and its width is not significantly increased after immersion and F-T cycles by contrast to that of virgin binder. In general, the appropriate use of PET additive is a good approach to promote the high-quality recycling of RCA into sustainable asphalt pavement. © 2022, The Authors. All rights reserved.

关键词： Polyethylene terephthalates

Effects of Speech Intelligibility and Reverberation Time on the Serial Recall Task in Chinese Open-Plan Offices: A Laboratory Study

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SSRN 2022年

作者： Kang, Shengxian Mak, Cheuk Ming Ou, Dayi Zhou, Xinxin Department of Building Environment and Energy Engineering The Hong Kong Polytechnic University Kowloon Hung Hom Hong Kong School of Architecture Huaqiao University Xiamen361021 China State Key Laboratory of Subtropical Architecture Science South China University of Technology Guangzhou510640 China Guangzhou Design Institute Group Co. Ltd. Guangzhou510620 China

Speech intelligibility is an essential index for evaluating acoustic performance in open-plan offices. Both speech-to-noise ratio (SNR) and reverberation time (RT) are critical parameters for determining the Speech Transmission Index (STI). STI is an important parameter for the objective prediction of speech intelligibility. Many studies explored the effects of speech intelligibility on work performance and acoustic environmental perceptions in open-plan offices by changing the SNR to obtain various STI conditions. However, few studies research how RT affects speech intelligibility and then influences work performance and perceptions of acoustic environments in open-plan offices. This study conducted a laboratory experiment to identify the changing trends of work performance and acoustic environment perceptions with the increase in STI under different RT conditions and to explore how room RT affects work performance and perceptions of the acoustic environment under the same STI condition. The acoustic conditions tested in this study varied in speech intelligibility (STI of 0.21, 0.42, and 0.61) and reverberation time (RT of 0.4s and 1.4s). The main outcome of this study is that occupants have less mental workload and higher acoustic adaptability in a long RT environment compared to a short RT environment at an STI of 0.42. Furthermore, the data show a decreased work performance and an increased speech disturbance with the increase in STI in the short RT environment, while that trend was not observed in the long RT environment. The effects of STI conditions on occupants may differ by gender and noise sensitivity. © 2022, The Authors. All rights reserved.

关键词： Speech intelligibility

Numerical study on the local reinforcing of RC columns by steel perforated sheeting

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AIP Conference Proceedings 2025年第1期3269卷

作者： Emilia Meglio Antonio Davino Antonio Formisano Department of Structures for Engineering and Architecture School of Polytechnic and Basic Sciences University of Naples Federico II P.le V. Tecchio 80 80125 Naples Italy

The vulnerability of existing RC buildings under both gravity loads and seismic actions underlines the importance of experimenting new techniques to reinforce the structural elements. This work aims to assess the effectiveness of a new technique made of steel perforated sheetings for the local reinforcement of RC columns. The evaluation was carried out with a numerical analysis by implementing an RC column in the software Abaqus with and without the reinforcement. After a parametrical study on different solutions, it was defined the optimal configuration of the steel perforated sheeting and compared to a traditional reinforcement with steel angles and strips.

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