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Effect of recycled brick powder on the properties of selfcompacting fiber reinforced mortars produced with different cement types

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Frontiers of Structural and civil engineering 2024年第5期18卷 743-759页

作者： Serkan ETLI department of civil engineering Kahramanmaras Sutcu Imam UniversityKahramanmaraş46040Turkey

It is known that clay-based building materials such as bricks and tiles accumulate in landfills at the end of their useful *** an alternative,recycling clay-based building material can reduce the negative environmental *** brick powder(RBP)is obtained by grinding waste brick and tile collected from end-of-life *** the scope of the study,the use of self-compacting fiber reinforced mortars(SCFRMs)produced with RBP using CEM-I 42.5R and 52.5R class cements for two different cement classes was *** accordance with EFNARC,a water binding ratio of 0.42 was used to control the workability and strength of the *** the produced SCFRM,1%,2%,and 3%by weight binder Polypropylene(PP)fiber was added to the blends with 10%,20%,and 30%RBP substitutes.A total of 32 SCFRM mixes were produced and *** flexural and compressive strengths at 7,28,56,and 90 d were evaluated on the produced *** addition,porosity and water absorbency values were examined since these are significant for durability *** was observed that the use of RBP increases durability,and the use of fiber can have positive effects in terms of both durability and strength.

关键词： cement strength tile/brick dust self-compacting fiberized mortar

Preface:Heavy metal(loid)s at mining&metallurgical sites:Fate,risk and remediation

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Journal of Central South University 2024年第4期31卷 1033-1035页

作者：薛生国李楚璇赵东叶吴川 School of Metallurgy and Environment Central South UniversityChangsha 410083China department of civil Constructionand Environmental EngineeringSan Diego State UniversitySan DiegoCA 92182USA

The contamination of heavy metal(loid)s at mining&metallurgical sites has been a major environmental challenge worldwide[1].Typically,large amounts of metal(loid)s-bearing wastes are generated at these sites,such as smelting slag,combustion residues,mine tailings,wastewater,and exhaust gas[2].Due to their high mobility in the environment,the released heavy metal(loid)s can easily enter the soil and water environment,posing long-term and widespread threats to ecological and human health[3].

关键词： mining wastewater smelting

Characterization of a smog chamber for studying formation of gas-phase products and secondary organic aerosol

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Journal of environmental Sciences 2024年第2期136卷 570-582页

作者： Qi Yuan Zhuozhi Zhang Meng Wang Kin Fai Ho Tao Wang Shuncheng Lee department of civil and environmental engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina School of Public Health and Primary Care The Chinese University of Hong KongShatinHong KongChina

Smog chambers provide a potent approach to explore the secondary organic aerosol formation under varied *** study describes the construction and characterization of a new smog chamber facility for studying the formation mechanisms of gas-phase products and secondary organic aerosol from the photooxidation of volatile organic *** chamber is a 5.4 m^(3) Fluorinated Ethylene Propylene(FEP)Teflon reactor with the potential to perform photooxidation experiments at controlled temperature and relative *** characterizations were conducted for evaluation of stability of environmental parameters,mixing time,background contamination,light intensity,and wall losses of gases and *** photolysis rate of NO_(2)(J_(NO2))ranged from(1.02-3.32)×10^(-3)sec^(-1),comparable to the average J_(NO2)in ambient *** wall loss rates for NO,NO_(2),and O_(3)were 0.47×10^(-4),0.37×10^(-4),and 1.17×10^(-4)min^(-1),while wall loss of toluene was obsoletely found in a 6 hr *** particle number wall loss rates are(0.01-2.46)×10^(-3)min^(-1)for 40-350 nm with an average lifetime of more than one day.A series of toluene photooxidation experiments were carried out in absence of NO_xunder dry *** results of the simulation experiments demonstrated that the chamber is well designed to simulate photolysis progress in the atmosphere.

关键词： Smog chamber Gas-phase oxidation Chamber characterization Chemical mechanism

Inverse reliability analysis and design for tunnel face stability considering soil spatial variability

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Journal of Rock Mechanics and Geotechnical engineering 2024年第5期16卷 1552-1564页

作者： Zheming Zhang Jian Ji Xiangfeng Guo Siang Huat Goh Key Laboratory of Ministry of Education for Geomechanics and Embankment engineering Hohai UniversityNanjing210098China department of civil and environmental engineering National University of SingaporeSingapore

The traditional deterministic analysis for tunnel face stability neglects the uncertainties of geotechnical parameters,while the simplified reliability analysis which models the potential uncertainties by means of random variables usually fails to account for soil spatial *** overcome these limitations,this study proposes an efficient framework for conducting reliability analysis and reliability-based design(RBD)of tunnel face stability in spatially variable soil *** three-dimensional(3D)rotational failure mechanism of the tunnel face is extended to account for the soil spatial variability,and a probabilistic framework is established by coupling the extended mechanism with the improved Hasofer-Lind-Rackwits-Fiessler recursive algorithm(iHLRF)as well as its inverse analysis *** proposed framework allows for rapid and precise reliability analysis and RBD of tunnel face *** demonstrate the feasibility and efficacy of the proposed framework,an illustrative case of tunnelling in frictional soils is presented,where the soil's cohesion and friction angle are modelled as two anisotropic cross-correlated lognormal random *** results show that the proposed method can accurately estimate the failure probability(or reliability index)regarding the tunnel face stability and can efficiently determine the required supporting pressure for a target reliability index with soil spatial variability being taken into ***,this study reveals the impact of various factors on the support pressure,including coefficient of variation,cross-correlation between cohesion and friction angle,as well as autocorrelation distance of spatially variable soil *** results also demonstrate the feasibility of using the forward and/or inverse first-order reliability method(FORM)in high-dimensional stochastic *** is hoped that this study may provide a practical and reliable framework for determining the stability of tunnels in complex

关键词： Limit analysis Tunnel face stability Spatial variability HLRF algorithm Inverse reliability method

Control of fine particulate nitrate during severe winter haze in“2+26”cities

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Journal of environmental Sciences 2024年第2期136卷 261-269页

作者： Chuang Qin Xiao Fu Tao Wang Jian Gao Jiaqi Wang Institute of Environment and Ecology Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China department of civil and environmental engineering Hong Kong Polytechnic UniversityHong Kong 99907China State Key Laboratory of environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 10084China

The“2+26”cities,suffering the most severe winter haze pollution,have been the key region for air quality improvement in *** prominent nitrate pollution is one of the most challenging environmental issues in this region,necessitating development of an effective control ***,we use observations,and state-of-the-art model simulations with scenario analysis and process analysis to quantify the effectiveness of the future SO_(2)-NO_(X)-VOC-NH_(3) emission control on nitrate pollution mitigation in“2+26”*** on a serious winter haze episode,we find that limited NO_(X)emission reduction alone in the short-term period is a less effective choice than VOC or NH_3emission reduction alone to decrease nitrate concentrations,due to the accelerated NO_(X)-HNO_(3)conversion by atmospheric oxidants and the enhanced HNO_(3)to NO_(3)^(-)partition by ammonia,although deep NO_(X)emission reduction is essential in the long-term *** synergistic NH_(3) and VOC emission control is strongly recommended,which can counteract the adverse effects of nonlinear photochemistry and aerosol chemical feedback to decrease nitrate *** extra benefits will be reduced if the synergistic NH_(3) and VOC reduction is delayed,and thus reducing emission of multiple precursors is urgently required for the effective control of increasingly severe winter nitrate pollution in“2+26”cities.

关键词： Nitrate Winter haze pollution Emission reduction “2+26”cities

A comprehensive comparison of different regression techniques and nature-inspired optimization algorithms to predict carbonation depth of recycled aggregate concrete

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Frontiers of Structural and civil engineering 2024年第1期18卷 30-50页

作者： Bin XI Ning ZHANG Enming LI Jiabin LI Jian ZHOU Pablo SEGARRA department of civil and environmental engineering Politecnico Di MilanoMilano 20133Italy Leibniz Institute of Ecological Urban and Regional Development(IOER) Dresden 01217Germany Universidad Politécnica de Madrid-ETSI Minas y Energía Madrid 28003Spain department of civil engineering KU Leuven CampusBrugge 8200Belgium School of Resources and Safety engineering Central South UniversityChangsha 410083China

The utilization of recycled aggregates(RA)for concrete production has the potential to offer substantial environmental and economic ***,RA concrete is plagued with considerable durability concerns,particularly *** advance the application of RA concrete,the establishment of a reliable model for predicting the carbonation is *** the one hand,concrete carbonation is a long and slow process and thus consumes a lot of time and energy to *** the other hand,carbonation is influenced by many factors and is hard to *** this,this paper proposes the use of machine learning techniques to establish accurate prediction models for the carbonation depth(CD)of RA *** types of regression techniques and meta-heuristic algorithms were employed to provide more alternative predictive *** was found that the best prediction performance was obtained from extreme gradient boosting-multi-universe optimizer(XGB-MVO)with R^(2) value of 0.9949 and 0.9398 for training and testing sets,***-MVO was used for evaluating physical laws of carbonation and it was found that the developed XGB-MVO model could provide reasonable predictions when new data were *** also showed better generalization capabilities when compared with different models in the ***,this paper emphasizes the need for sustainable solutions in the construction industry to reduce its environmental impact and contribute to sustainable and low-carbon economies.

关键词： recycled aggregate concrete carbonation depth nature-inspired optimization algorithms extreme gradient boosting technique parametric analysis

Factors hindering the degradation of pharmaceuticals from human urine in an iron-activated persulfate system

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Journal of environmental Sciences 2024年第1期135卷 130-148页

作者： Yiruiwen Xie Dao Guan Yangfan Deng Yugo Sato Yu Luo Guanghao Chen department of civil and environmental engineering Water Technology LabHong Kong Branch of Chinese National Engineering Research Center for Control&Treatment of Heavy Metal PollutionThe Hong Kong University of Science&TechnologyHong Kong 999077China

This study investigated the degradation of clofibric acid(CFA),bezafibrate(BZF),and sulfamethoxazole(SMX)in synthetic human urine using a novel mesoporous iron powderactivated persulfate system(mFe-PS system),and identified the factors limiting their degradation in synthetic human urine.A kinetic model was established to expose the radical production in various reaction conditions,and experiments were conducted to verify the modeling *** the phosphate-containing mFe-PS system,the 120 min removal efficiency of CFA decreased from 95.1%to 76.6%as the phosphate concentration increased from 0.32 to 6.45 mmol/L,but recovered to 90.5%when phosphate concentration increased to 16.10 mmol/***,the increased concentration of phosphate from 0.32 to 16.10mmol/L reduced the BZF degradation efficacy from 91.5%to 79.0%,whereas SMX removal improved from 37.3%to 62.9%.The m Fe-PS system containing(bi)carbonate,from 4.20 to166.70 mmol/L,reduced CFA and BZF removal efficiencies from 100%to 76.8%and 80.4%,respectively,and SMX from 83.5%to 56.7%within a 120-min reaction *** addition,alkaline conditions(pH≥8.0)inhibited CFA and BZF degradations,while nonacidic pH(pH≥7.0)remarkably inhibited SMX *** of the kinetic model indicated the formation of phosphate(H_(2)PO_(4)^(·)/HPO_(4)^(·-))and/or carbonate radicals(CO_(3)^(·-))could limit pharmaceutical *** transformation products(TPs)of the pharmaceuticals revealed more incompletely oxidized TPs occurred in the phosphate-and(bi)carbonate-containing m Fe-PS systems,and indicated that H_(2)PO_(4)^(·)/HPO_(4)^(·-)mainly degraded pharmaceuticals via a benzene ring-opening reaction while CO_(3)^(·-)preferentially oxidized pharmaceuticals via a hydroxylation reaction.

关键词： Pharmaceutical degradation Human urine Iron-activated persulfate system Phosphate radicals Carbonate radicals Transformation products

Comprehensive insight into the occurrence characteristics,influencing factors and risk assessments of antibiotics in the Chaohu Basin

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Frontiers of environmental Science & engineering 2024年第5期18卷 57-71页

作者： Shuanggang Hu Hongzhi Zhang Yongjie Yang Kangping Cui Junjie Ao Xuneng Tong Mengchen Shi Yi Wang Xing Chen Chenxuan Li Yihan Chen School of Resources and environmental engineering Hefei University of TechnologyHefei230009China Ministry of Education-Shanghai Key Laboratory of Children’s environmental Health Xinhua HospitalShanghai Jiao Tong University School of MedicineShanghai200092China department of civil & environmental engineering National University of SingaporeSingapore117576Singapore College of Resources and Environment Anhui Agricultural UniversityHefei230036China

The pollution of antibiotics in aquatic environments has received extensive ***,research on antibiotic contamination in river-lake systems,a significant form of modern aquatic environments,still needs to be *** study focuses on the Chaohu Basin(China)investigating the occurrence characteristics,influencing factors,and risk assessments of antibiotics in the river-lake *** total antibiotic concentrations in the water phase and sediment phase were 3.14–1887.49 ng/L and 0.92–1553.75 ng/g,*** was the predominant antibiotic in the water phase,whereas tetracycline prevailed in the sediment *** differences in concentration and structural composition of antibiotics between the tributaries(river system)and Chaohu Lake were observed,indicating the involvement of various geochemical processes in the attenuation of antibiotics during transport to the receiving *** analysis suggested that the western river is the primary source of antibiotics in Chaohu *** nutrient influx in heavily polluted areas is crucial to addressing the escalating issue of antibiotic pollution in the river-lake *** widespread occurrence of clindamycin in the waters is likely due to wastewater treatment plant discharges,and high-intensity human activities continue to exacerbate antibiotic *** assessment indicated that sulfamethoxazole,tetracycline,lincomycin,and clindamycin ranked in the top four with the highest risks to the most sensitive aquatic ***,the antibiotics presented no risk to consumer *** study provides valuable insights for controlling antibiotic pollution in riverlake systems.

关键词： Antibiotics Occurrence characteristics Influencing factors Risk assessments River-lake system

A CFD Model to Evaluate Near-Surface Oil Spill from a Broken Loading Pipe in Shallow Coastal Waters

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Fluid Dynamics & Materials Processing 2024年第1期20卷 59-77页

作者： Portia Felix Lee Leon Derek Gay Stefano Salon Hazi Azamathulla department of civil and environmental engineering The University of the West IndiesSt.AugustineTrinidad and Tobago National Institute of Oceanography and Experimental Geophysics-OGS TriesteItaly

Oil spills continue to generate various issues and concerns regarding their effect and behavior in the marine environment,owing to the related potential for detrimental environmental,economic and social *** is essential to have a solid understanding of the ways in which oil interacts with the water and the coastal ecosystems that are located *** study proposes a simplified model for predicting the plume-like transport behavior of heavy Bunker C fuel oil discharging downward from an acutely-angled broken pipeline located on the water *** results show that the spill overall profile is articulated in three major flow *** first,is the source field,i.e.,a region near the origin of the initial jet,followed by the intermediate or transport field,namely,the region where the jet oil flow transitions into an underwater oil plume flow and starts to move horizontally,and finally,the far-field,where the oil re-surface and spreads onto the shore at a significant distance from the spill *** behavior of the oil in the intermediate field is investigated using a simplified injection-type oil spill model capable of mimicking the undersea trapping and lateral migration of an oil plume originating from a negatively buoyant jet spill.A rectangular domain with proper boundary conditions is used to implement the *** Projection approach is used to discretize a modified version of the Navier-Stokes equations in two dimensions.A benchmark fluid flow issue is used to verify the model and the results indicate a reasonable relationship between specific gravity and depth as well as agreement with the aerial data and a vertical temperature profile plot.

关键词： CFD model Navier-Stokes equations projection method water surface oil spill shallow coastal waters