摘要：
In this study, inorganic hydrated salt Na2HPO4 & BULL;12H(2)O with a high enthalpy value and Na2SiO3 & BULL;9H(2)O were respectively selected as phase change material (PCM) and nucleating agent to obtain a modified PCM (modified-PCM). Then, by introducing the modified-PCM into expanded perlite (EP), a shape stable phase change material (DHPD-EP SSPCM) was prepared. Combined with the results of the leakage test and DSC, it was determined that the best adsorption rate of EP for the modified-PCM was 58wt %. SEM and N-2 adsorption-desorption experiments showed that modified-PCM was adsorbed in the surfaces and pores of EP. FT-IR, and XRD verified that the adsorption of EP for the modified-PCM was physical. The thermal performances of DHPD-EP SSPCM were also explored. Its enthalpy value, phase transition temperature, supercooling degree and thermal conductivity coefficient were 181.51 kJ/kg, 33.6 celcius, 5.8 celcius and 0.121 W/ (m & BULL;K), respectively. The heating-cooling experiment has confirmed the good thermal reliability of SSPCM, which has laid a foundation for the application of SSPCM in building enclosures in the future.
摘要：
In this paper, a single-tier beam-spring-damping system and a two-tier beam-spring-damping system are adopted to simulate the FT (fixed track) and FST (floating slab track) system, respectively. The tunnel is modeled as an infinitely long Euler—Bernoulli beam embedded in the layered saturated soil. By solving the governing equations of the saturated soil and employing the TRM (transmission and reflection matrices) method, the frequency response function of the tunnel-layered saturated soil model is obtained. Making use of the interaction between the tunnel and track systems, the track system is coupled with the tunnel-layered saturated ground model. The solutions for the dynamic response of the track system–tunnel-layered saturated ground model under moving loads in the time–space domain are obtained using the inverse Fourier integral transform. To evaluate the damping effect of the FST system on the vibration of tunnel and soil, four damping coefficients are defined and the vibration results of the FT system–tunnel-layered saturated soil model are compared with those of the FST system–tunnel-layered saturated soil under different moving loads and soil conditions. The numerical results show that both the vibration displacement and acceleration amplitude are attenuated after using the FST system, and the damping coefficient of acceleration is about 30% greater than that of the displacement. In addition, the damping effect of the FST system on the ground surface vibration is associated with the embedded depth of the tunnel and the soil stiffness.
期刊：
Construction and Building Materials,2023年409:133778 ISSN：0950-0618
通讯作者：
Zheng, ZS;Zhang, H
作者机构：
[Zeng, Chen] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Zheng, ZS; Zheng, Zhi-shan] Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;[Zhang, Hui; Zhang, H; Huang, Yu-jie] North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
通讯机构：
[Zheng, ZS ] W;[Zhang, H ] N;Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
关键词：
Early-age cracks;Steel corrosion;Mass transfer;Electrochemical corrosion;3D mesoscale cracked RC model
摘要：
Considering that reinforced concrete structures typically work with cracks, this work aims to investigate the chloride-induced non-uniform corrosion of steel by proposing a five-phase cracked reinforced concrete model at mesoscale, including realistic aggregate, matrix, steel, early-age crack, and damage zone. A physically-based 3D mesoscale modeling approach is developed to accommodate all the phases by integrating gravity-driven compaction and vibration as in real casting procedures. This modeling approach is further developed to capture coupled mass transfer and electrochemical corrosion of steel, enabling simulations of non-uniform corrosion along both the circumferential and longitudinal directions of steel. The considerable variation in corrosion morphology due to aggregate distribution demonstrates the necessity of using 3D mesoscale models to predict steel corrosion. Early-age cracks accelerate the diffusion of corrosive agents, intensifying the corrosion of steel. Increasing the crack width, depth, and length all contribute to a higher dissolution thickness of the steel. With the same crack size, longitudinal cracks result in a larger average dissolution thickness of the steel. In addition, the maximum dissolution thickness of the steel is highly correlated with the degree of pitting corrosion, and in most instances, transverse cracks lead to a higher degree of pitting, causing a greater maximum dissolution thickness.
期刊：
Construction and Building Materials,2023年409:133886 ISSN：0950-0618
通讯作者：
Zheng, ZS;Huang, YJ
作者机构：
[Zeng, Chen] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Wang, Xiang; Zheng, ZS; Zheng, Zhi-shan] Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;[Zhang, Hui; Huang, Yu-jie] North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
通讯机构：
[Zheng, ZS ] W;[Huang, YJ ] N;Wuhan Municipal Engn Design & Res Inst Co Ltd, Wuhan 430023, Peoples R China.;North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Peoples R China.
关键词：
Chloride diffusion;3D mesoscale model;Aggregate morphology;Hinder effect and corrosion of steel bar;Bi-directional diffusion
摘要：
This work proposes a novel numerical framework to investigate 3D chloride diffusion behavior in reinforced concrete (RC). An efficient dynamic modeling approach is developed to generate the RC models with real-shaped aggregates at mesoscale. A semi-closed form solution of Fick's second law is established to account for the time -varying chloride diffusion coefficient and surface chloride concentration through a genetic algorithm. Moreover, the effects of aggregate distribution and morphology on chloride diffusion are examined. The validated results demonstrate that the random distribution of aggregates leads to varied chloride concentration, and anisotropic aggregate morphology increases hindrance to chloride diffusion. Steel bar also affects chloride diffusion, causing an increase in chloride concentration on the steel surface. This hinder effect intensifies as the steel diameter increases and the protective layer thickness decreases. Additionally, bi-directional diffusion elevates chloride concentration on the corner steel surface, while smaller steel diameter and thicker protective layer render the corner steel bar more susceptible to bi-directional diffusion. The proposed framework has incorporated various influencing factors with comprehensive parametric analyses and holds potential for engineering design of RC structures considering durability, safety, and sustainability.
期刊：
WATER AIR AND SOIL POLLUTION,2023年234(2):1-15 ISSN：0049-6979
通讯作者：
Haijun Lu
作者机构：
[Luo, Fuwu; Liu, Mengyi; Lu, Haijun; Liu, Xiaofan] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Liu, Mengyi; Lu, Haijun] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.
通讯机构：
[Haijun Lu] S;School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan, China<&wdkj&>State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, China
关键词：
Contaminated soil;Industrial waste materials;Curing agent;Hydration products;Microstructure;Mengyi Liu contributed equally to this work and should be considered co-first author.
摘要：
Hexavalent chromium Cr (VI) pollution is prevalent at decommissioned industrial sites and poses a serious risk to the surrounding ecosystem and human health. In this study, we presented a novel heavy metal-contaminated soil curing agent derived from industrial slag (slag and desulfurization gypsum) for the treatment and remediation of Cr (VI)-contaminated soil. This curing agent was used to treat Cr (VI)-contaminated soil at pollution control (78 mg/kg), light contamination (380 mg/kg), and heavy contamination (1000 mg/kg) levels. The migratory properties of Cr (VI) in the cured contaminated soil were evaluated using toxic leaching and soil column tests. The mechanical strength and hydraulic conductivity of the cured contaminated soil were obtained using unconfined compressive, direct shear, and penetration tests. The mineralogical composition, chemical characteristics, and micromorphological features of the cured soils were analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The unconfined compressive strength and shear strength parameters (c and phi, respectively) increased significantly as the curing agent dosage was increased, whereas the Cr (VI) leaching concentration and hydraulic conductivity decreased. However, with an increase in Cr (VI) contamination, the cured soil metrics demonstrated the opposite trend. Most of the chromate (CrO42-) ions were encapsulated in hydration gelation products, such as C-S(A)-H and C-A-H. A small portion of Cr (VI) was reduced to Cr (III) or sequestered in the curing agent via charge adsorption. These test results demonstrated the multiple advantageous properties, including environmental safety, high strength, and low permeability, of this novel heavy metal curing agent derived from industrial waste.
摘要：
Aerobic granular sludge (AGS) is a promising technology for wastewater treatment due to its high biomass retention, nutrient removal, and resistance to toxic substances. However, the formation and stability of AGS are affected by various factors, such as feeding mode and antibiotic stress. This study investigated how three feeding modes, namely anaerobic plug-flow (APM), anaerobic mixed-flow (AMM), and aerobic feeding mode (AFM), influenced AGS formation and stability under exposure to a mixture of tetracycline, sulfamethoxazole, ofloxacin, and roxithromycin. The results showed that only APM and AMM achieved granulation within 40 d, while AFM failed to form AGS within 90 d due to the low shear force that led to a different composition and structure of extracellular polymeric substances and a high potential barrier calculated by extended Derjaguin-LandauVerwey-Overbeek (XDLVO) theory. The average granules diameters of APM (896.6 mu m) were larger than that of AMM (519.4 mu m), and the results of ultrasonic crushing experiment and XDLVO calculation showed that the structural stability of APM was slightly stronger. However, AMM outperformed APM and AFM in terms of total phosphorus removal, antibiotic removal, and long-term operational stability under low temperature conditions. Illumina MiSeq sequencing and qPCR results revealed that typical biofilm formers (Sediminibacterium and env. OPS_17) contributed to the stability of AGS and increased phosphorus accumulating organisms' genes abundance ensured the high TP removal in AMM. This study offers valuable insights into the effects of diverse feeding modes on aerobic granulation and stability under combined antibiotic stress and suggests that AMM is a promising mode for enhancing AGS performance and resilience in wastewater treatment applications.
摘要：
In most coastal and estuarine areas, tides easily cause surface erosion and even slope failure, resulting in severe land losses, deterioration of coastal infrastructure, and increased floods. The bio-cementation technique has been previously demonstrated to effectively improve the erosion resistance of slopes. Seawater contains magnesium ions (Mg2+) with a higher concentration than calcium ions (Ca2+); therefore, Mg2+ and Ca2+ were used together for bio-cementation in this study at various Mg2+/Ca2+ ratios as the microbially induced magnesium and calcium precipitation (MIMCP) treatment. Slope angles, surface strengths, precipitation contents, major phases, and microscopic characteristics of precipitation were used to evaluate the treatment effects. Results showed that the MIMCP treatment markedly enhanced the erosion resistance of slopes. Decreased Mg2+/Ca2+ ratios resulted in a smaller change in angles and fewer soil losses, especially the Mg2+ concentration below 0.2 M. The decreased Mg2+/Ca2+ ratio achieved increased precipitation contents, which contributed to better erosion resistance and higher surface strengths. Additionally, the production of aragonite would benefit from elevated Mg2+ concentrations and a higher Ca2+ concentration led to more nesquehonite in magnesium precipitation crystals. The slopes with an initial angle of 53° had worse erosion resistance than the slopes with an initial angle of 35°, but the Mg2+/Ca2+ ratios of 0.2:0.8, 0.1:0.9, and 0:1.0 were effective for both slope stabilization and erosion mitigation to a great extent. The results are of great significance for the application of MIMCP to improve erosion resistance of foreshore slopes and the MIMCP technique has promising application potential in marine engineering.
关键词：
Historic buildings;Building function;Space;Architectural appearance;Concession district
摘要：
A city is an organic system. It is necessary to correctly handle the valuable historic buildings and blocks to promote the sustainable development of the city, because they are non-renewable resources in urban development. This paper takes the renovation project of Wuhan Art Museum as the research object. It explored the general methods of the protection and renewal of historic buildings from the aspects of historical value, appearance design, functional layout, etc. This research used the method of combining theory with practice and summarized the key points of the renovation of historic buildings by case analysis. The purpose of this research is to find a way to reuse historic buildings in line with China's national conditions. This can provide a useful reference for other similar projects. The practice of the renovation project must be given appropriate uses, which is the key to continue their lives. Only in this way can old buildings meet the modern lifestyle.
通讯机构：
[Xiaosheng Wei] S;Room 201, West Building No. 6, School of Civil and Hydraulic Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, China
关键词：
Contact friction;Compressive strength;Concrete mesoscale concretization model;Numerical simulation;Size effect law
通讯机构：
[Rong Luo; Xiantao Qin] A;Authors to whom correspondence should be addressed.<&wdkj&>School of Civil Engineering and Architecture, Wuhan Polytechnic University, 68 Xuefu South Road, Wuhan 430023, China<&wdkj&>School of Transportation and Logistics Engineering, Wuhan University of Technology, 1178 Heping Avenue, Wuhan 430063, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>School of Transportation and Logistics Engineering, Wuhan University of Technology, 1178 Heping Avenue, Wuhan 430063, China
摘要：
In order to evaluate and improve the deformation behavior of cement-emulsified asphalt binder (CA) in cement-emulsified asphalt mixture, this study investigated the reinforcement of small additions of fibers (2%, 4%, and 6% addition by mass of cement) on the deformation resistance of CA. A repeated creep recovery test was implemented that measures the recovery rate of creep deformation and accumulated strain. Further, an improved piecewise curve-fitting method was used to determine the parameters of Burgers model, then the creep compliances were fitted and calculated. The results show the repeated creep recovery test to be a suitable method for obtaining useful information about creep and recovery deformation of fiber-reinforced CA. The influence of fiber types and dosages on the deformation recovery ability is determined based on the creep recovery ratio and accumulated strain. The improved piecewise curve-fitting method has high accuracy. Thereafter, the reinforcement effect was analyzed through the evolution of creep compliance under loading. Therefore, this paper can provide a reference for enhancing the properties of cement-emulsified asphalt mixture by maximizing the fiber reinforcement.
通讯机构：
[Junwu Wang] S;School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430062, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
early warning;construction safety risk;subway station;LSSVM;QPSO;accident causation theory
