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Civil engineering

Tao Zhang, Guojun Cai, Weihong Duan
The disposal of scrap rubber tires has induced critical environmental issue worldwide due to the rapid increase in the number of vehicles. Recycled scrap tires as a construction material in civil engineering have significant environmental benefits from a waste management perspective. A systematic study that deals with strength and microstructure characteristics of the rubber-sand mixtures is initiated, and mechanical response of the mixtures is discussed in this investigation. Experiments were conducted to evaluate the effects of rubber fraction on the basic properties including mass density (ρ), stress-strain characteristics, shear strength, and unconfined compression strength (q u) of the rubber-sand mixtures...
November 25, 2017: Environmental Science and Pollution Research International
Jean-Baptiste Legland, Yuxiang Zhang, Odile Abraham, Olivier Durand, Vincent Tournat
The field of civil engineering is in need of new methods of non-destructive testing, especially in order to prevent and monitor the serious deterioration of concrete structures. In this work, experimental results are reported on fault detection and characterization in a meter-scale concrete structure using an ultrasonic nonlinear coda wave interferometry (NCWI) method. This method entails the nonlinear mixing of strong pump waves with multiple scattered probe (coda) waves, along with analysis of the net effect using coda wave interferometry...
October 2017: Journal of the Acoustical Society of America
Xing Lu, Shuangyou Zhang, Xing Chen, Dohyeon Kwon, Chan-Gi Jeon, Zhigang Zhang, Jungwon Kim, Kebin Shi
Ultrahigh-resolution optical strain sensors provide powerful tools in various scientific and engineering fields, ranging from long-baseline interferometers to civil and aerospace industries. Here we demonstrate an ultrahigh-resolution fibre strain sensing method by directly detecting the time-of-flight (TOF) change of the optical pulse train generated from a free-running passively mode-locked laser (MLL) frequency comb. We achieved a local strain resolution of 18 pε/Hz(1/2) and 1.9 pε/Hz(1/2) at 1 Hz and 3 kHz, respectively, with large dynamic range of >154 dB at 3 kHz...
October 17, 2017: Scientific Reports
Junhwa Lee, Kyoung-Chan Lee, Soojin Cho, Sung-Han Sim
The displacement responses of a civil engineering structure can provide important information regarding structural behaviors that help in assessing safety and serviceability. A displacement measurement using conventional devices, such as the linear variable differential transformer (LVDT), is challenging owing to issues related to inconvenient sensor installation that often requires additional temporary structures. A promising alternative is offered by computer vision, which typically provides a low-cost and non-contact displacement measurement that converts the movement of an object, mostly an attached marker, in the captured images into structural displacement...
October 11, 2017: Sensors
Tianyong Jiang, Junbo Zheng, Linsheng Huo, Gangbing Song
With the development of the post-tensioning technique, prestressed concrete structures have been widely used in civil engineering. To ensure the long-term effectiveness of the prestressed tendon, the grouting quality of the tendon duct is one of the important factors. However, it is still a challenge to monitor the grouting quality of post-tensioning tendon ducts, due to the invisibility of the grouting. The authors' previous work proposed a real-time method that employed a stress wave-based active sensing approach with piezoceramic transducers to monitor the grouting compactness of a Post-Tensioning Tendon Duct (PTTD)...
September 29, 2017: Sensors
Clémence Essé, Véronique A Koffi, Abel Kouamé, Kouassi Dongo, Richard B Yapi, Honorine M Moro, Christiane A Kouakou, Marta S Palmeirim, Bassirou Bonfoh, Eliézer K N'Goran, Jürg Utzinger, Giovanna Raso
BACKGROUND: Integrated control programs, emphasizing preventive chemotherapy along with health education, can reduce the incidence of soil-transmitted helminthiasis and schistosomiasis. The aim of this study was to develop an educational animated cartoon to improve school children's awareness regarding soil-transmitted helminthiasis, diarrheal diseases, and related hygiene practices in Côte d'Ivoire. The key messages included in the cartoon were identified through prior formative research to specifically address local knowledge gaps...
September 2017: PLoS Neglected Tropical Diseases
Kamal Niaz, Faheem Maqbool, Haji Bahadar, Mohammad Abdollahi
Honey is known for its therapeutic properties from ancient civilizations but only since last few decades its mechanism has been studied on how it causes epithelial regeneration leading to wound and ulcer healing.. In the present review the health perspectives of honey, its chemical composition with special reference to flavonoids, polyphenol composition and other bioactive trace compounds used in tissue regeneration have been highlighted. Honey can inhibit carcinogenesis by moderating with molecular processes of initiation, advancement and progression stage of cancer cells, therefore it is considered a promising anti-cancer agent...
September 11, 2017: Current Drug Metabolism
Ueli M Angst, Carolina Boschmann, Matthias Wagner, Bernhard Elsener
The aging of reinforced concrete infrastructure in developed countries imposes an urgent need for methods to reliably assess the condition of these structures. Corrosion of the embedded reinforcing steel is the most frequent cause for degradation. While it is well known that the ability of a structure to withstand corrosion depends strongly on factors such as the materials used or the age, it is common practice to rely on threshold values stipulated in standards or textbooks. These threshold values for corrosion initiation (Ccrit) are independent of the actual properties of a certain structure, which clearly limits the accuracy of condition assessments and service life predictions...
August 31, 2017: Journal of Visualized Experiments: JoVE
Jaroslava Koťátková, Jan Zatloukal, Pavel Reiterman, Karel Kolář
This review article presents the current state-of-knowledge of the use of cementitious materials for radioactive waste disposal. An overview of radwaste management processes with respect to the classification of the waste type is given. The application of cementitious materials for waste disposal is divided into two main lines: i) as a matrix for direct immobilization of treated waste form; and ii) as an engineered barrier of secondary protection in the form of concrete or grout. In the first part the immobilization mechanisms of the waste by cement hydration products is briefly described and an up-to date knowledge about the performance of different cementitious materials is given, including both traditional cements and alternative binder systems...
November 2017: Journal of Environmental Radioactivity
Zhi Cao, Lei Shen, Amund N Løvik, Daniel B Müller, Gang Liu
Modern cities and societies are built fundamentally based on cement and concrete. The global cement production has risen sharply in the past decades due largely to urbanization and construction. Here we deployed a top-down dynamic material flow analysis (MFA) model to quantify the historical development of cement in-use stocks in residential, nonresidential, and civil engineering sectors of all world countries. We found that global cement production spreads unevenly among 184 countries, with China dominating the global production and consumption after the 1990s...
September 12, 2017: Environmental Science & Technology
Tarique Ahmad, Kafeel Ahmad, Mehtab Alam
Large volume of sludge is generated at the water treatment plants during the purification of surface water for potable supplies. Handling and disposal of sludge require careful attention from civic bodies, plant operators, and environmentalists. Quantification of the sludge produced at the treatment plants is important to develop suitable management strategies for its economical and environment friendly disposal. Present study deals with the quantification of sludge using empirical relation between turbidity, suspended solids, and coagulant dosing...
August 15, 2017: Environmental Monitoring and Assessment
Coleen M Carrigan
Computing is highly segregated and stratified by gender. While there is abundant scholarship investigating this problem, emerging evidence suggests that a hierarchy of value exists between the social and technical dimensions of Computer Science and Engineering (CSE) and this plays a role in the underrepresentation of women in the field. This ethnographic study of women's experiences in computing offers evidence of a systemic preference for the technical dimensions of computing over the social and a correlation between gender and social aspirations...
2017: Frontiers in Psychology
Feng Lin, Yu Dong, Xinxin Kuang, Le Lu
The strain rate effect of reinforcing steel bars is generally indispensable for modeling the dynamic responses of reinforced concrete structures in blast and impact events. A systematic experimental investigation was conducted on the strain rate behavior of reinforcing steel bar grades HPB235, HRB335, HRB400, and HRB500 which are widely used in the field of civil engineering in China. The dynamic testing was performed using a servo-hydraulic Instron VHS160/100-20 in a strain rate range from 2 to 75 s(-1). Stress-strain curves at preset strain rates were obtained...
December 15, 2016: Materials
How-Ji Chen, Ying-Chih Hsueh, Ching-Fang Peng, Chao-Wei Tang
The lightweight aggregates used by the civil engineering market are sintered at a high temperature, about 1200 °C. In times of high energy prices and regulation of carbon dioxide emissions, lightweight aggregate products of the high-temperature process in sales marketing are not readily accepted. This study developed a sintered-type paper sludge lightweight aggregate. In order to reduce energy consumption, substitution of some reservoir sediment clay in paper sludge substitutes is to be expected. The study used two types of paper sludge (green clay paper sludge and paper pulp sludge)...
October 27, 2016: Materials
Yun-Lai Zhou, Hongyou Cao, Quanmin Liu, Magd Abdel Wahab
Output-based structural damage detection is becoming increasingly appealing due to its potential in real engineering applications without any restriction regarding excitation measurements. A new transmissibility-based damage detection approach is presented in this study by combining transmissibility with correlation analysis in order to strengthen its performance in discriminating damaged from undamaged scenarios. From this perspective, damage detection strategies are hereafter established by constructing damage-sensitive indicators from a derived transmissibility...
July 27, 2017: Materials
Wei Xu, Maosen Cao, Keqin Ding, Maciej Radzieński, Wiesław Ostachowicz
Carbon fiber reinforced polymer laminates are increasingly used in the aerospace and civil engineering fields. Identifying cracks in carbon fiber reinforced polymer laminated beam components is of considerable significance for ensuring the integrity and safety of the whole structures. With the development of high-resolution measurement technologies, mode-shape-based crack identification in such laminated beam components has become an active research focus. Despite its sensitivity to cracks, however, this method is susceptible to noise...
June 15, 2017: Materials
José Marcos Ortega, María Dolores Esteban, Raúl Rubén Rodríguez, José Luis Pastor, Francisco José Ibanco, Isidro Sánchez, Miguel Ángel Climent
Nowadays, one of the most popular ways to get a more sustainable cement industry is using additions as cement replacement. However, there are many civil engineering applications in which the use of sustainable cements is not extended yet, such as special foundations, and particularly micropiles, even though the standards do not restrict the cement type to use. These elements are frequently exposed to the sulphates present in soils. The purpose of this research is to study the effects in the very long-term (until 600 days) of sulphate attack in the microstructure of micropiles grouts, prepared with ordinary Portland cement, fly ash and slag commercial cements, continuing a previous work, in which these effects were studied in the short-term...
May 30, 2017: Materials
Xianfeng Wang, Peipei Sun, Ningxu Han, Feng Xing
Encapsulation of healing agents embedded in a material matrix has become one of the major approaches for achieving self-healing function in cementitious materials in recent years. A novel type of microcapsules based self-healing cementitious composite was developed in Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University. In this study, both macro performance and the microstructure of the composite are investigated. The macro performance was evaluated by employing the compressive strength and the dynamic modulus, whereas the microstructure was represented by the pore structure parameters such as porosity, cumulative-pore volume, and average-pore diameter, which are significantly correlated to the pore-size distribution and the compressive strength...
January 1, 2017: Materials
Dong-Sheng Xu, Yu-Meng Zhao, Hua-Bei Liu, Hong-Hu Zhu
With the rapid construction of metro tunnels in many metropolises, a fast and convenient solution to capture tunnel deformation is desired by civil engineers. This contribution reports an automatic and wireless tunnel deformation monitoring system using ultrasonic transducers. A processing algorithm of the redundant ultrasonic information (RUI) approach is proposed to improve measurement accuracy. The feasibility of this tunnel deformation monitoring method is carefully examined with various probe angles, distances, and surrounding temperature variations...
August 1, 2017: Sensors
Navdeep K Dhami, Walaa R Alsubhi, Elizabeth Watkin, Abhijit Mukherjee
Microbially-induced CaCO3 precipitation (MICP) is a naturally occurring process wherein durable carbonates are formed as a result of microbial metabolic activities. In recent years, MICP technology has been widely harnessed for applications in civil engineering wherein synthesis of calcium carbonate crystals occurs at ambient temperature paving way for low energy biocement. MICP using pure urease (UA) and carbonic anhydrase (CA) producing bacteria has been promising in laboratory conditions. In the current study we enriched ureolytic and carbonic anhydrase communities in calcareous soil under biostimulation and bioaugmentation conditions and investigated the effect of microbial dynamics on carbonate precipitation, calcium carbonate polymorph selection and consolidation of biological sand column under nutrient limited and rich conditions...
2017: Frontiers in Microbiology
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