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Quantification of the concrete freeze–thaw environment across the Qinghai–Tibet Plateau based on machine learning algorithms

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Journal of Mountain Science 2024年第1期21卷 322-334页

作者： QIN Yanhui MA Haoyuan ZHANG Lele YIN Jinshuai ZHENG Xionghui LI Shuo Department of Civil Engineering Qingdao University of TechnologyQingdao 266520China Department of Geography Qinghai Normal UniversityXining 810008China

The reasonable quantification of the concrete freezing environment on the Qinghai–Tibet Plateau(QTP) is the primary issue in frost resistant concrete design, which is one of the challenges that the QTP engineering managers should take into account. In this paper, we propose a more realistic method to calculate the number of concrete freeze–thaw cycles(NFTCs) on the QTP. The calculated results show that the NFTCs increase as the altitude of the meteorological station increases with the average NFTCs being 208.7. Four machine learning methods, i.e., the random forest(RF) model, generalized boosting method(GBM), generalized linear model(GLM), and generalized additive model(GAM), are used to fit the NFTCs. The root mean square error(RMSE) values of the RF, GBM, GLM, and GAM are 32.3, 4.3, 247.9, and 161.3, respectively. The R^(2) values of the RF, GBM, GLM, and GAM are 0.93, 0.99, 0.48, and 0.66, respectively. The GBM method performs the best compared to the other three methods, which was shown by the results of RMSE and R^(2) values. The quantitative results from the GBM method indicate that the lowest, medium, and highest NFTC values are distributed in the northern, central, and southern parts of the QTP, respectively. The annual NFTCs in the QTP region are mainly concentrated at 160 and above, and the average NFTCs is 200 across the QTP. Our results can provide scientific guidance and a theoretical basis for the freezing resistance design of concrete in various projects on the QTP.

关键词： Freeze–thaw cycles Quantification Machine learning algorithms Qinghai–Tibet Plateau concrete

Intelligent Small Sample Defect Detection of concrete Surface Using Novel Deep Learning Integrating Improved YOLOv5

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 545-547页

作者： Yongming Han Lei Wang Youqing Wang Zhiqiang Geng IEEE College of Information Science and Technology Beijing University of Chemical TechnologyBeijing 100029 Engineering Research Center of Intelligent PSE Ministry of Education in ChinaBeijing 100029China

Dear Editor,This letter presents an intelligent small sample defect detection of concrete surface using novel deep learning integrating the improved YOLOv5 based on the Wasserstein GAN(WGAN)enhancement algorithm.The proposed method is capable of producing top-notch data sets to address the issues of insufficient samples and substandard quality.

关键词： concrete integrating algorithm

Experimental study on the size effect on the equation of state of concretes under shock loading

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Defence Technology（防务技术） 2024年第3期33卷 160-167页

作者： Mei Li Jian Cui Yanchao Shi Baijian Tang Xin Chen Key Laboratory of Coast Civil Structural Safety of the Ministry of Education Tianjin UniversityTianjin 300072China School of Civil Engineering Suzhou University of Science and Technology1701 Binhe RoadSuzhou 215011JiangsuChina School of Civil Engineering Tianjin UniversityTianjin 300072China

Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of concrete.The experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the EoS.Although some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one size.In this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete materials.The mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the specimen.According to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.

关键词： concrete Equation of state Size effect Shock wave Fly-plate impact test

Effect of Lateritic Stone Aggregate and Coconut Husk Fiber on the Properties of concrete

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Open Journal of Civil Engineering 2024年第2期14卷 240-257页

作者： Edmund Borbi Humphrey Danso Emmanuel Appiah-Kubi Department of Construction Technology and Management Education Akenten Appiah-Menka University of Skills Training and Entrepreneurial Development Kumasi Ghana Department of Architecture and Civil Engineering Akenten Appiah-Menka University of Skills Training and Entrepreneurial Development Kumasi Ghana

Natural stone aggregate forms the bulk volume of concrete and has contributed to the increased cost of concrete production. This has led to the search for alternate aggregates such as lateritic stone for concrete production. This paper investigates the engineering properties of concrete produced with lateritic aggregate (LA) as the coarse aggregate replacement and coconut husk fibre (CHF) as reinforcement. Natural stone aggregate was replaced by LA at 0%, 10%, 20%, 30%, 40%, and 50%, with 0.25% constant CHF by weight. A mix proportion of 1:1.5:3 with a water-cement ratio of 0.6 was used for producing concrete. A total of 162 specimens (90 cubes and 72 beams) were prepared and tested at the 7, 14, 21, and 28 days of curing. The highest compressive strength was 43.36 N/mm2 (10% LA replacement) as compared to the control of 41.51 N/mm2. The 10% LA replacement obtained the highest flexural strength of 5.35 N/mm2 as compared with the 5.29 N/mm2 for the control. The water absorption of the concrete increased from 2.8% (control) to 3.57% (50% replacement LA). Scanning electron microscopy (SEM) revealed micro gaps between CHF and LA concrete. The study, therefore, concludes that the use of LA and CHF positively influenced the strength properties of concrete. 10% LA replacement of coarse aggregate and 0.25% CHF is recommended to practitioners for use.

关键词： concrete Coarse Aggregate Compressive Strength Flexural Strength Natural Stone Aggregate SEM

Substitution of Aggregates in concrete and Mortar with Coltan Mining Waste: Mechanical, Environmental, and Economic Impact Case Study

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Journal of Minerals and Materials Characterization and Engineering 2024年第2期12卷 139-163页

作者： Alinabiwe Nyamuhanga Ally Élodie Ruffine Zang Masika Muhiwa Grâce Manjia Marcelline Blanche Ursula Joyce Merveilles Pettang Nana Ngapgue François Bella Nabil Chrispin Pettang Laboratory Engineering Civil and Mechanics Doctoral Research Unit for Engineering and Applications University of Yaound&#233 I Yaound&#233 Cameroon Department of Civil Engineering Faculty of Applied Sciences and Technologies Free University of Great Lakes Countries (ULPGL) Goma DRC Department of Civil Engineering National Advanced School of Engineering of Yaoundé University of Yaoundé I Yaoundé Cameroon Department of Civil Engineering Fotso Victor University Institute of Technology University of Dschang Bandjoun Cameroon FIMAS Laboratory Faculty of Technologies Tahri Mohamed University Bechar Algeria

The mining process involves drilling and excavation, resulting in the production of waste rock and tailings. The waste materials are then removed and stored in designated areas. This study aims to evaluate the mechanical strength and the environmental and economic impact of using Coltan Mining Waste (CMW) as a substitute for aggregates in concrete and mortar production. To achieve this, the CMW needs to be characterised. The Dreux Gorisse method was primarily used to produce concrete with a strength of 20 MPa at 28 days. The mortars, on the other hand, were formulated according to the NF P 18-452 standard. The environmental impact of using CMW as substitutes for natural aggregates in the production of concrete and mortar was analysed using SimaPro software. The results showed that mortars and concrete made with CMW have comparable compressive strengths to the reference mortar and concrete;reduce the negative impact on ecosystem quality, human health, resources, and climate change. It has also been shown that the substitution of aggregates by CMW reduces the cost of concrete and mortar as a function of the distance from the aggregate footprint.

关键词： Aggregate Coltan Mining Waste concrete Mortar Mechanical Strength Life Cycle Analysis

Development of a New Polymercement Waterproofing Screed with Secondary Materials

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Journal of Civil Engineering and Architecture 2024年第2期18卷 80-85页

作者： LubošTaranza Faculty of Civil Engieneering Brno University of TechnologyBrno 60200Czech Republic

Throughout the world the issue of waste raw materials is still a very important topic.This paper is focused on the possibility of the use of waste raw material originated at high temperatures by the combustion of black coal as a partial substitution of filler component during the development of new waterproof levelling material designated for concrete constructions.The use of the fly-ash as partial substitution of the filler component has important ecological and economic contribution.

关键词： Fly ash screed filler concrete

Countryside Police Station:An Unsolved Case

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The World of Chinese 2024年第2期 72-81页

作者：阿乙不详

Thirteen years on, that case at the Aocheng Chemical Plant still bothers me, poking and prodding somewhere deep down inside of me, like a riddle that I’ll never figure out. It was during a bright midday at the plant.... 详细信息

关键词： concrete bright Case

Stochastic fatigue damage model for concrete under complex stress states

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Science China(Technological Sciences) 2022年第11期65卷 2641-2648页

作者： WANG YanPeng LI Jie School of Civil and Transportation Engineering Guangdong University of TechnologyGuangzhou 510006China School of Civil Enginering Tongji UniversityShanghai 200092China

This paper presents a stochastic fatigue damage model for concrete subjected to complex stress states.A constitutive framework considering the tensile and shear damage mechanisms and elastic and plastic energy dissipations is employed.The damage law is established through a multiscale analysis of the damage evolution mechanism.Validation results against test data show that the model can effectively predict the static strength,stress-strain curve,fatigue life,and scattering range of concrete under various multidimensional loading scenarios.

关键词： concrete fatigue stochastic damageevolution complex stress states multiscale

Sprayable coating based on fluorinated silica nanocomposites with superhydrophobic and antibacterial properties for advanced concrete

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Progress in Natural Science:Materials International 2022年第4期32卷 472-481页

作者： Feng Yang Wuyifan Zhou Fuhai Li Ling Yuan Yangmin Diao Yinglu Liu Yuan Pu Yong Zhang Yong Zhao Ou Jiang Dan Wang Key Laboratory of Advanced Technology of Materials (Ministry of Education of China) Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle (Ministry of Education of China) School of Materials Science and Engineering Southwest Jiaotong University Superconductivity and New Energy R&D Center Southwest Jiaotong University School of Civil Engineering Southwest Jiaotong University State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical Technology Oncology Department The Second People's Hospital of Neijiang

The porous hydrophilic nature of concrete structures makes them highly susceptible to chemical attack and bacterial adhesion, and the durability of concrete structures gradually decreases. In this work, a kind of sprayable coating with superhydrophobic and antibacterial properties was developed, which was used for surface engineering of concrete via the hydrophilic property of concrete and capillary action. The treated surface of concrete exhibited significant superhydrophobicity, with a static water contact angle of 162.4°and a sliding angle of 5°.The water absorption values of the treated concrete samples in merged in deionized water and 3.5 wt% Na Cl solution for 7 days were measured as 1.85% and 2.71%, indicating the enhancement of water repellency by 72.03% and 80.11%, respectively. The antibacterial characterization revealed that the superhydrophobic coating enabled significantly reduced adhesion of bacteria, with the antibacterial rates of 84.57 ± 2.5% for E. coli and 90.43 ± 1.6% for S. epidermidis, respectively. The superhydrophobic coating provides hydrophobic protection for porous substrate structures and effectively reduce the corrosion damage of substrate materials, which is of practical significance for improving the durability of concrete structures.

关键词： Superhydrophobic Ultra-light Antibacterial Coating concrete