Civil and Environmental Engineering Commons^™

End Effect Of Corroded Steel Bar In Concrete Specimen During Corrosion Test By Galvanostatic Method, Peng Zhao, Gang Xu, Qing Wang, Xuan Wang

International Conference on Durability of Concrete Structures

The galvanostatic method is a commonly used accelerated corrosion method in studying the durability of concrete structures caused by steel corrosion. If this method is not adequately controlled, the ends of steel bars will be corroded seriously (this phenomenon is called end effect), which is not common in natural corrosion. How to effectively control the end effect during electrified corrosion is helpful to make the characteristics of electrified corrosion more similar to that of natural corrosion. In this paper, experimental and electromagnetic numerical simulation methods are used to study the influence of cathode and corrosion medium coverage area along the …

Investigation Of Chloride Transportation Mechanism In Reinforced Concrete Specimen Subjected To Eccentric Compression, Yong Dong Yan

International Conference on Durability of Concrete Structures

In order to deal with the chloride ion transportation mechanism in eccentric compressive concrete pier and column in marine environment, stress distribution in the section of eccentric compressive concrete specimen was analyzed firstly, relationship between chloride diffusion coefficient and stress level was developed according to porosity varying under different loads, at last a model of chloride diffusion coefficient under varying stress level was developed. Conversion-diffusion equation in COMSOL Multiphysics was used in this paper to calculate the chloride ion transportation process. Three test beams with different mixture were cast and then loaded to different stress level. After that, all of …

Finite Element Modeling Of Thermal Effect On Airport Slabs, Chuanyue Shen

International Conference on Durability of Concrete Structures

A sub-ground tunnel connecting two concourses of a terminal at Chicago O’Hare International Airport suffered from water leakage. The airport engineers suspected that the problem was caused by high stresses impinging on the tunnel structure by the pavement sections above the tunnel, acting to damage joints and waterproofing membranes that should have prevented such leakage. To provide a fundamental solution to this problem while minimizing the interference with airport operation, a repair strategy needs to be determined based on a clear understanding of the root cause. A preliminary field inspection confirmed that the concrete pavement slabs moved significantly when ambient …

Application Of Multi-Environmental Time Similarity Theory Based On Relative Information (Ri-Mets) Theory In Durability Of Concrete Structures In Marine Chloride Environment, Zhang Kai

International Conference on Durability of Concrete Structures

The Multi-environmental time similarity (METS) method is a testing method that establishes the similarity relationship between the indoor test environment and the on-site environment to evaluate the durability and predict service life of the proposed or under-constructed concrete structure. Based on the METS theory, a similarity ratio of chloride ion concentration and diffusion coefficient between the indoor accelerated environment and the on-site natural environment was established. Then the relative information entropy was introduced into the Multi-Environmental Time Similarity based on Relative Information (RI-METS) theory to consider the time variability of the diffusion coefficient and the surface chloride ion mass fraction. …

Durability Assessment Of Repairing Vertical Cracks In Concrete Using Microbially Induced Calcium Carbonate Precipitation Technique, Chunhua Lu

International Conference on Durability of Concrete Structures

No abstract provided.

End Effect Of Corroded Steel Bar In Concrete Specimen During Corrosion Test By Galvanostatic Method, Peng Zhao, Gang Xu, Qing Wang, Xuan Wang

International Conference on Durability of Concrete Structures

Corrosion of steel bars is the main durability problem of concrete structures, which seriously endangers the safety and service life of reinforced concrete (RC) structures. When studying such problems, the electrifying corrosion method is often used to obtain corroded components. How to effectively control the corrosion area of steel bars is the key to improve the applicability of the corrosion method. In this paper, experimental and electromagnetic numerical simulation methods are used to study the influence of cathode and corrosion medium coverage area along the longitudinal direction on the corrosion area of steel bar before concrete protective layer corrosion cracking. …

Causes Of Cement Concrete Pavement Diseases In High-Cold And High-Altitude Areas And Progress In Repairing Techniques, Tiejun Hou

International Conference on Durability of Concrete Structures

The climatic characteristics of high-cold and high-altitude areas are low temperature, large temperature differences, and strong ultraviolet radiation. This paper analyzes the causes of cement concrete pavement diseases in high-cold and high-altitude areas and summarizes the common disease types of cement concrete pavements in high-cold and high-altitude areas. Moreover, new repair techniques to improve the maintenance quality of cement concrete pavements in high-cold and high-altitude areas are introduced.

Application Of Acoustic Emission Technology In Monitoring Corrosion Induced Expansion Cracks Of Reinforced Concrete, Zhen Zeng, Gang Xu, Rui Zhang, Zewen Yang

International Conference on Durability of Concrete Structures

Acoustic emission (AE) technology is used to monitor the whole process of reinforced concrete rust expanding and cracking, and the accuracy of AE technology to distinguish the location and type of cracks in concrete rust expanding and cracking is studied and verified. The results show that the protective layer is accompanied by a large number of acoustic emission signals in the process of rust expansion and cracking, Moment tensor inversion can more accurately identify crack sources such as shear source, tensile source and mixed source; In the process of corrosion-induced expansion cracking, shear source cracks appear before tensile source cracks …

Ultra- Ductile Waterborne Epoxy-Concrete Composite Repair Material, Bo Pang, Zuquan Jin, Yunsheng Zhang, Xiaoyun Song

International Conference on Durability of Concrete Structures

With the extension of service time, the building structure is in urgent need of repair and reinforcement due to its deterioration in safety and durability with the years. Normal cement concrete exposes shortcomings such as high brittleness and low flexural-tensile strength for which fails to meet the requirement of construction repairing. In this paper, a novel waterborne epoxy-concrete composite repair material (WECM) was prepared by using self-synthesized water-based epoxy resin based on the molecular structure-activity relationship. The key flexural and tensile performance parameters of WECM were accurately obtained.

Effects Of Organic Corrosion Inhibitors On The Performance Of Repair Mortars, Ominda Nanayakkara Dr.

International Conference on Durability of Concrete Structures

Reinforced concrete (RC) structures are severely degraded due to the corrosion of the embedded reinforcing steel, and hence, the upgrading of RC structures is essential. Repairing mortar is widely used to improve durability and strengthen structures; however, further repairing might be required considering the extended life of the structure. The use of inhibitors to protect the reinforcement from corrosion has become of great interest. Therefore, it is vital to study the potential of using corrosion inhibitors in a newly repaired system.

This study investigated the performance of a commercially available polymer-modified mortar with migrating and admixed corrosion inhibitors. The study …

Corrosion Performance Of Embedded Steel Bar In Cl--Contaminated Limestone Calcined Clay Cement (Lc3) At Initial Stage Of Hydration, Weiwen Li, Zuhua Xu, Yaocheng Wang, Xin Wang, Feng Xing

International Conference on Durability of Concrete Structures

Limestone Calcined Clay Cement (LC3) presents brilliant properties in binding Cl^- so that the embedded steel bars are probably protected in Cl^--contaminated condition, which meets the need of sea sand application. However, the corrosion performance of steel bars embedded in LC3 paste with Cl^‑ is unclear, especially in early age hydration. Thus, a series of experiments were carried out to evaluate the corrosion performance of steel bars on initial and hardened stages of hydration, including concentration of OH^- and Cl^- in real pore solution, open circuit potential (OCP) and chemical elements of steel bars. …

Study On Strength And Volume Stability Of Coral Mortar, Qingzong Xue

International Conference on Durability of Concrete Structures

No abstract provided.

Investigation On The Properties Of Calcium Sulfoaluminate Cement Waterproof Repair Mortar Modified With Ethylene-Vinyl Acetate Powder, Dong Dong

International Conference on Durability of Concrete Structures

本文采用乙烯-醋酸乙烯酯（EVA）粉体和CSA水泥制备了防水修复砂浆，并对其水化和性能进行了研究。结果表明，EVA粉体延长了凝固时间，提高了防水修补砂浆的流动性，使其在实际工程中更容易应用。EVA粉提高了防水修复砂浆的不渗透性，降低了吸水性。虽然EVA粉降低了防水修补砂浆的抗弯强度和抗压强度，但它仍然符合JC/T 2381-2016标准对刚性修复砂浆的要求。EVA粉体降低了防水修复砂浆的收缩率，改善了界面过渡区和拉伸粘接强度、弯曲粘接强度等粘接性能。EVA粉末抑制CSA水泥的水合作用6 h，在3 d水化年龄时抑制作用消失。

Influence Of Biological Sulfuric Acid On Corrosion Mechanism Of Alkali-Activated Cement Concrete, 季 韬 教授

International Conference on Durability of Concrete Structures

生物硫酸对碱活化水泥混凝土腐蚀机理的影响

丁方硕、韬骥、潘伟杰

福州大学土木工程系

抽象的

讨论了不同浓度的生物硫酸对碱活化水泥混凝土（AACC）腐蚀的影响，并以化学硫酸为参考。AACC的质量和抗压强度、孔溶液的pH曲线和Ca ²⁺对其释放进行了研究，并通过 ESEM-EDS 和 XRD 揭示了 AACC 的腐蚀机理。结果表明，在不同浓度的化学硫酸和生物硫酸作用下，AACC的腐蚀产物主要是石膏。随着硫酸浓度的增加，AACC的失重率增加，AACC的抗压强度降低。石膏阻碍化学硫酸进入混凝土。然而，石膏为细菌提供了生存环境，细菌很容易渗透到混凝土中，加速了AACC的破坏。与化学硫酸相比，生物硫酸增加了AACC的质量损失率和抗压强度。

参考

荣H，Wu，C.，Ma，G.，Zheng，X.，和Liu，Z，2021。污水环境下混凝土微生物腐蚀研究进展。中国陶瓷学会学报，49（5）：988-999。

Scholz, F., 1997。微生物影响的材料腐蚀：科学和工程方面。固态电化学杂志，1（2）：181-181。

谢毅，林，X.，吉，T.，2019。普通硅酸盐混凝土与碱活化混凝土在生物硫酸侵蚀下的耐腐蚀机理比较。建筑和建筑材料，228（20）：1-12。

Frost Resistance And Pore Structure Properties Of Mortar Containing Air Entraining Agent Combined With Superabsorbent Polymer, Yanqun Xu, Qiang Yuan

International Conference on Durability of Concrete Structures

The air entraining effect of air entraining agent (AEA) is deeply affected by environment, which will further influence its function of improving frost resistance. To solve this problem, a strategy of using AEA combined with superabsorbent polymer(SAP) to improve the frost resistance of mortar was proposed in this study. Mass loss and relative dynamic elastic modulus of mortar were used to characterize frost resistance of mortar. Air void density, spacing factor, air void distribution and air content were measured to analyze its pore structure properties. The results verify that the combined use of AEA and SAP can improve the frost …

The Transportation Of Corrosion Products In Cementitious Material Under Chloride-Rich Environment, Yuzhou Wang

International Conference on Durability of Concrete Structures

Corrosion products, forming on steel bar in cementitious material, can lead to concrete cracking. Clear the transportation of corrosion products is of great significance to predict corrosion-induced structural deterioration. This study investigates the corrosion products in steel-reinforced concrete specimen. By Raman spectroscopy and SEM method, the chemical constituents and micromorphology of corrosion products at steel-concrete interface as well as those inside the pore of cement paste are investigated. The proportion of corrosion products filling into the cement paste is determined by EDTA titration method. The results reveal that corrosion products diffuse in forms of ion in solution under chloride-rich environment, …

Research On Water Absorption And Frost Resistance Of Concrete Coated With Different Impregnating Agents For Ballastless Track Structure, Xin Ge, Yanbin Tan, Xiaowei Wang, Yongjiang Xie, Qinfei Li, Linxiang Li, Lu Yang, Zhongwei Feng

International Conference on Durability of Concrete Structures

In consideration of performance requirement of ballastless track concrete in cold regions of China, 3 types of commercially available impregnating agents were employed to research their effect on water absorption and frozen resistance of concrete, containing silanes, potassium silicate and osmotic curing agent. The results presented that coating silanes was the most effective on the reduction of water absorption among all employed impregnating agents, because of the most significant character change of concrete surface from hydrophilicity to hydrophobicity which could be proved by the contact angle test of concrete. The promotion on frozen resistance of concrete was not as significant …

Study On Corrosion Resistance Of Portland Cement-Calcium Sulphoaluminate Cement Binary System In A Sodium Chloride Environment, Shilin Song, Tao Xing, Yu Zhang, Jianzheng Wang, Xiaodong Shen, Ying Ma

International Conference on Durability of Concrete Structures

Portland cement is widely used in civil engineering. However, Portland cement-based materials are easy to be corroded by seawater in marine environment. Many research show the corrosion resistance of Portland cement mortar can be improved by add appropriate amount of mineral admixture.Sulphoaluminate cement have high strength and good corrosion seawater resistance. However, the short setting time and high hydration heat of sulphoaluminate cement limit its application in civil engineering.Portland cement-sulphoaluminate cement (PC-CSA) not only have high strength and corrosion resistance but also long setting time.In this work, the sulphoaluminate cement was used to partially replace Portland cement. The replacement level …

Elemental Sulfur And Metal Sulfide Minerals For Autotrophic Denitrification: Applications To Aquaculture, Groundwater Treatment, And Domestic Wastewater Treatment, Erica Amah Dasi

USF Tampa Graduate Theses and Dissertations

Nutrient pollution of waterways, from excess N and P, is a global concern that results in harmful impacts the environment, human health, and aquatic animals. This dissertation harnesses sulfur autotrophic denitrification to remove nutrients from groundwater, domestic wastewater, and wastewaters produced from marine recirculating aquaculture systems (RAS). Part 1 evaluates the denitrification performance of woodchips and elemental sulfur in cyclic denitrification filters (WS-CDFs) integrated into marine RAS operated under saline conditions. Part 2 investigates the use of metal sulfide minerals, with and without oyster shells, for supporting nutrient removal from groundwater in batch reactors. Part 3 assesses …

Anti-Skid Characteristics Of Asphalt Pavement Based On Partial Tire Aquaplane Conditions, Miao Yu, Yao Kong, Zhanping You, Jue Li, Liming Yang, Lingyun Kong

Michigan Tech Publications, Part 1

This study presented a finite element model of radial tire-asphalt pavement interaction using ABAQUS 6.14 software to investigate the skid resistance properties of asphalt pavement under partial tire aquaplane conditions. Firstly, the pavement profile datum acquired by laser scanning were imported to Finite Element Analysis (FEA) software to conduct the pavement modeling. Secondly, a steady state rolling analysis of a tire on three types of asphalt pavements under drying conditions was carried out. Variation laws of the friction coefficient of the radial tire on different pavements with different pavement textures, tire pressures, and loads on the tire were examined. Subsequently, …

Uzbek Commands Recognition By Processing The Spectrogram Image, M M. Musayev, I Sh Khujayorov, M I. Abdullaeva, M M. Ochilov

Technical science and innovation

This paper describes the most common algorithms with image approach convolutional neural network and two-dimensional DCT with machine learning classification KNN, SVM and RF. These algorithms are evaluated for applicability to the Uzbek language and a comparative analysis on the accuracy and recognition rate. The command words of the Uzbek language were chosen for the experiments. According to the results, it was found that both methods give high rates of recognition accuracy and are 92% (CNN) and 90% (2DDCT+Zigzag+SVM). Also the combinations of 2D-DCT+Zigzag+ KNN and 2D-DCT+Zigzag+ RF with average recognition accuracy of 86% and 85%, respectively, were considered in …

An Investigation Of Emerging Technologies To Advance The Understanding Of Dynamics Between The Floodplain And Main Channel Due To Riparian Vegetation, Smriti Chaulagain

Civil Engineering ETDs

Riparian vegetation covers only about 0.4% of the land surface whereas rivers and streams cover about 0.3 to 0.56% but riparian vegetation still provides substantial ecosystem services including many that affect hydrodynamic processes. The ability to estimate the flow resistance caused by vegetation and the consequences for hydrodynamic processes has long been a vexing problem for engineers. Flow resistance is strongly influenced by local hydraulic conditions (water velocity and depth) and vegetation structures, and in turn, vegetation affects mass and momentum exchange processes. However, riparian vegetation conditions change continuously due to external stressors including climate change (e.g., extended drought in …

Thermodynamic And Kinetic Investigation Of U(Vi) And As(V) Reactions: Insights For Risk Assessment And Remediation, Maria Isabel Meza

Civil Engineering ETDs

The goal of this dissertation was to investigate the mechanisms of immobilization of uranium (U) and arsenic (As) in waters nearby to Native American Communities for remediation applications. This work sought to identify the physical or chemical processes affecting the complexation, sorption, and precipitation of U and As with calcium (Ca), carbonates (CO3)2-, and phosphate (PO4)3-. The current knowledge about the mechanisms affecting the reaction of metal mixtures such as U, As, and other co-occurring elements in natural waters with minerals such as limestone1-5 and hydroxyapatite for remediation applications is limited. A better understanding of thermodynamics and kinetics affecting the …

Permeability And Porosity Of Loose Granular Salt, Evan J. Babcock

Civil Engineering ETDs

In this study, permeability and porosity measurements are made and reported for loose granular salt from the Waste Isolation Pilot Plant (WIPP). Measurements are made on a particularly wide range of particle sizes of this salt in a permeameter constructed large enough to fit and represent mixtures containing salt particles up to 25.4 cm in size. Salt samples with different particle size distributions are constructed and tested at varying levels of consolidation due to induced vibrations. Permeability measurements are made at a varying range of porosities for a given sample. Measurements are also compared with a predictive model for permeability …

Chemical Toxicants In Water: A Geohealth Perspective In The Context Of Climate Change, Naveen Joseph, Tate Libunao, Elizabeth Herrmann, Shannon L. Bartelt-Hunt, Catherine R. Propper, Jesse E. Bell, Alan S. Kolok

Department of Civil and Environmental Engineering: Faculty Publications

The editorial focuses on four major themes contextualized in a virtual GeoHealth workshop that occurred from June 14 to 16, 2021. Topics in that workshop included drinking water and chronic chemical exposure, environmental injustice, public health and drinking water policy, and the fate, transport, and human impact of aqueous contaminants in the context of climate change. The intent of the workshop was to further define the field of GeoHealth. This workshop emphasized on chemical toxicants that drive human health. The major calls for action emerged from the workshop include enhancing community engagement, advocating for equity and justice, and training …

Applications Of Stretching Technique And Time Window Effects On Ultrasonic Velocity Monitoring In Concrete, Bibo Zhong, Jinying Zhu

Department of Civil and Environmental Engineering: Faculty Publications

Coda wave interferometry (CWI) has been used to measure the relative wave-velocity change (dV/V) caused by small changes in materials. This study uses the stretching processing technique which has been used for CWI analysis to investigate velocity changes of direct longitudinal (P) wave, direct shear (S) wave, and coda wave in concrete by choosing different time windows of ultrasonic signals. It is found that the obtained wave-velocity change depends on the time window position, because the relative contribution of P wave and S wave is different in each signal window. This paper presents three experimental scenarios of velocity …

Predicting Tensile Strength For Prestressed Reinforced Concrete-Driven Piles, Thuyet N. Nguyen, Thang Pham, Thuy Vu, Adnan A. Malik, Duc N. Dinh

Civil Engineering Faculty Publications

Reinforced concrete piles installed by impact hammers have been used as a common solution for deep foundations because they are cost effective and require less time for construction. Driven piles are often used in large volumes for infrastructure and industrial projects in rural areas. Unlike other installation methods, installing piles using impact hammers can generate tensile stress during construction, which can result in pile failures. Induced tensile stress occurs when piles are being driven through a hard soil layer to a softer soil layer, and transverse cracks happen when induced tensile stress exceeds the pile tensile strength. This issue is …

Revealing Driver Psychophysiological Response To Emergency Braking In Distracted Driving Based On Field Experiments, Ying Li, Li Zhao, Kun Gao, Yisheng An, Jelena Andric

Department of Civil and Environmental Engineering: Faculty Publications

Purpose – The purpose of this paper is to characterize distracted driving by quantifying the response time and response intensity to an emergency stop using the driver’s physiological states.

Design/methodology/approach – Field tests with 17 participants were conducted in the connected and automated vehicle test field. All participants were required to prioritize their primary driving tasks while a secondary nondriving task was asked to be executed. Demographic data, vehicle trajectory data and various physiological data were recorded through a biosignalsplux signal data acquisition toolkit, such as electrocardiograph for heart rate, electromyography for muscle strength, electrodermal activity for skin conductance and …

Learning From Machines: Insights In Forest Transpiration Using Machine Learning Methods, Morgan Thornwell

Dissertations and Theses

Machine learning has been used as a tool to model transpiration for individual sites, but few models are capable of generalizing to new locations without calibration to site data. Using the global SAPFLUXNET database, 95 tree sap flow data sites were grouped using three clustering strategies: by biome, by tree functional type, and through use of a k-means unsupervised clustering algorithm. Two supervised machine learning algorithms, a random forest algorithm and a neural network algorithm, were used to build machine learning models that predicted transpiration for each cluster. The performance and feature importance in each model were analyzed and compared …

Interfacial Interactions Of Uranium And Hdpe In Agricultural Soil And Their Bioacummulation In Mentha Arvensis, Casey Miller, Andrew Neidhart, Kendra Hess, Abdul-Mehdi S. Ali, Angelica Benavidez, Michael Spilde, Laura Green, José M. Cerrato, Jorge Gonzalez Estrella, Eliane El Hayek

Civil Engineering ETDs

We investigated the adsorption, precipitation, and phytoavailability of uranium after reactions with soil, high-density polyethylene particles, and Mentha arvensis through the integration of batch experiments, plant exposure, microscopy, and spectroscopy. Soluble U (initially 100 µM) decreased by 98.6% (1.09 µM) at pH 5 and 86.2% (13.81 µM) at pH 7.5 after 0.1 h of reaction with 10 g of soil in solution. Heterogenous U precipitates were observed in weathered HDPE surfaces for experiments without soil at both pH conditions. This suggests the weathering of the microplastic surfaces enhanced the nucleation of the U precipitates. Plants exposed to both U and …