Data-driven method for enhanced corrosion assessment of reinforced concrete structures

Corrosion is a major problem affecting the durability of reinforced concrete structures. Corrosion related maintenance and repair of reinforced concrete structures cost multibillion USD per annum globally. It is often triggered by the ingression of carbon dioxide and/or chloride into the pores of concrete. Estimation of these corrosion causing factors using the conventional models results in suboptimal assessment since they are incapable of capturing the complex interaction of parameters. Hygrothermal interaction also plays a role in aggravating the corrosion of reinforcement bar and this is usually counteracted by applying surface protection systems. These systems have different degree of protection and they may even cause deterioration to the structure unintentionally. The overall objective of this dissertation is to provide a framework that enhances the assessment reliability of the corrosion controlling factors. The framework is realized through the development of data-driven carbonation depth, chloride profile and hygrothermal performance prediction models. The carbonation depth prediction model integrates neural network, decision tree, boosted and bagged ensemble decision trees. The ensemble tree based chloride profile prediction models evaluate the significance of chloride ingress controlling variables from various perspectives. The hygrothermal interaction prediction models are developed using neural networks to evaluate the status of corrosion and other unexpected deteriorations in surface-treated concrete elements. Long-term data for all models were obtained from three different field experiments. The performance comparison of the developed carbonation depth prediction model with the conventional one confirmed the prediction superiority of the data-driven model. The variable importance measure revealed that plasticizers and air contents are among the top six carbonation governing parameters out of 25. The discovered topmost chloride penetration controlling parameters representing the composition of the concrete are aggregate size distribution, amount and type of plasticizers and supplementary cementitious materials. The performance analysis of the developed hygrothermal model revealed its prediction capability with low error. The integrated exploratory data analysis technique with the hygrothermal model had identified the surfaceprotection systems that are able to protect from corrosion, chemical and frost attacks. All the developed corrosion assessment models are valid, reliable, robust and easily reproducible, which assist to define proactive maintenance plan. In addition, the determined influential parameters could help companies to produce optimized concrete mix that is able to resist carbonation and chloride penetration. Hence, the outcomes of this dissertation enable reduction of lifecycle costs

Numerical Study of Concrete

Concrete is one of the most widely used construction material in the word today. The research in concrete follows the environment impact, economy, population and advanced technology. This special issue presents the recent numerical study for research in concrete. The research topic includes the finite element analysis, digital concrete, reinforcement technique without rebars and 3D printing

Research posters’ eBook: according to 1st WORKSHOP with “Focus on experimental testing of cement based materials”

COST Action TU 140

Research and Technology, 1998

This report selectively summarizes the NASA Lewis Research Center's research and technology accomplishments for the fiscal year 1998. It comprises 134 short articles submitted by the staff scientists and engineers. The report is organized into five major sections: Aeronautics, Research and Technology, Space, Engineering and Technical Services, and Commercial Technology. A table of contents and an author index have been developed to assist readers in finding articles of special interest. This report is not intended to he a comprehensive summary of all the research and technology work done over the past fiscal year. Most of the work is reported in Lewis-published technical reports, journal articles, and presentations prepared by Lewis staff and contractors. In addition, university grants have enabled faculty members and graduate students to engage in sponsored research that is reported at technical meetings or in journal articles. For each article in this report, a Lewis contact person has been identified, and where possible, reference documents are listed so that additional information can be easily obtained. The diversity of topics attests to the breadth of research and technology being pursued and to the skill mix of the staff that makes it possible. At the time of publication, NASA Lewis was undergoing a name change to the NASA John H. Glenn Research Center at Lewis Field

Gas Turbines

This book is intended to provide valuable information for the analysis and design of various gas turbine engines for different applications. The target audience for this book is design, maintenance, materials, aerospace and mechanical engineers. The design and maintenance engineers in the gas turbine and aircraft industry will benefit immensely from the integration and system discussions in the book. The chapters are of high relevance and interest to manufacturers, researchers and academicians as well

Processing and characterization of high performance piping materials for geothermal applications

Thesis (Master)--Izmir Institute of Technology, Energy Engineering, Izmir, 2003Includes bibliographical references (leaves: 111-116)Text in English; Abstract: Turkish and Englishxx, 121 leavesPolymer composite based pipes are being recently utilized in transportation of geothermal fluids.The utilization of composites is due to their resistance to aggressive chemicals and hot-wet environment with relatively high specific strength and design flexibility.Exposure of materials to wide range of temperatures and humidity level, while under the action of load, may degrade them and cause to severe reduction in their properties and service life.Understanding the complex degradation mechanism of the composites exposed to a variety of temperature and fluid chemistry (including geothermal fluid) is essential to improve their durability.This research focuses on the investigation of interactions between geothermal fluid and composite piping materials made of various matrices and the mechanism of degradation in these composites.The matrix materials include polyester, epoxy and graphite particle added epoxy materials.In this study, E-glass fiber reinforced polymer composites were fabricated by employing filament winding and tube rolling techniques.Fabricated composites and neat polymers were exposed to dry environment, distilled water and geothermal fluid of Balçova geothermal field until the saturation of weight gains due to water uptakes.In addition, the specimens with neat polymers were prepared to simulate and follow the degradation of matrix materials under hot-wet environments.Once the saturation occurred, the specimens were subjected compressive mechanical testing.For both dry and wet specimens, the mechanical testing was performed to obtain stress-strain behavior, modulus of elasticity, strain at failure values and energy absorption during the loading.The results were compared to evaluate the degradation of the properties due to various exposures.Moreover, the thermal conductivity of the various composites fabricated in this research was measured to determine the heat losses and temperature distribution within the materials.The temperature distribution within the cross-section of the pipes for various materials was analyzed using a finite element-modeling tool, LUSAS for uninsulated pipes.The heat loss occurring during the transportation of hot geothermal fluid was calculated as a case study to compare composites and traditional metal piping.It was found that polyester composite pipes have higher mechanical performance under axial and radial compression as compared to the composite with epoxy matrices. For all the composite types, some considerable degradations were measured due to exposure to hot-wet environments.The extend of degradation was less for graphite particles added epoxy composite pipes that exhibited the lowest water uptake values. The graphite particles incorporated into the matrix affected the water uptake and thermal conductivity of the epoxy.The water uptake of polyester matrix composite pipes was the highest that might be related to the most extensive degradation of polyester based composite.Moreover, it was found that the thermal conductivity of the composites is much lower than traditional materials.The graphite particles cause reduction in thermal conductivity, simultaneously in heat loss for uninsulated pipes.However, if the isolation is used, heat loss is not sensitive to pipe material

Sustainable Construction

Construction is one of the main sectors that generates greenhouse gases. This industry consumes large amounts of raw materials, such as stone, timber, water, etc. Additionally, infrastructure should provide service over many years without safety problems. Therefore, their correct design, construction, maintenance, and dismantling are essential to reducing economic, environmental, and societal consequences. That is why promoting sustainable construction has recently become extremely important. To help address and resolve these types of questions, this book explores new ways of reducing the environmental impacts caused by the construction sector, as well promotes social progress and economic growth. The chapters collect the papers included in the “Sustainable Construction” Special Issue of the Sustainability journal. The papers cover a wide spectrum of issues related to the use of sustainable materials in construction, the optimization of designs based con sustainable indicators, the life-cycle assessment, the decision-making processes that integrate economic, social, and environmental aspects, and the promotion of durable materials that reduce future maintenance