Current Search: Chopra, Manoj (x)
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- Title
- Beneficial Utilization of Municipal Solid Waste Incineration Ashes as Sustainable Road Construction Materials.
- Creator
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Tasneem, Kazi, Nam, Boo Hyun, Chopra, Manoj, Reinhart, Debra, Sohn, Yongho, University of Central Florida
- Abstract / Description
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Incineration of municipal solid waste (MSW) is common for energy recovery, and management of municipal solid waste incineration (MSWI) ashes has received a growing attention around the world. In the U.S., generation of MSW has increased up to 65% since 1980, to the current level of 251 million tons per year with 53.8% landfilled, 34.5% recycled and composted, and 11.7% incinerated with energy recovery. In the process of incineration, MSWI ash is being produced as byproducts; about 80 to 90%...
Show moreIncineration of municipal solid waste (MSW) is common for energy recovery, and management of municipal solid waste incineration (MSWI) ashes has received a growing attention around the world. In the U.S., generation of MSW has increased up to 65% since 1980, to the current level of 251 million tons per year with 53.8% landfilled, 34.5% recycled and composted, and 11.7% incinerated with energy recovery. In the process of incineration, MSWI ash is being produced as byproducts; about 80 to 90% of the MSWI ash is bottom ash (BA) and 10 to 20% is fly ash (FA) by weight. The current practice of the U.S. is to combine both BA and FA to meet the criteria to qualify as non-hazardous, and all combined ashes are disposed in landfills.European countries have utilized MSWI BA as beneficial construction materials by separating it from FA. The FA is mostly limited to landfill disposal as hazardous material due to its high content of toxic elements and salts. BA has been actively recycled in the areas of roadbed, asphalt paving, and concrete products in many of European and Asian countries. In those countries, recycling programs (including required physical properties and environmental criteria) of ash residue management have been developed so as to encourage and enforce the reuse of MSWI ashes instead of landfill disposal. Moreover, many studies have demonstrated the beneficial use of MSWI ashes as engineering materials with minimum environmental impacts.On the other hand, the U.S. has shown a lack of consistent and effective management plans, as well as environmental regulations for the use of MSWI ashes., Due to persistent uncertainty of engineering properties and inconsistency in the Federal and State regulations in the U.S., however, the recycling of the MSWI ashes has been hindered and they are mostly disposed in landfills.In this research work, current management practice, existing regulations, and environmental consequences of MSWI ashes utilization are comprehensively reviewed worldwide and nationwide with an emphasis of the potential area of its utilization in asphalt paving and concrete product. This research also entails a detailed chemical and microstructural characterization of MSWI BA and FA produced from a Refuse Derived Fuel (RDF) facility in Florida so that the MSWI ash is well characterized for its beneficial uses as construction materials.The material characterization includes Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction (XRD) techniques. In addition, leaching experiments have been conducted to investigate the environmental properties (e.g. leachate concentration) of BA and ash-mixed hot mix asphalt (HMA) and Portland cement concrete (PCC). Leaching results reveals the reduced leaching potential of toxic material from MSWI ashes while incorporated in HMA and PCC. Lastly, a preliminary experimental approach has been devised for the vitrification of FA which is a promising thermal process of transferring material into glassy state with higher physical and chemical integrity to reduce toxicity so that utilization of FA can be possible.
Show less - Date Issued
- 2014
- Identifier
- CFE0005425, ucf:50404
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005425
- Title
- Multi-physics modeling of geomechanical systems with coupled hydromechanical behaviors.
- Creator
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Mohamed, Ahmad Saeid Ammar, Yun, Hae-Bum, Chopra, Manoj, Sallam, Amr, University of Central Florida
- Abstract / Description
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Geotechnical structures under realistic field conditions are usually influenced with complex interactions of coupled hydromechanical behavior of porous materials. In many geotechnical applications, however, these important coupled interactions are ignored in their constitutive models. Under coupled hydromechanical behavior, stress in porous materials causes volumetric change in strain, which causes fluid diffusion; consequently, pore pressure dissipates through the pores that results in the...
Show moreGeotechnical structures under realistic field conditions are usually influenced with complex interactions of coupled hydromechanical behavior of porous materials. In many geotechnical applications, however, these important coupled interactions are ignored in their constitutive models. Under coupled hydromechanical behavior, stress in porous materials causes volumetric change in strain, which causes fluid diffusion; consequently, pore pressure dissipates through the pores that results in the consolidation of porous material. The objective of this research was to demonstrate the advantages of using hydromechanical models to estimate deformation and pore water pressure of porous materials by comparing with mechanical-only models. Firstly, extensive literature survey was conducted about hydro-mechanical models based on Biot's poroelastic concept. Derivations of Biot's poroelastic equations will be presented. To demonstrate the hydromechanical effects, a numerical model of poroelastic rock materials was developed using COMSOL, a commercialized multiphysics finite element software package, and compared with the analytical model developed by Wang (2000). Secondly, a series of sensitivity analyses was conducted to correlate the effect of poroelastic parameters on the behavior of porous material. The results of the sensitivity analysis show that porosity and Biot's coefficient has dominant contribution to porous material behavior. Thirdly, a coupled hydromechanical finite element model was developed for a real-world example of embankment consolidation. The simulation results show excellent agreement to field measurements of embankment settlement data.
Show less - Date Issued
- 2013
- Identifier
- CFE0004722, ucf:49826
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004722
- Title
- Use of Accelerated Calcite Precipitation Method to Investigate Calcium Carbonate Precipitation from Recycled Concrete for Drainage System Applications.
- Creator
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McCulloch, Toni, Nam, Boo Hyun, Chopra, Manoj, Arboleda Monsalve, Luis, An, Jin Woo, Filler, Dennis, University of Central Florida
- Abstract / Description
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Recycled concrete aggregate (RCA) is a sustainable construction material that is a viable option for use in drainage systems by replacing virgin aggregate. Replacing virgin aggregate with RCA is beneficial from both economic and environmental perspectives. However, the use of RCA as pipe backfill materials may cause a long-term performance issue such as potential clogging due to fines accumulation and calcite precipitation on filter fabric. Previous studies investigated the long-term...
Show moreRecycled concrete aggregate (RCA) is a sustainable construction material that is a viable option for use in drainage systems by replacing virgin aggregate. Replacing virgin aggregate with RCA is beneficial from both economic and environmental perspectives. However, the use of RCA as pipe backfill materials may cause a long-term performance issue such as potential clogging due to fines accumulation and calcite precipitation on filter fabric. Previous studies investigated the long-term performance of RCA regarding flow rate. Therefore, this study investigated calcite precipitation potential of RCA. The Accelerated Calcite Precipitation (ACP) procedure was devised and used to estimate (")life-time(") calcite precipitation of RCA for French Drains. The ACP procedure was studied further and improved to optimize the calcite precipitation procedure. The enhanced method was used to compare the calcite precipitation of limestone and RCA samples - sources with varying chemistry and history. Key findings are (1) the clogging due to calcite precipitation of RCA is not as significant as clogging due to the existing and/or accumulated fines, (2) the calcite precipitation can be increased with a temperature of 75(&)deg;C and 17-hour heating time, and (3) the potential for calcite precipitation from RCA is not as significant as limestone for Type I underdrain gradation.
Show less - Date Issued
- 2018
- Identifier
- CFE0007321, ucf:52132
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007321
- Title
- Structural Identification through Monitoring, Modeling and Predictive Analysis under Uncertainty.
- Creator
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Gokce, Hasan, Catbas, Fikret, Chopra, Manoj, Mackie, Kevin, Yun, Hae-Bum, DeMara, Ronald, University of Central Florida
- Abstract / Description
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Bridges are critical components of highway networks, which provide mobility and economical vitality to a nation. Ensuring the safety and regular operation as well as accurate structural assessment of bridges is essential. Structural Identification (St-Id) can be utilized for better assessment of structures by integrating experimental and analytical technologies in support of decision-making. St-Id is defined as creating parametric or nonparametric models to characterize structural behavior...
Show moreBridges are critical components of highway networks, which provide mobility and economical vitality to a nation. Ensuring the safety and regular operation as well as accurate structural assessment of bridges is essential. Structural Identification (St-Id) can be utilized for better assessment of structures by integrating experimental and analytical technologies in support of decision-making. St-Id is defined as creating parametric or nonparametric models to characterize structural behavior based on structural health monitoring (SHM) data. In a recent study by the ASCE St-Id Committee, St-Id framework is given in six steps, including modeling, experimentation and ultimately decision making for estimating the performance and vulnerability of structural systems reliably through the improved simulations using monitoring data. In some St-Id applications, there can be challenges and considerations related to this six-step framework. For instance not all of the steps can be employed; thereby a subset of the six steps can be adapted for some cases based on the various limitations. In addition, each step has its own characteristics, challenges, and uncertainties due to the considerations such as time varying nature of civil structures, modeling and measurements. It is often discussed that even a calibrated model has limitations in fully representing an existing structure; therefore, a family of models may be well suited to represent the structure's response and performance in a probabilistic manner.The principle objective of this dissertation is to investigate nonparametric and parametric St-Id approaches by considering uncertainties coming from different sources to better assess the structural condition for decision making. In the first part of the dissertation, a nonparametric St-Id approach is employed without the use of an analytical model. The new methodology, which is successfully demonstrated on both lab and real-life structures, can identify and locate the damage by tracking correlation coefficients between strain time histories and can locate the damage from the generated correlation matrices of different strain time histories. This methodology is found to be load independent, computationally efficient, easy to use, especially for handling large amounts of monitoring data, and capable of identifying the effectiveness of the maintenance. In the second part, a parametric St-Id approach is introduced by developing a family of models using Monte Carlo simulations and finite element analyses to explore the uncertainty effects on performance predictions in terms of load rating and structural reliability. The family of models is developed from a parent model, which is calibrated using monitoring data. In this dissertation, the calibration is carried out using artificial neural networks (ANNs) and the approach and results are demonstrated on a laboratory structure and a real-life movable bridge, where predictive analyses are carried out for performance decrease due to deterioration, damage, and traffic increase over time. In addition, a long-span bridge is investigated using the same approach when the bridge is retrofitted. The family of models for these structures is employed to determine the component and system reliability, as well as the load rating, with a distribution that incorporates various uncertainties that were defined and characterized. It is observed that the uncertainties play a considerable role even when compared to calibrated model-based predictions for reliability and load rating, especially when the structure is complex, deteriorated and aged, and subjected to variable environmental and operational conditions. It is recommended that a family-of-models approach is suitable for structures that have less redundancy, high operational importance, are deteriorated, and are performing under close capacity and demand levels.
Show less - Date Issued
- 2012
- Identifier
- CFE0004232, ucf:48997
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004232
- Title
- Remediation of Polychlorinated Biphenyl (PCB) Contaminated Building Materials Using Non-metal and Activated Metal Treatment Systems.
- Creator
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Legron-Rodriguez, Tamra, Yestrebsky, Cherie, Clausen, Christian, Elsheimer, Seth, Sigman, Michael, Chopra, Manoj, Quinn, Jacqueline, University of Central Florida
- Abstract / Description
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PCBs are recalcitrant compounds of no known natural origin that persist in the environment despite their ban by the United States Environmental Protection Agency in 1979 due to negative health effects. Transport of PCBs from elastic sealants into concrete, brick, and granite structures has resulted in the need for a technology capable of removing these PCBs from the materials. This research investigated the use of a nonmetal treatment system (NMTS) and an activated metal treatment system ...
Show morePCBs are recalcitrant compounds of no known natural origin that persist in the environment despite their ban by the United States Environmental Protection Agency in 1979 due to negative health effects. Transport of PCBs from elastic sealants into concrete, brick, and granite structures has resulted in the need for a technology capable of removing these PCBs from the materials. This research investigated the use of a nonmetal treatment system (NMTS) and an activated metal treatment system (AMTS) for the remediation and degradation of PCBs from concrete, brick, and granite affixed with PCB-laden caulking. The adsorption of PCBs onto the components of concrete and the feasibility of ethanol washing were also investigated.NMTS is a sorbent paste containing ethanol, acetic acid, and fillers that was developed at the University of Central Florida Environmental Chemistry Laboratory for the in situ remediation of PCBs. Combining NMTS with magnesium results in an activated treatment system used for reductive dechlorination of PCBs. NMTS was applied to laboratory-prepared concrete as well as field samples by direct contact as well as by a novel sock-type delivery. The remediation of PCBs from field samples using NMTS and AMTS resulted in a 33-98% reduction for concrete, a 65-70% reduction for brick, and an 89% reduction in PCB concentration for granite. The limit of NMTS for absorption of Aroclor 1254 was found to be roughly 22,000 mg Aroclor 1254 per kg of treatment system or greater. The activated treatment system resulted in a 94% or greater degradation of PCBs after seven days with the majority of degradation occurring in the first 24 hours. The adsorption of PCBs to individual concrete components (hydrated cement, sand, crushed limestone, and crushed granite) was found to follow the Freundlich isotherm model with greater adsorption to crushed limestone and crushed granite compared to hydrated cement and sand. Ethanol washing was shown to decrease the concentration of laboratory-prepared concrete by 68% and the concentration of PCBs in the ethanol wash were reduced by 77% via degradation with an activated magnesium system.
Show less - Date Issued
- 2013
- Identifier
- CFE0005197, ucf:50625
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005197