Current Search: Concrete construction (x)
View All Items
Pages
- Title
- Experimental evaluation of the durability of fly ash-based geopolymer concrete in the marine environment.
- Creator
- Edouard, Jean-Baptiste., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
The construction industry is increasingly turning to the use of environmentally friendly materials in order to meet the sustainable aspect required by modern infrastructures. Consequently, for the last two decades, the expansion of this concept, and the increasing global warming have raised concerns on the extensive use of Portland cement due to the high amount of carbon dioxide gas associated with its production. The development of geopolymer concretes offers promising signs for a change in...
Show moreThe construction industry is increasingly turning to the use of environmentally friendly materials in order to meet the sustainable aspect required by modern infrastructures. Consequently, for the last two decades, the expansion of this concept, and the increasing global warming have raised concerns on the extensive use of Portland cement due to the high amount of carbon dioxide gas associated with its production. The development of geopolymer concretes offers promising signs for a change in the way of producing concrete. However, to seriously consider geopolymer binders as an alternative to ordinary Portland cement, the durability of this new material should be evaluated in any comparative analysis. The main purpose of this study was to evaluate the durability characteristics of low calcium fly ash-based geopolymer concretes subjected to the marine environment, compared to ordinary Portland cement concrete with similar exposure. To achieve this goal, 8 molar geopolymer, 14 molar geopolymer and ordinary Portland cement concrete mixes were prepared and tested for exposure in seawater. Compressive strengths in the range of 2900 to 8700 psi (20-60 MPa) were obtained. The corrosion resistance performance of steel-reinforced concrete beams, made of these mixes, was also studied, using an accelerated electrochemical method, with submergence in salt water. The test results indicated that the geopolymer concrete showed excellent resistance to chloride attack, with longer time to corrosion cracking, compared to ordinary Portland cement concrete.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3170960
- Subject Headings
- Reinforced concrete, Corrosion, Testing, Reinforced concrete construction, Concrete, Mixing, Quality control, Environmental chemistry, Industrial applications, Polymer composites
- Format
- Document (PDF)
- Title
- Flexural Behavior of Concrete Using Basalt FRP Rebar.
- Creator
- Trotsek, Dylan, Arockiasamy, Madasamy, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
The objective of this research is to determine if the deflection equations currently adopted in ACI 440.1r-15 and previously ACI 440.1r-06 accurately reflect the flexural behavior of an overreinforced Basalt Fiber Reinforced Polymer (BFRP) concrete beam. This was accomplished with experimental, analytical and numerical models. The experiment consisted of two beams doublyreinforced with BFRP rebar. A three-point flexural test on beams with a 30 in. clear span was performed and the deflections...
Show moreThe objective of this research is to determine if the deflection equations currently adopted in ACI 440.1r-15 and previously ACI 440.1r-06 accurately reflect the flexural behavior of an overreinforced Basalt Fiber Reinforced Polymer (BFRP) concrete beam. This was accomplished with experimental, analytical and numerical models. The experiment consisted of two beams doublyreinforced with BFRP rebar. A three-point flexural test on beams with a 30 in. clear span was performed and the deflections were recorded with a dial gauge and LVDT system. This data was compared to the equations from ACI 440.1r-06, ACI 440.1r-15, Branson’s equation and a numerical model created in ANSYS Mechanical APDL. Experimental results show a stiffer beam than expected when compared to the four predictive models for deflection. This can be due to the level of over-reinforcement and the small clear-span to depth ratio. Further research should be conducted to determine the cause for the additional stiffness.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004920, http://purl.flvc.org/fau/fd/FA00004920
- Subject Headings
- Reinforced concrete construction--Mathematical models., Structural analysis (Engineering), Fiber-reinforced concrete.
- Format
- Document (PDF)
- Title
- Debond of CFRP laminate bonded with concrete exposed to harsh environmental conditions.
- Creator
- Baker, William Arnold., Florida Atlantic University, Arockiasamy, Madasamy
- Abstract/Description
-
This study evaluates the effectiveness of using externally bonded CFRP plates for repairing damaged prestressed concrete structures as an alternative to the metal sleeve splice. Currently the metal sleeve splice is the most often used method for the repair of damaged prestressed concrete bridges. The use of bonded CFRP plates could be a viable alternative to the use of steel in this type of repair because of their high strength and stiffness, resistance to corrosion and low weight. The bond...
Show moreThis study evaluates the effectiveness of using externally bonded CFRP plates for repairing damaged prestressed concrete structures as an alternative to the metal sleeve splice. Currently the metal sleeve splice is the most often used method for the repair of damaged prestressed concrete bridges. The use of bonded CFRP plates could be a viable alternative to the use of steel in this type of repair because of their high strength and stiffness, resistance to corrosion and low weight. The bond strength of CFRP plates bonded to concrete was evaluated by the use of a peel test and correlated by a finite element analysis. The peel test showed that the structural system was not significantly adversely effected by harsh environmental conditions. The results of this study showed that the use of CFRP plates is a feasible alternative to steel in the metal sleeve splice repair with some limiting factors.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15721
- Subject Headings
- Fiber reinforced plastics, Concrete--Environmental testing, Prestressed concrete construction--Maintenance and repair
- Format
- Document (PDF)
- Title
- Feasibility studies on carbon fiber composite cables in reinforced/prestressed concrete structures.
- Creator
- Kanneganti, Srikanth., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The feasibility studies on the use of non-metallic continuous fiber reinforcement in reinforced and prestressed concrete structures are presented herein. Experimental results from studies on relaxation, bond and transfer length of Carbon Fiber Composite Cables (CFCC) are presented followed by results of flexural load tests on concrete beams reinforced and prestressed with CFCC. Durability of the CFCC is another prime concern, and hence part of the study also focuses on establishing the...
Show moreThe feasibility studies on the use of non-metallic continuous fiber reinforcement in reinforced and prestressed concrete structures are presented herein. Experimental results from studies on relaxation, bond and transfer length of Carbon Fiber Composite Cables (CFCC) are presented followed by results of flexural load tests on concrete beams reinforced and prestressed with CFCC. Durability of the CFCC is another prime concern, and hence part of the study also focuses on establishing the durability of the CFCC exposed to aggressive environments like alkali solution and sea water. The basic mechanics that govern the structural behavior of the beams, provide important insight into the potential that CFCC has to offer.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/15080
- Subject Headings
- Fiber reinforced plastics, Reinforced concrete, Fiber, Composite materials, Prestressed concrete construction--Deterioration, Carbon fibers
- Format
- Document (PDF)
- Title
- Evaluation of the structural applicability of centrally prestressed, unreinforced concrete (CPUC) columns with modified Freyssinet hinges for marine and seismic environment.
- Creator
- Periyaiah, Rathinam., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
An innovative concept of the Centrally Prestressed, Unreinforced Concrete (CPUC) column with modified Freyssinet hinges formulated by Paul Csagoly, to prevent rebar corrosion and additionally mitigate seismic damage, was investigated. The first phase of this work emphasized the mode of failure, ultimate strength, and ductility characteristics of the CPUC columns. As expected, CPUC columns showed adequate axial and flexural resistance as well as ductility. The ultimate strengths of most of the...
Show moreAn innovative concept of the Centrally Prestressed, Unreinforced Concrete (CPUC) column with modified Freyssinet hinges formulated by Paul Csagoly, to prevent rebar corrosion and additionally mitigate seismic damage, was investigated. The first phase of this work emphasized the mode of failure, ultimate strength, and ductility characteristics of the CPUC columns. As expected, CPUC columns showed adequate axial and flexural resistance as well as ductility. The ultimate strengths of most of the CPUC columns were about 10 to 20% higher than those of conventional ones. The second phase dealt with an energy absorbing device compatible with CPUC column to meet the occasional high ductility demand of the CPUC columns in earthquake conditions. Hinges were tested for compressive strength and moment-rotation capability. Parametric studies of the hinges were conducted for different filler materials, and width-to-height ratios. The confined filler material in the Freyssinet type hinge was found to have excellent compressive strength and moment-rotation capability. The parameters, width-to-height ratios and different filler material, had significant effect on hinge's performance.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/15253
- Subject Headings
- Columns, Concrete--Testing, Prestressed concrete construction--Testing, Strength of materials
- Format
- Document (PDF)
- Title
- Hydrogen embrittlement of cathodically protected prestressing steel.
- Creator
- Kliszowski, Stanislas Henri., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Cathodic protection is currently recognized as the most practical mean for arresting corrosion of reinforcing steel tendons in existing concrete structures, however, its appropriateness in the case of prestressed concrete is questioned because prestressing steels are relatively susceptible to environmental cracking (hydrogen embrittlement). For the purpose of studying embrittlement tendencies a series of experiments using the slow strain rate technique were performed. The susceptibility to...
Show moreCathodic protection is currently recognized as the most practical mean for arresting corrosion of reinforcing steel tendons in existing concrete structures, however, its appropriateness in the case of prestressed concrete is questioned because prestressing steels are relatively susceptible to environmental cracking (hydrogen embrittlement). For the purpose of studying embrittlement tendencies a series of experiments using the slow strain rate technique were performed. The susceptibility to environmental cracking was compared for different steels corresponding to ASTM grades 270 and 250 polarized at $-$900 and $-1300$ mV (SCE) in deaerated saturated Ca(OH)$\sb2$ solutions. The influence of different notch and pit geometries was studied to simulate the behavior of corroded tendons and investigate the transition between smooth and severely notched specimen behavior. Also evaluated was the evolution of the mechanical properties of tendons after excessive polarization. The different cracking processes are discussed based on test data, fractography and exposures conditions associated with concrete structures.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/14999
- Subject Headings
- Cathodic protection, Metals--Hydrogen embrittlement, Tendons (Prestressed concrete), Prestressed concrete--Deterioration, Prestressed steel construction
- Format
- Document (PDF)
- Title
- Obstruction of chloride diffusion in concrete by embedded reinforcing bars.
- Creator
- Cros, Pascal., Florida Atlantic University, Hartt, William H.
- Abstract/Description
-
A study was performed of the effect of reinforcing bars on chloride diffusion into concrete. These bars act as obstacles to chloride movement, and this obstruction allows the chloride concentration to build-up faster along the top of the reinforcing bar than elsewhere. As a consequence, the critical chloride threshold to initiate corrosion of the steel is reached sooner than otherwise expected. This research was performed using two different methods. First, chloride analyses were performed on...
Show moreA study was performed of the effect of reinforcing bars on chloride diffusion into concrete. These bars act as obstacles to chloride movement, and this obstruction allows the chloride concentration to build-up faster along the top of the reinforcing bar than elsewhere. As a consequence, the critical chloride threshold to initiate corrosion of the steel is reached sooner than otherwise expected. This research was performed using two different methods. First, chloride analyses were performed on chloride exposed concrete blocks by taking cores in the concrete and drillings along the trace of the top bars. Second, concrete blocks models were analyzed by finite element analysis and the effect of the obstruction by the bar quantified. The role of the reinforcing bar in the chloride diffusional flow is discussed considering these two methods.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/13239
- Subject Headings
- Reinforcing bars--Corrosion, Reinforced concrete construction--Corrosion, Concrete--Additives, Chlorides--Diffusion rate
- Format
- Document (PDF)
- Title
- Embrittlement susceptibility of corroded pre-stressing steel in concrete during cathodic polarization.
- Creator
- Poeydomenge, Arnaud., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Experiments and analyses were performed to better define the limits of concern regarding hydrogen embrittlement in association with application of cathodic protection to prestressed concrete. To accomplish this, prestressed concrete specimens were locally corroded to different levels by anodic polarization and then polarized to -1.30 V SCE. A procedure of examination was developed using strain gauges to determine the level of prestrain. Relatively few brittle failures of wires resulted due,...
Show moreExperiments and analyses were performed to better define the limits of concern regarding hydrogen embrittlement in association with application of cathodic protection to prestressed concrete. To accomplish this, prestressed concrete specimens were locally corroded to different levels by anodic polarization and then polarized to -1.30 V SCE. A procedure of examination was developed using strain gauges to determine the level of prestrain. Relatively few brittle failures of wires resulted due, at least in part, to a relatively low prestrain of the pretensioned tendons. A model was developed which, coupled with data from parallel research, permitted definition of the minimum cross section for brittle failure as a function of the magnitude of prestrain and corrosion morphology of the wire. These results were tabulated in a format that can be used during field inspection to identify structural elements for which fracture could occur upon application of cathodic protection.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/15417
- Subject Headings
- Prestressed concrete--Corrosion, Cathodic protection, Prestressed concrete--Embrittlement, Prestressed steel construction
- Format
- Document (PDF)
- Title
- Stress distribution around a transverse circular opening through the midspan of a double reinforced beam.
- Creator
- Anesta, Heather R., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
This manuscript predicts the behavior of a doubly reinforced concrete beam with a circular opening at its midspan by closely analyzing traditional beam theory and design. It then confirms these predictions with finite element modeling software while providing design suggestions. The analysis is limited to the tensile and compressive stresses and cracking behavior. The objectives are to determine the stress distribution around a circular opening that agrees with conventional beam theory. The...
Show moreThis manuscript predicts the behavior of a doubly reinforced concrete beam with a circular opening at its midspan by closely analyzing traditional beam theory and design. It then confirms these predictions with finite element modeling software while providing design suggestions. The analysis is limited to the tensile and compressive stresses and cracking behavior. The objectives are to determine the stress distribution around a circular opening that agrees with conventional beam theory. The beam behavior is examined from zero load to failure load. ANSYS is utilized in lieu of real world testing, and the appendix includes the finite element results for a beam including design recommendations. The results lay the foundation for a possible new design procedure of concrete beams with single or multiple circular openings. This research offers useful information that was unavailable previously. More research can be conducted to help designers to design lighter, more efficient concrete beams.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/2867327
- Subject Headings
- Reinforced concrete construction, Structural design, Strains and stresses, Fracture mechanics
- Format
- Document (PDF)
- Title
- Polyethylene duct cracking in post-tensioning tendons of Florida segmental bridges.
- Creator
- Suarez, Jorge Alejandro, Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
For the purpose of investigating the cause of duct cracking in post-tensioning tendons and improving the durability of this type of structure, a series of experiments was performed. These were divided in two groups, the first to simulate the state of stress inside the tendon ducts and the second to compare the properties of new materials approved according to new regulations on the subject and those used in the construction of the structures. A proposed mechanism of cracking was studied and...
Show moreFor the purpose of investigating the cause of duct cracking in post-tensioning tendons and improving the durability of this type of structure, a series of experiments was performed. These were divided in two groups, the first to simulate the state of stress inside the tendon ducts and the second to compare the properties of new materials approved according to new regulations on the subject and those used in the construction of the structures. A proposed mechanism of cracking was studied and its validity verified. According to simulations performed on specimens that were fabricated and others developed by the finite element method, new major factors were found to explain the duct failure. Finally, a comparison of mechanical properties indicated a difference between virgin and aged materials.
Show less - Date Issued
- 2003
- PURL
- http://purl.flvc.org/fcla/dt/13071
- Subject Headings
- Post-tensioned prestressed concrete construction, Bridges--Florida, Polyethylene
- Format
- Document (PDF)
- Title
- Correlation of Chloride Diffusivity and Electrical Resistance for Cracked Concrete.
- Creator
- Merantus, Stanley W., Reddy, Dronnadula V., Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
The durability of Reinforced Concrete (RC) structures in the Marine environment is causing serious concern in the structural infrastructure. Reinforced concrete structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that causes degradation is Chloride Diffusion, due to shrinkage, atmospheric corrosion, and tide-induced wet and dry conditions at the air-water...
Show moreThe durability of Reinforced Concrete (RC) structures in the Marine environment is causing serious concern in the structural infrastructure. Reinforced concrete structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that causes degradation is Chloride Diffusion, due to shrinkage, atmospheric corrosion, and tide-induced wet and dry conditions at the air-water interfaces of coastal structures. Therefore, chloride diffusivity, which correlates with the electrical resistivity, has a significant impact on the durability of concrete. Concrete chloride diffusivity has been experimented by multiple agencies and researchers on sound concrete, but there is a considerable need for investigation of the durability of cracked concrete in the marine environment. The two test methods carried out are presented: Standardized American Society for Testing and Materials (ASTM) C1202 for Rapid Chloride Permeability (RCP) and ASTM D257 for Surface Resistivity (SR), and Nordtest (NT) Build 492 for Rapid Chloride Migration (RCM) and Bulk Resistivity (BR) for both sound (uncracked) and cracked (micro and macro) concrete. The limitations of the ASTM method, due to measurements before the steady-state migration is reached, does not account for leakage in cracked concrete, and the heating of the specimen due to higher current that increase the conductivity are indicated. The Rapid Chloride Migration test provides for the non-steady state of diffusion. Again, Bulk Resistivity, in contradistinction to Surface Resistivity is more accurate for cracked concrete. The correlation betweeen RCM-BR are plotted. Chloride Permeability/Migration is an important parameter that governs the Durability of Concrete. The principal contribution is the highlighting of the inadequacy of the current widely used standard ASTM C1202 for diffusivity testing, and the need for revision with further investigation.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004942, http://purl.flvc.org/fau/fd/FA00004942
- Subject Headings
- Reinforced concrete--Construction--Corrosion., Reinforced concrete--Deterioration., Concrete--Corrosion., Concrete--Chemical resistance., Chlorides--Environmental aspects., Chlorides--Diffusion rate.
- Format
- Document (PDF)
- Title
- Initiation and propagation of corrosion in dry-cast reinforced concrete pipes.
- Creator
- Balasubramanian, Hariharan, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This study investigates corrosion initiation and propagation in instrumented specimens obtained from segments of dry-cast reinforced concrete pipes. Potential, LPR and EIS measurements were carried out. During the propagation stage in different exposures, reinforcement eventually reached negative potentials values, which suggest mass transfer limitations. So far these specimens show no visual signs of corrosion such as cracks or corrosion products with one exception; where corrosion products...
Show moreThis study investigates corrosion initiation and propagation in instrumented specimens obtained from segments of dry-cast reinforced concrete pipes. Potential, LPR and EIS measurements were carried out. During the propagation stage in different exposures, reinforcement eventually reached negative potentials values, which suggest mass transfer limitations. So far these specimens show no visual signs of corrosion such as cracks or corrosion products with one exception; where corrosion products have reached the surface. Moreover, the apparent corrosion rate values obtained suggest high corrosion rate. No crack appearance so far, could be explained by the high porosity of the specimens; the corrosion products are filling these pores. It is speculated that although, there might be mass transfer limitations present, the current demanded by the anode is being balanced by a larger cathode area due to macrocell effects, since the high moisture conditions likely reduced the concrete resistivity and increased the throwing power.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362341
- Subject Headings
- Concrete, Deterioration, Tubular steel structures, Deterioration, Pipelines, Design and construction, Concrete construction, Corrosion and anti-corrosives
- Format
- Document (PDF)
- Title
- Behavior of precast single-cell segmental box bridges with external post-tensioning subjected to cyclic loading and temperature changes.
- Creator
- Sinha, Vikas., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The behavior of a precast single-cell segmental box bridge with external post-tensioning is studied based on a 1:3.5 scale model of the Long Key bridge in the Florida Keys. Constant amplitude fatigue loading was applied on the model at a critical location simulating HS20-44 AASHTO truck loading. The performance of the bridge model was evaluated in terms of deflections, strains in concrete and across the joints, and behavior of joints between the segments with increasing number of cycles of...
Show moreThe behavior of a precast single-cell segmental box bridge with external post-tensioning is studied based on a 1:3.5 scale model of the Long Key bridge in the Florida Keys. Constant amplitude fatigue loading was applied on the model at a critical location simulating HS20-44 AASHTO truck loading. The performance of the bridge model was evaluated in terms of deflections, strains in concrete and across the joints, and behavior of joints between the segments with increasing number of cycles of fatigue loading. Thermal response of the bridge model was also studied using finite element analysis and the predicted temperature distributions were compared with the experimental values.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14729
- Subject Headings
- Precast concrete construction--Fatigue, Post-tensioned prestressed concrete construction--Fatigue, Bridges, Box girder, Strains and stresses
- Format
- Document (PDF)
- Title
- Microcomputer and exsysp based expert system for selection and design of retaining structures.
- Creator
- Sinha, Anuradha., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The automation of retaining structure selection and design by utilizing artificial intelligence tools is presented herein. The study involved the development of a microcomputer based expert system, RESTEX (REtaining STructure EXpert). The modules of the expert systems RETAININGEARTH, with M.1 knowledge base, and REFLEXYS have been updated and the resulting RESTEX modules are written in C using Exsys Professional for high speed and efficient utilization of memory. RESTEX is an interactive menu...
Show moreThe automation of retaining structure selection and design by utilizing artificial intelligence tools is presented herein. The study involved the development of a microcomputer based expert system, RESTEX (REtaining STructure EXpert). The modules of the expert systems RETAININGEARTH, with M.1 knowledge base, and REFLEXYS have been updated and the resulting RESTEX modules are written in C using Exsys Professional for high speed and efficient utilization of memory. RESTEX is an interactive menu-driven system consisting of modules for Structure Selection, Preliminary Design, Soils Classification, Stability Analysis, and Reinforcement Design. The system is capable of performing selection, analysis, and design of gravity walls, cantilever walls, counterfort walls, reinforced earth, gabion, cantilever and anchored sheet piles.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14937
- Subject Headings
- Precast concrete construction--Fatigue, Post-tensioned prestressed concrete construction--Fatigue, Bridges, Box girder, Strains and stresses
- Format
- Document (PDF)
- Title
- Experimental Evaluation of the Structural Integrity of the Repairs for Corrosion-Damaged Marine Piles.
- Creator
- Bolivar, Juan Carlos, Reddy, Dronnadula V., Florida Atlantic University
- Abstract/Description
-
Corrosion damage is the mam cause of deterioration for reinforced concrete marine structures. Given the current economic downturn, it has become increasingly important to repair existing structures with techniques that prolong their life-cycle. The process to identify suitable repairs is affected by the lack of a consistent methodology to predict the outcome of the repairs. This investigation intends to compare the performance of seven different repairs, in terms of corrosion resistance,...
Show moreCorrosion damage is the mam cause of deterioration for reinforced concrete marine structures. Given the current economic downturn, it has become increasingly important to repair existing structures with techniques that prolong their life-cycle. The process to identify suitable repairs is affected by the lack of a consistent methodology to predict the outcome of the repairs. This investigation intends to compare the performance of seven different repairs, in terms of corrosion resistance, structural integrity, and cost-effectiveness. Following initial exposure to corrosion, the specimens were repaired using the proposed techniques. They were then tested for durability under simulated tidal conditions with periodic corrosion monitoring. The structural integrity was evaluated by crack scoring and ultimate load testing, and a comprehensive evaluation matrix was prepared, to determine which repairs were most adequate for corrosion damage. The results of this investigation substantiate that the repairs including carbon wrapping, HDPE jacketing, and MMFX steel, outperformed the rest of the repairs.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012506
- Subject Headings
- Reinforced concrete--Corrosion, Underwater concrete construction--Maintenance and repair, Materials--Deterioration--Prevention, Fibrous composites--Evaluation
- Format
- Document (PDF)
- Title
- Evaluation of Chloride Threshold for Steel Fiber Reinforced Concrete Composited in Aggressively Corrosive Environments.
- Creator
- Vogel, Dietrich H., Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Highway drainage pipes utilize concrete reinforced with steel wire to help mitigate water, earth, and traffic loads. Drainage pipes reinforced with zinc electroplated steel fibers offer a lower steel alternative to traditional steel wire cage reinforcements. The objective of the thesis research was to determine the physical and electrochemical characteristics of zinc electroplated steel fiber corrosion propagation. Experimental programs include: Fracture analysis of zinc electroplated steel...
Show moreHighway drainage pipes utilize concrete reinforced with steel wire to help mitigate water, earth, and traffic loads. Drainage pipes reinforced with zinc electroplated steel fibers offer a lower steel alternative to traditional steel wire cage reinforcements. The objective of the thesis research was to determine the physical and electrochemical characteristics of zinc electroplated steel fiber corrosion propagation. Experimental programs include: Fracture analysis of zinc electroplated steel fibers embedded in dry-cast concrete pipes exposed to varying chloride concentrations; Visual analysis of zinc electroplated steel fibers embedded in concrete exposed to varying chloride concentrations; Electrochemical analysis of zinc electroplated steel fibers embedded in concrete exposed to varying chlorides; Chloride threshold determination for zinc electroplated steel fibers immersed in simulated pore solution. Between the four experimental programs the most significant conclusion is that oxygen, moisture, and chlorides past the chloride threshold must be present for corrosion to propagate significantly on the zinc electroplated steel fibers.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004637, http://purl.flvc.org/fau/fd/FA00004637
- Subject Headings
- Fiber-reinforced concrete--Cracking., Cement composites., Reinforced concrete construction., Reinforced concrete--Corrosion., Corrosion and anti-corrosives., Structural engineering.
- Format
- Document (PDF)
- Title
- Accelerated Testing Protocol for Durability of Roller Compacted Recycled Aggregate Concrete (RCRAC).
- Creator
- Fraser, Jamie Barbara, Sobhan, Khaled Dr., Florida Atlantic University
- Abstract/Description
-
With the growing environmental concerns related to the ever increasing waste disposal problem in the US, the utilizing of recycled materials in Civil Engineering construction has become an attractive option, which not only supports the concept of green buildings, but can also bring about economic savings by conserving natural resources and landfill spaces. However, the questionable long-term performance of recycled materials often hinders the widespread use in structural applications. The...
Show moreWith the growing environmental concerns related to the ever increasing waste disposal problem in the US, the utilizing of recycled materials in Civil Engineering construction has become an attractive option, which not only supports the concept of green buildings, but can also bring about economic savings by conserving natural resources and landfill spaces. However, the questionable long-term performance of recycled materials often hinders the widespread use in structural applications. The primary focus of this study was to develop accelerated aging/testing protocols for predicting the durability of recycled aggregate concrete (RAC), Type I Portland Cement, and up to 50% fly ash replacement. Accelerated aging was accomplished by curing the specimens at elevated temperatures regimes for specific durations. Stiffness-time master curves were constructed using Time-Temperature Superposition (TTS) and Stepped Isothermal Method (SIM) based on the Arrhenius Equation. All the methods demonstrated that the stiffness decreased with time regardless of the amount of fly ash. The Arrhenius method allowed stiffness prediction up to an equivalent age of 14,000 hours developed from short-term tests lasting up to 144 hours. It was also found that SIM and TTS provide equitable results, potentially reducing the number of specimens and testing time for durability prediction.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012517
- Subject Headings
- Joints (Engineering)--Testing, High strength concrete--Testing, Concrete--Mechanical properties--Testing, Concrete construction, Cement composites--Testing
- Format
- Document (PDF)
- Title
- Theoretical analysis of reinforced and prestressed concrete bridge members strengthened with CFRP laminates.
- Creator
- Qu, Rong., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Nonlinear finite element analyses of the reinforced rectangular beams, prestressed solid slab and prestressed voided slab retrofitted with CFRP laminates are carried out using the software ANSYS(version 5.0) on the Sunwork station. The computer analyses are based on the proposed stress-strain relationship considering the effects of tensile stress on both elastic modulus and maximum compressive stress of concrete. Several assumptions are made in predicting the loss of tensile strength due to...
Show moreNonlinear finite element analyses of the reinforced rectangular beams, prestressed solid slab and prestressed voided slab retrofitted with CFRP laminates are carried out using the software ANSYS(version 5.0) on the Sunwork station. The computer analyses are based on the proposed stress-strain relationship considering the effects of tensile stress on both elastic modulus and maximum compressive stress of concrete. Several assumptions are made in predicting the loss of tensile strength due to crack, confinement due to the laminate bonding, tensile strength due to the prestress force, failure pattern due to the concentrated stress adjacent to the loading point and concrete crushing due to large compressive strain. A subroutine is developed using macro commands of ANSYS. In this research, Branson's equation or Ie procedure is assumed in the prediction of deflection of retrofitted concrete members. The modifications needed due to laminate bonding are the cracking moments of inertia (Icr) of the beams or slabs bonded with CFRP laminates, which are included in the analysis.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/15083
- Subject Headings
- ANSYS (Computer system), Reinforced concrete--Plastic properties, Carbon composites, Fiber reinforced plastics, Bridges--Design and construction, Prestressed concrete construction
- Format
- Document (PDF)
- Title
- Fatigue behavior of corrosion notched weathering steel samples.
- Creator
- Chen, Di, Granata, Richard D., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Weathering steel has been a primary construction material for bridges in the United States. Notches caused by corrosion are observed on the flange of steel I-beams. These notches reduce the cross section area of the structure and are threats to bridge safety. A606-04 Type 4 cold rolled weathering steel samples were studied in this thesis to understand the effect of notches that caused by corrosion. Weathering steel samples were in the shape of plates, which simulated flange of I-beams. The...
Show moreWeathering steel has been a primary construction material for bridges in the United States. Notches caused by corrosion are observed on the flange of steel I-beams. These notches reduce the cross section area of the structure and are threats to bridge safety. A606-04 Type 4 cold rolled weathering steel samples were studied in this thesis to understand the effect of notches that caused by corrosion. Weathering steel samples were in the shape of plates, which simulated flange of I-beams. The plate samples were notched across their surfaces by applying electrical current through an electrochemical circuit composed of an anode, a cathode and electrolyte. Sixteen samples were notched and cut into appropriate shape for fatigue testing. S-N (Stress-Number of cycles to failure) diagram established from fatigue data indicated that the fatigue strength decreased below AASHTO category B. Weibull analysis was also performed to understand the reliability distribution.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004092, http://purl.flvc.org/fau/fd/FA00004092
- Subject Headings
- Iron and steel bridges -- Corrosion, Protective coatings -- Evaluation, Reinforced concrete construction, Steel -- Fatigue, Steel, Structural -- Corrosion
- Format
- Document (PDF)
- Title
- Accelerated corrosion of steel in dry-cast reinforced concrete pipes after initiation.
- Creator
- Weber, Brian W., Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Instrumented dry-cast reinforced concrete pipe (DC-RCP) specimens in which corrosion of the reinforcing steel had initiated were selected to accelerate the corrosion. Type C and type F DC-RCP were used. An anodic current density of various magnitudes (0.5 μA/cm2, 1 μA/cm2 and 2.5 μA/cm2) was applied during the corrosion propagation stage. The specimens were placed in high humidity and selected specimens were later covered with wet sand. Selected specimens were terminated for visual...
Show moreInstrumented dry-cast reinforced concrete pipe (DC-RCP) specimens in which corrosion of the reinforcing steel had initiated were selected to accelerate the corrosion. Type C and type F DC-RCP were used. An anodic current density of various magnitudes (0.5 μA/cm2, 1 μA/cm2 and 2.5 μA/cm2) was applied during the corrosion propagation stage. The specimens were placed in high humidity and selected specimens were later covered with wet sand. Selected specimens were terminated for visual examination and gravimetric analysis. Typically, the reinforcement potentials during the accelerated corrosion period were more negative for F specimens compared to C specimens. The C specimens experienced ~2× more corrosion than the F specimens. The accumulated corrosion products did not cause cracks. A method was developed that allows for modest corrosion acceleration during the corrosion propagation stage of DC-RCP.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004233, http://purl.flvc.org/fau/fd/FA00004233
- Subject Headings
- Concrete -- Deterioration, Corrosion and anti corrosives, Pipelines -- Design and construction, Tubular steel structures -- Deterioration
- Format
- Document (PDF)