Current Search:  Concrete -- Chemical resistance (x)

View All Items

  • CSV Spreadsheet
(1 - 8 of 8)
Centrally prestressed fiber reinforced concrete columns
Title
Centrally prestressed fiber reinforced concrete columns.
Creator
Grijalba, Daniel A., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description
With the need to improve corrosion resistance in columns and piles, the innovative idea of Centrally Prestressed Fiber Reinforced Concrete (CPFRC) columns is a promising solution. The first step is to compare if the compressive strength of any mix is affected by the size, geometry, or even the inclusion of polyolefin fibers in a specimen. The results showed that the cylinder size of 4 in. x 8 in., which is the most common size used by the testing labs, has the highest compressive strength....
Show moreWith the need to improve corrosion resistance in columns and piles, the innovative idea of Centrally Prestressed Fiber Reinforced Concrete (CPFRC) columns is a promising solution. The first step is to compare if the compressive strength of any mix is affected by the size, geometry, or even the inclusion of polyolefin fibers in a specimen. The results showed that the cylinder size of 4 in. x 8 in., which is the most common size used by the testing labs, has the highest compressive strength. There was no sign on compressive strength improvement with the use of polyolefin fibers, except for reduction in cracking size and concrete spalling. The second step compared the ultimate strength, ductility characteristics and failure mode of CPFRC columns to conventional columns. CPFRC showed adequate axial and flexural resistance, in addition to ductile behavior similar to regular reinforced concrete columns.
Show less
Date Issued
2011
PURL
http://purl.flvc.org/FAU/3332253
Subject Headings
Prestressed concrete construction, Strength of materials, Composite reinforced concrete, Concrete, Chemical resistance
Format
Document (PDF)
Chloride penetration into concrete structures exposed to the marine atmosphere
Title
Chloride penetration into concrete structures exposed to the marine atmosphere.
Creator
Shill, Scott Thompson, Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Chloride ions present in the marine atmosphere contained in marine aerosols is investigated for a relationship with chloride that accumulated into concrete. Chloride profiles are conducted on several concrete mixes containing fly ash, silica fume, and slag, with water to cementitious ratios of 0.35, 0.41, and 0.47. The chloride accumulation in concrete samples exposed to the environment is investigated with relation to the chloride deposition from the marine atmosphere measured via the wet...
Show moreChloride ions present in the marine atmosphere contained in marine aerosols is investigated for a relationship with chloride that accumulated into concrete. Chloride profiles are conducted on several concrete mixes containing fly ash, silica fume, and slag, with water to cementitious ratios of 0.35, 0.41, and 0.47. The chloride accumulation in concrete samples exposed to the environment is investigated with relation to the chloride deposition from the marine atmosphere measured via the wet candle test. Results indicate a possible relationship for the total accumulated chloride in the concrete with the accumulated chloride deposition (wet candle). Over the exposure periods, concrete specimens with 50% slag addition and 0.47 w/cm had the lowest average rates of chloride accumulation for deposition under 100 g/m2day. Chloride accumulation was lower in concrete containing 20% fly ash and 8% silica fume with 0.35 w/cm for chloride deposition rates over 200 g/m2day.
Show less
Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004227, http://purl.flvc.org/fau/fd/FA00004227
Subject Headings
Chlorides -- Diffusion rate, Chlorides -- Environmental aspects, Concrete -- Chemical resistance, Concrete -- Permeability, Reinforced concrete -- Construction -- Corrosion
Format
Document (PDF)
Corrosion initiation and propagation on corrosion resistant alloys embedded in concrete by accelerated chloride transport
Title
Corrosion initiation and propagation on corrosion resistant alloys embedded in concrete by accelerated chloride transport.
Creator
Gutierrez Tellez, Francisco., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Two duplex stainless steels rebars: UNS32304SS and UNS32101SS, were selected to investigate the corrosion initiation and propagation in reinforced concrete specimens. The investigation is divided in two phases with two different methods to accelerate the transport of chlorides through the concrete and initiate corrosion in a short period of time. After corrosion had initiated and propagated for some time; selected specimens were terminated for visual examination. On specimens selected for...
Show moreTwo duplex stainless steels rebars: UNS32304SS and UNS32101SS, were selected to investigate the corrosion initiation and propagation in reinforced concrete specimens. The investigation is divided in two phases with two different methods to accelerate the transport of chlorides through the concrete and initiate corrosion in a short period of time. After corrosion had initiated and propagated for some time; selected specimens were terminated for visual examination. On specimens selected for autopsy, the rebars in the top row showed corrosion to various degrees. Corrosion had propagated to such extent on the terminated specimens that the specimen showed cracks. Stray current might have caused accelerated corrosion on rebars where corrosion had initiated. Based on chloride concentrations measured at the rebar trace, corrosion initiated: on S32101 rebars on average at 7.9 kg/m3, and S32101 rebars on average at 6.0 kg/m3. The findings suggest that S32304 rebars corroded at a slower than S32101.
Show less
Date Issued
2013
PURL
http://purl.flvc.org/fcla/dt/3362380
Subject Headings
Concrete, Corrosion, Concrete construction, Reinforced concrete, Chemical resistance, Steel, Structural, Corrosion
Format
Document (PDF)
Initiation and propagation of corrosion in dry-cast reinforced concrete ring specimens
Title
Initiation and propagation of corrosion in dry-cast reinforced concrete ring specimens.
Creator
Seo, Bongjoon, Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The corrosion propagation stage of D-CRP (types F and C) was tested under immersion in water, high humidity, and covered with wet sand. The half-cell potential, linear polarization test, and electrochemical impedance spectroscopy measurements were performed. Selected specimens were terminated after 300 days of exposure and visually inspected. Based on corrosion potential measurements obtained during the corrosion propagation observation, and calculated corrosion rate based on LPR measurements...
Show moreThe corrosion propagation stage of D-CRP (types F and C) was tested under immersion in water, high humidity, and covered with wet sand. The half-cell potential, linear polarization test, and electrochemical impedance spectroscopy measurements were performed. Selected specimens were terminated after 300 days of exposure and visually inspected. Based on corrosion potential measurements obtained during the corrosion propagation observation, and calculated corrosion rate based on LPR measurements: all specimens were actively corroding. Additionally, EIS-Rc values were calculated for FS, CS and CH specimens. The Rc_EIS were generally greater than Rc_LPR values. EIS spectra for CI and FI specimens usually included mass transport limitations, as these specimens were immersed. Both type of specimens immersed in water (FI and CI), appeared to have higher corrosion rate based on LPR-Rc. However, upon autopsy it was revealed that a more modest amount of corrosion occurred on the reinforcing steel of FI and CI terminated specimens.
Show less
Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004226, http://purl.flvc.org/fau/fd/FA00004226
Subject Headings
Concrete -- Deterioration, Concrete construction, Corrosion and anti corrosives, Reinforced concrete -- Chemical resistance, Tubular steel structures -- Deterioration
Format
Document (PDF)
Experimental and Modeling Study of Chloride Ingress into Concrete and Reinforcement Corrosion Initiation
Title
Experimental and Modeling Study of Chloride Ingress into Concrete and Reinforcement Corrosion Initiation.
Creator
Yu, Hui, Hartt, William H., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Effects of reinforcement and coarse aggregate on chloride ingression into concrete and reinforcement corrosion initiation have been studied with experimental and modeling (finite element method) analyses. Once specimens were fabricated and exposed to a chloride solution, various experimental techniques were employed to determine the effect of reinforcement and coarse aggregate on time-to-corrosion and chloride ingress and concentration at corrosion locations. Model analyses were performed to...
Show moreEffects of reinforcement and coarse aggregate on chloride ingression into concrete and reinforcement corrosion initiation have been studied with experimental and modeling (finite element method) analyses. Once specimens were fabricated and exposed to a chloride solution, various experimental techniques were employed to determine the effect of reinforcement and coarse aggregate on time-to-corrosion and chloride ingress and concentration at corrosion locations. Model analyses were performed to verify and explain the experimental results. Based upon the results, it was determined that unexpectedly higher chloride concentrations were present on the top of the rebar trace than that to the side at the same depth and an inverse concentration gradient (increasing [Cl-] with increasing depth) occurred near the top of rebars. Also, coarse aggregate volume profile in close proximity to the rebar and spatial distribution of these aggregates, in conjunction with the physical obstruction afforded by reinforcement to chloride flow, complicates concrete sampling for Cl- intended to define the critical concentration of this species to initiate corrosion. Modeling analyses that considered cover thickness, chloride threshold concentration, reinforcement size and shape, and coarse aggregate type and percolation confirmed the experimental findings. The results, at least in part, account for the relatively wide spread in chloride corrosion threshold values reported in the literature and illustrate that more consistent chloride threshold concentrations can be acquired from mortar or paste specimens than from concrete ones.
Show less
Date Issued
2007
PURL
http://purl.flvc.org/fau/fd/FA00012582
Subject Headings
Reinforced concrete construction--Corrosion, Chlorides--Diffusion rate, Composite reinforced concrete, Concrete--Chemical resistance
Format
Document (PDF)
Corrosion Propagation of Rebar Embedded in High Performance Concrete
Title
Corrosion Propagation of Rebar Embedded in High Performance Concrete.
Creator
Nazim, Manzurul, Presuel-Moreno, Francisco, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The FDOT has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over 3 decades. Previous findings indicated that such additions in concrete mix makes the concrete more durable. To better understand corrosion propagation of rebar in high performance concrete: mature concrete samples that were made (2008/2009) with Portland cement, a binary mix, a ternary mix and recently prepared (April 2016 with 50% OPC + 50% slag and 80%...
Show moreThe FDOT has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over 3 decades. Previous findings indicated that such additions in concrete mix makes the concrete more durable. To better understand corrosion propagation of rebar in high performance concrete: mature concrete samples that were made (2008/2009) with Portland cement, a binary mix, a ternary mix and recently prepared (April 2016 with 50% OPC + 50% slag and 80% OPC + 20% Fly ash) concrete samples were considered. None of these concretes had any admixed chloride to start with. An accelerated chloride transport process was used to drive chloride ions into the concrete so that chlorides reach and exceed thechloride threshold at the rebar surface and initiate corrosion. Electrochemical measurements were taken at regular intervals (during and after the electro-migration process) to observe the corrosion propagation in each sample.
Show less
Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004941, http://purl.flvc.org/fau/fd/FA00004941
Subject Headings
Reinforced concrete--Corrosion., Reinforced concrete--Chemical resistance., Reinforced concrete--Deterioration., Concrete--Corrosion., Concrete--Mechanical properties.
Format
Document (PDF)
Concrete diffusivity and its correlation with chloride deposition rate on concrete exposed to marine environments
Title
Concrete diffusivity and its correlation with chloride deposition rate on concrete exposed to marine environments.
Creator
Echevarria, Victor Anthony., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The aim of this study was to investigate the diffusion of chloride ions into concrete samples that were exposed in scenarios that simulate the splash, tidal, atmospheric, and immersed portions of a marine structure. To study the atmospheric deposition, the project also investigated the relationship between chloride ion deposition on the wet candle and its accumulation into concrete samples. Results from the wet candle experiment indicated that between 2% and 45% of the chlorides deposited per...
Show moreThe aim of this study was to investigate the diffusion of chloride ions into concrete samples that were exposed in scenarios that simulate the splash, tidal, atmospheric, and immersed portions of a marine structure. To study the atmospheric deposition, the project also investigated the relationship between chloride ion deposition on the wet candle and its accumulation into concrete samples. Results from the wet candle experiment indicated that between 2% and 45% of the chlorides deposited per square meter of exposed area could be found within the concrete samples. After 6 months, slag G1a blocks showed the most resistance to chloride penetration in the tidal and splash simulations. After 10 months of exposure, fly ash samples had the slowest rates of diffusion in the tidal simulation while the fly ash + silica fume samples and the slag samples measured similar rates of diffusion within the tidal zone. After 90 days of curing, cylinders composed of 20% fly ash & 8% silica fume measured the highest average resistivity values and were found to be less vulnerable to chloride ion penetration than the 20% fly ash and the 50% slag concrete through rapid migration tests.
Show less
Date Issued
2012
PURL
http://purl.flvc.org/FAU/3358557
Subject Headings
Reinforced concrete, Construction, Corrosion, Composite reinforced concrete, Corrosion, Testing, Concrete, Fluid dynamics, Concrete, Chemical resistance, Chlorides, Diffusion rate
Format
Document (PDF)
Correlation of Chloride Diffusivity and Electrical Resistance for Cracked Concrete
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)