Current Search: Concrete -- Mechanical properties (x)
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- 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
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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)
- Title
- Durability prediction of recycled aggregate concrete under accelerated aging and environmental exposure.
- Creator
- Gonzalez, Lillian, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
This study is to compare the performance of recycled aggregate concrete and the impact of up to 50% cement replacement with fly ash on durability. Water content, sieve analysis, standard and modified compaction tests were performed to assess the physical properties of the recycled aggregate concrete. Accelerated aging tests were performed to predict the long term durability of the recycled aggregate concrete. Following Arrhenius modeling and TTS and SIM accelerated aging protocols, a time...
Show moreThis study is to compare the performance of recycled aggregate concrete and the impact of up to 50% cement replacement with fly ash on durability. Water content, sieve analysis, standard and modified compaction tests were performed to assess the physical properties of the recycled aggregate concrete. Accelerated aging tests were performed to predict the long term durability of the recycled aggregate concrete. Following Arrhenius modeling and TTS and SIM accelerated aging protocols, a time versus stiffness master curve was created. This allowed the prediction of equivalent age using experimental data and theoretical analysis. To account for environmental exposure, the specimens underwent 24 and 48 hours of wet-dry cycling and subjected. Overall there was an increase in stiffness and strength from the specimens containing fly ash. All tests performed predicted equivalent age beyond the testing period of 144 hrs. and up to 7 years. Specimens containing fly maintained a constant and higher density to environmental exposure.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/3353087
- Subject Headings
- Concrete, Mechanical properties, Testing, Concrete, Environmental aspects, Sustainable construction, High strength concrete, Testing, Cement composites, Testing
- Format
- Document (PDF)
- Title
- Mechanical properties of fiber-reinforced polymer (FRP) composites for concrete bridge deck reinforcement.
- Creator
- Manav, Mukbil Ozan., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Durability of concrete bridge decks reinforced with conventional structural steel is a major concern in aggressive environments. To address this problem, there have been efforts, in recent years, to develop and evaluate alternatives to conventional steel. One alternative is fiber reinforced polymer (FRP) composite reinforcement. FRP composites have been used successfully in many industrial applications. This thesis investigates short-term mechanical properties of FRP rebars as reinforcement...
Show moreDurability of concrete bridge decks reinforced with conventional structural steel is a major concern in aggressive environments. To address this problem, there have been efforts, in recent years, to develop and evaluate alternatives to conventional steel. One alternative is fiber reinforced polymer (FRP) composite reinforcement. FRP composites have been used successfully in many industrial applications. This thesis investigates short-term mechanical properties of FRP rebars as reinforcement for concrete bridge decks and discusses results of extensive laboratory tests. Four test methods (tension, flexure, shear and bond) are developed and test protocols are proposed for adoption by AASHTO.
Show less - Date Issued
- 2002
- PURL
- http://purl.flvc.org/fcla/dt/12988
- Subject Headings
- Fibrous composites--Mechanical properties, Polymeric composites, Reinforced concrete, Fiber
- Format
- Document (PDF)
- Title
- Fire performance of high strength concrete materials and structural concrete.
- Creator
- Liu, Lixian., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
In recent years, high strength concrete (HSC) is becoming an attractive alternative to traditional normal strength concrete (NSC), and is used in a wide range of applications. With the increased use of HSC, concern has developed regarding the behavior of such concrete in fire. Until now, the fire performance of HSC is not fully understood and more research is needed. Full-scale fire testing is time consuming and expensive, and the real fire scenario is different from the standard fire....
Show moreIn recent years, high strength concrete (HSC) is becoming an attractive alternative to traditional normal strength concrete (NSC), and is used in a wide range of applications. With the increased use of HSC, concern has developed regarding the behavior of such concrete in fire. Until now, the fire performance of HSC is not fully understood and more research is needed. Full-scale fire testing is time consuming and expensive, and the real fire scenario is different from the standard fire. Performance-based assessment methods, including numerical analysis and simplified method, are being accepted in an increasing number of countries. In this dissertation, the fire testing results both of HSC and NSC are presented, performance-based numerical models are developed to study the fire performance of reinforced concrete (RC) members, and simplified calculation methods are proposed to estimate the load capacity of fire-damaged RC columns/beams. A detailed and comprehensive literature review is presented that provides background information on the high temperature behavior of concrete materials and RC members, as well as information on fire performance assessment procedures and objectives. The fire testing results of seven batches of HSC and NSC are presented and discussed. The test results indicated that the post-fire re-curing results in substantial strength and durability recovery, and its extent depends upon the types of concrete, temperature level, and re-curing age. The fire tests also showed that violent explosive reduced the risk of HSC explosive spalling. The surface crack widths were also reduced during the re-curing process, and in most cases, they were found within the maximum limits specified by the American Concrete Institute (ACI) building code., Numerical models are developed herein to investigate the behavior in fire of RC columns and beams. The models have been validated against fire test data available in literature, and used to conduct parametric studies, which focused on the size effect on fire resistance of RC columns, and the effect of concrete cover thickness on fire endurance of RC beams. Simplified calculation methods have been developed to predict the load capacity of fire damaged RC columns/beams. This method is validated by five case studies, including thirty-five RC columns tested by other investigators. The predicted results are compared with the experimental results, and the good agreement indicates the adequacy of the simplified method for practical engineering applications.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/369189
- Subject Headings
- Reinforced concrete, Thermodynamics, Concrete, Effect of temperature on, Heat engineering, High strength concrete, Mechanical properties, Concrete, Permeability, Testing
- Format
- Document (PDF)
- Title
- SYNTHETIC FIBER REINFORCED CONCRETE PERFORMANCE AFTER PROLONGED ENVIRONMENTAL EXPOSURE UTILIZING THE MODIFIED INDIRECT TENSILE TEST.
- Creator
- Ellis, Spencer G., Presuel-Moreno, Francisco, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
In order to study the mechanical performance of dry-cast synthetic fiber reinforced concrete (SynFRC), samples of varying geometry, fiber content, and environmental exposure were developed and tested using the modified indirect tensile test. The samples created consisted of three different thicknesses (with two different geometries), and six different fiber contents that differed in either type, or quantity, of fibers. Throughout the duration of this research, procedures for inflicting...
Show moreIn order to study the mechanical performance of dry-cast synthetic fiber reinforced concrete (SynFRC), samples of varying geometry, fiber content, and environmental exposure were developed and tested using the modified indirect tensile test. The samples created consisted of three different thicknesses (with two different geometries), and six different fiber contents that differed in either type, or quantity, of fibers. Throughout the duration of this research, procedures for inflicting detrimental materials into the concrete samples were employed at a number of different environments by implementing accelerated rates of deterioration using geometric adjustments, increased temperature exposure, wetting/drying cycles, and preparation techniques. The SynFRC samples studied were immersed in a wide range of environments including: the exposure of samples to high humidity and calcium hydroxide environments, which served at the control group, while the sea water, low pH, and barge conditioning environments were used to depict the real world environments similar to what would be experienced in the Florida ecosystem. As a result of this conditioning regime, the concrete was able to imitate the real-world effects that the environments would have inflicted if exposed for long durations after an exposure period of only 20-24 months. Having adequately conditioned the samples in their respective environments, they were then tested (and forensically investigated) using the modified indirect tensile testing method to gather data regarding each sample’s toughness and load handling capability. By analyzing the results from each sample, the toughness was calculated by taking the area under the force displacement curve. From these toughness readings it was found that possible degradation occurred between the fiber-matrix interface of some of the concrete samples conditioned in the Barge environment. From these specimens that were immersed in the barge environment, a handful of them exhibited multiple episodes of strain softening characteristics within their force displacement curves. In regard to the fibers used within the samples, the PVA fibers tended to pull off more while the Tuff Strand SF fibers had the highest tendency to break (despite some of the fibers showing similar pull off and breaking failure characteristics). When it comes to the overall thickness of the sample, there was clear correlation between the increase in size and the increase in sample toughness, however the degree to which it correlates varies from sample to sample.
Show less - Date Issued
- 2020
- PURL
- http://purl.flvc.org/fau/fd/FA00013466
- Subject Headings
- Reinforced concrete, Fiber-reinforced concrete--Testing, Reinforced concrete--Mechanical properties, Tensile Strength, Concrete—Environmental testing
- 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
- Durability of a recycled aggregate concrete base course material under coupled environmental exposure and cyclic.
- Creator
- Gonzalez, Lillian, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Long term durability is a major concern for wide-scale use of recycled aggregate materials in civil engineering construction. The purpose of this study is to provide an insight into the damaging effects of combined wet-dry cycles and repeated mechanical loading in a recycled aggregate concrete (RAC) base course material made from recycled crushed concrete aggregate and cement. A coordinated experimental program followed by a mechanistic pavement modeling and life cycle analysis was conducted...
Show moreLong term durability is a major concern for wide-scale use of recycled aggregate materials in civil engineering construction. The purpose of this study is to provide an insight into the damaging effects of combined wet-dry cycles and repeated mechanical loading in a recycled aggregate concrete (RAC) base course material made from recycled crushed concrete aggregate and cement. A coordinated experimental program followed by a mechanistic pavement modeling and life cycle analysis was conducted as part of this research study. This laboratory investigation was divided into three phases each consisting of both wet-dry exposed specimens (WD), and control or non wet-dry exposed specimens (NWD). Phase I experiments involved monotonic loading tests under compression and flexure to evaluate the strength properties. Phase II involved testing a total of 108 cylindrical specimens in cyclic compressive loading at three different stress ratios. After each regime of cyclic loading, residual compressive strengths were determined. In addition, the load-deformation hysteresis loops and the accumulated plastic deformation were continuously monitored through all loading cycles. Phase III included a flexural fatigue test program on 39 beam specimens, and fracture testing program on 6 notched beam specimens, each one having 19-mm initial notch. Traditional SR-N curves, relating the Stress Ratio (SR) with the number of cycles to failure (N or Nf), were developed. Fatigue crack growth rate and changes in Stress Intensity Factors were obtained to determine Paris Law constants and fracture toughness. A mechanistic analysis of a typical highway pavement incorporating RAC base was performed with KENPAVE program, followed by a Life Cycle Analysis (LCA) using the GaBi software. It was found that the specimens subjected to wet-dry cycles suffered significantly higher damage expressed in terms of accumulated plastic deformation, and loss of residual compressive strength, modulus, fatigue endurance limit, and design life, compared to specimens not exposed to wet-dry cycles. Although such degradation in material properties are important considerations in pavement design, a concurrent Life Cycle Analysis demonstrated that recycled aggregate concrete base course still holds promise as an alternative construction material from environmental stand point.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004116, http://purl.flvc.org/fau/fd/FA00004116
- Subject Headings
- Aggregates (Building materials ) -- Recycling, Concrete -- Mechanical properties, Construction and demolition debris -- Recycling, Structural engineering, Sustainable construction, Waste products as road materials
- Format
- Document (PDF)