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Title: Assessment of the Long-Term Durability of Recycled Aggregate Concrete.
Creator: Martins, Caique, Sobhan, Khaled
Abstract/Description: This study tests the long-term durability that can be developed in concrete batches made with recycled aggregate concrete. Durability is a broad term used to define the resistance of a material to weathering effects, but in this scenario, durability will be defined as a drop in the compressive strength of the concrete. To test this, thermal sensing was used to determine the maturity of the concrete, or in other words how far along the curing process the concrete is. This was then plotted...
Show moreThis study tests the long-term durability that can be developed in concrete batches made with recycled aggregate concrete. Durability is a broad term used to define the resistance of a material to weathering effects, but in this scenario, durability will be defined as a drop in the compressive strength of the concrete. To test this, thermal sensing was used to determine the maturity of the concrete, or in other words how far along the curing process the concrete is. This was then plotted against the corresponding concrete compressive strength to create a relationship that can be exploited to project the later age strength of the concrete. This data is paramount in determining the viability of recycled concrete aggregate because it is a sustainable alternative to other coarse aggregate material, an essential part to making concrete, but its’ properties are largely unknown since they can be highly variable.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FAU_SR00000044
Subject Headings: College students --Research --United States.
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.
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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: Permanent strain accumulation in a granular material due to cyclic loading.
Creator: Genduso, Michael J., Florida Atlantic University, Sobhan, Khaled Dr.
Abstract/Description: To better characterize the accumulation of permanent deformation in a granular material, 40 Consolidated Drained (CD) triaxial tests (14 static and 26 cyclic) were performed under various stress conditions. A Digital Image Correlation (DIC) technique was utilized in some Repeated Load Triaxial (RLT) tests to measure global and localized strains visually in a non-contact manner. Additionally, the experimentally determined resilient material properties were used in a finite element based...
Show moreTo better characterize the accumulation of permanent deformation in a granular material, 40 Consolidated Drained (CD) triaxial tests (14 static and 26 cyclic) were performed under various stress conditions. A Digital Image Correlation (DIC) technique was utilized in some Repeated Load Triaxial (RLT) tests to measure global and localized strains visually in a non-contact manner. Additionally, the experimentally determined resilient material properties were used in a finite element based pavement modeling software called MICH-PAVE. Under cyclic loading, the permanent strain accumulation was found to obey the relationship of the form epsilonp =aNb, and the Resilient Modulus was used to develop the nonlinear K-theta model for granular materials. The observed/measured permanent strains using DIC/LVDT techniques compared favorably with the values obtained by the finite element simulation, and the evaluation of granular material by multiple methods seems promising for improved pavement design.
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/13264
Subject Headings: Soils--Testing, Soil mechanics, Soil-structure interaction, Engineering geology, Rocks--Testing, Materials--Dynamic testing
Format: Document (PDF)

Title: Use of piezocone penetration tests for rapid in-situ characterization of Florida organic soil.
Creator: Huynh, Hieu H., Florida Atlantic University, Sobhan, Khaled
Abstract/Description: Organic soils generally are characterized by low strength and high compressibility. Visual observations of State Road 15/US 98 in western Palm Beach County, Florida indicate numerous cracking and significant rutting and raveling along the roadway caused by the consolidation and long-term secondary compression of the organic soils due to soil and pavement dead load. Since sampling of undisturbed soft organic soils is difficult, and subsequent laboratory tests are expensive and time-consuming,...
Show moreOrganic soils generally are characterized by low strength and high compressibility. Visual observations of State Road 15/US 98 in western Palm Beach County, Florida indicate numerous cracking and significant rutting and raveling along the roadway caused by the consolidation and long-term secondary compression of the organic soils due to soil and pavement dead load. Since sampling of undisturbed soft organic soils is difficult, and subsequent laboratory tests are expensive and time-consuming, there is a need for rapid in-situ characterization of these unstable foundation soils. This study evaluates the capabilities of Piezocone Penetration tests (CPTu), coupled with pore pressure dissipation tests, for estimating the strength, modulus, compressibility, and time rate of consolidation characteristics of organic soils and peat in Florida. The compression index (Cc) and coefficient of consolidation (cv), predicted from CPTu, showed reasonable correlation with laboratory-derived properties.
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Date Issued: 2006
PURL: http://purl.flvc.org/fcla/dt/13379
Subject Headings: Soil stabilization--Florida, Soil consolidation--Florida, Soil mechanics--Florida, Soil penetration test
Format: Document (PDF)

Title: EFFECTS OF SALTWATER INTRUSION ON THE COMPRESSIBILITY BEHAVIOR OF THE EVERGLADES SOILS.
Creator: Ribeiro, Camila, Sobhan, Khaled, Florida Atlantic University, Department of Civil, Environmental and Geomatics Engineering, College of Engineering and Computer Science
Abstract/Description: The Florida Everglades is considered as a vulnerable wetland composed primary of organic rich peat soils, experiencing saltwater intrusion. Impact of increasing salinity on the strength and deformation properties of peat is unknown. A laboratory study was undertaken to evaluate how the growing salinity level due to sea level rise may alter the compressibility behavior of the Everglades soils. Sixteen 1-dimensional oedometer tests were conducted on undisturbed Everglades peat soils in two...
Show moreThe Florida Everglades is considered as a vulnerable wetland composed primary of organic rich peat soils, experiencing saltwater intrusion. Impact of increasing salinity on the strength and deformation properties of peat is unknown. A laboratory study was undertaken to evaluate how the growing salinity level due to sea level rise may alter the compressibility behavior of the Everglades soils. Sixteen 1-dimensional oedometer tests were conducted on undisturbed Everglades peat soils in two phases. Phase I included samples from Site 1 (saltwater) and Site 3 (freshwater) without any salinity addition. Phase II consisted of soil from Site 3 (freshwater) saturated in six different levels of salinity artificially added to the samples. Compressibility properties investigated in this study include compression index (Cc), coefficient of consolidation (Cv), hydraulic conductivity (K), and the Ca/Cc ratio. In general, it was observed that the increase in salinity beyond a threshold value tends to increase the soil compressibility properties, indicating a possible reduction in soil stability with saltwater intrusion.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013783
Subject Headings: Everglades (Fla.), Peat soils, Saltwater encroachment, Compressibility
Format: Document (PDF)

Title: Coupled Effect of Geosynthetics and Randomly Distributed Fibers on the Stability of Reinforced Slopes.
Creator: Martins, Caique, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Graduate College
Abstract/Description: The coupled effect of using geosynthetic reinforcement and randomly distributed fibers on the stability of slopes was evaluated using finite element modeling and limit equilibrium methods by analyzing a case study in Oslo, Norway. The main objective was to simulate the failure condition of the original slope and quantify the improved stability of a hypothetical reinforced slope constructed with geosynthetic layers and distributed discrete fibers. The stability of the slope was evaluated in...
Show moreThe coupled effect of using geosynthetic reinforcement and randomly distributed fibers on the stability of slopes was evaluated using finite element modeling and limit equilibrium methods by analyzing a case study in Oslo, Norway. The main objective was to simulate the failure condition of the original slope and quantify the improved stability of a hypothetical reinforced slope constructed with geosynthetic layers and distributed discrete fibers. The stability of the slope was evaluated in both the short-term condition with its' undrained shear strength parameters, and the long-term drained condition. Results indicate that the combination of the techniques was found to have a possible increase of about 40% in the short-term condition and about 60% in the long-term condition of the factor safety associated with the slope.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013236
Subject Headings: Geosynthetics, Slope stability, Shear strength of soils
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.
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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)

Title: Fracture and Fatigue Behavior of Geosynthetic Reinforced Asphalt Concrete for Pavement Overlays.
Creator: Polidora, Jamie Barbara, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Flexible or asphalt pavements constitute nearly 94% of the 2.7 million miles of existing roadways in the United States. In a typical rehabilitation project, the existing asphalt pavement is milled up to a prescribed depth for removing the near surface distresses such as excessive cracking and rutting, and a new overlay is placed. The average time between resurfacing projects varies depending on the level of pavement deterioration which is significantly accelerated when poor subgrade...
Show moreFlexible or asphalt pavements constitute nearly 94% of the 2.7 million miles of existing roadways in the United States. In a typical rehabilitation project, the existing asphalt pavement is milled up to a prescribed depth for removing the near surface distresses such as excessive cracking and rutting, and a new overlay is placed. The average time between resurfacing projects varies depending on the level of pavement deterioration which is significantly accelerated when poor subgrade conditions are encountered. The use of geosynthetic reinforcement within the new asphalt overlay is often perceived as a mitigation strategy that can delay the onset and propagation of reflection cracking, and also control the rutting and differential settlement. However, some mixed reviews about the performance of the geosynthetic reinforced overlays have been reported in the literature. In Phase I of this study, a laboratory investigation was conducted for evaluating the flexural fatigue behavior, permanent deformation response, and fracture characteristics of geogrid reinforced asphalt beam specimens made from a typical overlay material. The laboratory specimens included geogrid as a single-layer inclusion either at the bottom third depth or at the mid height, and as double-layer inclusion, with geogrid placed both at the bottom third and at the middle of the beam. In Phase II, a case study involving geogrid reinforced overlay constructed over a deteriorated pavement underlain by soft subgrade in southeastern Florida was numerically simulated. It was found that the geogrid reinforcement significantly improved the fatigue and fracture properties of the asphalt beams compared to unreinforced specimens. Results from numerical simulation demonstrated that the double reinforced overlay resulted in the minimum tensile stress at the bottom of the asphalt layer (reducing the cracking potential) and minimum vertical strain on the top of the subgrade (reducing the rutting potential), compared to unreinforced or bottom-third reinforced overlays. Accordingly, it is concluded that the double layer reinforcement of asphalt overlays with an appropriate geosynthetic product can be beneficial for the performance and long term preservation of the pavement system when soft soils are encountered.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00004972, http://purl.flvc.org/fau/fd/FA00004962
Subject Headings: Dissertations, Academic -- Florida Atlantic University, Reinforced concrete., Asphalt pavements., Geosynthetics., Pavements--Overlays--Evaluation.
Format: Document (PDF)

Title: Effects of Repeated Wet-Dry Cycles on Compressive Strength of Fly-Ash Based Recycled Aggregate Geopolymer Concrete (RAGC).
Creator: Mendelson, Monica, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Geopolymer concrete (GC) is a sustainable construction material and a great alternative to regular concrete. GC is a zero-cement material made from a combination of aluminate, silicate and an activator to produce a binder-like substance. This investigation focused on the effects of wet and dry cycles on the strength and durability of fly ash-based recycled aggregate geopolymer concrete (RAGC). The wet-dry cycles were performed approximately according to ASTM D559 standards. RAGC specimens...
Show moreGeopolymer concrete (GC) is a sustainable construction material and a great alternative to regular concrete. GC is a zero-cement material made from a combination of aluminate, silicate and an activator to produce a binder-like substance. This investigation focused on the effects of wet and dry cycles on the strength and durability of fly ash-based recycled aggregate geopolymer concrete (RAGC). The wet-dry cycles were performed approximately according to ASTM D559 standards. RAGC specimens with nearly 70% recycled materials (recycled aggregate and fly ash) achieved a compressive strength of approximately 3600 psi, after 7 days of heat curing at 60ºC. Although the recycled aggregate is prone to high water absorption, the compressive strength decreased by only 4% after exposure to 21 wet-dry cycles, compared to control specimens that were not exposed to the same conditions. Accordingly, the RAGC material developed in this study can be considered as a promising environmentally friendly alternative to cement-based regular concrete.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013016
Subject Headings: Polymer-impregnated concrete, Recycled materials, Fly ash, Polymers--Compression testing
Format: Document (PDF)

Title: Effects of Granulometric Parameters and Mix Proportions on the Shear Strength of Binary Granular Mixtures.
Creator: Gonzalez Moya, Daniel E., Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Geotechnical engineers are commonly faced with the need to perform ground improvement techniques to achieve the necessary bearing capacity for a project. Some of the most common techniques involve the excavation and replenishment of problematic geomaterial with one of better quality. Common projects, such as road embankments and retaining walls, also require the selection of backfill material. The guidelines for selecting backfill material are typically limited to complying with certain...
Show moreGeotechnical engineers are commonly faced with the need to perform ground improvement techniques to achieve the necessary bearing capacity for a project. Some of the most common techniques involve the excavation and replenishment of problematic geomaterial with one of better quality. Common projects, such as road embankments and retaining walls, also require the selection of backfill material. The guidelines for selecting backfill material are typically limited to complying with certain gradation bands, relative densities and allowable fines content. Round-grained silica sand, and beach sand from Boca Raton, FL, were used to generate a total of 16 binary granular mixtures containing different amounts of finer material, for which a series of direct shear tests were conducted. Based on the experimental results, it may be possible to provide an alternative criteria for selecting backfill material based on granulometric parameters and the amount of finer material.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004714, http://purl.flvc.org/fau/fd/FA00004714
Subject Headings: Continuum mechanics, Geotechnical engineering, Granular materials -- Dynamic testing, Micromechanics -- Mathematical models, Soil liquefaction
Format: Document (PDF)

Title: Identifying Shallow Foundation Failure Modes and Mechanisms Using Surveillance of a Transparent Granular Soil Surrogate.
Creator: Purdy, Denys W., Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: A transparent soil model of granular fused quartz is developed to study the mechanics of shallow foundations. Soil models, unreinforced and reinforced, prepared at relative densities 0.34 (loose) and 0.64 to 0.69 (medium dense) are tested using a rectangular footing (25 mm wide x 40 mm long) under strain-controlled loading. Digital Image Correlation is used to identify displacements of a seeded central plane parallel to footing width (B) and construct vector fields and contour plots. Fiber...
Show moreA transparent soil model of granular fused quartz is developed to study the mechanics of shallow foundations. Soil models, unreinforced and reinforced, prepared at relative densities 0.34 (loose) and 0.64 to 0.69 (medium dense) are tested using a rectangular footing (25 mm wide x 40 mm long) under strain-controlled loading. Digital Image Correlation is used to identify displacements of a seeded central plane parallel to footing width (B) and construct vector fields and contour plots. Fiber-reinforced soil model data analysis is inconclusive. For the unreinforced medium-dense soil, minimum and peak magnitude horizontal displacements occurred directly under the footing at the footing edges; whereas in the loose soil, peak magnitude horizontal displacement occurred directly under the footing. Vector and contour plots revealed that a medium dense soil gradually distributes smaller magnitude displacements over a broad area, in contradistinction to acute, highly localized displacements of larger magnitude in a loose soil.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00004832, http://purl.flvc.org/fau/fd/FA00004832
Subject Headings: Soils--Testing., Soils.
Format: Document (PDF)

Title: Influence of Median Grain Size Ratio on the Strength and Liquefaction Potential of Loose Granular Fills.
Creator: Waganaar, Spencer, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: The characterization of silty soils is usually designated by the percentage of silt contained within the soil matrix, along with the soil’s void ratio, which is used to describe the soil’s current state. The use of these parameters to assess a soil’s strength and undrained behavior is limited when finer material is contained within the soil. Therefore, additional parameters must be considered in order to correctly assess the strength and liquefaction potential of silty soils. These additional...
Show moreThe characterization of silty soils is usually designated by the percentage of silt contained within the soil matrix, along with the soil’s void ratio, which is used to describe the soil’s current state. The use of these parameters to assess a soil’s strength and undrained behavior is limited when finer material is contained within the soil. Therefore, additional parameters must be considered in order to correctly assess the strength and liquefaction potential of silty soils. These additional parameters include the skeleton void ratio, equivalent void ratio and granulometric factors. The current research investigates the influence of granulometric parameters, specifically the Median Grain Size Ratio (D50/d50), denoted as μDR (or MDR within graphs and charts), on the strength and liquefaction potential of loose silty sands. A series of undrained monotonic triaxial compression tests (σ3’= 69, 83, and 103 kPa) are performed on reconstituted soil samples, using three different base sand samples and a constant silt material. As a result, three distinct median grain size ratios (μDR = 4.2, 6.75, and 9) were tested with fines content ranging from 0-30% for each μDR. The undrained shear strength at all confining pressures tends to increase with in μDR; beyond 10% fines content there was no noticeable influence of μDR. At any μDR the excess PWP is higher than that of clean sand, when fines content is larger than 5% fines content. The slope of the instability line and phase transformation line are directly affected by the μDR and fines content, with an increase in the instability line and decrease in the phase transformation line with a growing μDR. The results indicate loose granular fills can be designed to be stronger and more resilient under extreme conditions by careful choice of materials in which the μDR>6.75 and the fines content does not exceed 10%.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004639, http://purl.flvc.org/fau/fd/FA00004639
Subject Headings: Slopes (Soil mechanics), Soils., Soil liquefaction., Geotechnical engineering.
Format: Document (PDF)

Title: Time- stress-compressibility characteristics of cementitiously stabilized organic soils.
Creator: Sarsour, Anhar, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Effect of cementitious stabilization on the stress-compressibility characteristics of three different South Florida organic soils were evaluated in this study. The objectives of the research were to (l) determine if the secondary compression characteristics of organic soils and peats can be stabilized with (a) cement only, (b) binary blends of cement/slag (C-S), cement/gypsum (C-G), and cement/cement-kiln-dust (C-CKD) and (c) ternary blend of cement-slag-gypsum in equal proportions; (ll)...
Show moreEffect of cementitious stabilization on the stress-compressibility characteristics of three different South Florida organic soils were evaluated in this study. The objectives of the research were to (l) determine if the secondary compression characteristics of organic soils and peats can be stabilized with (a) cement only, (b) binary blends of cement/slag (C-S), cement/gypsum (C-G), and cement/cement-kiln-dust (C-CKD) and (c) ternary blend of cement-slag-gypsum in equal proportions; (ll) quantify the effectiveness of cementitious stabilization by evaluating the time-stress-compressibility (t-log σ'v - e) relationship in terms of the Cα / Cc ratio; and (lll) provide some guidelines for selecting optimum dosage of cementitious materials in deep mixing methods when organic soils and peats are encountered. It was concluded that cementitious mixes containing various waste materials is effective in controlling the secondary compression behavior of organic soils, and therefore should be considered in deep mixing methods as a sustainable practice.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004326, http://purl.flvc.org/fau/fd/FA00004326
Subject Headings: Environmental geotechnology, Pavements, Soil cement, Soil consolidation, Soil mechanics, Soil penetration test, Soil stabilization
Format: Document (PDF)

Title: Strength and Modulus of Recycled Aggregate Concrete Subjected to Wetting and Drying Cycles.
Creator: Alawadi, Farah, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: The reuse of crushed aggregates for producing structural concrete is a major concern especially when it comes to its strength and durability. This study evaluated recycled aggregate concrete (RAC) for its strength and durability under simulated environmental degradation in the form of wetting-drying (W-D) cycles. The study consisted of two phases, each involving the determination of the compressive strength and modulus of elasticity using the conventional method and also a nondestructive...
Show moreThe reuse of crushed aggregates for producing structural concrete is a major concern especially when it comes to its strength and durability. This study evaluated recycled aggregate concrete (RAC) for its strength and durability under simulated environmental degradation in the form of wetting-drying (W-D) cycles. The study consisted of two phases, each involving the determination of the compressive strength and modulus of elasticity using the conventional method and also a nondestructive ultrasonic pulse velocity method (Pundit Lab). Phase 1 involved 7-day curing followed by 30 W-D cycles, while Phase 2 included 28-day cured samples subjected to 15 W-D cycles. It was found that RAC specimens subjected to W-D cycles had minimal degradation in strength, making the use of RAC in construction very promising. Results from Pundit Lab compared reasonably well with conventional test results, showing promise as a nondestructive tool for the evaluation of RAC properties.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013162
Subject Headings: Concrete, Durability of concrete, Strength of materials, Recycled aggregate concrete
Format: Document (PDF)

Title: Strength and durability of fly ash-based fiber-reinforced geopolymer concrete in a simulated marine environment.
Creator: Martinez Rivera, Francisco Javier, Sobhan, Khaled, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: This research is aimed at investigating the corrosion durability of polyolefin fiber-reinforced fly ash-based geopolymer structural concrete (hereafter referred to as GPC, in contradistinction to unreinforced geopolymer concrete referred to as simply geopolymer concrete), where cement is completely replaced by fly ash, that is activated by alkalis, sodium hydroxide and sodium silicate. The durability in a marine environment is tested through an electrochemical method for accelerated corrosion...
Show moreThis research is aimed at investigating the corrosion durability of polyolefin fiber-reinforced fly ash-based geopolymer structural concrete (hereafter referred to as GPC, in contradistinction to unreinforced geopolymer concrete referred to as simply geopolymer concrete), where cement is completely replaced by fly ash, that is activated by alkalis, sodium hydroxide and sodium silicate. The durability in a marine environment is tested through an electrochemical method for accelerated corrosion. The GPC achieved compressive strengths in excess of 6,000 psi. Fiber reinforced beams contained polyolefin fibers in the amounts of 0.1%, 0.3%, and 0.5% by volume. After being subjected to corrosion damage, the GPC beams were analyzed through a method of crack scoring, steel mass loss, and residual flexural strength testing. Fiber reinforced GPC beams showed greater resistance to corrosion damage with higher residual flexural strength. This makes GPC an attractive material for use in submerged marine structures.
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Date Issued: 2013
PURL: http://purl.flvc.org/fau/fd/FA0004037
Subject Headings: Concrete mixing -- Quality control, Green chemistry, Polymer composites, Reinforced concrete -- Corrosion -- Testing, Reinforced concrete construction
Format: Document (PDF)

Title: Stability Analysis of Geosynthetic Reinforced MSW Landfill Slopes Considering Effects of Biodegradation and Extreme Wind Loading.
Creator: Pant, Sharmila, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: A numerical investigation was conducted to evaluate the geotechnical safety and slope stability of Municipal Solid Waste (MSW) landfills, considering the effects of geosynthetic reinforcements, biodegradation of the waste, and associated changes in material properties, and extreme wind force simulating hurricane conditions. Three different landfill slopes, 1:1, 1:2, and 1:3 having the height of 122m and width of 2134m, were analyzed using Limit Equilibrium Method (SLOPE/W) and Finite Element...
Show moreA numerical investigation was conducted to evaluate the geotechnical safety and slope stability of Municipal Solid Waste (MSW) landfills, considering the effects of geosynthetic reinforcements, biodegradation of the waste, and associated changes in material properties, and extreme wind force simulating hurricane conditions. Three different landfill slopes, 1:1, 1:2, and 1:3 having the height of 122m and width of 2134m, were analyzed using Limit Equilibrium Method (SLOPE/W) and Finite Element Modeling (ANSYS). Techniques developed in this study were used to analyze a case history involving a geogrid reinforced mixed landfill expansion located in Austria. It was found that few years after construction of the landfill, there is a significant decrease in the FS due to biodegradation. Extreme wind loading was also found to cause a substantial loss in the FS. The geosynthetic reinforcement increased the slope stability and approximately compensated for the damaging effects of biodegradation and wind loading.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004707, http://purl.flvc.org/fau/fd/FA00004707
Subject Headings: Engineering geology -- Mathematical models, Fills (Earthwork), Geogrids -- Performance, Geosynthetics, Reinforced soils, Retaining walls -- Performance, Sanitary landfills, Slopes (Soil mechanics) -- Stability, Soil stabilization, Structural analysis (Engineering)
Format: Document (PDF)

Title: An Experimental Evaluation of High Volume Fly Ash Structural Concrete made from Recycled Aggregate.
Creator: Theodorou, Anthony Lloyd, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Three vital factors, namely environmental protection, savings in costs, and strength/durability benefits, make it advantageous to incorporate fly ash of controlled quality and composition in all concrete made from construction demolition (C&D) recycled aggregate. The specific objective of this research was to compare the performance characteristics of High-Volume-Fly-Ash (HVFA) structural concrete containing C&D aggregate with that of normal recycled aggregate concrete containing no fly ash....
Show moreThree vital factors, namely environmental protection, savings in costs, and strength/durability benefits, make it advantageous to incorporate fly ash of controlled quality and composition in all concrete made from construction demolition (C&D) recycled aggregate. The specific objective of this research was to compare the performance characteristics of High-Volume-Fly-Ash (HVFA) structural concrete containing C&D aggregate with that of normal recycled aggregate concrete containing no fly ash. A coordinated experimental program was undertaken which comprised of ( 1) Compressive and Split Tensile strength tests; (2) ASTM durability tests by measuring resistance to chloride-ion penetration; and (3) Flexural strength tests on reinforced concrete beam specimens. Three mix designs were used, all of which had the same water/cement ratio of 0.45 and the same amount of recycled aggregate/yd^3. Mix 1 contained cement and no fly ash, Mix 2 contained 16% replacement of cement by weight, and Mix 3 contained 40% replacement of cement, called a HVF A mix. Results indicate that fly ash increases compressive strength, improves both moment carrying capacity and tension resistance, and increases resistance to chloride-ion attack.
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Date Issued: 2008
PURL: http://purl.flvc.org/fau/fd/FA00012563
Subject Headings: Aggregates (Building materials)--Recycling, Fly ash--Recycling, Concrete--Additives--Evaluation, Concrete--Permeability, Industrial minerals--Evaluation
Format: Document (PDF)

Title: Primary and secondary compression behavior of Florida organic soils.
Creator: Riedy, Kristopher W., Florida Atlantic University, Sobhan, Khaled, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: A comprehensive laboratory investigation was conducted to evaluate the primary and secondary compression behavior of undisturbed organic silts and peats obtained from 11 locations along SR 15/US 98 in Palm Beach County, Florida. A total of 43 consolidation tests were performed. The primary objectives were as follows: (i) to conduct a series of standard consolidation tests to determine the Compression Index, Cc, and the Coefficient of Consolidation, cnu; (ii) to determine the Secondary...
Show moreA comprehensive laboratory investigation was conducted to evaluate the primary and secondary compression behavior of undisturbed organic silts and peats obtained from 11 locations along SR 15/US 98 in Palm Beach County, Florida. A total of 43 consolidation tests were performed. The primary objectives were as follows: (i) to conduct a series of standard consolidation tests to determine the Compression Index, Cc, and the Coefficient of Consolidation, cnu; (ii) to determine the Secondary Compression Index, Calpha, at stress levels (sigmanu'/sigmap') ranging from 0.30 to 1.15; and (iii) to employ the well-known Time-Stress-Compressibility concept to establish a unique relationship between C alpha and Cc. It was found that for all practical purposes, the Calpha/C c ratio at any stress level is 0.03, which is consistent with the values reported in the literature for similar soils. A constant Calpha/Cc ratio provides an approximation of Calpha once C c is determined from a standard consolidation test, and without the need of ongoing laboratory testing to predict long-term settlement.
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Date Issued: 2006
PURL: http://purl.flvc.org/fcla/dt/13386
Subject Headings: Soil consolidation--Measurement--Florida, Soil mechanics--Florida--Palm Beach County, Soils--Testing
Format: Document (PDF)

Title: Innovative Expansion of Landfill Capacity Using Geogrid Reinforcements.
Creator: Templeton, R. Hayes, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: An analytical investigation was conducted to evaluate the geotechnical safety and stability of MSW landfills constructed with significantly steepened slopes achieved through geosynthetic reinforcement. The primary motivation for this endeavor was to propose a new design/construction methodology for innovative expansion of landfill capacity. A 2-D plane strain linear elastic analysis was performed with ANSYS finite element software on full-scale MSW landfill structures (with and without...
Show moreAn analytical investigation was conducted to evaluate the geotechnical safety and stability of MSW landfills constructed with significantly steepened slopes achieved through geosynthetic reinforcement. The primary motivation for this endeavor was to propose a new design/construction methodology for innovative expansion of landfill capacity. A 2-D plane strain linear elastic analysis was performed with ANSYS finite element software on full-scale MSW landfill structures (with and without geogrids), having slopes of 1:1, 1:2, and 1:3. Both local and global factors of safety were determined employing the Mohr-Coulomb failure criteria, and compared with traditional solutions using the Bishop's Modified Method. It was found that the landfill slopes could be steepened up to 1:1 using geogrid reinforcement, resulting in higher storage capacity and consequential environmental and economic benefits.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00012561
Subject Headings: Sanitary landfills--Design and construction, Refuse and refuse disposal, Soil mechanics--Mathematical models, Geosynthetics--Mathematical models, Soil stabilization
Format: Document (PDF)

FAU Theses and Dissertations (18)	+ -
FAU Undergraduate Student Research (1)	+ -

Soil stabilization (3)	+ -
Geosynthetics (2)	+ -
Soil mechanics (2)	+ -
Soil penetration test (2)	+ -
Soils--Testing (2)	+ -

Soils. (2)	+ -
Aggregates (Building materials ) -- Recycling (1)	+ -
Aggregates (Building materials)--Recycling (1)	+ -
Asphalt pavements. (1)	+ -
Cement composites--Testing (1)	+ -
College students --Research --United States. (1)	+ -
Compressibility (1)	+ -
Concrete (1)	+ -
Concrete -- Mechanical properties (1)	+ -
Concrete construction (1)	+ -
Concrete mixing -- Quality control (1)	+ -
Concrete--Additives--Evaluation (1)	+ -
Concrete--Mechanical properties--Testing (1)	+ -
Concrete--Permeability (1)	+ -
Construction and demolition debris -- Recycling (1)	+ -
Continuum mechanics (1)	+ -
Dissertations, Academic -- Florida Atlantic University (1)	+ -
Durability of concrete (1)	+ -
Engineering geology (1)	+ -
Engineering geology -- Mathematical models (1)	+ -
Environmental geotechnology (1)	+ -
Everglades (Fla.) (1)	+ -
Fills (Earthwork) (1)	+ -
Fly ash (1)	+ -
Fly ash--Recycling (1)	+ -

Electronic Thesis or Dissertation (18)	+ -
poster (1)	+ -

Florida Atlantic University (17)	+ -
Sobhan, Khaled (17)	+ -
College of Engineering and Computer Science (15)	+ -
Department of Civil, Environmental and Geomatics Engineering (14)	+ -
Martins, Caique (2)	+ -

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