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This thesis broadly addresses the issue of materials sustainability in the production of Portland cement concrete. Two methods are presented, both aimed at achieving more sustainable concrete through the use of waste and recycled materials. The first method involves utilizing reclaimed asphalt pavement (RAP) as an aggregate in structural concrete, and the second method involves utilizing waste quarry fines as partial replacement of Portland cement in concrete mixes. Many efforts have been made in recent years to justify the use of RAP aggregates in concrete. All previous efforts appear to unanimously report a reduction in concrete performance with varying proportions of RAP usage. The poor performance of RAP aggregates in concrete is attributed mainly to a larger, more porous interfacial transition zone (ITZ) and to the cohesive failure of the asphalt. It is hypothesized that the detrimental impact on the ITZ is attributable to organic compounds leached from the asphalt in the high pH pore solution. This study proves the presence of organic compounds in the pore solution and demonstrates that there is an apparent retardation of cement hydration. This study also attempted to pretreat the RAP in a sodium hydroxide (NaOH) solution to pre-leach the organic compounds. The pretreatment demonstrated that organic compounds were leached and that NaOH modified the asphalt surface chemistry. However, only a marginal improvement in compressive strength was observed by completing the pretreatment. Replacement of Portland cement by filler products is a practice aimed at reducing the carbon footprint of concrete, such as is common with Type IL Portland limestone cement. This study investigates the impact of replacing cement with seven different quarry fines materials. The quarry fines were used to replace cement at 5% to 20% by volume in either cement paste or mortar samples that were then analyzed for various physicochemical properties. It was found that all the quarry fines had detrimental impact on the hydration kinetics of cement pastes. The inclusion of quarry fines was also found to cause varying degrees of reduction in mortar compressive strength. While further analyses of the quarry fines are required, quarry fines 2, 5 and 7 did display encouraging signs to suggest the potential for use as a filler material in blended cements. / Master of Science / This thesis broadly addresses the issue of sustainability in the cement and concrete industry. Sustainability is a significant problem for the cement and concrete industry due to the large amount of carbon emissions produced in the manufacturing process of Portland cement. One method to reduce the carbon footprint of concrete is to use recycled aggregates, and reclaimed asphalt pavement (RAP) is investigated in this thesis as a recycled aggregate option. Previous studies have shown that the use of RAP in concrete results in poor mechanical performance when compared to conventional concrete. In this thesis, the RAP was pretreated by soaking it in sodium hydroxide (NaOH) to see if any improvement is noted. It was determined that the pretreatment resulted in marginal improvements in concrete performance. Another method to reduce the carbon footprint of concrete is through the use of substitutions of Portland cement. In this thesis, quarry fines from around Virginia were investigated for potential as substitutive material. Quarry fines are a by-product from quarrying operations and are often considered a waste material because they have limited applications. This study analyzed the performance of cementitious materials prepared with various substitutive percentages of quarry fines and found that, in general, the inclusion of quarry fines resulted in a decrease of mechanical performance. In total, seven quarry fines were tested and only two showed potential for use as a substitution in Portland cement concrete. These two investigations are essential in reaching the goal of reducing the carbon footprint of the cement and concrete industry.

Die ASFiNAG unterhält mehr als 5.000 Brückenobjekte im Straßennetz. Die meisten von ihnen wurden in Stahlbeton- oder Spannbetonbauweise errichtet und insbesondere die Stützen sind hohen Belastungen durch Chlorid ausgesetzt. Dies führt langfristig zu einer Verringerung der Dauerhaftigkeit und Instandsetzungen sind daher erforderlich. Eine genaue Ermittlung der Depassivierung und ein Prognosemodell sind bei Chloridbelastung besonders wichtig für eine kosteneffiziente Erhaltung. Die neue Methode LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) ermöglicht exaktere Ergebnisse als die traditionelle Chloridbestimmung mittels Titration. Die Vorteile der beiden Methoden werden im Beitrag diskutiert und die Ergebnisse verglichen. Es wird gezeigt, dass die LA-ICP-MS-Methode zuverlässigere Ergebnisse liefert und durch die hohe Ortsauflösung der Chloridprofile sowie die genaue Bestimmung des Chloridgehalts noch nicht dagewesene Möglichkeiten für eine exakte Beurteilung und Prognose eröffnet.

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) is now a well established analytical technique used to sample solid materials and determine their elemental composition. Two areas that are becoming increasingly important, and for which LA-ICP-MS is a key tool, are bio-imaging and the analysis of micro-particulates. However, current instrumental designs limit the practicality of the technique for these applications. This study investigates the development of a high speed, high efficiency LA-ICP-MS interface through modelling of the flow dynamics of a newly designed laser ablation cell and experimental investigation of single laser pulse response. Through this work the Sniffer-Dual Concentric Injector interface was realised. This interface reduced particle residence times within the laser cell and transport tubing. The interface was also used to investigate turbulence related aerosol dispersion within the ICP and potential designs to overcome this. The resulting design yields an interface with improved sensitivity and reduced aerosol dispersion such that a lower limit of detection is achieved, important when considering the mass of analyte in a single cell or micro-particulate, compared to existing designs. Thus the interface can be used to improve image spatial resolution as the ablation spot size, and thus pixel information, can be reduced; and also reduces total analysis time. The calibration technique Laser Ablation of a Sample In Liquid (LASIL) was also investigated as a means of calibration for solid samples. The investigation lead to the development of LASIL in a droplet, a technique that can be used to calibrate solid samples when a matrix matched standard is unavailable. The mechanism of the technique resulted in an improved laser-energy sample coupling efficiency and a reduction in the liquid to ablated mass ratio, thus decreasing sampling time. As the technique captures the ablated particulate in solution, post chemistry techniques can be used to remove analyte interferences.

The field of ambient desorption/ionization mass spectrometry (ADI-MS) has existed for over a decade. ADI-MS is a technique that offers benefits including fast analysis time, simple ionization sources that are easily constructed, and little to no required sample preparation. The research presented here describes efforts to better understand plasma-based ADI-MS sources and to explore the use of hydrogen-doped plasma gases with these sources. The use of hydrogen-doped argon (H2/Ar) and hydrogen-doped helium (H2/He) as plasma gases for a dielectric barrier discharge (DBD) and an AC glow discharge is presented first. When using the DBD, the intensity of the signal obtained when analyzing organic molecules in positive ion mode was increased by factors up to 37 times. In negative ion mode, only H2/Ar was shown to enhance the signal of an organic analyte. The limits of detection for caffeine when using hydrogen-doped plasma gases were found to decrease by factors of 78 and 1.9 for H2/Ar and H2/He respectively. The same phenomenon was observed when using H2/Ar with the AC discharge, but no signal enhancement was observed when using hydrogen-doped helium with the AC discharge. Similarly, if the DBD was allowed to ground through a wire rather than through the air, no signal enhancement was observed for H2/He. Using H2/Ar with metal samples is presented second. By using the metal sample as the grounded electrode for the AC glow discharge, many different metals could be detected directly with a time-of-flight mass spectrometer (TOF-MS) in the form of atomic ions both on their own and in combination with water and ammonia from the discharge. Any refractory metals tested did not yield signal. In addition to direct analysis with a TOF-MS, the AC discharge was used as a sampling method for an inductively coupled plasma mass spectrometer (ICP-MS). When coupled with an ICP-MS, the AC glow discharge was found capable of sampling even refractory elements, though the power of the ICP was required for ionization and detection. Scanning electron microscope (SEM) images of a copper surface exposed to the plasma discharge showed signs of melting when using the H2/Ar. Finally, a computer simulation of the chemistry and flow dynamics of a DC glow discharge generated in helium is presented. The simulation explores many of the fundamental processes at work and how they depend on the composition of the plasma gas. The generation of important species in the plasma was found to depend more on the amount of N2 and H2O impurities in the plasma gas rather than on the humidity or air pressure.

GaN nanopore arrays with pore diameters of approximately 75 nm were fabricated by inductively coupled plasma etching (ICP) using anodic aluminum oxide (AAO) films as etch masks. Nanoporous AAO films were formed on the GaN surface by evaporating an Al film onto a GaN epilayer and subsequently anodizing the aluminum. To minimize plasma-induced damage, the template was exposed to CF4-based plasma conditions. Scanning electron microscopy (SEM) analysis shows that the diameter and the periodicity of the nanopores in the GaN were directly transferred from the original anodic alumina template. The pore diameter in the AAO film can be easily controlled by tuning the anodization conditions. Atomic force microscopy (AFM), photoluminescence (PL) and micro-Raman techniques were employed to assess the quality of the etched GaN nanopore surface. Such a cost-effective method to produce nano-patterned GaN template would be useful for growth and fabrication of III-Nitrides based nanostructures and photonic band gap materials. / Singapore-MIT Alliance (SMA)

Capillary electrophoresis (CE) is in comparison with other chromatographic techniques, CE has several advantages such as high resolving power, small sample volume requirement, minimal buffer consumption and high sample throughtput. As a detection technique, inductively coupled plasma mass spectrometry (ICPMS) provides the advantages of low detection limit, multielement detection, and element- and isotope-specific detection capabilities. Therefore, the use of CE as a high resolution separation technique with ICP-MS as a sensitive element specific detector is of growing interest for analytical research. Four studies in our research are described below, respectively. A preliminary study of a modified microconcentric nebulizer (CEI-100, CETAC) as the sample introduction device of capillary electrophoresis inductively coupled plasma mass spectrometry (CE-ICP-MS) for the determination of monophosphate nucleotides is described. The monophosphate nucleotides studied include adenosine 5¡¦-monophosphate (AMP), guanosine 5¡¦-monophosphate (GMP), uridine 5¡¦-monophosphate (UMP) and inosine 5¡¦-monophosphate (IMP). The species studied were well separated using a 70 cm length ¡Ñ 75 £gm id fused silica capillary while the applied voltage was set at -22 kV and a 20 mmol/L ammonium citrate/citric acid buffer (pH 4.0) containing 0.1% m/v cationic polymer (hexadimethrine bromide, Polybrene) was used as the electrophoretic buffer. The electroosmotic flow was reversed by flushing the fused silica capillary with 0.2% m/v Polybrene to accelerate separation. The detection limit of various species studied was in the range of 0.036~0.054 £gg P/mL, which corresponded to the absolute detection limit of 1.1~1.6 pg P based on the injection volume of 30 nl. We determined the concentrations of nucleotides in two IG-enriched monosodium glutamates purchased from the local market. The recovery was in the range of 100~112% for various species, and the concentrations of IMP and GMP in these samples were in the range of 0.15¡V0.18% m/m. Capillary electrophoresis dynamic reaction cellTM inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the determination of sulfur-containing amino acids is described. The sulfur-containing amino acids studied include L-cysteine, L-cystine, DL-homocystine and L-methionine. The species studied were well separated using a 70 cm length ¡Ñ 75 £gm i.d. fused silica capillary while the applied voltage was set at +22 kV and a 10 mmol/L disodium tetraborate buffer (pH 9.8) containing 0.1 mmol/L EDTA and 0.5 mmol/L Triton X-100 was used as the electrophoretic buffer. The sulfur-selective electropherogram was determined at m/z 48 as 32S16O+ by using its reaction with O2 in the reaction cell. The method avoided the effect of polyatomic isobaric interferences at m/z 32 caused by 16O16O+ and 14N18O+ on 32S+ by detecting 32S+ as the oxide ion 32S16O+ at m/z 48, which is less interfered. The detection limit of various species studied was in the range of 0.047~0.058 £gg S/mL, which corresponded to the absolute detection limit of 1.3~1.6 pg S based on the injection volume of 27 nl. We determined the concentrations of selected sulfur-containing amino acids in urine and nutritive complement samples. The recovery was in the range of 92~128% for various species. Capillary electrophoresis-dynamic reaction cell inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the speciation of iron (III/II), vanadium (V/IV) and chromium (VI/III) is described. Two different CE migration modes were employed for separating the six metal ions using pre-capillary complexation. One is counter-electroosmotic mode in which iron (III/II) and vanadium (V/IV) ions were well separated using a 60 cm ¡Ñ 75 £gm i.d. fused silica capillary. The voltage was set at +22 kV and a 15 mmol/L tris(hydroxymethyl)aminomethane (Tris) buffer (pH 8.75) containing 0.5 mmol/L ethylenediaminetetraacetic acid (EDTA) and 0.5 mmol/L ortho-phenanthroline (phen) was used as the electrophoretic buffer. The other is co-electroosmotic mode in which chromium (VI/III) ions were well separated while the applied voltage was set at −22 kV and a 10 mmol/L ammonium citrate buffer (pH 7.7) containing 0.5 mmol/L diethylenetriaminepentaacetic acid (DTPA) and 0.01% polybrene was used as the electrophoretic buffer. The mass spectra were measured at m/z 51, 52 and 56 for V, Cr and Fe, respectively. The interfering polyatomic ions of 35Cl16O+, 40Ar12C+ and 40Ar16O+ on 51V+, 52Cr+ and 56Fe+ determination were reduced in intensity significantly by using NH3 as the reaction cell gas in the DRC. The detection limits were in the range of 0.1~0.5, 0.4~1.3 and 1.2~1.7 £gg/L for V, Cr and Fe, respectively. Applications of the method for the speciation of V, Cr and Fe in wastewater were demonstrated. The recoveries were in the range of 92~120% for various species. A capillary electrophoresis-inductively coupled plasma-mass spectrometric (CE-ICPMS) method for the speciation of six arsenic compounds, namely arsenite [As(III)], arsenate [As(V)], monomethyl arsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine is described. The separation has been achieved on a 70 cm length ¡Ñ 75 £gm ID fused-silica capillary. The electrophoretic buffer used was 15 mmol/L Tris (pH 9.0) containing 15 mmol/L sodium dodecyl sulfate (SDS), while the applied voltage was set at +22 kV. The arsenic species in biological tissues were extracted into 80% v/v methanol-water mixture, put in a closed centrifuge tube and kept in a water bath, using microwaves at 80¢J for 3 min. The extraction efficiencies of individual arsenic species added to the sample at 0.5 mg As/g level were between 96% and 107%, except for As(III), for which it was 89% and 77% for oyster and fish samples, respectively. The detection limits of the species studied were in the range 0.3~0.5 £gg As/L. The procedure has been applied for the speciation analysis of two reference materials, namely dogfish muscle tissue (NRCC DORM-2) and oyster tissue (NIST SRM 1566a), and two real-world samples.