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Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Oceanography." Includes bibliographical references (p. 35-39).

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1917. / Cover title. Reprinted from Journal of agricultural research, vol. XII, no. 8 (25 Feb. 1918). Includes bibliographical references (p. 500-504).

M.Sc. / Dissolved salts, mainly carbonates and sulphates such as those of calcium and magnesium, form hard water, which when heated produces an insoluble precipitate of scale forming crystals. Scale formation affects performance in industry and ouseholds. Besides the problem of energy costs, there are all the additional problems and maintenance costs of scale removal. Traditional methods of combatting scale build-up based on chemical water treatment do exist. These include: the addition of strong acid to remove the bicarbonate ion from the water, the use of chemicals to prevent or retard the formation of hard scale and, other techniques such as ion exchange process. A cost-effective alternative to these methods is Physical Water Treatment (PWT). Many different types of equipment claiming to treat water physically, for scale reduction are commercially available. These include magnetic, electric (high frequency or radio frequency) or electrostatic, catalytic and ultrasonic devices. In this work attempts have been made to unravel the mechanisms involved in PWT. For this it was necessary to develop experimental methods to determine the effect of electromagnetic fields and selected magnetic and radio frequency (rf) water treatment devices on precipitation reactions. The most significant finding of this study involves the effect of Zn on scale formation. When supersaturated Ca(HCO3 )2 solutions were tested in a glass heat exchanger, a 77% reduction in the formation of scale was found when the solutions were spiked with Zn.

M.Sc. / Calcium carbonate scale formation is a major problem in industrial water and cooling systems as well as in household systems. The resulting reduction in heat transfer and the removal of the scale are very costly processes. One of the methods used in the past 50 years and investigated for nearly a century, is the use of physical fields to reduce, remove and / or inhibit scale formation. These physical fields are usually magnetic fields, but RF electric and electrostatic fields are also used. These fields are claimed to reduce the cost involved in the removal of scale to a minimum. To investigate these claimed effects on scale formation, a pure calcium bicarbonate solution was exposed to some of the commercial available units: The exposed solution was then forced to precipitate by elevating the temperature. The pH was monitored against time, to investigate the nucleation process of CaCO 3 and the resulting precipitate analysed for changes in crystal morphology. The principle conclusions made from the results were, firstly that the nucleation of CaCO 3 was significantly delayed in one of the units tested and that the preferred morphology was changed from the thermodynamically more stable calcite to the more unstable aragonite in that unit. Secondly, that a direct correlation existed between the release of trace amounts of metals from the unit and the observed effects.

Titanium dioxide (TiO2) is an essential component in a white paint formulation due to its excellent light scattering ability. TiO2 also happens to make up most of the raw materials cost. Viable replacements to TiO2 do not currently exist in a feasible manner. Rising costs in the recent TiO2 supply shortage have forced coatings formulators to find a balance between cost and performance. One method includes partial substitution of TiO2 with cheaper material such as calcium carbonate (CaCO3), which serves to occupy volume. The purpose of this study was to compare the coating spread rate of paints with varying TiO2 and CaCO3 pigment volume concentration (PVC). Different sized CaCO3 particles were used in this study. A series of PVC ladder studies were performed at keeping CaCO3 PVC constant. Paints were formulated at the same volume solids to minimize variability. Weighed coating draw-downs were prepared to measure the contrast ratio. The coating spread rates were obtained with the DuPont Spread Rate program, which relies on Kubelka-Munk relationships, which takes into account the physical properties of the paint. These spread rate values were compared to one another across type and size to find common trends. Critical pigment volume concentration (CPVC) values were determined through regression of the spread rate values and compared to oil absorption tests. It was found that replacement of up to 20 PVC of TiO2 with CaCO3 could marginally increase the spread rate, thus increasing the efficiency of TiO2. The spread rate increased modestly as similarly sized extender particles were initially introduced, then dropped at higher extender levels. Data analysis revealed that CPVC was influenced based on the size and amount of the extender particle present, which can be used to predict resin demand of a paint system.

Mg/Ca and d18O derived from marine biogenic carbonates have been widely used as reliable paleoenvironmental proxy for seawater temperature, salinity and water mass circulation reconstructions. The use of Mg/Ca is based on long residence time in seawater and uniform distribution with habitat depth of planktonic foraminifera. Fluid Mg/Ca affects mineralogy of CaCO3, thus high seawater Mg/Ca favors precipitation of aragonite instead of calcite. The records of d18O in carbonates yield strong correlation with seawater temperature, salinity and d18O. Distribution of d18O in water is highly heterogeneous within longitude, latitude and depth. Therefore a combination of foraminieral d18O and Mg/Ca could resolve temperature, d118Owater, and hence salinity, which is linked to variability in fresh water balance and glacial ice volume throughout geologic history. In this work we study the effects of important seawater/fluid parameters on Mg/Ca in inorganic and d18O in natural samples and provide data for improving paleoceanographic reconstructions.

This dissertation presents the results of a study performed to investigate methods for increasing the damping capacity of concrete. A variety of additives, both particle and latex based, were added to standard concrete mixtures by replacing up to 20% of the fine aggregate to measure their effects on strength, stiffness, damping, and air content. The additives included rubber particles from recycled tires, calcium carbonate particles, styrene butadiene rubber (SBR) latex, and a commercially available product named ConcreDamp which contains vegetable gum suspended in styrene butadiene latex. An initial investigation resulted in the observation that all of the additives with the exception of the SBR latex would both increase air content and decrease compressive strength. As a result, combinations of additives were investigated to see if both the mechanical and dynamic properties could be improved. The addition of steel fibers to mixtures with ground rubber were found to significantly increase air content which offset any gains in compressive strength. The combination of ground rubber and latex was shown to improve both increase compressive strength and reduce air content. The study advanced to investigate the effects of rubber size on air content, strength, and damping. It was found that for the same volume of rubber, a larger rubber particle would decrease air content, decrease compressive strength, and improve damping. The results of this study show that the best performing additive was the vegetable gum latex which improved the concrete damping by a factor of 2 when added as 15% of the fine aggregate. Additionally, an equation is presented for calculating a strength reduction factor for concrete containing rubber particles of different sizes. Finally, two full scale footbridge laboratory specimens were tested to investigate the effect of increased material damping at the structural level. One footbridge was constructed using a base concrete mixture without damping admixtures. The second was constructed with a concrete mixture that contained a replacement of 15% of the fine aggregate with ground rubber. The results were used to create a finite element model in SAP2000 that was used to predict the effects that high damping concretes would have on the footbridge specimen. / Ph. D.