The objective of this research was to compare the efficacy of portland cement to that of lime for improving the strength and durability of plastic clays. The scope of work associated with this research involved laboratory strength and durability testing of three plastic clays treated with portland cement or lime. To ensure a broad application of the work, the clays were obtained from three different regions of the United States, specifically from project sites near Bloomington, Indiana; San Antonio, Texas; and Monticello, Utah. Laboratory testing included evaluation of selected properties of the three clays in the untreated condition and in the treated condition. For the untreated condition, testing included measurements of soluble sulfate concentration, analysis of particle-size distribution, determination of treatment concentration using the Eades and Grim test, determination of Atterberg limits, development of moisture-density relationships, and measurement of California bearing ratio. In the treated condition, each clay sample was treated with either portland cement or lime, and testing included determination of Atterberg limits, development of moisture-density relationships, measurement of unconfined compressive strength (UCS), evaluation under wet-dry cycling, and evaluation under freeze-thaw cycling. For each of the three clay types, statistical analysis was performed to compare the strength and durability of the cement-treated specimens and the lime-treated specimens at each treatment concentration. Across all three clays, lime-treated specimens exhibited greater reductions in the plasticity index when compared to cement-treated specimens. In general, increased treatment concentrations corresponded to increased strength and strength retention. Percent strength retention of the cement-treated specimens was higher, on average, than that of the lime-treated specimens for the Indiana and Texas clays at low and medium concentrations. Similar strength retention was observed for cement-treated specimens and lime-treated specimens at high stabilizer concentrations across all three clays. In general, similar or significantly higher strengths were observed for specimens treated with cement than specimens treated with lime after 7 days, 28 days, and freeze-thaw cycling. Cement-treated specimens retained similar or greater mass after wet-dry cycling than lime-treated specimens. Cement-treated specimens also retained similar or greater strength after freeze-thaw cycling than lime-treated specimens, except for the Texas clay treated at the high concentration and the Utah clay treated at the medium concentration.

The objectives of this research were to evaluate the sensitivity of indirect tensile strength (ITS) test results to stabilizer type, stabilizer concentration, and curing time for multiple clayey soils with varying plasticity indices (PIs), identify cases in which an ITS of 30 psi can be obtained, and create a general linear model that predicts ITS. The scope of work included laboratory testing of three clayey soils sampled from Monticello, Utah; Bloomington, Indiana; and San Antonio, Texas. Each soil was tested using two stabilizers, cement or lime, at three concentrations, and two replicate samples were prepared for each combination. ITS testing was performed on two specimens of each combination at curing times of both 7 days and 28 days, for a total of 72 tests. The procedures outlined in this study include soil characterization, determination of moisture-density relationships, Eades and Grim testing, soil preparation, soil compaction, ITS testing, and statistical analysis. Regarding stabilizer type, treatment with cement consistently yielded higher ITS values than treatment with lime. Regarding stabilization concentration, ITS consistently increased with increasing concentrations of cement for all three soils; however, the effect of lime concentration depended on the PI of the soil, where increasing ITS values were only apparent with higher PI values. Regarding curing time, the ITS values corresponding to 28 days were generally higher than those corresponding to 7 days. Differences in ITS among the soils were largely attributable to differences in PI, which can influence pozzolanic reactivity. A cement or lime concentration that was equal to or 2% above the lime concentration indicated by the Eades and Grim test was typically required for a minimum 28-day ITS value of 30 psi to be attained. For the model developed to predict ITS, the significant predictor variables included PI, stabilizer type, actual stabilizer concentration, and curing time, as well as the two-way interactions between PI and stabilizer type, PI and actual stabilizer concentration, PI and curing time, and stabilizer type and actual stabilizer concentration. Overall, the model has an R2 value of 0.943 and an adjusted R2 value of 0.936. The model is best suited for soils having a fines content greater than 50%, a PI greater than 20, and a soluble sulfate concentration less than 3000 ppm.

<p> A simplistic equilibrium, computer model was devised to simulate the removal of orthophosphates from wastewater. The components of the model were calcium, magnesium, carbonate and orthophosphate present as simple hydrated ions, ligands, acid-base dissociation products, ion pairs, ion pair complexes, ion complexes and precipitates. Data from laboratory experiments were tested in the model to determine the apparent activity products of calcite, hydroxyapatite, tricalcium phosphate and brucite. The results indicated a degree of supersaturation of hydroxyapatite between 15 to 20 orders of magnitude dependent on the aqueous species included in the calculations. The apparent pKsp values for different sets of data showed the mean ranging from 95 to 102.5 with standard deviations 2 to 5. The inclusion of the aqueous ion complexes Ca2·HPO4·CO^o 3 and Ca2·PO4·CO- 3 when calculating the apparent activity products results in a pKsp of 102.5 which varies little with pH or the presence of magnesium. The solubility of tricalcium phosphate varies more with pH than hydroxyapatite, a mean pKsp of 26.8 was calculated which compares favourably with the pKsp of 27.0 quoted in the literature. The apparent activity product of brucite was strongly dependent on pH while that of calcite was extremely variable. When hydroxyapatite precipitated, there was a minimum residual phosphate between pH 8.5 - 9.0, followed by an increase of phosphates in solution due to calcium being removed by the precipitation of calcite. Beyond pH 10, the phosphate concentration in solution decreased rapidly as there was an increase in the precipitation of hydroxyapatite coupled with a decrease of calcite. Under identical initial conditions, the precipitation of tricalcium phosphate compared to hydroxyapatite resulted in similar orthophosphate residuals. The use of the apparent activity products compared to literature solubility products results in 2 to 3 orders of magnitude greater phosphate residuals in solution.</p> / Thesis / Master of Science (MSc)

The purpose of this study was to screen the effect of some food-grade ingredients on the off-odors caused by geosmin and 2-methylisoborneol (MIB) compounds in catfish fillets by sensory evaluation. The study revealed that geosmin and MIB odor intensity were reduced to different degrees when fillets were dipped in lime flavor (94% and 67%, respectively), 0.5% acetic acid (AA) (70% and 16%, respectively), hardwood liquid smoke (98% and 86%, respectively), or hickory liquid smoke (98% and 100% respectively) in cooked products. A 0.5% AA proved to be effective in decreasing odor intensity of geosmin (70%) in cooked products, whereas lime flavor (94%), hardwood liquid smoke (98%), and hickory liquid smoke (98%) were very effective in decreasing odor intensity of geosmin in cooked products. These agents added desirable flavors as well, except for AA by panelists? comments. These flavors could be added to a marinade or incorporated in an injection/tumbling solution when catfish fillets are processed.

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Well-cuttings data and wireline logs in conjunction with limited core and outcrop data are used to generate a regional, three dimensional high resolution sequence framework for Upper Mississippian (Chesterian), Big Lime carbonates, West Virginia, U.S.A.. The analysis was done using the washed coarse fraction (1-2 mm) of cuttings for each sample interval, which were separated into Dunham rock types, counted to determine relative abundance and the data presented as percent lithology plotted against depth for each well. Digitized wireline logs and the cuttings-percent logs were slipped to take into account drilling lag and lithologic columns produced from the combined data. Sequence stratigraphic cross sections through the basin and into the outcrop belt, with a resolution of 10 feet were then produced. Sequence stratigraphic time slices were generated as isopachs maps of the sequences, and of lowstand-transgressive, and highstand tracts with major facies shown. This data was then used to document the stratigraphic response of the foreland basin to tectonics and, with isotope data from the slope section, evaluates evidence for glacio-eustasy during the transition into ice-house times. The major mappable sequences are fourth-order sequences, a few meters to over 90 meters (300 feet) thick. They consist of updip red beds and eolianites, lagoonal muddy carbonates, ooid grainstone and skeletal grainstone-packstone shoal complexes, deeper ramp and slope wackestone-mudstone, and laminated argillaceous lime mudstone. Maximum flooding surfaces on the ramp slope occur at the base of deeper water facies that overlie lowstand- to transgressive siliciclastic or carbonate complexes, whereas on the ramp, maximum flooding surfaces cap near-shore shale or lime mudstone beneath widespread grainstones. The highstand systems tracts contain significant grainstone units, interlayered with extensive lagoonal lime mudstones. In spite of differential subsidence rates across the foreland, fourth-order eustatic sea level changes documented by isotopic signals in basinal facies, controlled regional sequence development. Thrust-load induced differential subsidence of fault-blocks of the foreland basement controlled the rapid basinward thickening of the depositional wedge while subtle structures such as arches at high angles as well as parallel to the margin, affected thicknesses and facies development. / Ph. D.

The main purpose behind this thesis was to study the variations of strength in a soil after it had been stabilized with various percentages of lime, cement, and combinations of the two. In both cases where the additives were added separately to the soil, the percentages used were 5 and 10 per cent by dry weight of soil. In the additive combination study, lime-cement percentage additions were 2-3, 3-2, 4-6, and 6-4 by dry weight of soil. The first two percentages, when added together, amount to 5 per cent stabilizing agent, while the latter two total 10 per cent. Since these two totals were the same as those used in the separate lime and cement studies, an analysis of strength changes when lime, cement, and lime-cement combinations were added to the soil could be made. Strength studies which were made consisted of unconfined compression immediately after compaction and after a four-day curing period in a 100 per cent humidity curing room. Atterberg limit tests were also run at the various percentages of additive. The laboratory test results indicate: 1. For cured specimens containing a stabilizing agent, the greatest four-day strengths will occur at or above OMC, in most cases. This may not always be true in the case of cement, since moisture condition is not as significant in cement stabilization as it is in other types. 2. Control of moisture at or near OMC during field compaction appears to be much more important in lime stabilization than in cement stabilization if maximum strengths are to develop. This statement is supported by a statistical analysis which was performed on the strength data. 3. The variation of' the lime-cement percentage trom 6-4 to 4-6 has no effect on four-day cured strengths. / M.S.