Master of Science, University of Toledo, 2017, Civil Engineering

Microbially induced calcite precipitation (MICP) has recently emerged as a potential ground improvement technique, where microorganisms play an active role in catalyzing urea hydrolysis and inducing chemical precipitation of calcite, leading to the reduction of porosity and improvement of strength and stiffness. This ground improvement technique has a great potential in a variety of engineering applications, including bearing capacity boost, geo-hazard mitigation, geological CO2 sequestration, ground remediation and unconventional oil/gas recovery. Despite successful implementations achieved on laboratory scales, there remain many critically unanswered questions as to the predictability and controllability of altered/engineered soil properties, demanding improved understanding of the fundamental mechanisms across multiple scales. The present study focuses on a number of challenges in achieving successful and efficient calcite precipitation. Explored in this thesis are several phenomena related to this aspect: the short effective precipitation distance, clogging of the sand near the injection point, the flushing of bacterial cells out of the system (generally columns), inability to monitor in situ reactions and uneven distribution of biological activity and precipitated calcite. The primary objectives of the present study are: 1) to explore and recommend an injection method that helps reduce/prevent the clogging near injection point 2) to analyze in-situ bacterial survival in the soil throughout the treatment period 3) to monitor calcite precipitation evolution during treatment, and finally 4) to analyze calcite distribution along treated samples. The first part of the experimental study is focused on a series of batch experiments where the bacteria activity and chemical concentrations were monitored during urea hydrolysis and calcite precipitation. It was found that when mixed together, unhindered in the absence of a porous medium, urea hydrolysis and calci (open full item for complete abstract)

Committee: Liangbo Hu Ph.D. (Advisor) Subjects: Engineering

Master of Science, Miami University, 2002, Geology and Environmental Earth Science

The goal of this laboratory study was not only to examine portions of the aragonite to calcite transformation, but to do so with conditions that were similar to a modern carbonate environment. Specifically, it was concerned with diagenetic changes that occur in an aquifer when unstable carbonate sediments are exposed to meteoric water. Flow through the freshwater phreatic zone of an aquifer was simulated in Plexiglas columns by circulating water through a column of modern, aragonite ooids. Based on geochemical analyses, only portions of the aragonite to calcite transformation were observed. Dissolution of the aragonite ooids occurred at both a PCO2 of 10-3.5 and a PCO2 of 10-2. Aragonite dissolution rates ranged from 12.77 mmolcm-2s-1 to 13.78 mmolcm-2s-1. The column water reached saturation with respect to calcite in approximately seven days. However, no calcite precipitation was observed by measuring the Sr/Ca, even after seeding the columns with calcite crystals.

Committee: Mark Boardman (Advisor) Subjects: Geochemistry; Geology

Master of Science, University of Akron, 2024, Chemical Engineering

This research aims to uncover effective nutrient compositions that enable fungi growth in concrete microcracks with carrier-protected fungal spores pre-embedded in concrete, thus facilitating the self-healing of cracks through fungal biomineralization. For fungi to grow, carbon sources are an absolute requirement. Furthermore, the calcite formation by biomineralization in cracks can only occur if calcium and carbonate ions are present or can be generated. On the other hand, adding nutrients that support fungal growth and biomineralization can negatively impact concrete properties. Finding a balance between the quantity of these necessary nutrients for successful crack healing and minimal impact on concrete properties is the primary objective of this study. This objective has been successfully fulfilled by making mortar samples infused with nutrients in a wide range, replicating the nutrient range in the concrete mix to test for concrete properties in a trial-and-error process, and arriving at a composition that balances both sides. Moreover, successful crack healing of lab-scale mortar specimens was achieved by testing the effectiveness of different nutrient compositions and identifying the necessary environmental conditions.

Committee: Lu-Kwang Ju (Advisor); Jie Zheng (Committee Member); Anil Patnaik (Committee Member) Subjects: Chemical Engineering

Master of Science (M.S.), University of Dayton, 2023, Civil Engineering

This research investigates into the fascinating realm of Roman concrete, renowned for its enduring nature and self-healing capabilities, characteristics that have mystified and intrigued modern civil engineering. Investigation deals with replicating the ancient Roman concrete recipe, substituting original materials with accessible contemporary equivalents. A crucial aspect of this research involved replacing the traditional volcanic ash (pozzolan) with white pozzolan, alongside the use of quick lime, pumice, and sea water - materials closely resembling those used by the Romans. In a methodical approach, various samples were crafted employing differing ratios of these materials. Following a meticulous curing process submerged in water for 28 days, the samples underwent a compression test. This test was designed to induce hairline cracks, simulating the wear and tear experienced by concrete over time. Post-creation of these fissures, the samples were exposed to moisture and submerged once again, this time for a 30-day observation period to monitor the self-healing process. Remarkably, the results after this period were conclusive: the concrete exhibited a complete self-healing of the cracks. This phenomenon not only echoes the resilience of ancient Roman construction but also offers insightful implications for modern concrete technology. The study demonstrates that with precise material selection and proportioning, concrete's longevity and sustainability can be significantly enhanced.

Committee: Joseph Saliba (Advisor); Elias Toubia (Committee Member); Namgyun Kim (Committee Chair); Amirsalar Esfahani (Committee Member); Riad Alakkad (Committee Member) Subjects: Civil Engineering

Master of Science, University of Akron, 2022, Geology

Summit Lake is an urban kettle lake located in Akron, Ohio. Once used by industry, Summit Lake is currently being revitalized to provide recreational opportunities. It is important to study the lake's overall health to ensure it is suitable for increased recreational use. Seasonal water column profiles were measured and reveal that from May to October the lake is thermally stratified, the hypolimnion becomes anoxic, and orthophosphate as phosphorus is released from the sediment into the hypolimnion and averages 1100 μg/L by October. This phosphorus release may contribute to harmful algal blooms (HABs). During the sunny productive season, the drawdown of CO2 by algae and increased temperatures results in the precipitation of calcite in the epilimnion and deposition of a white calcite-rich sediment layer. During the remainder of the year organic matter deposition produces a brown sediment layer. The white-brown sediment rhythmites observed from 0-58.7 cm composite core depth have been shown to be varves based upon correlation to year 2003 sediment cores and 210Pb dating. Productive season meteorological precipitation was assessed to determine if heavy rain events increased algal productivity and in-turn produced thicker brown sediment layers. Results were inconclusive, but years with extreme rain events (2003, 2004, and 2011) corresponded to thicker brown layers the following non-productive season. The varve-age model allowed the sediment record to be divided into three time periods. The Industrial Period is defined by sediment with no calcite laminations below 58.7 cm composite core depth which varve-dated to 1980. At this time the residence time of Summit Lake water was short due to high input and extraction of water by industry and resulted in unfavorable conditions for abundant calcite precipitation. A massive brown mud layer from 58.7-96.2 cm composite core depth is interpreted as dredged spoil or possibly sediment disrupted by the 1977 bor (open full item for complete abstract)

Committee: John Peck (Advisor); John Senko (Committee Member); Caleb Holyoke (Committee Member) Subjects: Biogeochemistry; Environmental Geology; Environmental Science; Geochemistry; Geology; Hydrology; Limnology; Sedimentary Geology

Master of Science, The Ohio State University, 2020, Earth Sciences

The isotopic composition and mineralogy of modern microbialites provides us with tools useful for interpreting the formation processes and environments of ancient microbialites. Growing in the hypersaline and turbid Storr's Lake on San Salvador Island in The Bahamas today are microbialites with low levels of photosynthesis and high levels of sulfate reduction-in contrast to many of their modern counterparts. Living planktonic, motile microorganisms and suspended algal and bacterial debris create the high turbidity of the shallow lake (<2 m) and rapidly attenuate sunlight in the water column. Within Storr's Lake microbial metabolisms induce precipitation of carbonate within microenvironments of the microbial mats. Both high-Mg calcite (HMC) and aragonite are found within a majority of the microbialites measured leading to the hypothesis that the organomineralization process involves a step where HMC transforms to aragonite. Mineralogy and elemental analysis of a wide sampling of microbialites was undertaken to understand the extent of aragonite within Storr's Lake microbialites. It was found that aragonite occurs at water depths greater than 40 cm within the lake and was present in all but one microbialite measured in this study. New calcium (Ca) stable isotopic analyses from the thermal ionization mass spectrometer using a 42Ca-43Ca double spike provides evidence for exploring the systems fractionating Ca within Storr's Lake water and microbialites. In contrast to geochemical data and previous Mg stable isotopic measurements on the same waters, the Ca stable isotopic value (δ44/40Ca) of water in Storr's Lake is not homogeneous. While the northern sector is primarily influenced by seawater, the southern sector δ44/40Ca is shifted away from seawater to lower values, suggesting internal variability within the lake. In both microbialites measured, δ44/40Ca is strongly correlated to mineralogy and trace elements in the carbonate. To explore the potenti (open full item for complete abstract)

Committee: Elizabeth Griffith PhD (Advisor); Matthew Saltzman PhD (Committee Member); Thomas Darrah PhD (Committee Member) Subjects: Biogeochemistry; Earth; Geobiology; Geochemistry; Geological; Geology; Morphology; Petroleum Geology

Doctor of Philosophy, The Ohio State University, 1963, Graduate School

Committee: Not Provided (Other) Subjects: Chemistry

Master of Science (MS), Bowling Green State University, 2015, Geology

Hydraulic fracturing of shale is currently a major and rapidly growing area of hydrocarbon production in the United States and around the world. Given their almost total lack of permeability, the transmission of fluids through shale requires the presence of fractures; hence, once the fissures are formed they must remain open. However, the opening of conduits to promote hydrocarbon flow also encourages mineral precipitation along the fracture, ultimately, resulting in its resealing and a reduction in permeability. With calcite as one of the most common vein filling minerals, multiple studies have been done to characterize and classify calcite veins, although none have been done experimentally on natural fractures in an open system. Using a novel flow-through apparatus, aqueous fluids saturated in calcite were passed through vessels containing black shale samples to quantify the rate as which calcite grows. As fluid travels through the apparatus it reaches saturation by passing through a reaction vessel, R0, containing powdered calcite and travel to another reaction vessel, R1, where an increase in temperature drives supersaturation resulting in precipitation. Calcite precipitation is shown here as a result of temperature gradients, time and flow rate. Fluids traveling begin to precipitate calcite where temperatures are the highest, on the downstream end of samples in the R1 vessel. The longer the experiment duration, the more calcite will precipitate. The amount of calcite growth decreases as flow rate increases. Saturation indices must be positive after leaving R0 and reach at least 0.58 while traveling through R1. Morphology changes if saturation index values drop below 0.60 traveling through R1, resulting in dissolution pits on the faces and edges of the calcite crystals.

Committee: John Farver (Advisor); Charlie Onasch (Committee Co-Chair); Kurt Panter (Committee Member) Subjects: Geology

Master of Science (MS), Ohio University, 2014, Geological Sciences (Arts and Sciences)

Impact craters in carbonate rock account for ~30% of all impacts on Earth, yet little research has been conducted to study shock metamorphism on such targets. This study examined the petrography of carbonate rocks at Jeptha Knob, a 4.26 km diameter structure east of Shelbyville, KY, to investigate whether evidence of shock metamorphism is present and to determine peak pressures experienced by a previously postulated impact event. Petrographic observations and XRD analyses of calcite/dolomite have the potential to confirm shock metamorphism and constrain peak pressures in impact sites because certain petrographic features are correlated with increasing shock pressures. Specifically, XRD peaks in calcite/dolomite broaden and peak intensities decrease, mechanical twin density increases, and twin spacing decreases. Thin section petrography and XRD analysis of samples collected from the JK78-3 core show that the structure is highly deformed and provide evidence of these rocks experiencing pressures of > 4.6 GPa. The results collected from JK78-3 are consistent with that of an impact origin and provide insight into the development of other impact craters in carbonate rocks.

Committee: Keith Milam (Advisor); Doug Green (Committee Member); Alycia Stigall (Committee Member) Subjects: Geological; Geology

Master of Science in Civil Engineering, University of Toledo, 2014, Civil Engineering

Chemo-mechanical interaction processes in multifarious environmental circumstances may strongly affect the evolution of the mechanical and transport properties of geomaterials. Such interaction is believed to occur at the microscopic scale at the level of inter-granular contact but its effects are often manifested at higher scales leading to critical mechanisms in many natural geomechanical processes. The present work focuses on establishing the chemo-mechanical coupling effects at the granular scale and explores the macro-scale response of siliceous and calcareous sands using Distinct Element Method as a modeling tool. The effect of the mineral dissolution on the mechanical response at the grain contact is incorporated into a modified linear contact model. Two kinetic rate formulations to account for mechanically enhanced dissolution are examined, both allowing the evolving local mechanical response to be considered in the enhanced dissolution process at each grain contact. The results show the importance of the kinetic characteristics of the mass dissolution and precipitation processes in the behavior of geomaterials. Compared to siliceous sands, the interaction of pore fluid with carbonate minerals leads to much accelerated dissolution of carbonate minerals which results in more enhanced deformation of the calcareous sands. The presented numerical analysis is a feasibility study of the use of DEM to model coupled chemo-mechanical phenomena.

Committee: Liangbo Hu (Committee Chair); Brian Randolph (Committee Member); Youngwoo Seo (Committee Member) Subjects: Civil Engineering

Master of Science (MS), Wright State University, 2011, Chemistry

The purpose of this work was to examine the effects of polished crystal-surface orientation and degree of solution undersaturation (Ωcalcite) on the dissolution kinetics of calcite as a means of improving our understanding of fundamental reactions that may influence the efficacy of CO2 sequestration in geological formations. Crystallographic surface orientations utilized in this study included ~ 1 cm2 areas of natural calcite specimens polished approximately parallel to the (104) plane, giving rise to surfaces with flat terraces with few steps, as well as fully kinked surfaces created by sectioning approximately parallel to the (001) plane. Results from inductively coupled plasma (ICP-OES) and vertical scanning interferometry (VSI) investigations revealed how crystallographic orientations of calcite with higher initial surface morphologies were associated with greater Ca2+ release, greater surface retreat, and therefore, greater initial transient dissolution rates than those with lower initial surface morphologies. However, both the ICP-OES and atomic force microscopy (AFM) results confirm that the effects of crystal orientation become minimal under long-term conditions since (1.) varyingly oriented calcite surfaces exhibited similar “steady” rates and (2.) orientations with high initial reactive site densities developed lower energy morphologies. Results from this study are significant for predicting long term calcite dissolution rates because they suggest the “steady” dissolution rate of any calcite surface with any degree of initial surface energy will be similar to that of a surface with natively low surface energy.

Committee: Steven Higgins PhD (Advisor); Steven Higgins PhD (Committee Chair); David Dolson PhD (Committee Member); Ioana Pavel PhD (Committee Member) Subjects: Chemistry