Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (MTech (Chemical engineering))--Cape Technikon, Cape Town, 2001 / Approximately 40% of the surface waters of South Africa, and the surface waters of Lesotho, are soft and acidic with low calcium, alkalinity and carborrate species concentration. Distribution of such waters results in aggressive attack of cement concrete pipes and linings, and corrosive attack of metal pipes. valves, etc. within the distribution network. The impact of such attack is usually significant, and usually includes the loss of water, the need for expensive repairs and deterioration in drinking-water quality. Water conditioning to prevent aggression and/or corrosion (termed stabilization) is conventionally achieved by the addition of lime (Ca(OH)2) and carbon dioxide (C02). Although this process is well documented and understood, it has a number of drawbacks which include the use of troublesome lime, high chemical operating costs, and the need for high quality white lime which is currently in short supply in South Africa. An alternative stabilization process is stabilisation via contact with limestone (solid calcium carbonate), which has been shown to have many advantages over Iime-mediated stabilization. However, the use of limestone mediated stabilization has hitherto been limited to smaller water treatment works as a result of the large contact tanks required. Use of limestone for larger water treatment works was made viable by the development by CSIR of the limestone mediated Sidestream Stabilisation Process (SSP). The SSP consists of taking a sidestream of approximately 2 - 5% of the unstabilised water, dosing high levels of C02, and then contacting the COr acidified stream with limestone. The acidified sidestream takes up considerable amounts of calcium carbonate (CaC03), increasing the alkalinity and the calcium concentration.

abstract: The demand for portland cement concrete is expected to increase over time. There is a need to develop a more sustainable cementitious systems in order to reduce the negative environmental impacts associated with ordinary portland cement (OPC) production. An attempt is made to investigate sustainable binder solutions through the use of alternative cementitious materials at high levels of volume replacement. Limestone, an abundant material is used as a filler in low water-to-powder concretes where a substantial fraction of the portland cement remains unhydrated. At high volume OPC replacement, 20% and 35%, the combination of limestone and an alumina source has been shown to improve mechanical and durability performance. At 20% OPC replacement levels the migration coefficient which is an indication of chloride penetration in concrete is lower than the OPC control mixture at 28 and 56 days of hydration. The use of limestone with a similar particle size distribution to that of the OPC is used in each of these blended systems. A 20% binary limestone blend provide similar strength to an OPC mortar at all ages and comparable transport properties to that of the OPC concrete. Fly ash and metakaolin are the two alumina sources for the ternary blended mixes with concrete. The metakaolin shows the highest increase in the amount of hydration products formed out of all the mixes, including calcium-silicate-hydrate and carboaluminate phases in combination with limestone powder. At both levels of replacement the metakaolin blends show a substantially lower migration coefficient which is contributed to the smaller pore sizes found in the metakaolin blends. The fracture response of these systems show that at all replacement levels the ductility of the systems increase indicated by the large critical crack tip opening displacement. The fracture toughness is the highest for the blend containing metakaolin indicative of the smaller pore sizes allowing more dissipation of energy. An attempt is made to relate all mechanical and durability parameters to the reaction products and pore-structure developing at later ages. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2014

The literature on acid rain provides evidence that large (>5 μm) alkaline particles in the atmosphere, which derived from surface soil, play an important role in mitigating the effect of acid rain. Not only do they help to neutralize acidity but they also are a source of nutrients to the terrestrial and aquatic environments. While ground-up limestone has been added to the forests and the lakes of regions deficient in alkalinity, this mode of application is prohibitively expensive. An economic alternative method of distribution would utilize the advective and turbulent diffusive processes within the troposhere in order to supply limestone particles of approximately 10 μm diameter to the terrestrial and the aquatic environments. However, while the particles are being transported through the atmosphere they will also interact to some degree with the atmospheric pollutants (SO₂, NOx, photochemical oxidants, etc.). While the two-phase chemical interaction of water droplets and gaseous pollutants has been extensively studied, little is known about the reaction between limestone particles and gaseous pollutants under ambient conditions. As a first step in understanding these processes laboratory experiments were conducted in order to measure the rate of the heterogeneous reaction between limestone particles and sulphur dioxide (SO₂) gas in clean humid air. Calcitic limestone (200-270 mesh Tyler) from Texada Island, B.C., was reacted with 30-80 ppb SO₂ at room temperature (17-22°C) over a humidity range of 70-100%. Ancillary experiments were also conducted to determine the maximum dissolution rate of these limestone particles in an acidic, aqueous environment. The overall rate (r) for the SO₂ reaction with Texada Island limestone was determined to be approximately first-order with respect to the SO₂ concentration and to be strongly dependent upon the relative humidity: [Formula Omitted] Limited experiments with precipitated dolomite indicated that it reacts with SO₂ somewhat faster than does the calcitic limestone. A study of the individual mass transfer and reaction processes indicated that the rate limiting step for the overall reaction was the aqueous phase oxidation of the bisulphite ion. Limestone dissolution (determined experimentally), and estimated gas and aqueous phase diffusive processes, were not rate limiting. In a clean humid atmosphere, free of photochemical oxidants, a limestone aerosol would react very slowly with SO₂ (SO₂ removal rate of about 3x10⁻³% per hour). However, in a humid polluted atmosphere rich in photochemical oxidants, similar to that responsible for acid fog and acid rain, the aqueous phase oxidation of dissolved SO₂ is not expected to be rate limiting. Under such conditions bisulphite dissociation: [Formula Omitted] Therefore in humid, polluted atmospheres limestone aerosol will act as a "sink." for SO₂ for soluble photochemical oxidants, and probably also for HNO₃ (nitric acid). Since the oxidants are considered to be phytotoxic while the other pollutants are responsible for creating acid rain we conclude that the deployment of a limestone aerosol may have a positive impact on the atmospheric environment, besides being beneficial to the aquatic and terrestrial environments. It is strongly recommended that further research be done in this area in order to better quantify the rate processes, and perhaps also to identify practical methods for increasing the atmospheric concentration of alkaline aerosol in those geographic regions which are deficient. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The decomposition of CaCO3 has been studied extensively for many decades. This reaction is the backbone of lime industry. The desired product of the decomposition of CaCO3 is CaO (lime), which is the integral part of many lime products. The decomposition is described by the following reaction: CaCO3 --> CaO + CO2 Limestone is a term that includes calcium carbonate with varying amounts of impurities, the most of which are silica and alumina. Therefore, the analysis of the decomposition of CaCO3 is the same as that of limestone, since CaCO3 is the major component of limestone. The main objectives of the studies revolved around acquiring qualitative, quantitative, kinetic and mechanistic information. The most frequently used methods of analysis have always been thermal methods (TG, DTG, DSC, etc). Due to many possible experimental conditions, reaction-influencing factors and the property of the product (lime), varying conclusions on mechanistic and kinetic properties of the decomposition of CaCO3 have been drawn. However, thermal methods are time consuming and use extremely small mass of samples. Other methods of analysis which gave excellent results (in agreement with thermal methods) were photoacoustic spectroscopy and loss-on-ignition. These methods are also prone to errors and could be umbiguous. In the present work, Fourier-Transform infrared spectroscopy was investigated for possible application to the quantitative study of this reaction. This was done on the mixtures of CaCO3 and Ca(OH) 2 containing 100, 85, 70, 50, 30, 15 and 0% of each component on the Brucker 113v spectrometer. A calibration curve of regression coefficient of 0.9950 was obtained. Following these good results, the FT-IR was then applied to the decomposition of natural limestone to obtain the kinetic information of the reaction. Four different industrial sample sizes of limestone were decomposed isothermally at 900, 950 and 1000°C. The results showed that the isothermal decomposition of limestone in air atmosphere can best be described by Contracting Volume or Ginstling-Brounshtein model. The kinetic parameter values fall within the range specified in the literature (as obtained using thermal methods). Furthermore, the quantitative FT-IR method was investigated for possible application to the determinations of the content of limestone used as an admixture to the cement blends. FT-IR quantitative analysis was performed on the cement blend samples containing gradually increasing amounts of limestone. Again, a good calibration curve with average regression coefficient of 0.9970 was obtained. A complementary study involving the weighing of the same samples before and after decomposition (for a set time at 1000°C) gave comparably good results (averaged regression coefficient of 0.9950). / Dissertation (MSc)--University of Pretoria, 2000. / Chemistry / unrestricted

Sustainability and reduction of environmental impacts have continued to increase in importance in the concrete marketplace. Portland-limestone cement (PLC) has been shown to reduce total energy consumed and CO2 produced during the cement manufacturing process. This material may also have the ability to benefit concrete properties, such as compressive strength and time of set. Other concrete performance measures of potential interest evaluated in this study include durability and modulus of elasticity. In this dissertation PLC was evaluated for its ability to further increase concrete sustainability, while at the same time providing advantageous properties. This study’s focus was to show that PLC can improve concrete mixtures that are similar to commonly used ordinary portland cement (OPC) mixtures. PLC was also evaluated for its ability to increase the amount of total cement replacement (further increasing sustainability). Additionally PLC properties and concrete mixture combinations were evaluated in an attempt to clarify which PLC properties are crucial in performance benefits. Approximately 2000 concrete specimens were tested along with approximately 1000 cement paste specimens. This dissertation also includes an evaluation of PLC being used in a large scale construction and renovation project on a college football stadium. The scope of the dissertation included 12 cements from four manufacturing facilities that represent a large portion of the cement industry in the southeast US. Supplementary cementitious materials (SCMs), Class C fly ash, Class F fly ash, and slag cement, were also evaluated in single and dual SCM concrete mixtures at replacement rates up to 70%. Replacement rates of this magnitude are not being used in common practice but may become preferred in some conditions with PLC. Results indicated that PLC outperformed OPC in areas tested, in almost all cases at up to 50% replacement with single and dual SCMs. PLC also showed considerable advantages at 60% replacement but was often outperformed by OPC at 70% replacement. Aggregate type played a large role at 70% replacement. Elastic modulus, durability, and variability were all similar with PLC and OPC. Combinations of certain SCMs were more advantageous than others, and optimal SCM combinations changed depending on cement source.

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This dissertation covers concrete and cement paste (CP) containing portland-limetsone cement (PLC) for the purpose of understanding mainly mechanical property behaviors. PLC has been consistently investigated by researchers over the past decade who have found equal and often superior performance with PLC, but few researchers have found reasons why. Throughout this dissertation CP cylinders are used to help understand concrete. By understanding the CP (cementitious materials, water, admix, and no fine or coarse aggregates) portion of concrete, it is believed further understanding can be achieved. The interaction of CP and aggregates, or paste aggregate bond (PAB), is exceptionally important. Literature review suggests PAB can be affected by chemical and physical properties of aggregates as well as cement which dictates the mechanical property performance of concrete. CP measurements used herein are mainly compressive strength, however there were other measurements, such as thermal setting, collected as well. CP properties whether thermal or mechanical, generally agreed with concrete results. Additionally, CP compressive strengths were found to have value beyond what was previously known. Mainly that CP compressive strengths can help diagnose concrete behavior. CP used with concrete measurements can give some indication, not previously available, concerning PAB and bonding efficiency. However, the CP measurements had high variability. As such, a new CP production method was developed alongside different analysis techniques to reduce the variability. CP was further used with concrete to recommend a factor for balancing fineness and limestone percentage in PLC. Next, CP measurements were used with 74 concrete mixtures for investigating the Mississippi Department of Transportation fly ash replacement level limits for ordinary portland cement (OPC) and PLC for implementation into the Mississippi market. Lastly, this dissertation delved into non-production concrete mixtures with few ingredients (washed aggregates, cementitious materials, and water) to discover mechanisms behind PLC and OPC behaviors. From CP and concrete measurement perspectives, it is recommended that PLC in the MS marketplace be implemented without hesitation. From the conclusions herein, there does not appear to be many cases where OPC considerably outperforms PLC. In almost every case, PLC performs equivalent or better than OPC when numerous properties are considered.

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Made available in DSpace on 2014-06-11T19:24:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-09-05Bitstream added on 2014-06-13T18:52:22Z : No. of bitstreams: 1 manetti_fa_me_botfca.pdf: 473618 bytes, checksum: e05c02e7c8f686cc2f1ffa75ea5e1616 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / Com a finalidade de avaliar os efeitos do momento da aplicação isolados e conjuntos do calcário e do gesso no crescimento vegetativo de plantas de milho. O experimento foi instalado em casa de vegetação e conduzido na área experimental do Departamento de Recursos Naturais - Ciência do Solo, localizado na Fazenda Experimental Lageado, da Faculdade de Ciências Agronômicas - FCA da Universidade Estadual Paulista - UNESP, Campus de Botucatu, em um Latossolo Vermelho Distrófico, textura média, Unidade Patrulha. Os tratamentos foram:- T1- sem calcário calcítico e sem gesso (testemunha); T2 - com calcário calcítico e sem gesso; T3 - sem calcário calcítico e com gesso; T4 - calcário calcítico aplicado 30 dias antes da aplicação do gesso; T5 - calcário calcítico aplicado 15 dias antes da aplicação do gesso; T6 - calcário calcítico aplicado junto ao momento de aplicação do gesso (mistura); T7 - calcário calcítico aplicado 15 dias após a aplicação do gesso; T8 - calcário calcítico aplicado 30 dias após a aplicação do gesso; T9 - calcário calcítico e gesso (mistura) aplicado na superfície 30 dias antes da semeadura (das); T1- sem calcário dolomítico e sem gesso (testemunha); T2 - com calcário dolomítico e sem gesso; T3 - sem calcário dolomítico e com gesso; T4 - calcário dolomítico aplicado 30 dias antes da aplicação do gesso; T5 - calcário dolomítico aplicado 15 dias antes da aplicação do gesso; T6 - calcário dolomítico aplicado junto ao momento de aplicação do gesso (mistura); T7 - calcário dolomítico aplicado 15 dias após a aplicação do gesso; T8 - calcário dolomítico aplicado 30 dias após a aplicação do gesso; T9 - calcário dolomítico e gesso (mistura) aplicado na superfície 30 dias antes da semeadura (das). Esses tratamentos foram aplicados nos três primeiros anéis de 7,0 cm cada, totalizando 21 cm, de colunas de PVC de... / With the purpose to appraise the effects of the superposition, isolated and together, of the limestone and the gypsum in the vegetative growth of maize plants, to the forty days after the emergence, as well as in the extraction of the nutrients by the aerial portion of the plants, beyond its effects on the behavior of some chemical features from the superficial layer of the soil, was accomplished this study. The experiment had been settled and guided at the experimental area on Natural Resources Department - Soil Science, located in the Experimental Farm Lageado, of the Faculdade de Ciências Agronômicas - FCA - from Universidade Estadual Paulista - UNESP, Campus of Botucatu, in a dystrophic clayey Rhodic Hapludox, average texture, Unidade Patrulha.The treatments had been defined by the moments of the applications of the two types of limestones, calcitic and dolimitic, with and without gypsum and agricultural gypsum only. These treatments had been applied in three first rings of 7,0cm each, totalizing 21cm, from PVC columns of 49cm of height and 10cm of diameter. The experimental outlining had been made in blocks, in factorial arrangement of 9x2, with four repetitions.The harvest had been made to the forty days after the emergence, having been the plants cut close to the soil and measured like: heights from the stalk's base to the first sheath and the edge of the biggest leaf; stalk's diameter; numbers of leafs for plants; fresh and dry matter...(Complete abstract click electronic access below)