Thesis (E.E.)--Princeton University, 1921. / Typewritten ms. Correspondence and fold. maps in pocket at end. Bibliography: v.1, ℓ. 280-282. Also available in print.

Thesis (E.E.)--Princeton University, 1921. / Typewritten ms. Correspondence and fold. maps in pocket at end. Bibliography: v.1, ℓ. 280-282. Also available as E-Book.

Note:

The replacement of asbestos fibres with cellulose fibres in producing corrugated fibre reinforced cement sheets by the Hatschek process resulted in edge cracking for stacked sheets. This was due to the hydrophilic nature of cellulose, which increases its tendency for exchanging water with the surroundings. The drying process of corrugated sheets, in a stack, resulted in shrinkage hence edge cracking along the sheet. To reduce the magnitude of drying shrinkage and edge cracking potential, several mitigation strategies were proposed including the surface treatment of cellulose fibres, incorporation of wollastonite microfibres, addition of admixtures and superplasticizers, kaolin inclusion as partial replacement of cement and different exposure conditions. A fundamental understanding in mechanisms behind volume changes and how cracks form was crucial for optimization of the mitigation strategies. This thesis initially used a review approach to understand the mechanisms involved in different types of shrinkage and the role of different mitigation techniques. The ultimate goal was to achieve lower drying shrinkage and cracking risks in corrugated sheets along with reducing its economic impact. As a result, surface treatment of cellulose fibres, based on transforming the hydrophilic nature of cellulose to hydrophobic state, was investigated. Furthermore, inclusion of wollastonite/ kaolin as partial replacement of cement, were evaluated. Also, the potential of adding admixtures/ superplasticizers was explored. Finally, investigation on development of edge cracks in stacked corrugated fibrecement sheets was conducted under different exposure conditions. The results and findings of this research showed no significant improvement in permeability with cellulose surface treatment. Wollastonite microfibres promoted pore discontinuity hence significant reduction in permeability thus lower drying shrinkage. However, the resultant sheets were brittle. By reducing water content with addition of superplasticizers, density was enhanced thus reducing volume change from drying and wetting. Kaolin acted as internal restraint for shrinkage, refining the microstructure at the interfacial transition zone thus increasing density and its pozzolanic reaction enhanced mechanical properties. The inclusion of kaolin in the fibrecement mix in conjunction with controlling exposure conditions managed to eliminate edge cracking.

A Research Report submitted to the Faculty of Architecture, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Building. / Environmental and health considerations have led to the substitution of cellulosic fibres for asbestos fibres in many cement-based products. Inevitably, the substitution has required modifications to the manufacturing process. Certain production techniques associated with the switch to cellulosic fibres and other additives needed elucidation. It is possible that to ensure the required concentration of certalr additives in the final product, an excess is being used in the process because of uncertainties about the quantitative balance of the process. My intention was to examine the potential tole for Fourier Transform Infrared (FTtR) Spectroscopy in the investigation of the materials constituting fibre-reinforced cement boards. I was able to show that qualitative and quantitative determination of certain of the components in the final product are possible with adequate precision and reproducibility to be of value to the manufacturer, I also showed that care taken in the preparation of standard and analytical samples was essential for the success of such analyses. / Andrew Chakane 2018

A Research Report submitted to the Faculty of Architecture, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Building. / Environmental and health considerations have led to the substitution of cellulosic fibres for asbestos fibres in many cement-based products. Inevitably, the substitution has required modifications to the manufacturing process. Certain production techniques associated with the switch to cellulosic fibres and other additives needed elucidation. It is possible that to ensure the required concentration of certaln additives in the final product, an excess is being used in the process because of uncertainties about the quantitative balance of the process. / Andrew Chakane 2019

The necessity to reduce CO2 emissions has increased the driving force for the cement research community to develop alternatives to traditional Portland cement (PC). One of the alternative cements being investigated is calcium sulfoaluminate cement (CS ̅A), first developed commercially in China in the 1970's. CS ̅A cements are produced by clinkering together limestone, bauxite, clay and calcium sulfate to produce mainly ye'elimite (C4A3S ̅) and belite (C2S). Due to the presence of ye'elimite, SO3 content is typically between 6 – 10 wt%. The abundance of elemental sulfur arising from the desulfurisation of oil and gas and its use to produce CS ̅A clinkers were the starting points of the Green Concrete Project (GCP), which aimed to develop a novel approach to produce CS ̅A cement via the combustion of elemental sulfur, recycling this by-product and reducing the dependence on hydrocarbon fuels. Integrating the current knowledge on the production of CS ̅A, a new generation of CS ̅A belite calcium sulfoaluminate (BCS ̅A) and belite-ye'elimite-ternesite (BYT) clinkers incorporating the combustion of elemental sulfur has been successfully developed and produced in a pilot plant production process. A high-temperature thermodynamic model was developed to predict stable assemblages and to complement and validate experimental results. Within the frame of the GCP, the title thesis focused on collecting conditional thermodynamic data for ye'elimite and ternesite (enthalpy of formation) that were determined experimentally using isothermal conduction calorimetry. The enthalpies of formation of ye'elimite and ternesite at 25 °C were determined to be -8523 kJ/mol and -5993 kJ/mol, respectively. The thesis was also focus on characterising two clinkers of interest (designated BCS ̅A and BYT) obtained from a pilot plant trial (with the novelty of sulfur combustion). The obtained clinkers, BCS ̅A and BYT, have a distinctive mineralogy where alpha prime belite (α΄-C2S) and ternesite (C5S2S ̅) are present, respectively. Both phases are candidates to replace a significant amount of ye'elimite and therefore reduce the need of expensive bauxite to establish a more sustainable cement. The alpha prime polymorph of belite proved to be more reactive than the beta. However, actions had to be taken to control the fast setting of this BCS ̅A cement. To provide a solution to the fast setting problem a variety of retarders were investigated: 0.5 wt% citric acid with an additional 5 wt% gypsum showed the best results. A fundamental solution was also Abstract 5 investigated in order to avoid the use of any retarders. The results showed that the clinkering temperature should be around 1300 °C. The hydration of ternesite in the BYT cement was found to be moderate. Therefore, a thorough investigation was conducted to understand and find ways to enhance its reactivity. It was found that the addition/presence of 0.4 wt% MgO, 0.2 wt% K2O and 0.1wt% Na2O in the raw meal required for the synthesis of ternesite, can increase its reactivity. Furthermore, it was found that particle size distribution above 600 m2/kg can also accelerate its reactivity. Single-phase chemically activated ternesite hydrated rapidly at 25 °C, achieving compressive strengths of ≈ 30 and ≈ 65 MPa at 28 and 90 days respectively, with C-S-H and gypsum as hydration products.

陳國輝, 林炎南, 田向平. / 論文(碩士)--香港中文大學, 1995. / 參考文獻: leaf 2. / Chen Guohui, Lin Yannan, Tian Xiangping. / Lun wen (shuo shi)--Xianggang Zhong wen da xue, 1995. / Chapter 1. --- 中國近期經濟情況與投資環境 --- p.3 / Chapter 2. --- 中國基建發展與建材工業前景 --- p.5 / Chapter 3 . --- 中國水泥製造業現況與前景 --- p.6 / Chapter 3.1 --- 發展與佈局 / Chapter 3.2 --- 生產工藝 / Chapter 3.3 --- 品種與用途 / Chapter 3.4 --- 效益分折 / Chapter 3.5 --- 市場分析 / Chapter 3.6 --- 國家政策與適用法規 / Chapter 4 . --- 投資建議 --- p.13 / Chapter 4.1 --- 產品選擇 / Chapter 4.2 --- 地區選擇 / Chapter 4.3 --- 企業選擇 / Chapter 4.4 --- 投資策略 / Chapter 4.5 --- 環境保護 / Chapter 5 . --- 個案說明 --- p.17 / Chapter 5.1 --- 華北山東省“甲廠´ح個案 / Chapter 5.2 --- 華東長江下游江蘇省“乙廠´ح企業 改造可行性研究分析 / Chapter 6. --- 總結 --- p.50 / Chapter 6.1 --- 中國水泥市場總論 / Chapter 6.2 --- 合資發展水泥業總論 / Chapter 6.3 --- 合資企業的風險分析 / Chapter 6.4 --- 合資企業重整後的企業股權轉讓 / Chapter 6.5 --- 投資總論

D. Tech. Chemistry / The cement industry plays a major role in the world economy. Analytical techniques are central to its success. Many of the techniques currently in use, mainly wet classical methods, could be improved and optimized to increase economic benefits. The aim of this study was to identify and optimized selected analytical techniques. Four analytical methods were selected: the determination of available lime in lime, Cr(VI) in cement and cement-related materials, chloride in various cementitious materials as well as minor and trace elements in cement clinker and gypsum.

No description available.