Implementation of lean helps many organizations to improve their productivity and efficiency; on the other hand numerous organizations have failed to benefit from lean philosophy. The lean thinking was originated in the automobile manufacturing sector and it widely spreads within the discrete industries; however the today’s challenge is to implement the lean philosophy within continuous manufacturing industries and different organizations regardless to the type, size, or mission of the applicant organization. This has motivated the undertaken research to propose a standard generic transition steps which can be adopted by different organizations in order to become lean. The cement industry is ideal example of the continuous industry sector and it will be used to demonstrate that the lean philosophy is applicable to all deferent organisation types. There are numerous challenges facing the cement industry in today’s competitive environments; one of the major challenges is the capability of the cement industry to adopt and introduce the improvement approaches and techniques by which the overall enhancement can be achieved. The need for improving the efficiency of the cement production line is widely acknowledged in order to reduce the downtime rates, and satisfy high levels of market demand where the demand for cement is mostly second substance behind water. In response to this respect this thesis has investigated and addressed the implementation of the lean philosophy within the cement industry. The main contribution of this study is to convey the message to the decision makers that the lean philosophy is the proposed solution by which the continuous industry and different organisation types can be improved through eliminating or minimising wastes and non-value added activities within the production line.

Currently in the UK, composite blends of Portland cement (PC) and blastfurnace slag (up to 90%) are commonly used for the encapsulation of low and intermediate level wastes. The high volume replacement of PC is considered necessary in order to to reduce the high heat generation resulting from cement hydration in 500 litre waste packages. While suited to the majority of waste streams, the high pH environment in such systems (usually around 12.5 -13), will cause the corrosion of certain waste metals such as aluminium. Since aluminium is only passive between pH4 - 8.5, the use of an alternative low-pH cement system could serve to reduce/inhibit the corrosion. However, before such cements can be considered, two main research problems must be addressed, as follows: (1) quantitative evaluation of alternative cement systems based on their corrosion performance with aluminium; (2) high heat generation due to the rapid rate of hydration. The research in this thesis was thus divided into two strands, as follows: (1) The design and development of a novel, scientifically robust testing facility for the quantitative monitoring of aluminium corrosion in cement pastes; (2) the development of novel cement composites based on weakly alkaline calcium sulfoaluminate (CSA) cement for the encapsulation of aluminium from nuclear wastes. The output from this research is considered to be of interest to the UK nuclear industry.

At present, cementitious binders are used extensively in the construction industry and principally in concretes. They are also used in some applications like ground improvement. In these applications the cost of the binder, typically Portland cement, accounts for a considerable proportion of the total cost of the technique. In addition to the financial cost there is also the environmental impact of quarrying and processing of raw materials to produce Portland cements. Gypsum waste, by-pass dust and fly ash by-products have been identified as the alternative sources of cementitious binder. Using these materials has two advantages: they have little or no production cost; and the re-use of such material would negate the need for expensive disposal. This thesis describes a programme of laboratory testing and study on the possible field trials to investigate the possibility of using mentioned by-product materials as construction materials. Laboratory trials carried out to investigate the properties of waste materials in different combinations; binary and ternary using the same water content. Specimens were evaluated on the basis of Unconfined Compressive Strength at 3,7 and 28 days curing. It was found that pastes containing waste gypsums, Basic oxygen Slag and Run of station ash achieved the highest unconfined compressive strengths (up to 20 MPa) and five mixes of these groups were selected for further tests such as viscosity, permeability, expansion, XRD and freeze and thaw. Data obtained from the ternary combinations were analyzed using two different methods, i.e. Response Surface method and Artificial Neural Network. Two prediction models were created using MINITAB and MATLAB software and the predicted results were compared. It was concluded that the Artificial Neural Network had fewer errors than the response surface model. The feasibility of using by-product materials in two field trials was also studied and the possibility of 100% cement replacement in low strength concrete used in subway backfilling (using 80%BOS-15% Plasterboard Gypsum-5%bypass dust) and light weight blocks (60% run of station ash-20%plaster board gypsum-20% bypass dust) was investigated. It was found that waste gypsum could be used in both trials and the basic oxygen slag could be used for subway backfilling because it improved the flow. However it was not a good idea to use the steel slag in light weight products because of its density. The thesis concludes that there are several potential applications for the use of the waste gypsums in combination with other waste materials in the construction industry but further work is required before it can be used commercially. However the sources and differing chemical contents of the by-product materials may have significant impact on the cementitious behaviour of by product materials.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2006. / The study presented in this thesis symbolises one of the first ever efforts to better understand and describe the durability of geopolymers used in large scale commercial applications. In terms of the construction industry, geopolymers can be seen as a value-added approach to substitute the Ordinary Portland Cement (OPC) monopoly. It is particularly the fly ash-based geopolymers that are the main attraction, due to their economic and environmental advantages, over and above the large quantities of this material that are commonly available. Despite the fact that geopolymers have been around for thousands of years, it is only now that the accumulation of research across the globe has pooled their knowledge to broadly define this material in terms of its physical and chemical composition. The development of geopolymers for construction applications remains quite new, therefore requiring insight into the durability that can be expected from these materials, consequently leading to this work. Concrete technology and -science is one of many techniques which can offer considerable insight into effective durability studies, in addition to acting as a reference for firm material comparisons. Thus, this work is based on a collection of concrete durability studies and recommendations which resulted from a broad range of investigations. Principally, this work aims to confirm the superiority of geopolymers in terms of corrosion resistance. Chloride induced corrosion has been identified as being the main cause for deterioration of OPC structures and subsequently the origin of very costly, and frequent, reconstructive requirements. Geopolymers now have the opportunity to be introduced into this monopoly due to its advanced, yet credible, chloride penetration resistance. This thesis reports the development of the experimental design, as well as the associated analyses to describe the diffusive properties exhibited by fly ash-based geopolymers. Ultimately, two independent methods showed that Chloride Diffusion Coefficients (CDC) for all of the geopolymeric formulations are significantly lower (typically 1.43 x 10-15 cm2/s) than for cement (typically 0.5 x 10-8 cm2/s) or any other concrete mixture. Furthermore, the work presented here will consider the diffusive behaviour of the geopolymer formulations in an acidic sulphate environment, presenting this material’s superior resistance not only to the sulphate ion, but more so to the acid attack. Probable geopolymer applications are now further expanded to industrial applications, due to its acid resistance along with reduced Sulphate Diffusion Coefficients (SDC). In addition, the development of a time-to-corrosion software-tool is discussed. This tool may prove to be a valuable instrument for future geopolymer durability research, as well as iv commercial users in which extended material comparisons can be made. It may even assist the formulation-tailoring process where the relevant CDC/SDC can be chosen for a specific life-expectancy, reaching far beyond the limited scope of recipes covered in this work. Finally, this thesis provides the stepping-stone in proving geopolymer durability superiority. The formulations which proved to show the best results in terms of durability and acid resistance are highlighted and valuable recommendations are made towards the selection of suitable starting materials for optimum material robustness. The findings of this work, however, can be fortified by future research and exposure.

published_or_final_version / Business Administration / Master / Master of Business Administration

<p>Tanzania is one of the world’s poorest countries. But it has a lot to offer and in recent years both tourists and companies have realised this. This thesis focuses on the companies and takes a closer look at the growth performance and the inflow of Foreign Direct Investments (FDI) to Tanzania. By presenting a case on the cement industry in Tanzania the thesis also provide some insight in the mechanisms of FDI on a more practical level. The findings conclude that the FDI and growth have both increased extensively since the 1990’s, but I refrain from comments on the causality of this relationship. The economic reforms that the country underwent in the 1990’s are thought to have played a key role in the development of the country. From the case presented we draw the conclusion that a FDI can affect the value chain as well as the whole country in numerous ways.</p>

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Cement Industry in Ethiopia is an emerging industry where only few pioneers were regulating the market. The complacent conditions have led them to be driven by transactional suppliers relationships, not that much customer focused, energy sources and environmental issues were not to the level required and information communications infrastructures and linkages were not that much developed. However, this oligopoly nature of the market is starting to vanish soon as a lot of national and multinational firms are appearing into the market. Accordingly, this report would identify the level of perception of organization on the general issues of supply chain management, mainly suppliers partnership, customer relationship, environmental issues and information communication; analyze their level of impacts and relationships on the competitive position of Cement Factories in Ethiopia.

Dental restorative cements are placed in a harsh oral environment where they are subjected to thermal shock, chemical degradation, and repeating masticatory force. The ideal restorative dental cements should have superior mechanical properties, chemical stability, aesthetic, good handling properties, biocompatibility, antibacterial properties, and preferably bioactivity. This thesis presents research on dental restorative cements with enhanced properties. The overall aim was to increase the bioactivity and antibacterial properties of dental restorative cements without affecting their other properties. The effect from adding calcium silicate to glass ionomer cement (GIC) was investigated. The results showed that calcium silicate could increase the bioactivity and reduce the cytotoxicity of conventional glass ionomer cement without compromising its setting and mechanical properties. Hydroxyapatite (HA) with a high aspect ratio and thin nacreous-layered monetite sheets were also synthesized. Nano HA particles with an aspect ratio of 50 can be synthesized by both precipitation and hydrothermal methods. The aspect ratio was controlled via the pH of reaction medium. Thin nacreous-layered monetite sheets were synthesized through a self-assembly process in the presence of an amine based cationic quaternary surfactant. Temperature, pH, and presence of surfactant played essential roles in forming the nacreous-layered monetite sheets. Then the effect from adding silver doped HA and monetite particles was investigated. The results showed that the antibacterial properties of GIC could be increased by incorporating silver doped HA and monetite particles. Further examination showed that the pH change, F- ion release, and concentration of released Ag+ ions were not responsible for the improved antibacterial properties. The quasi-static strengths and compressive fatigue limits of four types of the most commonly used dental restorations were evaluated. In our study, resin modified GIC and resin-based composite showed superior static compressive strength and fatigue limits compared to conventional GIC. The static compressive strength of dental cements increased with the aging time. However, aging had no effect on the compressive fatigue limit of resin modified GIC and resin-based composite. The compressive fatigue limit of conventional GIC even showed a drastic decrease after aging.

Energy is essential to economic prosperity and quality of life. However it can have detrimental effects on the environment if not used properly. Moreover, if energy resources are scarce in a given country, then its use will impose economic and financial burdens on the national economy. The cement industry is energy-intensive, which adds a micro dimension to the macro issues mentioned above. Reducing energy consumption without due consideration to production requirements is not an optimal situation. What is needed is to arrive at a situation whereby energy is used rationally. The concept of rational use of energy has two embedded principles. The first is increased energy-use efficiency and the second is environmental protection. Jordan Cement Factories (JCF), located in a developing country where energy resources are not indigenously available and, therefore, costly energy requirements are imported, have realised the importance of addressing the energy management and conservation issues. This thesis describes the efforts initiated and conducted by the author, to address the research problem of improving energy usage through the application of effective management techniques aimed at reducing energy consumption per unit of cement produced. This present research has been concerned with energy management and efficient use of energy. The Jordan Cement Factories were used as a vehicle to demonstrate the proposed research methodology that aimed at improving energy consumption and thus operational efficiency. The methodology is based on establishing statistically significant relationships between interacting problem factors, and assessing the economic impact of improving these factors. Economic evaluation entailed the development of economic models and an application methodology combined with illustrative case studies. Consequently, the problem of energy management has been presented in a wider perspective that addressed the whole management system at the organisation. Towards that end, it was first necessary to show the significance of energy cost with respect to the overall manufacturing costs. The analysis of production costs, which demonstrated the significance of energy costs, was followed by the investigation and examination of the basic management factors that have direct impact on energy consumption at the JCF. Among these factors are, for instance, production line availability, production rate, average number of stoppages, and average duration of stoppages. These factors were determined using preliminary data analysis and the experience and technical knowledge of the researcher. The statistical analysis proved the existence of strong relationships between energy consumption and management factors. Several models were developed for a set of selected production lines, in the JFC at Fuhais and Rashadiya plants. These statistical models were generated using actual data for electrical energy and fuel consumption. The derived models have demonstrated the existence of strong relationships between energy consumption and management control factors; for instance, the values of R2 range from 60% to 90%. This implies that an equivalent percentage of the variations in energy consumption can be attributed to the selected management factors. The economic model developed in this research is concerned with demonstrating that effective management practices associated with proper maintenance and housekeeping can result in highly significant savings in energy usage. Although a simplistic methodology was used to evaluate the economic impact of any improvement programme, the economic treatment showed that the cost of improvement is actually negligible compared to the realisable savings in energy usage. The research has dealt with the details of developing a coherent energy management model whose objective is to establish transformational management processes of certain high-level management factors into daily operations and controls. The high-level management .factors are the same factors used as independent variables in the statistical and economic models, which statistically proved to be the major factors affecting the energy consumption at JCF. The research has also presented a detailed analysis of the organisational and procedural aspects of energy management with concentration on management functions, especially planning, controlling, executing, organising, and auditing. A detailed mapping and analysis of these functions as the main components of an Energy Management System (EMS) resulted in establishing job descriptions, organisational charts, work instructions and procedures for all-important functions of the EMS. The type of work described in this thesis could be extrapolated for application in other industries, particularly energy-intensive ones, to arrive at the objective of rational use of energy at the national and international levels. Comprehensive studies would need to be carried out for each type of industry prior to implementation. The cost benefit analysis presented in this research proved, beyond any doubt, the importance of implementing the EMS in JCF. As a result of this implementation it is demonstrated that huge annual savings were realised. Finally, as a result of improving energy control factors, introducing energy conservation measures and employing management techniques at JCF to guarantee the effectiveness of all such activities, resulted in an annual savings amount to about USS 3.5 million. Therefore, if the same or similar actions are undertaken by all cement, or other highly energy intensive industries then the savings could reach billions of dollars.