Investigating mechanical properties of ordinary portland cement. Investigating improvements to the mechanical properties of Ordinary Portland Cement (OPC) bodies by utilizing the phase transformation properties of a ceramic (Zirconia).
Tait, Simon J.
KeywordMechanical properties, Ordinary Portland Cement (OPC), Zirconia, Phase transformation properties, Thermal analysis, X-ray, Porosity distribution, Vacuum infiltration methods, Bell-shaped curves, Young's modulus of OPC composites, Crystallite sizes and structures
The University of Bradford theses are licenced under a Creative Commons Licence.
InstitutionUniversity of Bradford
DepartmentSchool of Engineering, Design and Technology
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AbstractThe effects of metastable tetragonal zirconia on the properties of Ordinary Portland Cement were observed during which the effect of crystallite size pH on the preparation solution, precursor salt, and the presence of co-precipitates, Fe(OH)3, SnO2 and SiO2 on the crystallization temperature, enthalpy and crystal structure, immediately following the crystallization exothermic burst phenomenon in ZrO2 were measured. Thermal analysis and x-ray methods were used to determine crystallite sizes and structures immediately following the exothermic burst. Comparisons were made for zirconias prepared from oxychloride, chloride and nitrate solutions. The existence of tetrameric hydroxidecontaining ions in oxychloride precursor is used to rationalise low values of crystallization enthalpy. The position of the crystallization temperature, Tmax was not dependent on crystallite size alone but also on the pH at which the gel was made, the surface pH after washing, and the presence of diluent oxides. Enthalpy v r1/2 and Tmax v (diluent vol)1/3 relationships indicate that surface coverage effects dominate a surface nucleated phenomenon. The data established for ZrO2 systems was used to develop tetragonal-ZrO2-SnO2 powders capable of improving the mechanical properties of Ordinary Portland Cement discs. The ZrO2-OPC discs were prepared by powder mixing, water hydration and uniaxial pressing. Vicat needle tests showed that tetragonal-ZrO2 increases the initial setting rate. Microscopy indicated that porosity distribution changes near to ZrO2 particles. Zirconia has also been introduced into OPC discs by vacuum infiltration methods developed for solutions and colloidal suspensions. Comparisons between OPC discs and the OPCtetragonal ZrO2 composites have been made on the basis of diametral compression strength, Young’s modulus, hardness and toughness (K1c), as estimated by the cracked indentation method. Bell-shaped curves are found for the way the mechanical properties are changed as a function of Zirconia content.
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Recycling of uPVC window profile wasteKelly, Adrian L.; Coates, Philip D.; Rose, R.M.; Weston, S. (2007)Methods of recycling unplasticized polyvinyl chloride (uPVC) window frame waste were investigated. The quality of untreated granular waste was compared to that of waste treated by a range of contaminant removal processes including melt filtration and dissolution. Processability of each recyclate was evaluated by using a highly instrumented single screw extruder that enabled melt viscosity and process variation to be monitored in real time. Product quality measurements such as mechanical properties and surface defects were made on extruded strip, and the nature of the stabilizers present was determined. The mechanical properties of recyclates were found to be comparable to or better than those of virgin material in all cases and conformed to industry standards for window profile. Contaminant removal stages significantly reduced the amount of large surface defects detected in extrudate. Processability was comparable to that of virgin compounds, but melt viscosity varied among different batches of recyclate, depending on the source and composition of the original PVC formulation.
An examination of the intellectual property regimes in the Gulf Co-operation Council (GCC) states and a series of recommendations to develop an integrated approach to intellectual property rightsNaim, NadiaThis thesis aims to examine the intellectual property regimes in the Gulf Co-operation Council (GCC) states and assess the relationships between legislation, enforcement mechanisms and sharia law. The GCC states, currently Bahrain, Oman, Kuwait, Saudi Arabia, UAE and Qatar, all have varied mechanisms in place for both the implementation and enforcement of intellectual property rights. The thesis pays close attention to the evolution of intellectual property laws and regulations in the GCC states with particular interest directed towards the development of national intellectual property laws within the GCC states from the 1970’s onwards1. Intellectual property protection in the GCC states is considered from two perspectives. The first perspective addresses the international demand for higher standards of intellectual property protection in the GCC states. The second perspective defines intellectual property within the laws of Islam and explores the relationship between Islam and intellectual property. The latter part analyses religious influence, societal and cultural norms, economic reality and the developmental stage of each GCC state. It is an important area of study as developing Muslim countries are struggling with meeting international standards and a successful integrated framework will impact not only on GCC states but other Islamic states and as a result could potentially lead to more informed negotiation in trade agreements with developed states. The research argues there are systematic flaws in the GCC states adopting intellectual property laws which are in essence a procrustean modification of foreign laws which have developed from colonial occupation or laws taken from donor countries. The GCC legal systems of the states have evolved utilising different sets of legal principles and therefore it could be argued the foreign laws that have been adopted are somewhat unsuitable for the GCC states. The research has focused on the implications of the national and international legislative regimes on the protection of intellectual property rights on the GCC states. Consideration is given to compliance, mainly how compliant the GCC is to its World Trade Organisation (WTO) membership and Trade Related Intellectual Property Rights (TRIP’s) Agreement and to what extent the European Union (EU) and the United States (US) influence the intellectual property protection regimes in the GCC. The research has examined the development of the GCC in three distinct stages; pre-TRIPS, TRIPS compliance stage and TRIPS plus. Furthermore, the thesis argues that the somewhat simplistic formula of the GCC states passing a large number of intellectual property laws to appease the EU and US does not have the significant economic impact on the GCC economy as the international agreements would suggest. Not all trade is intellectual property related and not all foreign direct investment is contingent upon intellectual property protection. However, as the GCC states are largely oil dependent, they do need to diversify their trade and as such an intellectual property protection model that accounts for international intellectual property law and the bespoke cultural and religious views amongst GCC citizens can produce tangible results for both the GCC and its trading partners. What sets the research apart from previous research is two-fold. Firstly, the research is qualitative and has scratched beneath the surface of intellectual property law in the GCC and examined in detail the Islamic law principles that have been used to justify sharia compliance, the western perspective on international intellectual property and the impact of multilateral trade agreements. Secondly, the analysis of Islamic finance and the application of successful sharia compliant models in Islamic finance to intellectual property is innovative as it acts as a springboard to creating a modified sharia compliant intellectual property protection model. Finally, the thesis will conclude by making a series of recommendations to develop an integrated approach to intellectual property rights which takes into account; the structure of the GCC states, international agreements and pressures, the international institutions, Islamic finance and both societal and religious views.
Electrical and magnetic properties of organic semiconductors: Electrical conductivity and electron spin resonance studies of semiconducting, organic, charge transfer salts.Shields, L.; Ahmad, Muhammad M. (University of BradfordPostgraduate School of Studies in Chemistry., 2009-09-24)Charge transfer salts of Tetracyanoquinodimethane (TCNQ) were synthesised and their electrical and magnetic properties were investigated. These salts show unusual electrical and magnetic behaviour in contrast to conventional organic compounds. These salts have crystal structures which in general consist of TCNQ radical ions stacked in chains, isolated from each other by the diamagnetic cations. They are thus regarded as "one-dimensional" electrical and magnetic systems. The ESR spectra of these salts are attributed to triplet excitons showing that the spin-spin and electronelectron correlation effects are important. In the ESR spectra (Chapter III) of some TCNQ salts dipolar splitting is observed confirming the spin-spin interaction. These triplet excitons are regarded as bound electron-hole pairs. The experimentally determined dipolar splitting tensors are presented in Chapter III and the intensity data in Chapter IV. A large number of fine structure lines are observed in the ESR spectra of Pyridinium-TCNQ and 4-Aminopyridinium-TCNQ apart from regular triplet exciton lines (Chapter III). These lines are attributed to the trapping of excitons on an extended formula finit (TCNQ2 )n. In Chapter IV the temperature dependent magnetic susceptibilities are discussed in terms of Heisenberg antiferromagnetism and Pauli paramagnetism. In Chapter V temperature dependent behaviour of electrical conductivity is discussed in terms of an exciton band model, the lattice structure of the salts and one-dimensional lattice consisting of defects giving rise to high and low conducting segments. Low temperature electrical and magnetic phases are discussed (Chapters IV and VII) in terms of a band and hopping mechanisms.In Chapter VI self consistent field calculations are made with reference to the tight binding one electron band theory using simplified Roothaan equations considering CNDO approximations. Theoretical results are related to experimental band gaps, spinspin interactions and charge alteration.