Recently, there has been renewed interest in the use of hydraulic lime mortars. They are attractive not only to the modern architect, but also have extensive use in the restoration and protection of historic architecture. This has led to a demand for an increasing quantity of research into these materials as much current knowledge is drawn from anecdotal accounts rather than validated scientific research. In this thesis the link between the mineralogy and physico-chemical properties of a series of hydraulic limes was investigated; the series being chosen to represent the various commercial grades, ranging from feebly to eminently hydraulic (class 2 to 5 MPa according to BS EN 459-1). A preliminary study of as received samples indicated key differences in the physical (e.g particle size, surface area profiles) and chemical (mineralogy) of samples from the five selected grades. Further analysis of these limes using a range of complementary physical and solid-state techniques on both mortars and pastes of hydraulic limes, have shown for the initial strengths, a good link between the bulk density I water demand of hydraulic limes. There was also strong evidence of a link between the consumption of belite (through hydration) and the development of strength through the deposition of hydration products to form a complex crystalline matrix. This influence was seen to reduce the porosity which had a critical influence on obtained strengths of both the mortars and hydraulic lime pastes. The durability of the hydraulic limes was investigated using freeze thaw testing. An increased resistance to frost damage was observed as the grade of the hydraulic lime increased, and with the ageing of the hydraulic lime mortars. The observed frost resistance was strongly influenced by the hydraulicity of the materials thereby providing further evidence for the impact of both qualitative and quantitative differences in mineralogy on hydraulic performance.

The role of elasticity and disorder and their interplay in plastic deformation processes is investigated on different length scales. Random disorder, in the form of impurities, fluctuations of defect densities and spatial heterogeneities, is responsible for a wealth of phenomena including surface roughening, non-linear dynamic response, stick-slip behaviour and temporal intermittency, which are observed in a wide variety of physical systems. A theoretical description of these phenomena is provided by theories of pinning and depinning transitions. In this work, these aspects are investigated in the context of plastic deformation of random media, such as real crystals with disordered microstructures or disordered elastic continua. Under the effect of an external force, these systems exhibit a complex behaviour arising form the competition between elasticity and disorder. Disorder tends to perturb the system, which reacts by opposing elastic restoring forces. This complex small scale dynamics determines the macroscopic behaviour of irreversibly deforming materials. These aspects are studied on different length scales. The problem of the depinning transition occurring in dislocation assemblies is first investigated. Dislocations are microstructure defects mediating plastic deformation. Under the effect of external forces, they are driven through disordered landscapes and rearrange into complex assemblies. A theory of pinning and collective behaviour of linear and planar dislocation arrays is formulated. Non-local elastic properties arise naturally form long-range dislocation interactions and influence dramatically statics and dynamics of these systems in the presence of disorder. Comparison with numerical results and experimental data confirms the validity of this approach. An application to vortex lattices in Type II superconductors is then considered. Dislocation assemblies such as low angle grain boundaries are often observed in these systems, determining the emergence of a polycrystalline phase. A theory of vortex polycrystals is proposed, in the conceptual framework of grain boundary pinning. Several aspects, including grain growth, transport properties, hysteretic behaviour and vortex lattice melting are investigated. Results are found in agreement with numerical simulations and experimental observations. On larger length scales, a theory of plastic flow in the presence of random stress fluctuations is discussed. The problem proves to be described by a continuum mean-field pinning model, where disorder is produced by randomness in dislocation densities. Such a description provides a theoretical framework to understand the origin of the critical behaviour often observed in plastically deforming crystals in the form of self-affine surface roughening and intermittent avalanche motion.

The primary purpose of this research was to contribute to the establishment of a scientific basis for the allocation of "compensating relaxation" allowances in time study practice. Preliminary studies of variations in the output of industrial workers engaged on repetitive unpaced manual tasks had indicated the existence of a pattern of activities. and it was considered that a new investigation of this pattern might provide data relating to C.R. requirements, provided that this was carried out in sufficient detail over lengthy and continuous working periods. Variations in the time taken to perform typical factory operations were, therefore, recorded during normal working periods of a complete shift, together with detailed observations of the nature, duration and distribution of non-productive time. A comparative analysis of the data thus recorded confirmed the use of the term "pattern" in describing output variations over the working shift, since these are fourd to display a number of characteristics which are common to the wide range of tasks studied. These common characteristics, many of which have not previously been recognised by research workers, as contributing to the overall output pattern,may be summarized as follows:- (1) Operation and constituent element times are substantially constant, within close limits, throughout the working day, with no statistically significant trend discernable. (2) The range of element times throughout the working day is no greater than that which could be expected to arise from random variations. There is no statistically significant trend. (3) The Variations which occur in the pattern of motion element times are attributable to voluntary changes in the operator's working pace. (4) Personal delays, under the worker's control, where these occur, tend to be grouped towards the beginning and end of each work period. (5) A slightly greater percentage of time (but not necessarily more time) is lost by reason of personal delays during the afternoon than during the morning work period. (6) Ancillary work and operational delays, where these occu~ tend to be grouped towards the beginning and end of each work period. (7) Non-standard or-foreign"operation elements result from the interruption of the repetitive work pattern by personal and operational delays. The cumulative effect of these characteristics is revealed in the "saddle back" output curve. This curve, however, does not reflect changes in the operator's pace of working, as has hitherto been supposed, but merely records the proportion of time spent productively. It is also clear that only a small part of present C.R. allowances is required for "compensating relaxation" or "personal needs". The balance must be regarded as a contingency allowance for ancillary work and operational delays, otherwise uncatered for. In some firms, part of the C.R. allowance now made is a concealed "policy allowance" provided to bring earnings up to some predetermined level.

Auxetic materials have a negative Poisson's ratio, that is, they expand laterally when stretched longitudinally. Negative Poisson's ratio is an unusual property that affects many of the mechanical properties of the material, such as indentation resistance, compression, tension and shear stiffness, and certain aspects of the dynamic performance. Auxetic foam was fabricated from a conventional polymeric foam. The unusual mechanical properties of auxetic foams are attributed to the deformation characteristics of re-entrant microstructures. There are four main aspects to the project. Firstly, the fabrication method for auxetic foams has been examined and developed further. Secondly, the microstructure of the foams has been characterised using electron and optical microscopy. Thirdly, the foams have been tested for their static and dynamic mechanical properties. Comparative tests have also been performed on conventional, non-auxetic foams. Fourthly, theoretical models have been developed to relate the observed microstructures to their properties.

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