High strength steels have provided a unique opportunity for the automotive industry to achieve weight reduction via reduced material thickness whilst maintaining performance requirements such as crash worthiness. However, the initial success of HSLA steels was constrained by inconsistencies in the final mechanical properties. Although significant improvements in both mechanical and dimensional properties have since been made, increasingly stringent customer specifications for high strength steels mean that the challenge to reduce variability in automotive HSLA steel products and enure their continued competitiveness has never been greater. This investigation addresses the issues concerning the controlled hot rolling of Nb-HSLA strip steels through a series of laboratory and commercial trials, both to optimise the mechanical properties and uniformity of properties. Both sets of data established that: (i) the strength was decreased by reducing the soak temperature from 1250°C to 1150°C; (ii) the presence of furnace skid chills during soaking locally reduced the strength; (iii) lowering of the finishing temperature towards the Ars reduced the overall strength, but improved the coil-width property consistency, and; (iv) the existence of an optimum coiling temperature developed higher strengths and improved property consistency. The programme of work conducted also observed that by finishing near the Ars temperature, very fine ferrite subsurface grains are created which limit the fall in strength. Additionally, the commercial trials highlighted the need to compensate for the exposure-related cooling effects of the inner and outer most laps of the hot-rolled coil, thereby reducing any potential for developing further inconsistencies. Furthermore, the work undertaken has established that prudent additions of niobium, coupled with the use of a low finishing temperature and an optimum coiling temperature, will lead not only to higher strengths steels but also to significant improvements to the through-coil uniformity of properties

Stone masonry response to changing environmental conditions is complex. Growing recognition of the problems associated with stone exposed to prolonged wet conditions means that it is increasingly necessary to understand environmental controls on stone decay, not just in a dynamic world, but also in a world in which the nature of the environmental dynamics themselves are changing. This thesis assesses the impact of climate and changing dynamics on the environmental controls on sandstone decay in three ways: 1) Environmental monitoring, to identify links between external conditions and sandstone temperature and moisture response; 2) Experimental simulation, exploring material-environment interactions during heating/cooling and wetting/drying of sandstone; 3) Modelling techniques, to develop future climate projections for Northern Ireland (statistical downscaling) and to simulate the stone thermal and moisture response to observed and potential future environmental change (hygrothermal simulation). Results demonstrate that stone microenvironmental conditions differ from external environmental conditions and exhibit distinct variability in, and of, themselves. Sandstone temperature and moisture conditions vary with aspect and depth, depending on incident radiation and material properties, and the nature and timing of moisture inputs and outputs, respectively. Asynchronous surface/subsurface stone moisture dynamics relate to the nonlinearity between wetting and drying processes, with 'deep wetness' potential much more widespread than previously thought. Material heterogeneity during drying contributes to complex and spatially variable rates of evaporation. Under projected future changes in seasonal air temperature and precipitation totals, stone moisture conditions are projected to experience little change. Stone temperatures are projected to increase at a rate proportional to ambient change and, with all things remaining equal, stone thermal gradients and rates of change should experience little change. Ambient conditions should not be used as a substitute for stone microenvironmental dynamics - it is necessary to consider the material-environment interactions that mediate stone micro environmental response to wider environmental trends.

Architectured material is a term that has emerged to describe the application of geometry at multiple dimensional scales. This hierarchical approach to material engineering encompasses the breadth of methods in the material science field from the macro- to nanoscopic, as a method of creating materials with increasingly complex functionalities to meet our diversifying needs. Recent advancements in Additive Manufacturing provide opportunities by which to build architectured materials that have not been previously possible. Current generation Selective Laser Sintering (SLS) is investigated as a potential method of producing architectured objects — an object constructed of an architectured material. The process provides the key capabilities for commercial manufacture: robust mechanical performance, high resolution and a broad dimensional range due to a comparatively large maximum component size. Architectured objects produced through SLS present opportunities to achieve new performances and higher levels of control than prior methods of manufacturing could afford. Such objects are likely to both define new and disrupt a range of commercial markets. For this potential to be realised, two key tasks have been identified — the validation of SLS as means of architectured material manufacture, and the development of methods by which architectured objects can be designed. This thesis deals with the issues of quantifying the SLS processes, identifying the key parameters behind architectured materials, complex digital representation and mechanical assessment and there by establishes the fundamentals of creating architectured objects.

The last few decades have seen unprecedented levels of change both in the production of building materials and in the ways they are deployed in building. Despite rigorous debates about materials in architecture from very different areas of theory and practice – ranging from the new materialists' critique of the concept of matter to ecological concerns with embodied energy and life cycle analysis of building materials – the extent to which these developments might demand more adequate conceptualisations of materials remains unexplored. The position this research takes is that building materials cannot be assumed to be nothing more than particular instances of matter in general – whether matter is understood in its classical philosophical hylomorphic relation to form, or as the physical substances of science. Here, the architectural specification – a document usually considered to be merely 'technical' and therefore outside theoretical enquiry – provides descriptions of building materials drawn from inside architectural practice. It yields a number of types of description – from 'naming' to the 'recipe' to performance – and the differences between these 'forms of clause' and the degree to which each is contained by or exceeds the notion of hylomorphic matter are shown to involve radically different conceptualisations of materials. Moreover, the specification makes visible the changing historical and industrial contexts that constitute its format and content. Part I sets out this variation and constructs a typology of forms of clause, and Part II studies two of them in detail. The key philosophical move derives from Gilbert Simondon's work on individuation in so far as materials are considered not as substances or as matter (as already individuated individuals) but in terms of the dynamic processes through which they are constituted (individuation). First, process-based clauses provide found descriptions of form taking in terms of such operations, and expand Simondon's account of the preparations which set up the possibility of individuation in a technical object to include statutory, social and other operations in addition to the physical ones he describes. Second, the performance clause requires us to understand how specific use (excluded by Simondon in his accounts of technical systems) might itself become preparatory in the new industrial conditions of performance-engineered materials. Part III takes up Simondon's 'complete system' of individuation and understands the variety of forms of clause as evidence of a variety of 'systems of material' which necessarily include the full range of the preparations which make possible the specific deployment of any given material in building. Furthermore, what is constituted in any individuating system is not so much an individual as the possibility of a transductive mediation between hitherto disparate realities. It is, in particular, the possibilities of new mediations that are produced in industry – between a terrorist threat and a piece of glass – in addition to more familiar ones – between a notion of form and a lump of clay for example, that demand attention and new conceptualisations. For Simondon, transduction is also a process of thought which derives problems and resolutions from within a domain rather than seeking a principle from elsewhere. If we are to understand how concepts emerge from applied practices and their productions, and not just from philosophy and science, then the transductive method has applications well beyond the question of building materials that is put into motion via the architectural specification in the process of this research.

Earth building materials or unfired clay masonry have a strong potential to regulate indoor humidity variations. This was identified through observations of historical buildings where earth was used as a major building material. A stable relative humidity provides many benefits such as a healthier environment for the occupants, a reduced surface condensation or a reduced energy consumption for air conditioning systems. Building physicists have started to bring attention to this phenomenon called moisture buffering where the building envelope plays a major role in the moisture balance of the building. Yet only a limited amount of research has been done on one of the most promising materials in terms of moisture buffering performance. This study aimed to characterise the moisture buffering capacity of unfired clay masonry. Steady-state and dynamic hygric properties of 146 samples were measured. A selection of soils were selected to represent the high variability of these building materials and to determine the influence of composition and material properties on moisture buffering. The moisture buffering test protocol used was primarily based on the Nordtest project yet the influence of boundary conditions and test protocol was investigated to obtain reliable dynamic results. This showed that results from different boundary conditions could be compared as they remained proportional. The surface film resistance showed to have a significant influence. Additional investigations were made on the dynamic adsorption process using a Dynamic vapour sorption (DVS) system which showed the influence of the hysteresis. Samples were prepared as compressed earth blocks (CEB) or plasters. The CEB and plasters were further investigated with the addition of natural fibres to explore the potential to improve their buffering capacity. Overall not only was the performance of the materials characterised but it could be identified which properties influence the adsorption capacity also it was possible to compare the results with existing classifications for buffering materials. It became clear that not only are these materials out performing most of conventional materials but their own performance can also be adjusted and improved for required applications.

Every 1 t of china clay produced in the UK generates 9 t of waste material. A limited quantity of the coarser waste has beneficial use as a building stone or secondary aggregate in concrete and asphalt, but there are currently limited uses for the finest waste fraction. ‘Mica’ waste is a mixture of fine minerals and is one of the forms of waste with little beneficial use other than the restoration of old quarries. Looking for innovative solutions for the needs of a new Eco-town in the UK and with an aim to find new commercially viable and low environmental impact uses in construction, this PhD introduces the idea of using the china clay waste in alkali-activated binders. First, it was investigated whether the contained mica mineral could be used as an alkali-activated binder. This was done using different MAS NMR and XRD analysis, and mechanical strength tests based on European standards. The material was shown to have low reactivity and some direct trials of alkali-activation of thermally treated mica mineral produced in average weak binders. Later, three series of alkali-activated binders were studied, one based on Ground Granulated Blastfurnace Slag (GGBS), one based on Fly Ash (FA) and one based on a 50%GGBS-50%FA blend (50/50). The china clay waste was incorporated in selected optimum binders from the three series as aggregate to make mortars and concrete. Compared to control specimens, the test specimens using the china clay waste always showed lower strength. It is suggested that the high water demand of the waste is the main problem. When the waste was used in mortars, the impact of the water declined over time, with sand waste from china clay extraction showing approximately equivalent strength to the control silica based mortar after 6 months of curing for the GGBS and 50/50 series. For the same series, mica-waste specimens gave about 50% of the strength of the control mortar on the 7th day of curing but increased to 70-80% of the control compressive strength at 6 months. In the FA series, the impact of additional water resulted in very low strengths and that series did not proceed in concrete making. The concrete design was accompanied by an environmental analysis to ensure environmentally beneficial outcomes were obtained. Testing in compression shows a similar decreasing strength for the Portland and the alkali-activated series for increasing amounts of waste used. However, the test specimens of the GGBS series showed potential for replacing Portland control specimens. The potential for making blocks and tiles using the new concrete would be greater if the mix design is optimized. Durability testing will be required on an optimized design and final product, but initial analysis of test results and the literature indicate this is unlikely to be a concern. Not using the final product to run durability tests would lead to arbitrary conclusions. The environmental analysis shows that although the carbon emissions would be reduced using alkali-activated concrete, most of the other environmental impact categories would be affected negatively which has to be considered when making the final decision on whether to use this new material in the Eco-town or elsewhere.

Geosynthetic Clay Liners (GCLs) are an innovative construction material that has been developed over the last two and a half decades. As of recent times, various types of GCLs are used as composite contaminant barriers or as structural waterproofing in the construction industry. A factory controlled prehydration with cation exchange resisting polymer prior to installation is most desirable in hostile geochemical environments. This research investigated the need to retard the moisture loss in hostile thermal environments. The cffect of drying on the flexibility of the clay mat has been demonstrated in this thesis. When exposed to various thermal environments, the moisture content of the GCL can fall to such levels where it can become brittle at the stage of rolling out the liner prior to installation. A suitable improvement needed to be made in the manufacturing process to retard the moisture loss within the prehydrated GCL. With this in mind, the drying characteristic of clays has been revisited and a mathematical model to predict moisture change has been developed and is presented in this thesis. The development of the mathematical model has accounted for the factors controlling the moisture movement within the bentonite clay core for a range of temperature (20 - 40 'C) and relative humidity level (15 - 70%) for two different clay mats. Strong correlations between aforesaid parameter and drying characteristics were observed and are discussed in detail. The laboratory controlled drying observation were complemented and compared with 'on site' observation. The research contribution from the study includes: the establishment of an appropriate drying model; the laboratory evidence to show a strong correlation between the modified Brinell Hardness and the flexural stiffness for the clay mat; the laboratory information on the ductile to brittle transition of the clay mat during drying; the development of a quality control tester to assess the level of moisture in the GCL after manufacture as well as at the point of installation of the liner.

Construction growth has become a causal factor in economic competitiveness with rapid urbanisation. Consequently upstream businesses, such as cement and concrete manufacture, also expand. Sustainability balances economic, environmental and societal issues and although this philosophy is well developed in the European Union (EU), there seems to be less practical awareness amongst the ten countries in the Association of Southeast Asian Nations (ASEAN). This thesis investigates and compares the flow of key mineral-based components of national construction materials (cement, aggregates and concrete) from extraction to disposal in two case studies: Great Britain (EU) and Thailand (ASEAN), from the perspective of sustainable resource and waste management. The study considers material needs and wastes arising associated with future and expected demolition of residential accommodation, measured as national floor area including future concrete demand and concrete waste from national housing, as concrete is mostly used in the Thai residential sector. To compare the difference between the two national and continental strategies in more depth, it also identifies and evaluates policies and taxations influenced by EU regulation that enable Great Britain to achieve the highest rates of recycled aggregates (29%) and the 70% reuse and recycling rate of construction and demolition waste (C&D waste). Then, options for Thai policy integrally relating to construction materials and waste are developed using lessons learned from the EU and Great Britain. Material Flow Analysis (MFA) is used to combine results from both national cement and concrete industries, together with primary and recycled aggregates from the aggregate market made for annual concrete manufacturing in Great Britain, and primary aggregates only for Thailand. Government and manufacturing data for 2012 were used for calculating national cement production by chemical calcination. Then, all MFA outcomes (cement production, virgin and recyled aggregates including waste and emissions) of each nation are presented using Sankey diagrams. This research also considers national estimates of future and prospective demolition of floor area including future concrete demand and waste in the residential sector using Stock Dynamic Analysis (SDA) with Gross Domestic Product (GDP) to indicate demand. Great Britain with its 61.9 million and Thailand with 64.5 million inhabitants had quite similar populations in 2012. MFA results show that more than 30% of Thai cement and clinker were exported as cementitious products to ASEAN trading countries, in particular, which is double the annual amount of domestic cement used for concrete manufacturing in the whole of Great iii Britain. Moreover, the results also show that Thailand used six times more indigenous minerals for cement manufacturing and exporting than Great Britain. The 2012 Thai concrete stock is approximately 3.8 times (256.14 million tonnes: Mt) greater than Great Britain (67.73 Mt). For aggregates used for concrete production, Great Britain uses both primary (48.04 Mt) and recycled aggregates (5 Mt) while Thailand consumes only primary aggregates (214.66 Mt). The results of SDA show that Thailand uses a large amount of concrete for the housing sector presently due to a shorter lifetime of housing compared to Great Britain. Using 50 years of Thai housing lifespan to compare with Great Britain scenarios, concrete waste generation in Thailand will peak mostly around 2050. This period will produce a similar amount of concrete waste to a scenario of 100 years lifespan in Great Britain (2100). In addition to longer lifetime of housing, an increase in renovation activities and higher quality of housing construction like Great Britain can extend the time of demolition activities and can delay the problem of concrete waste that needs to be disposed of properly in Thailand. Thailand has no strategy for encouraging recycling of construction materials, with no registered data and no integrated sustainability policy. In the foreseeable future, Thailand may experience problems such as rapidly depleted resources and improper C&D waste management. In contrast, Great Britain has experience in managing C&D waste (particularly concrete waste) as well as conservative consumption of natural resources, involving environmental taxes with cement and associated natural resources used only within the country. Contractors are also encouraged to use recycled aggregates for construction activities, including producing new concrete following a standard from the British Standards Institute (BSI, BS EN 12620:2013 Aggregates for Concrete), with other supporting organisations such as the Mineral Products Association (MPA) and Waste Resource Action Programme (WRAP). However, with the above strategies, Great Britain still has not achieved the anticipated target of recycled aggregate use. Shortly, the ASEAN countries will form the ASEAN Economic Community (AEC) aiming to achieve a single market and production base. Therefore, there is an opportunity to report on cement and other material requirements and wastes in construction, including comparing awareness and performance of natural resources and waste management practices of two main trading regions. Capitalising on the experiences from the Great Britain case study to cope with rapid economic growth and societal change, this thesis gives some valuable insights into the use of appropriate tools for policy-makers that consider the construction industry and its raw materials including its waste management systems for Thai national policy but also other ASEAN countries.

No description available.

No description available.