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his investigation deals with the influence of hot and temperate curing environments on the hardened properties of concrete and mortar mixes. Condensed silica fume was blended with OPC as a potential alternative cementitious material to plain OPC for use in the hot Iraqi climate, in an attempt to find a cement combination that would overcome some of the durability problems experienced when using a plain OPC concrete in such an environment. Throughout the investigation two curing environments were used: the first simulating the UK temperate climate and the second simulating the hot Iraqi climate. Temperature and humidity were varied to simulate day and night time. The first stage of the experimental study was the development of a mix design method capable of producing an OPC-CSF cement concrete of a medium workability and a specific 28-days compressive strength ranging between 25 to 55 MPa, both with and without superplasticizer. Three grades of concrete strength were chosen (25,40 and 55 MPa) and the effect of four cement replacement levels (5,10,15 and 20%) of silica fume on concrete compressive strength was assessed. Test results showed that CSF was relatively more effective in lean mixes than in rich ones. Compressive strength of CSF concrete increased with increasing CSF percentages for both normal and superplasticized mixes up to an optimum levels of 10-15% and 15-20%, respectively. The amount of OPC (kg/m`3) necessary to bring a change in compressive strength of 1MPa was also determined and the theoritical blend proportions of OPC-CSF necessary to produce 28-day compressive strength equivalent to the plain OPC mixes were determined from the produced data above. The theoretical blend proportions were examined experimentally and the data were used to establish the relationship between strength and water/cementitious ratio for the blend mixes with and, without superplasticizer. Results showed that this basic relationship had changed quantitatively but not qualitatively when CSF was used. A cost study using current OPC and CSF material costs -was performed in an attempt to determine'the- most economic blend proportions. A total of eleven different concrete -mixes were selected to study the effect of curing environment (hot and temperate), initial curing time (0,1,3 and`-7 days) and curing method (water and polythene sheeting) on the compressive strength, permeability and absorption properties of the CSF concretes. Tests were carried out at 3,7, '14, 28,56,90 and 180 days of age. In addition five different mortar, mixes were used to examine the effect of curing environment (temperate and hot) an the *permeability, pore size distribution and durability to magnesium sulphate attack. Test results showed that hot Iraqi curing environment was favourable to the early-age strength, absorption and permeability of plain OPC mixes. However, - the later-age properties were significantly lower than those obtained for concretes cured in a temperate UK environment. For plain OPC mixes a critical curing period of 3 days was found under both temperate and hot environment. For the CSF blend mixes critical curing periods for the temperate and hot environment were found to be 3 and 1 day respectively. Results also reveal the importance of curing specimens immediately after casting for one day. Research work has also confirmed the superiority of water curing over polythene sheeting in a temperate environment for the rich plain OPC and CSF mixes. However, there was no significant difference between water and polythene for lean mixes. The reduction in , permeability and absorption properties of CSF mixes cured in a both temperate and hot environments is thought to be due to the changes in the pore structure brought about by the use of silica fume. Combining CSF with OPC was found to increase the percentages and volume of fine pores at the expense-of coarse pores. This effect may be described as a "refining" effect. Finally, the performance of CSF mortar mixes cured in a temperate and hot environment and their resistance to magnesium sulphate attack was significantly better than the plain OPC ones.

The present studies are concerned with the modelling of the manufacturing process of nitrocellulose-base propellant in which cellulose acetate is substituted as a model for the explosive nitrocellulose. An investigation of the inter-relationships between processing and rheological and morphological properties has been carried out on cellulose acetate doughs, using modified torque and capillary extrusion rheometers. Some of the doughs show a yield stress and behave as Herschel-Bulkley fluids. The yield stress is found to be smaller than that of nitrocellulose doughs, and there is some evidence of shear heating. Mixing time and mixing temperature showed no influence on the rheological parameters of the doughs. These results suggest that the change in rheological properties of propellant doughs is attributed to the change in crystallinity and fibrosity after processing. The rheological properties of doughs are greatly affected by extrusion temperature, solvent, plasticiser and filler content. The interaction between the solvents and plasticisers with cellulose acetate was explained by adopting a model consisting of a rigid backbone chain from which protruded flexible side groups. In good solvents these side groups extend causing interactions between molecules, giving rise to dough up and elasticity. In poor solvents, dough up becomes difficult and the elasticity is low because the flexible side groups retract towards the stiff backbone chain. The morphology of solvated doughs is examined using solution viscometry, infrared spectroscopy, scanning electron microscope, differential scanning calorimetry, x-ray diffraction and dynamic mechanical thermal analysis. All these techniques showed that the solvation process had no significant effect on the molecular architecture of the cellulose acetate, in which the original crystallinity of the material is low. From this it was concluded that changes in the rheological properties of nitrocellulose doughs as a function of the process variables was due to changes induced in the crystallites rather than in the amorphous regions.

Ideally, asphalt pavements are designed to achieve sufficient stiffness prior to the application of traffic to resist rutting while also maintaining enough flexibility after years of service to minimize the amount of durability/brittleness related distresses (e.g. cracking and weathering). Multiple factors have caused an industry transition to mixes which are much more susceptible to crack, and durability related distresses are often the primary mechanism by which pavements fail. To restore a balance between rutting and durability distresses in asphalt pavements, the industry has started investigating balanced mix designs (BMDs). While mitigating only rutting or cracking behaviors is a straightforward exercise based on the collection of knowledge, simultaneously considering the two types of distresses is challenging considering that rutting is an early life distress and durability distresses are not typically observed until longer term aging has occurred. Mixture conditioning protocols to simulate field aging in conjunction with tests to fairly evaluate mixture integrity after conditioning are needed to scrutinize asphalt mixtures for durability related distresses during the mixture design phase. The current longer term conditioning protocol (R30) adopted by the American Association of State Highway and Transportation Officials (AASHTO) is not as severe as suggested when considering durability/brittleness (Isola et al. 2014; Yin et al. 2016; Cox et al. 2017). This dissertation’s primary objective is to provide guidance on asphalt mixture aging by contributing in four areas: 1) ensuring proper density measurement of field aged cores, 2) provide guidance on increased short term aging time effects in asphalt mixtures, 3) suggest improved mixture conditioning protocols to simulate longer term field aging, and 4) make suggestions for improving binder conditioning protocols to simulate longer term field aging. To these ends, a series of mixture and extracted binder tests were conducted on materials that were used to construct a full-scale test section in Columbus, MS that was monitored for aging for up to 5 after construction. The overall work presented provides simple recommendations or protocols which have the potential to improve the level of scrutiny that can be given to paving materials during the mix design phase and thus improve overall pavement performance.

Call number: LD2668 .T4 1959 F62

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Crack Attenuating Mix (CAM) is relatively a new asphalt mixture type used by the Texas Department of Transportation (TxDOT). These mixtures are fine graded, designed using relatively small stone sized aggregates and screenings with a high asphalt content, specifically for retarding the reflective cracking in thin asphalt overlays without sacrificing rutting resistance. The main goal of this study is to promote the use of local aggregates in CAM design. In order to achieve the goal, the development of a mix design procedure and aggregate quality guidelines for CAM design with local aggregates are essential. Several aggregate sources were identified and characterized in terms of their frictional, strength, and durability properties. A refined mix design procedure is recommended using a Superpave gyratory compactor with the capability to measure shear stress during compaction. The emphasis was on preventing rutting and flushing resulting from overfilling of binder in these mixtures, which was observed during compaction by consistent shear failures. The Hamburg Wheel Tracking Device (HWTD) was used for performance evaluation of rutting, whereas the Overlay Tester (OT) was used for cracking evaluation. It is hypothesized that current performance criteria in terms of HWTD and OT are too severe for being applicable to CAM mixes with local aggregates. A modification in HWTD failure criterion is recommended and is used in developing new aggregate guidelines. A correlation analysis was conducted relating aggregate properties and CAM performance in rutting and cracking. Finally, aggregate quality guidelines were developed for CAM using local aggregates based on the correlation study. The mix design recommendations as well as aggregate guidelines and quality criteria provided in the report are based on laboratory investigations and field validation of these is strongly recommended before implementation. / text

Studying the effectiveness of environmental policies is of primary importance to address the unsustainable use of resources that threatens the entire society. Thus, the aim of this paper is to investigate on the effectiveness of environmental policy instruments to decouple waste generation and landfilling from economic growth. In order to do so, the paper analyzes the case study of the Slovakian municipality of Palarikovo, which has drastically improved its waste management system between 2000 and 2012, through the utilization of differentiated waste taxes and awareness-raising and education campaigns, as well as targeting increased recycling and municipal composting. We find evidence of absolute decoupling for landfilled waste and waste generation, the latter being more limited in time and magnitude. These policy instruments could therefore play an important role in municipalities that are still lagging behind in waste management. More specifically, this policy mix was effective in moving away from landfilling, initiating recycling systems, and to some extent decreasing waste generation. Yet, a more explicit focus on waste prevention will be needed to address the entirety of the problem effectively. (author's abstract)

The University of Manchester, PhD by Published Work, 2018 For several reasons, small and medium enterprises (SMEs) are an important group of firms. In most market economies SMEs contribute significantly to wealth and job creation, economic growth, and product and service innovation. At the same time, SMEs are said to produce environmental impacts that are significant and that need managing and regulating. Their importance, from an economic and environmental perspective, is reflected in the fact that SMEs have become an established subject for research, with a distinct area of analysis focusing on how they manage their environmental impacts. Despite considerable interest in this area, aspects of their behaviour are in need of further examination, for there are still misunderstandings and gaps in knowledge. An area where gaps exist is how SMEs respond to different forms of environmental regulation (e.g., command-based or market-based approaches) and different forms of regulatory pressure (e.g., such as those pressures from civil society that might induce compliance-related activities or market forces that might flow through, and affect, the value chain). Why the gaps? On the one hand, and generally speaking, a common claim among those who have considered issues affecting smaller firms is that regulation is an important driver of environmental behaviour. There is a well-documented set of linked claims and empirical findings that smaller firms tend to be motivated by compliance with regulatory standards, yet owing to their scarce resources can find themselves hovering on the edge of compliance. Typically, SMEs will attempt to do no more than the law requires of them. They tend not, as it were, to go beyond compliance. Of course, this is an important observation - one that might say much, even if indirectly, about the motivations and intentions of smaller firms. It might indicate that SMEs, rather than addressing environmental issues, are more concerned with making cost savings and efficiency gains, or with satisfying the requirements of customers over such matters as product or service quality and delivery. While significant, there are at least three reasons why this view remains incomplete as an explanation for the interaction between SMEs, regulation and the environment. Firstly, this view tends to over-homogenise smaller firms. By treating them as a standardized group, the inference is that SMEs view and respond to regulation - i.e., they are all driven by regulation - in a broadly similar way. Secondly, it says little about how and why regulation drives behaviour. Claiming that regulation drives behaviour is helpful, but the claim is unduly narrow and leaves several important questions. In what ways does regulation drive behaviour? Does regulation drive all smaller firms in the same way? Thirdly, and finally, it suggests that different forms of regulation drive SME behaviour and that different forms of regulation drive this behaviour in broadly similar ways. That is, it is incomplete as it lacks appreciation of the widening scope of regulation and governance, and the nature of smart mixes of regulation. It fails to properly consider whether and how SMEs might respond differently to command-based regulation, market- or information-based measures, or self- or so-called civil regulatory pressures. On the other hand, and again in general terms, while those who have examined regulation have looked at how it can influence firms, they have tended to pay too little regard to how firms of different size may respond to different approaches or to how the factors and characteristics relating to size may shape the effectiveness of regulation. SMEs particularly are often discussed as an unusual sideshow that might raise different issues in relation, say, to the impacts of regulation on performance or innovation. That we often pay too little regard to how firms of different size may respond raises difficulties, particularly given our increasing understanding that there is no guarantee that a particular instrument will work in all situations. In other words, we are becoming more aware of the fact that the effectiveness or ineffectiveness of regulation is likely to be context-sensitive, and that the size of the enterprise is likely to be an important determinant of context. This thesis does take, and provides evidence for, the view that the organisational context is crucial to understanding how regulation functions. The thesis does not claim to provide all answers, but it does adopt the position that, in aggregate terms, a firm's size, or the factors that can be associated with size (e.g., resources, skills, knowledge, visibility, profile, stakeholder relations), and related factors concerning a firm's mind-set, can affect two things; first, the types of regulatory influences that may affect organizational behaviour and, second, how firms will respond to those influences. By focusing on SMEs, the thesis in some ways reinforces the dominant view that regulation is a driver of behaviour. Nevertheless, it goes much farther than this by showing, both theoretically and empirically, that there are important differences across SMEs and that these differences determine how and why they respond to regulation. It extends the common view by showing how SMEs differ not only in terms of the types of regulatory influences that shape their behaviour, but also in terms of how they react to these different influences. The emerging picture thus shows that the responses of firms are determined by their particular characteristics. The term used in this thesis is 'receptive capacity', which is shown to be a composite measure that includes the capabilities (e.g., resources, skills, knowledge) and orientations (e.g., views) of firms. It is suggested here that the range of receptive capacities across firms is enormous, since no two firms will be identical. Yet, it is argued - and demonstrated - that firms can be grouped according to certain identifiable characteristics, and that these groups of firms will respond to regulatory pressures in broadly similar ways; that is, there are groups of firms that have broadly similar resources and broadly similar worldviews. Thus, as well as suggesting that differences can be found at the micro level, it is demonstrated that there are sufficient commonalities across some firms that we can understand them as groups - groups of individual firms with some common characteristics. In conclusion, it is the differences across firms that provide us with a more sophisticated view of how SMEs are influenced by, and respond to, regulation. It is the nature of differences that is the main contribution of this research to both the fields of regulation and organisational and management studies. It is suggested finally that these differences have implications for how we design regulation, for how we may expect regulation to work or indeed not work, and for issues such as regulatory complexity and smart mixes.