Self-compacting concrete (SCC) can flow into place and compact under its own weight into a uniform void free mass even in areas of congested reinforcement. The research reported in this thesis examined the production of SCC with readily available UK materials, with the overall aims of evaluating test methods and establishing a suitable mix design procedure. There have been significant recent developments and applications of SCC in several countries, notably Japan. A literature survey gave an understanding of the advantages and properties of SCC, test methods and the range of constituent materials and their relative proportions for its successful production. A range of SCC mixes can be produced with the common features of a lower aggregate content than conventional concrete and the use of superplasticizers. Most mixes also contained one or more of pulverized fuel ash, ground granulated blast furnace slag and an inert powder filler. A four stage experimental programme was carried out: *tests on pastes to assess the effect of the types and proportions of the powders and superplasticizers on the rheology. *tests on mortars to determine suitable dosage of superplasticizers for high fluidity, low segregation and low loss of workability with time after mixing. Flow spread and funnel tests were used. *tests on fresh concrete to enable suitable types and quantities of coarse aggregate to be combined with these mortars to produce SCC. Fluidity and viscosity were measured using slump flow and V-funnel tests, and passing ability using L- and U-type tests. Two-point workability tests were also carried out, and a novel way of assessing segregation resistance was developed. *tests on hardened concrete to determine compressive strength, bond to reinforcement and drying shrinkage. A mix design procedure, based on a method suggested by Japanese workers, has been developed. This includes optimisation of the mix with a linear optimisation tool from a commercial spreadsheet package.

This thesis considers the tensile deformation characteristics of polypropylene fibre reinforced hardened cement paste having heterogeneous fibre geometries and a range of volume concentrations. Polypropylene fibres were prepared under various manufacturing conditions using a laboratory extruder, to ascertain the effect of these conditions on fibre characteristics. The relevant properties of cement paste likely to influence the polypropylene fibres and the eventual composite were investigated. An investigation of continuous aligned fibre composites in tension, containing various volume concentrations of fibres, showed that multiple cracking occurred despite the elastic modulus of the fibre being considerably lower than that of the hardened cement paste. Factors which enabled fibre/matrix contact to be maintained during the multiple cracking process, despite the unfavourable Poisson's ratio of polypropylene, were considered. Discontinuous aligned fibre composites were tested in tension, to ascertain the effect of volume concentration and length of fibres on the shear stress transfer between fibre and matrix and on multiple cracking. Composites containing parallel fibres, with fibre directions at varying angles to the direction of applied tensile stress, allowed an assessment to be made of the role of inclination. Crack distributions, pull-out behaviour of fibres and the ultimate stress of composites were investigated. Finally, random fibre reinforced composites were evaluated to provide a comparison with the Continuous, Discontinuous and Inclined fibre reinforced systems. In addition to determining the mechanical deformation of the various composites, the acoustic emission associated with internal deformation mechanisms was studied. This was undertaken with equipment capable of monitoring a range of acoustic pulse parameters.

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Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Carl T. Haas. Vita. Includes bibliographical references. Also available from UMI.

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A review of the previous work on the mechanics of vibratory conveying is given., It is found that several theoretical studies have been made in the past but the predictions of the theories and the comparisons of these' with experimental results have only been applicable to a very limited range of the relevant variables. In the present work, a theoretical analysis is described which enables the mean conveying velocity of a component on a conventional vibratory conveyor to be determined for'a wide range of the relevant variables. Since an alternative method of vibration is discussed, "conventional" refers' to vibratory conveyors which are commercially available. The results of this theory are compared with the results of experimental work conducted on apparatus specially designed for the purpose. Within practical limits, good agreement is obtained. From this work it is concluded that fundamental limitations eXist in conventional vibratory conveying, the most important of which are that the conveying velocity is very sensitive to changes in the coefficient of friction between the component and the track and for low coefficients of friction, the conveying velocity for steady conveying is inadequate. • A further analysis is then described which considers the mechanics of Vibratory conveying where a phase difference exists between the normal and parallel motions of the track, (known as "out of phase" conveying). Again, within certain limits, the new theory is in good agreement with experimental results. It is apparent from this work that with the correct phase relationship between the two components of vibration, definite practical advantages exist over conventional conveying. With "out of phase" conveying, the component velocity is virtually independent of the nature of the component and track materials and conveying velocities significantly higher than those obtainable on a conventional vibratory conveyor axe possible. Further, with this vibration system, components can be conveyed separately and without erratic motion up an inclined track. A practical method of obtaining an "out of phase" vibration on the track of a vibratory bowl feeder is suggested. The results of performance tests on two commercially available vibratory bowl feeders with conventional drives are presented and it is shown that in both cases their performance is very sensitive to changes in the bowl load. A method for reducing this effect by re-tuning the bowl spring support system is demonstrated. Some suggestions for improving the performance of conventional bowl feeders are discussed which include details of how the track angle, vibration. angle, track material and suspension spring stiffness should be determined.

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