The aim of this work was to use simulation as a tool to better understand areas of orthokinetic (shear-induced) aggregation which are still not well understood. These areas include aggregate structure, aggregate strength, breakup and restructuring and combined perikinetic/orthokinetic aggregation. Previous simulation studies were reviewed and it was concluded that the methodology of Chen and Doi (1989) was an appropriate starting point for this study. The modified simulation was validated by comparison with theoretical and experimental results. Orthokinetic aggregates were found to have a fractal structure with an estimated value of 1.65. Scaling exponents, which were shown to be indicative of fractal dimension, of 2.1-2.7 were also obtained. Flexible bonds allowed restructuring to occur which led to an increase in the co-ordination number, scaling exponent, aggregate strength and a reduction in aggregate size. Thus aggregate strength increases with fractal dimension. It was confirmed that both restructuring and breakup/reformation could lead to the formation of small, compact aggregates. The high shear conditions simulated favoured breakup/reformation, while restructuring was expected to dominate with more flexible bonds, possibly at lower shear rates. Taking some account of hydrodynamic interactions by the inclusion of Kirkwood-Riseman theory led to an increase in the compactness of the aggregates and the co-ordination numbers, as well as a decrease in size of the aggregates. The results showed that hydrodynamic interactions can not be ignored. The explanation for the dramatic effects was that particles/microflocs on the outer edges of the aggregates broke off and reformed in a more compact way. Erosion was found to dominate in all cases, thus supporting the theory that erosion dominates at higher fractal dimensions. The shearing range simulated was found to be relatively high (equivalent to &lt200s-1 for particles of 2-5??m), producing relatively small aggregates. Hence it is proposed that under high shear conditions, erosion dominates. It was shown by extension of the DLCA algorithmic restructuring work of Meakin and Jullien (1988, 1989) that the scattering patterns observed in gently sheared aggregating systems are consistent with the interpretation that the shearing causes partial restructuring at large length scales.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed February 4, 2008) Includes bibliographical references (p. 65-69).

Thesis (Ph. D.)--University of New South Wales, 2005. / Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: David W. Fowler. Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.S.)--Oregon State University, 1987. / Typescript (photocopy). Includes bibliographical references (leaves 135-139). Also available on the World Wide Web.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 1998 / Aggregate stiffness is known to influence the magnitude of creep of concrete. The purpose of this research project was to quantify the influence of aggregate stiffness on the measured and predicted long-term creep behaviour of plain concrete. Basic and total creep tests were conducted on concrete specimens of two different strength grades for each of three different commonly used South African aggregate types (quartzite, granite and andesite). In addition, elastic modulus tests Were conducted on cores of the aggregate types considered. The test results revealed that no correlation exists between the creep of concrete and the stiffness of the included aggregate. These results appear to be attributable to the stress-strain behaviour of the aggregate/paste interfacial zone, in the case of aggregates with an elastic modulus in excess of 70 GPa. The experimental basic and total creep values from this investigation were compared with those predicted for each mix at the corresponding ages by the BS 8110 (1985), ACI 209 (1992), AS 3600 (1988), CEB-FIP (1970), CEB-FIP (1978), CEB-FIP (1990) and the RILEM Model B3 (1995). This comparison indicated that the results predicted by each model vary widely and that no correlation exists between the magnitude of the aggregate stiffness and the creep strains predicted by each model. / MT2017

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 139-148).

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Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.