Thesis (doctoral)--University of Canterbury, 1983.

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 184 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 145-157).

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (M.E.)--University of Canterbury, 2005. / Typescript (photocopy). Includes bibliographical references (leaves 222-228). Also available via the World Wide Web.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on August 7, 2009). Includes bibliographical references (p. 101-103).

Doctor of Philosophy / Department of Civil Engineering / Christopher A. Jones / Kyle A. Riding / Pumping is the most utilized placement technique to deliver fresh concrete from the concrete mixer to the formwork on construction site. Compared to other available placement methods, such as bucket-and-crane or conveyor belts, pumping offers superior placement rates while reducing the required labor cost. Despite the fact that concrete pumping has been utilized on job sites around the world since the early 1960s, there is still a lack of knowledge, supported by research evidence, as to what affects concrete pumpability and how pumping changes concrete properties both in the plastic and hardened state. A four-phase research study was carried out to: (1) improve the existing methodology of rheological characterization of the lubrication layer formed during pumping, (2) evaluate the effect of concrete mixture constituents and proportioning on rheological properties of concrete and the lubrication layer, (3) asses the effect of pumping and pumping pressure on concrete fresh properties and the air void system under controlled conditions, and (4) to evaluate the effect of pumping on concrete fresh properties and the air void system in the field conditions. In the first phase of this research program, a correction procedure was developed evaluating 3D flow at the bottom of the cylindrical concrete interface rheometer. Results showed that the correction procedure can be successfully used for characterization of lubrication layer properties, and that the bottom of the cylinder can cause measurement error of up to 10% depending on concrete rheological properties and the interface rheometer geometry. The second phase of this research program consisted of a laboratory study to evaluate rheological properties and properties of the lubrication layer of large variety of concrete mixtures. Considered mixture proportion variables included air void content, water-to-cement ratio, paste volume, fly ash replacement ratio, fine-to-coarse aggregate ratio, aggregate shape, use of viscosity-modifying admixture, and use of nano-clay particles. Results indicated that the changes in rheological properties of the lubrication due to mixture proportioning adjustments corresponded in most cases to changes of the bulk concrete rheological properties. In the third phase of the study, a full-scale controlled pumping experiment was conducted. During the experiment, three different concrete mixtures were pumped and both fresh and hardened properties of concrete were determined. Additionally, the pumping circuit was equipped with a system to monitor pumping pressures. The obtained results revealed that concrete pumping can significantly modify concrete fresh properties. Additionally, it was shown that changes in the fresh properties as well as in the concrete air void system are independent of applied concrete pressure. Finally, the forth phase of this research program consisted of field evaluation of concrete pumping. Six concrete bridge project sites were visited and concrete samples were collected before and after pumping. Analysis results indicated that the changes in concrete properties appear to be influenced not only by mixture characteristics but also by discharge conditions in the formwork.

Falsework is a temporary structure supporting the permanent structure while it is not self-supporting. Falsework is commonly required in concrete construction which involves a number of parties such as the design engineer, contractor, subcontractor, supplier and checking engineer. In the past, many failures occurred due to procedural inadequacy such as confusion in responsibility delineation and communication. In Hong Kong, during the last six years, at least eight major falsework collapses have been reported. Researchers studying falsework failures have devised models for analysis and prediction. However, procedural inadequacy has not been adequately considered and assessed in these models. Further, these models were mainly used to predict the likelihood of eventual failure at loading stage without evaluating the safety condition at various stages of falsework construction. The overall aim of this thesis was to develop a procedural framework that can be used to assess the proneness to failure at different stages of constructing falsework in Hong Kong, thus, warning can be given promptly.