Thesis (M.S.)--Missouri University of Science and Technology, 2008. / Appendix included as 690 pages at end of thesis. Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 8, 2009) Includes bibliographical references (p. 133-138).

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Kurtis, Kimberly E., Committee Co-Chair ; Kahn, Lawrence F., Committee Co-Chair ; Lai, James S., Committee Member ; Gokhale, Arun M., Committee Member ; Castrodale, Reid W., Committee Member. Vita.

Title from title page (April 27, 2010) Graduate School of Engineering. Dept. of Civil and Environmental Engineering. Includes bibliographical references (p. 293-297).

Thesis (M.S. in civil engineering)--Washington State University, August 2006. / Includes bibliographical references (p. 157-167).

Foamed concrete is produced when a foaming agent IS added to cement-based slurry consisting of cement, water, cement extender and filler. This lightweight building material can contribute significantly to uplift disadvantaged communities when used during the development of infrastructure. To achieve this goal, in depth research into the structural properties of the material is essential. Since 1992 tests to determine structural properties of foamed concrete have been conducted at the University of Pretoria. The results show that the compressive strength of foamed concrete is a function of age, ash/cement ratio and porosity and for a given porosity and age there is an optimum ash content, resulting in the maximum compressive strength. The focus of this research is therefore on foamed concrete mixtures with target densities varying between 700 kg/m3 and 1500 kg/m3 where the question that needed to be answered is: what is the influence of the microstructure on the physical and structural properties of these mixtures? The study is restricted to the effect of the microstructure on the relation between the physical properties (such as density, ash/cement ratio and porosity), and the structural property (compressive strength) of foamed concrete. In order to evaluate the influence of the microstructure on these relationships it was necessary to develop parameters to explain and quantify the microstructure of foamed concrete. An image processing and analysis system was applied to develop the air-void size distribution parameters and the air-void spacing parameters. These parameters were used to represent the microstructure (entrained air-void structure) of the foamed concrete mixtures. It was therefore now possible to plot graphs showing the effect of the microstructure on the physical and structural properties of foamed concrete. It was established that the 28-day dry densities have an influence on the air-void size distribution. In turn the air-void size distribution has an influence on the average % porosities and 28-day compressive strength of foamed concrete. The 28-day dry densities have no influence on the spacing of air-voids and in turn the spacing of the air-voids does not have any influence on the average % porosity and 28-day compressive strength. / Dissertation (M Eng ( Structural Engineering))--University of Pretoria, 2007. / Civil Engineering / unrestricted

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Master of Science / Department of Civil Engineering / Asadollah Esmaeily / Reinforced concrete exceptional durability is a major reason why it is the most popular structural material in many infrastructures around the world. Most concrete structures serve for several decades; therefore problems of concrete durability gradually arise. To insure that concrete structures perform functionally, it is necessary to maintain and inspect them regularly. The durability of the reinforced concrete structures generally depends on four major factors: structure design and construction, maintenance, concrete aggregates, and environmental conditions. The most common causes of concrete deterioration are carbonation, design and construction errors, alkali-aggregate reactions, freeze-thaw cycles, and corrosion. Each type of concrete deterioration has its own signs and characteristics. Choosing the best repair technique to address concrete deterioration requires specific analysis and tests to find the cause of the deterioration and the extent of the damage. This study analyzes concrete structures inspection techniques to recognize the source of the problem and the part of the structure which has been affected. Choosing the most proper repair and strengthening techniques to prevent the structure from getting exposed to any further environmental and chemical are the next steps.

The effects of the variability in strength and loading on the reliability of slender, reinforced concrete columns are investigated using the Monte Carlo simulation technique. The columns are considered to be axially loaded with equal end eccentricities and no lateral load. Variabilities in strength, axial load and eccentricity of axial loads are considered. A new procedure called the Implicit Uncorrelation Procedure has been developed to find the values of the failure function from the values of the basic variables named above. The allowable axial load at various eccentricity levels corresponding to a probability of failure of one in one hundred thousand has been found for three different cross sections. Seven different slenderness ratios are considered for each cross section. The results are compared with those obtained by following the code procedures outlined in CAN3-A23.3-M77 and CSA-A23.3 (1984). A change in the performance factor for moment magnification, ⌀m , (as given in CSA-A23.3 (1984)) is recommended in order to obtain a more accurate and consistent level of reliability in the design of slender reinforced concrete columns. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Concrete used in pavements has to be durable to withstand the load and wear imposed by vehicles moving across it and the effects of drying shrinkage and thermal changes. Failure of the pavement by either excessive cracking or degradation of the surface results in poor riding quality and low skid resistance. The inclusion of Pulverised Fuel Ash (PFA), otherwise known as fly ash, generally improves the quality of pavement concrete and thus extends its useful life. The PFA used for the thesis was from the Lethabo power station's second electrostatic precipitator field (Lethabo Field 2 PFA). This Field 2 PFA has a very close resemblance to the expected classified commercial Lethabo PFA of the future. PFA is characterised by its fineness. The Field 2 PFA had 7.7 percent retained on the 45 micron sieve. This was considerably finer than the current commercial Matla PFA with about 12 percent retained. It was thus expected that the higher quality Lethabo Field 2 PFA could be used to produce higher quality concrete. The other mix materials were those commonly used in the Western Cape. The aggregates used were Cape Flats Dune sand and Malmesbury shale (hornfels). The dune sand typically has very little fines content, causing severe bleeding problems in normal concrete mixes. The crushed coarse aggregate was 13 mm and flaky in shape. Ordinary Portland cement (OPC) was obtained from the De Hoek cement factory. The investigation was carried out in two parts. First was the development of a wide range of mixes, varying 28 day design strength (10, 20, 30, 40, 50 MPa), percentage of PFA as part cement replacement (OPC only, 15% PFA, 30% PFA, 50% PFA and 70% PFA) and the coarse aggregate content to give under-, average- and over-sanded mixes. Over this wide range of mixes, the fresh properties and development of the compressive strength were observed. Secondly, properties affecting pavement quality concrete were observed on a similar range of mixes. These properties were flexural strength, surface wear resistance by wire brush, sand blasting and ball race abrasion and the drying shrinkage.

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