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The use of reinforcing bar (rebar) anchored with resin is a common method of rock support in both hard and soft rock mining. The average bond strength, or the load that the support can sustain for a linear length of bond to the rock, is typically determined through a series of pull tests. The average value of bond strength varies widely, since it is dependent on in-situ rock properties and environment. It is an important value because it allows mine engineers to select the appropriate length and pattern spacing of installation for the support. When a stiff support, like resin-anchored rebar, is placed in a weak, soft material, such as potash, the average bond strength tends to be lower in magnitude than for a typical hard rock installation. This research was primarily aimed at determining the failure mechanism, in soft rock applications, by which the support loses adhesion and begins to fail by sliding. Results of field pull testing determined that the resin-rock bond strength was the limiting factor controlling when adhesion loss occurred. This study investigated how the bond strength may vary given a number of variables typically found in a potash mine environment. Results reported from testing did not indicate variation in the bond strength of resin anchored rebar, significant for mining applications, given changes in resin cure time, vicinity to active mining areas, or the rock type to which the resin was adjacent. Using the results of laboratory and field testing, an equation was developed to estimate load on in-situ resin anchored rebar given deformation measurements taken from the field. This equation will help determine safe limits for fracture separations opening in the backs of potash drifts. Investigating the behaviour of resin anchored rebar in potash may lead to methods to improve bond strength and calculation of factors of safety for patterned ground support.

Deterioration of reinforced concrete structures due primarily to chloride induced corrosion of plain carbon-steel reinforcement is a widespread problem, particularly in areas close to marine environments and where de-icing salts are used to keep roadways clear of ice. Replacing plain carbon-steel rebar with highly corrosion resistant stainless steel rebar has been shown to greatly increase the lifespan of concrete structures in harsh environments, and yields favourable life-cycle costs despite high initial costs. In attempt to lower stainless steel rebar’s initial cost of processing, this research compared its corrosion resistance in the pickled (mill scale removed) and as-rolled (mill scale intact) surface conditions. Rebar was embedded in highly-chloride contaminated concrete, and corrosion performance between the two surface types was compared in order to determine if conventional pickling of stainless steel rebar is necessary. A second part of this research addressed possible concern of reduced corrosion resistance of pickled stainless steel rebar in concrete exposed to chlorides when subjected to dynamic loading due to micro-motion at the concrete/crack interface. It was concluded that as-rolled stainless steel rebar in aggressive environments would provide sufficient corrosion resistance for the 75 year lifespan currently specified by the Canadian Bridge Code (CAN/CSA-S6-06, 2006), however it is recommended that monitoring of these specimens be continued to ensure high corrosion rates and/or concrete cracking do not develop. As well, investigation into the effects crevice corrosion cells found in typical concrete structures could have on as-rolled stainless steel rebar’s corrosion resistance should be undertaken. With regard to loading conditions, no significant evidence was found suggesting that pickled stainless steel rebar has reduced corrosion resistance when loaded dynamically versus statically. Therefore pickled stainless steel rebar is recommended for use in dynamically loaded concrete structures if others factors permit. However, the higher electrochemical noise measured during cyclic loading suggests that corrosion behaviour could be influenced largely by frequency of loading, and so further study should be undertaken for applications involving more extreme cyclic loading conditions than those used in this experiment.

Corrosion of carbon (black) steel reinforcing bars (rebar) is the major cause of damage and deterioration of reinforced concrete structures in maritime regions and in climates where de-icing salts are used. The cause of the corrosion is diffusion of chloride ions to the steel surface through the concrete in which it is placed. The bars are naturally passivated by the high pH of concrete interstitial pore fluid, and will not corrode in chloride-free concrete. Chloride ions break down the passive film, allowing dissolution of the steel. Corrosion of reinforcing steel drastically reduces the service lives of concrete structures. Where chlorides can not be avoided, stainless steel is becoming increasingly popular as an alternative reinforcing material. Stainless steel is able to withstand greater concentrations of chlorides, extending the service lives of structure in which they are placed. Due to high initial cost, stainless steel is often avoided in the design of new structures. In order to reduce the cost of stainless rebar, it has been proposed that the standard process of abrasive blasting and pickling of the steels not be performed, as these steps are mainly used to restore a bright and shiny surface, a quality not required for steels embedded in concrete. AISI 304LN, AISI 316LN and 2205 duplex stainless steels were tested with pickled surfaces as well as with mill-scale intact (as-rolled) in order to determine the affect of pickling vs. not pickling on the corrosion behaviour of the steels. Steels were tested in solutions simulating concrete interstitial pore fluid containing from 0 to 16% Cl- by mass of solution, simulating cement paste with 0 to 7.5% Cl- by mass of cement, which is near the solubility limit of Cl- in pore fluid. Steels were also tested in thin mortar shells, with Cl- ions being rapidly diffused to the surface due to an applied potential gradient. The microcell corrosion performance of the as-rolled steels was slightly worse than that of pickled steels; however, the corrosion rates of the as-rolled steels at 16% Cl- in pore fluid are near 3 µm/year, while black steel is normally observed to be actively corroding at 10 µm/year in cement containing as low as 0.1% Cl- by mass of cement, or 0.2% Cl- by mass of solution. No significant difference was observed between different grades of stainless steel in either the as-rolled or pickled conditions. As-rolled stainless steels exhibited poor pitting resistance when an anodic potential is applied, but the corrosion occurs at potentials much higher than experienced in service and at Cl- concentrations far greater than that needed to initiate corrosion on black steel; the time required to reach these higher Cl- levels would allow for maintenance free service long enough to justify the cost of as-rolled stainless steel over black steel. The Canadian Highway Bridge Design Code, CSA S6-06, specifies that reinforced concrete bridges should meet a service life of 75 years. It is concluded that, given the time required for concentrated chlorides to accumulate at the steel, the stainless steel rebar in the as-rolled condition would allow reinforced concrete structures to reach the specified service life, as long as care is taken to avoid contamination of the steel/surface by black steel from handling, or by secondary phases within the steel, Cr23C6 and MnS in particular.

Deterioration of reinforced concrete structures due primarily to chloride induced corrosion of plain carbon-steel reinforcement is a widespread problem, particularly in areas close to marine environments and where de-icing salts are used to keep roadways clear of ice. Replacing plain carbon-steel rebar with highly corrosion resistant stainless steel rebar has been shown to greatly increase the lifespan of concrete structures in harsh environments, and yields favourable life-cycle costs despite high initial costs. In attempt to lower stainless steel rebar’s initial cost of processing, this research compared its corrosion resistance in the pickled (mill scale removed) and as-rolled (mill scale intact) surface conditions. Rebar was embedded in highly-chloride contaminated concrete, and corrosion performance between the two surface types was compared in order to determine if conventional pickling of stainless steel rebar is necessary. A second part of this research addressed possible concern of reduced corrosion resistance of pickled stainless steel rebar in concrete exposed to chlorides when subjected to dynamic loading due to micro-motion at the concrete/crack interface. It was concluded that as-rolled stainless steel rebar in aggressive environments would provide sufficient corrosion resistance for the 75 year lifespan currently specified by the Canadian Bridge Code (CAN/CSA-S6-06, 2006), however it is recommended that monitoring of these specimens be continued to ensure high corrosion rates and/or concrete cracking do not develop. As well, investigation into the effects crevice corrosion cells found in typical concrete structures could have on as-rolled stainless steel rebar’s corrosion resistance should be undertaken. With regard to loading conditions, no significant evidence was found suggesting that pickled stainless steel rebar has reduced corrosion resistance when loaded dynamically versus statically. Therefore pickled stainless steel rebar is recommended for use in dynamically loaded concrete structures if others factors permit. However, the higher electrochemical noise measured during cyclic loading suggests that corrosion behaviour could be influenced largely by frequency of loading, and so further study should be undertaken for applications involving more extreme cyclic loading conditions than those used in this experiment.

Corrosion of carbon (black) steel reinforcing bars (rebar) is the major cause of damage and deterioration of reinforced concrete structures in maritime regions and in climates where de-icing salts are used. The cause of the corrosion is diffusion of chloride ions to the steel surface through the concrete in which it is placed. The bars are naturally passivated by the high pH of concrete interstitial pore fluid, and will not corrode in chloride-free concrete. Chloride ions break down the passive film, allowing dissolution of the steel. Corrosion of reinforcing steel drastically reduces the service lives of concrete structures. Where chlorides can not be avoided, stainless steel is becoming increasingly popular as an alternative reinforcing material. Stainless steel is able to withstand greater concentrations of chlorides, extending the service lives of structure in which they are placed. Due to high initial cost, stainless steel is often avoided in the design of new structures. In order to reduce the cost of stainless rebar, it has been proposed that the standard process of abrasive blasting and pickling of the steels not be performed, as these steps are mainly used to restore a bright and shiny surface, a quality not required for steels embedded in concrete. AISI 304LN, AISI 316LN and 2205 duplex stainless steels were tested with pickled surfaces as well as with mill-scale intact (as-rolled) in order to determine the affect of pickling vs. not pickling on the corrosion behaviour of the steels. Steels were tested in solutions simulating concrete interstitial pore fluid containing from 0 to 16% Cl- by mass of solution, simulating cement paste with 0 to 7.5% Cl- by mass of cement, which is near the solubility limit of Cl- in pore fluid. Steels were also tested in thin mortar shells, with Cl- ions being rapidly diffused to the surface due to an applied potential gradient. The microcell corrosion performance of the as-rolled steels was slightly worse than that of pickled steels; however, the corrosion rates of the as-rolled steels at 16% Cl- in pore fluid are near 3 µm/year, while black steel is normally observed to be actively corroding at 10 µm/year in cement containing as low as 0.1% Cl- by mass of cement, or 0.2% Cl- by mass of solution. No significant difference was observed between different grades of stainless steel in either the as-rolled or pickled conditions. As-rolled stainless steels exhibited poor pitting resistance when an anodic potential is applied, but the corrosion occurs at potentials much higher than experienced in service and at Cl- concentrations far greater than that needed to initiate corrosion on black steel; the time required to reach these higher Cl- levels would allow for maintenance free service long enough to justify the cost of as-rolled stainless steel over black steel. The Canadian Highway Bridge Design Code, CSA S6-06, specifies that reinforced concrete bridges should meet a service life of 75 years. It is concluded that, given the time required for concentrated chlorides to accumulate at the steel, the stainless steel rebar in the as-rolled condition would allow reinforced concrete structures to reach the specified service life, as long as care is taken to avoid contamination of the steel/surface by black steel from handling, or by secondary phases within the steel, Cr23C6 and MnS in particular.

No description available.

Master of Science / Department of Architectural Engineering / Kimberly W. Kramer / Recent years have witnessed the advent of many innovative materials to the construction industry. These materials often offer benefits to the projects on which they are used, but only if they are utilized in the proper applications. Among these new materials is high-strength reinforcing steel for use in reinforced concrete structural elements. This material is not new from the perspective of chemical composition, but rather the applications that it is being selected for. The following paper details the evaluation of the use of high-strength steel reinforcement in the design of reinforced concrete tilt-up panels and compares those designs to that of standard strength reinforcement. For the purpose of this study, standard strength is defined as reinforcement having a tensile yield stress of 60ksi while high-strength reinforcement refers to reinforcing steel with a tensile yield stress of 80ksi. 120 panels are designed for both high-strength and standard strength reinforcement, and the resulting steel spacings are compared. This study provides data from which designers and contractors can improve their ability to provide quality tilt-up panel designs.

This research explores the use of carbon/epoxy and fiberglass/epoxy fiber-reinforced polymer (FRP) composite rebar manufactured on a three-dimensional braiding machine for use as reinforcement in concrete beams under four-point bending loads. Multiple tows of prepreg composite fibers were pulled to form a unidirectional core. The core was consolidated with spirally wound Kevlar fibers which were designed to also act as ribs to increase pullout strength. The rebar was cured at 121â—¦C (250â—¦F) in an inline oven while keeping tension on the fibers. Five configurations of reinforcing bars were used in this study as reinforcement in concrete beam specimens: carbon/epoxy rebar and fiberglass/epoxy rebar were manufactured on the three-dimensional braiding machine and cured in an inline oven while still under tension immediately after production; carbon/epoxy rebar was manufactured by IsoTruss industries on the three-dimensional braiding machine and was rolled and stored before curing; fiberglass/epoxy rebar was purchased from American Fiberglass; conventional No. 4 steel rebar was also purchased. All bars were embedded in 152 cm (60 in) long, 11 cm (4.5 in) wide, and 15 cm (6.0 in) tall concrete beams. Beams were tested under four-point bending loads after which three 30 cm (12 in) specimens were taken from the ends of each configuration to be tested under axial compression loads in order to investigate the effects of the concrete voids on the concrete strength. Concrete beams reinforced with BYU glass/epoxy rebar manufactured on the three-dimensional braiding machine exhibited 5% greater compression bending stress and 11% greater tension bending stress than concrete beams reinforced with industry manufactured glass/epoxy rebar. Concrete beams reinforced with BYU carbon/epoxy rebar manufactured on the three-dimensional braiding machine exhibited 18% lower compression bending stress and 64% lower tension bending stress than concrete beams reinforced with industry manufactured carbon/epoxy rebar. BYU glass/epoxy rebar has a 3% greater stiffness and 1% greater displacement than industry manufactured glass/epoxy rebar and BYU carbon/epoxy rebar has a 40% greater bending stiffness and 19% lower displacement than industry carbon/epoxy rebar. BYU carbon/epoxy rebar has 49% lower compression bending stress, 1% lower tension bending stress, 28% lower displacement, and a 68% greater bending stiffness than BYU glass/epoxy rebar. BYU glass/epoxy rebar has 38% greater compression bending stress, 30% lower tension bending stress, 26% greater center displacement, and a 105% lower bending stiffness than conventional steel. BYU carbon/epoxy rebar has 8% lower compression bending stress, 31% lower tension bending stress, and 22% lower bending stiffness than steel. The deflections of steel reinforced concrete and BYU carbon/epoxy reinforced concrete are comparable with steel rebar displaying a 1% greater center displacement than BYU carbon/epoxy rebar.

Media industry has been through various changes in past two decades due to technological advancement, merger and acquisition. Also, privatization and de-regulation took places throughout of 1980s, which has caused various changes and provided opportunities for the media industries. This thesis aims to find out the financial performance of two media companies in Taiwan whilst such changes and opportunities took place and also to highlight whether so call “synergy” created through diversification, mergers and acquisitions provides real financial incentives and whether public interests are the sacrifice of such financial incentives and highlight the legal framework which affects the media industry in Taiwan. The media industry covers a wide range of businesses, it is almost everything we live with; technological changes made the boundaries between media blurry and common trend of convergence occurred and this has a strong social impact of who is really controlling the information that is provided through the different media. Therefore, the analysis of content control in the media industry will be evaluated with reference to the theories of public interests. Furthermore, conglomeration becomes a phenomenon from 1990’s when many industries consolidated in the economic downturns. Especially, in the USA and Europe, media industries were soon riding the wave of the phenomenon from more than a hundred companies reduced to less than a handful of the gigantic big six media corporations. On the other hand, Taiwan’s media companies are also dominated by a few big business conglomerates and two of them have substantial business interests in the media industry. The two media companies under the two biggest conglomerates in Taiwan are chosen to examine their financial performance and using statistical tool to forecast its key ratios. Keywords Media industry, Synergy, Public interests, Conglomerates, Convergence, Social impact, Business integration, media regulation, Media democracy, global media.