Compatibility of ultra high performance concrete as repair material : bond characterization with concrete under different loading scenarios

The rehabilitation of concrete structures, especially concrete bridge decks, is a major challenge for transportation agencies in the United States. Often, the most appropriate strategy to preserve or rehabilitate these structures is to provide some form of a protective coating or barrier. These surface treatments have typically been some form of polymer, asphalt, or low-permeability concrete, but the application of UHPC has shown promise for this application mainly due to its negligible permeability, but also as a result of its excellent mechanical properties, self-consolidating nature, rapid gain strength, and minimal creep and shrinkage characteristics. However, for widespread acceptance, durability and performance of the composite system must be fully understood, specifically the bond between UHPC and NSC often used in bridge decks. It is essential that the bond offers enough strength to resist the stress due to mechanical loading or thermal effects, while also maintaining an extended service-life performance. This report attempts to assess the bond strength between UHPC and NSC under different loading configurations. Different variables, such as roughness degree of the concrete substrates, age of bond, exposure to freeze-thaw cycles and wetting conditions of the concrete substrate, were included in this study. The combination of splitting tensile test with 0, 300, 600 and 900 freeze-thaw cycles was carried out to assess the bond performance under severe ambient conditions. The slant-shear test was utilized with different interface angles to provide a wide understanding of the bond performance under different combinations of compression and shear stresses. The pull-off test is the most accepted method to evaluate the bond strength in the field. This test which studies the direct tensile strength of the bond, the most severe loading condition, was used to provide data that can be correlated with the other tests that only can be used in the laboratory. The experimental program showed that the bond performance between UHPC and NSC is successful, as the strength regardless the different degree of roughness of the concrete substrate, the age of the composite specimens, the exposure to freeze-thaw cycles and the different loading configurations, is greater than that of concrete substrate and largely satisfies with ACI 546.3R-06.

Not your mother's Latinas : film representations for a new millennium

This dissertation seeks to contribute to film, feminist and Latino/a studies by exploring the construction and ideological implications of representations of Latinas in four recent, popular U.S. films: Girlfight (Kusama 2000), Maid in Manhattan (Wang 2002), Real Women Have Curves (Cardoso 2002) and Spanglish (Brooks 2004). These films were released following a time of tremendous growth in the population and the political and economic strength of the Latina/o community as well as a rise in popularity and visibility in the 1990s of entertainers like Selena and actresses such as Jennifer Lopez and Salma Hayek. Drawing on the critical concepts of hybridity, Latinidad, and Bakhtinian dialogism, I analyze these films from a cultural and historical perspective to consider whether and to what degree, assuming changes in the situation of Latinas/os in the 1990’s, representations of Latinas have also changed. Specifically, in this dissertation I consider the ways in which the terrain of the Latina body is articulated in these films in relation to competing societal, cultural and familial conflicts, focusing on the body as a site of struggle where relationships collide, interact and are negotiated. In this dissertation I argue that most of the representations of Latinas in these films defy easy categorization, featuring complex characters grappling with economic issues, intergenerational differences, abuse, mother-daughter relationships, notions of beauty, familial expectations and the very real tensions between Latina/o cultural beliefs and practices and the dominant Anglo culture of the United States. Specifically, I argue that narrative and visual representation of Latina bodies in these films reflects a change in the Latinas offered for consumption to film viewers, presenting us with what some critics have called ‘emergent’ Latinas: conflicted and multilayered representations that in some cases challenge dominant ideologies and offer new demonstrations of Latina agency.