In-situ Molibdenum X-ray powder diffraction study of the early hydration of cementitious systems on a humidity chamber

The durability of cement-based construction materials depends on the environmental conditions during their service life. A further factor is the microstructure of the cement bulk, established by formation of cement hydrates. The development of the phases and microstructure under given conditions is responsible of the high strength of cementitious materials. The investigation on the early hydration behavior of cements and cementing systems has been for a long time a very important area of research: understanding the chemical reactions that lead to hardening is fundamental for the prediction of performances and durability of the materials. The production of 1 ton of Ordinary Portland Cement, OPC, releases into the atmosphere ~0.97 tons of CO2. This implies that the overall CO2 emissions from the cement industry are 6% of all anthropogenic carbon dioxide. An alternative to reduce the CO2 footprint consists on the development of eco-cements composed by less calcite demanding phases, such as belite and ye'elimite. That is the case of Belite-Ye’elimite cements (BY). Since the reactivity of belite is not quick enough, these materials develop low mechanical strengths at intermediate hydration ages. A possible solution to this problem goes through the production of cements which jointly contain alite with the two previously mentioned phases, named as Belite-Alite-Ye’elimite (BAY) cements. The reaction of alite and ye'elimite with water will develop cements with high mechanical strengths at early ages, while belite will contribute to later values. The final goal is to understand the hydration mechanisms of a variety of cementing systems (OPC, BAY and pure phases) as a function of water content, superplasticizer additives and type and content of sulfate source. In order to do so, in-situ laboratory humidity chambers with Molybdenum X-ray Powder diffraction are employed. In the first 2h of hydration, reaction degree (α) of ye'elimite had been decreased for superplasticizer.

Mapping the Liminal Experience of Eastern Europe in Selected American Works, 1965-2002

The purpose of this dissertation is to study literary representations of Eastern Europe in the works of celebrated and less-known American authors, who visited and narrated the region between the mid-1960s and early 2000s. The main critical body focuses on Eastern Europe before 1989 and encompasses three major voices of American literature: John Updike, Joyce Carol Oates, and Philip Roth. However, in the last chapter I also explore American literary perceptions of the area following the collapse of communism. Importantly, the term “Eastern Europe” as used in this dissertation is charged with significance. I approach it not only as a space on the map or the geopolitical construct which emerged in the aftermath of the Second World War, but rather as a conceptual category and a repository of meanings built out of fact and fantasy: specific historical, political and cultural realities interlaced with subjective worldviews, preconceptions, and mental images. The critical framework of this dissertation is twofold. I reach for the concept of liminality to elucidate the indeterminacy and malleability which lies at the heart of the object of study—the idea, image, and experience of Eastern Europe. Bearing in mind the nature of the works under analysis, all of which were inspired by actual visits behind the Iron Curtain, I propose to interpret these transatlantic literary journeys in terms of generative experience, where Eastern Europe is mapped as a liminal space of possibility; a contact zone between cultures and, potentially, the locus of self-discovery and individual transformation. If liminality is the metaphor or a lens that I employ in order to account for the nature of the analyzed works and the complex terrain they map, imagology, whose purpose is to study the processes of constructing selfhood and otherness in literature, provides me with the method and the critical vocabulary for analyzing selected literary representations. The dissertation is divided into six chapters, the last of which serves as coda to the previous discussion. The first two chapters constitute the critical foundation of this work. Then, in chapters 3, 4, and 5 I study American images of Eastern Europe in the works written by John Updike, Joyce Carol Oates, and Philip Roth, respectively. The last, sixth chapter of this dissertation is divided into two parts. In the first one, I discuss new critical perspectives and avenues of research in the study of Eastern Europe following the collapse of communism. Then, I carry out a joint analysis of four works written after 1989 by Eva Hoffman, Arthur Phillips, John Beckman, and Gary Shteyngart. The dissertation ends with conclusions in which I summarize my findings and reflections, and suggest implications for future research. As this dissertation seeks to demonstrate, Eastern Europe portrayed in the analyzed works oscillates between contradictory representations which are contingent upon a number of factors, most importantly who maps it and in what context. Even though each experience of Eastern Europe is distinct and fueled by the profiles, identities, and interests of the characters and their creators, I have found out that certain patterns of othering are present in all the works. Thus, my research seems to suggest that there is something of a recurrent literary image of Eastern Europe, which goes beyond the context of the Cold War. Accordingly, while this dissertation hopes to be a valid contribution to the study of literary and cultural mappings of Eastern Europe, it also generates new questions regarding the current, post-communist representation of the area and its relationship to the national tropes explored in my work.