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.

Buscando inspiración musical en el universo computacional

Throughout the history of western music, composers have relied on “outside-of-time” structures which have served as musical “prime matter” until the moment of their temporal inscription. These structures have traditionally been the scales, rhythmic values, formal schemes, harmonic rules, etc., that composers have employed over and over again. They are to the composer what marble is to the sculptor or colors are to the painter. The advent of computer technology has opened new avenues that allow composers to develop new structures and enlarge their creative horizon. I started my musical training at a very early age, and at the same time I had a lot of scientific curiosity. As soon as I had my first computer (a Commodore 64), I started to experiment, to establish relationships between scientific processes and the world of sound. To date, and following the footsteps of I. Xenakis (although from a different aesthetic perspective), my compositions have always been informed, to a lesser or greater degree, by some underlying scientific idea, and this task can hardly be achieved without computation. Furthermore, today, computer-composers open the possibility to access and use an ever-growing repository of musical material goes a step forward in this direction. And this raises many questions, some of them of a deep philosophical ground.