Diversos casos de reação álcalis-sílica têm sido diagnosticados em estruturas de concreto nas quais foram utilizadas rochas graníticas. No entanto, este tipo de rocha é geralmente considerado como inócuo ou de reactividade pouco provável aos álcalis. As rochas graníticas são amplamente exploradas no norte e centro de Portugal, representando quase metade da produção total de agregados no país. O Projeto IMPROVE surgiu da necessidade de diagnosticar corretamente a potencial reatividade aos álcalis de granitos. No âmbito desse projeto foram estudadas diversas amostras colhidas em diferentes regiões de Portugal, apresentando-se neste artigo os resultados de oito destas. Os ensaios realizados incluem a caracterização petrográfica dos agregados e ensaios de expansão de barra de argamassa e prisma de concreto. Concluiu-se que o conteúdo em quartzo microcristalino se correlaciona melhor com os resultados do ensaio em prisma de concreto RILEM AAR-4.1 do que com os outros ensaios de expansão.

Several cases of alkali-silica reaction involving granitic aggregates have been diagnosed in damaged concrete structures in Portugal. Nonetheless, this kind of rock is usually regarded as slow/late reactive or even non-reactive to alkalis. Granitic rocks are widely exploited in Northern and Central Portugal, representing almost half of the produced aggregates in this country. Project IMPROVE rose from the need to accurately diagnose the potential reactivity of granites to alkalis. The study involved about forty granites collected from different regions in Portugal, from which the results of eight samples are being presented in this paper. The tests carried out include the petrographic analyses of the aggregates and mortar and concrete expansion tests. It was concluded that the content of microcrystalline quartz correlates better with the results of AAR-4.1 than with the other expansion tests.

Abstract The objective of this paper was to use a thermodynamic analysis to find operational conditions that favor the production of hydrogen from steam and oxidative reforming of liquefied petroleum gas (LPG). We also analyzed the performance of a catalyst precursor, LaNiO3, in order to compare the performance of the obtained catalyst with the thermodynamic equilibrium predictions. The results showed that it is possible to produce high concentrations of hydrogen from LPG reforming. The gradual increase of temperature and the use of high water concentrations decrease the production of coke and increase the formation of H2. The reaction of oxidative reforming of LPG was more suitable for the production of hydrogen and lower coke formation. Furthermore the use of an excess of water (H2O/LPG =7.0) and intermediate temperatures (973 K) are the most suitable conditions for the process.

The effect of the addition of Mg and Ca to Ni/ a-Al2O3 catalysts was investigatedstudied, aiming to detail the promotion mechanismaddress their role as promoters in the steam reforming reaction. Temperature- programmed reduction and H2 and CO temperature-programmed desorption experiments indicated that Mg interacts with the metallic phase. Mg-promoted catalysts showed a greater difficulty for Ni precursors reduction besides different probe molecules (H2 and CO) adsorbed states. In the conversion of cyclohexane, Mg inhibited the formation of hydrogenolysis products. Nonetheless, the presence of Ca did not influence the metallic phase.

A review of the EXAFS data analysis methods is presented. A detailed description of the EXAFS signal extraction and the Fourier transform of the data are discussed. The procedure for determining interatomic distances, coordination numbers and disorder effects from EXAFS data is described. This paper also discusses the data analysis statistics. Finally, one example of catalyst characterization by the EXAFS technique is reported.