Efeito do agregado na diminuição da retracção de argamassas

Na actualidade, face ao desenvolvimento de betões de alto desempenho caracterizados por apresentarem muito baixa razão água cimento (A/C), tornou-se pertinente o estudo da retracção autogénea, por motivos relacionados com a resistência, durabilidade e estética destes materiais. Nesta dissertação foi elaborado um estudo prático com o intuito de avaliar o impacto da adição de agregado na redução da retracção autogénea, em seis misturas cimentícias. Através de ensaios foram obtidos valores reais de retracção autogénea, sendo estes posteriormente comparados com os valores obtidos teoricamente com recurso ao modelo proposto por Hobbs na década de 70. Tendo em consideração os valores teóricos e sua comparação com os valores reais obtidos nos ensaios é proposta uma alteração ao modelo teórico, que tem em conta a maior resistência à compressão dos betões actuais. Esta modificação permitiu estimar com maior exactidão os valores de retracção autogénea nas diferentes misturas. /ABSTRACT: Nowadays the development of high performance concretes characterized by a low water-to­ cement ratio (W/C), it became relevant to study the autogenous shrinkage, for reasons relating to the strength, durability and aesthetics of these materials. ln this study the effect of adding aggregate in six cementitious mixtures was evaluated. The results obtained in the experimental test were compared with theoretical values from a model propose by Hobbs in the 70's for autogenous shrinkage. Given the theoretical values and its comparison with the actual values obtained in the tests an amendment is proposed to the theoretical model that takes into account the higher compressive strength of actual concrete. This modification allowed us to estimate accurately the values of autogenous shrinkage in the different mixtures.

Assessing the ability of rural agrarian areas to provide cultural ecosystem services (CES): A multi scale social indicator framework (MSIF)

Assessing the ways in which rural agrarian areas provide Cultural Ecosystem Services (CES) is proving difficult to achieve. This research has developed an innovative methodological approach named as Multi Scale Indicator Framework (MSIF) for capturing the CES embedded into the rural agrarian areas. This framework reconciles a literature review with a transdisciplinary participatory workshop. Both of these sources reveal that societal preferences diverge upon judgemental criteria which in turn relate to different visual concepts that can be drawn from analyzing attributes, elements, features and characteristics of rural areas. We contend that it is now possible to list a group of possible multi scale indicators for stewardship, diversity and aesthetics. These results might also be of use for improving any existing European indicators frameworks by also including CES. This research carries major implications for policy at different levels of governance, as it makes possible to target and monitor policy instruments to the physical rural settings so that cultural dimensions are adequately considered. There is still work to be developed on regional specific values and thresholds for each criteria and its indicator set. In practical terms, by developing the conceptual design within a common framework as described in this paper, a considerable step forward toward the inclusion of the cultural dimension in European wide assessments can be made