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Abstract(s)
Esta dissertação, essencialmente de cariz experimental, aborda indiretamente o tema da reabilitação de edificações históricas, através do estudo de caldas de cimento comumente utilizadas na técnica de consolidação de paredes por injeção.
Nesta investigação compara-se o desempenho de caldas económicas com fuidez semelhante. Para o efeito é substituído metade do cimento por adições sustentáveis/recicladas (pó de vidro, pó cerâmico, metacaulino, fíler calcário e biomassa).
O comportamento reológico das caldas no estado fresco foi avaliado através dos ensaios de espalhamento (mini slump) e através do reómetro Viskomat NT para determinação dos parâmetros tensão de cedência e viscosidade plástica relativa. Ainda neste estado foram efetuados ensaios de injetabilidade num meio poroso. Para a avaliação do comportamento mecânico foram realizados ensaios no estado endurecido relativos à resistência à flexão e à compressão, ao módulo de elasticidade dinâmico, à retração livre e à absorção de água por capilaridade.
Dos ensaios realizados, verificou-se que as caldas com metacaulino ou pó de vidro são as menos viscosas, mas a que apresentou maior facilidade de penetração foi a calda com pó cerâmico. Nos ensaios também foram identificadas características pozolânicas nas caldas com pó de vidro, pó cerâmico ou metacaulino por terem apresentado aumentos de resistência após os 28 dias de cura. No entanto, nesta atividade laboratorial foram verificados alguns problemas, tais como, a segregação estar acima dos níveis aconselhados pela literatura quando as misturas são deixadas em repouso num meio impermeável, o que merece maior aprofundamento pois ambiciona-se que estas sejam injetadas em meios porosos.
This dissertation, of essentially experimental nature, indirectly tackles the rehabilitation of historic buildings, through the study of grouts commonly used in wall consolidation by injection. The performance of economic grouts with similar fluidity is compared. For this effect half the cement was replaced by sustainable/ recycled additions (glass powder, clay, metakaolin, limestone filler and biomass). The rheological behavior of the cement pastes while fresh was evaluated by mini-slump essays and by rheometer (viskomat NT) for determination of tension parameters of shear stress and consistency. Essays of injectability into porous structures were also performed to the fresh grouts. To evaluate mechanic behavior, essays were performed to the hardened state studying resistance to flexion and compression, Young modulus, grouting retraction and capillary water absorption. The essays performed showed that the cement pastes with metakaolin and glass powder are the least viscous, but the clay grout presented the best penetration into porous structure. The essays identified pozzolanic properties in the grouts with glass powder, clay and metakaoline which showed increased resistance after the 28 day curing period. There were however some problems with segregation being above the levels advised by literature when mixes are left to rest in an impermeable media. This deserves further investigation as injectability into porous structures is ambitioned.
This dissertation, of essentially experimental nature, indirectly tackles the rehabilitation of historic buildings, through the study of grouts commonly used in wall consolidation by injection. The performance of economic grouts with similar fluidity is compared. For this effect half the cement was replaced by sustainable/ recycled additions (glass powder, clay, metakaolin, limestone filler and biomass). The rheological behavior of the cement pastes while fresh was evaluated by mini-slump essays and by rheometer (viskomat NT) for determination of tension parameters of shear stress and consistency. Essays of injectability into porous structures were also performed to the fresh grouts. To evaluate mechanic behavior, essays were performed to the hardened state studying resistance to flexion and compression, Young modulus, grouting retraction and capillary water absorption. The essays performed showed that the cement pastes with metakaolin and glass powder are the least viscous, but the clay grout presented the best penetration into porous structure. The essays identified pozzolanic properties in the grouts with glass powder, clay and metakaoline which showed increased resistance after the 28 day curing period. There were however some problems with segregation being above the levels advised by literature when mixes are left to rest in an impermeable media. This deserves further investigation as injectability into porous structures is ambitioned.
Description
Keywords
Edifícios históricos - Reabilitação Reabilitação de edifícios - Caldas cimentícias Reabilitação de edifícios - Caldas cimentícias - Comportamento reológico Caldas - Materiais constituintes - Sustentabilidade Caldas - Propriedades