Browsing by Author "Oliveira, Luiz António Pereira de"
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- Mechanical and Durability Properties of Concrete with Ground Waste Glass SandPublication . Oliveira, Luiz António Pereira de; Gomes, João Castro; Santos, P.This paper examines the possibility of using finely ground waste glass as partial natural sand replacement in concrete. The reduction of waste glass particle size was accomplished in the laboratory by crushing and grinding the waste glass in a jar mill. The compressive strength at 7, 28 and 90 days, was determined for different ground waste glass sand percentage replacement in concrete. Absorption and permeability tests were also carried out. A test method was followed to verify the potential concrete expansion caused by the alkali silica reaction. The results showed a very significant compressive strength improvement with the increasing of percentage replacement of natural sand by ground waste glass. A higher compressive strength was obtained with a lower expansion verified by the bar tests. The same trend for durability properties were also observed in this study. The results obtained attested the high possibility of recycling and using of the ground waste glass collected in central region of Portugal as natural sand replacement in concrete mixtures.
- Optimization of pozzolanic reaction of ground waste glassPublication . Gomes, João Castro; Santos, P.; Oliveira, Luiz António Pereira deThis paper examines the possibility of using finely ground waste glass of the three most common coloured glass bottles used in Portugal as partial cement replacement in mortar and concrete. The pozzolanic activity of ground glass was optimised as function of different particle size. The reduction of waste glass particle size was accomplished in the laboratory by crushing and grinding the waste glass using a jar mill. The particle fineness, to obtain a required reactivity, was studied as function of grinding time. The compressive strength activity index, at 7, 28 and 90 days, was determined for different ground waste glass particle size and partial cement replacement percentage in mortar. Test method described in ASTM C 1260 was applied to verify the potential expansion caused by the alkali silica reaction. The results obtained confirm the pozzolanic activity of the ground waste glass of different colour collected in central region of Portugal.
- Parameters for Self-compacting Concrete Mortar PhasePublication . Oliveira, Luiz António Pereira de; Nepomuceno, MiguelThis paper reports an experimental study on the mortar phase for selfcompacting concrete. A series of mortars were produced with similar flow properties, measured by spread and v-funnel tests, adequate to produce self-compacting concrete. The water content and the modified carboxylic superplasticizer dosage were determined experimentally for each mortar. Different percentages of cement replacement materials were used in binary blends, each one combining one of the two types of cement with one of the three mineral additions selected: limestone powder, granite filler and fly ash. Each of the binary blends of powders was combined in five different proportions in volume with the fine aggregate (Vp/Vs). Mortars were tested for compressive strength at 28 days age and this value was related to the water/cement ratio, the percentage of replacement materials, and Vp/Vs parameter. The analysis revealed the possibility of establishing adequate mortar parameters to obtain simultaneously the self-compactability and the required compressive strength of self-compacting concrete.
- Resíduos reciclados como componentes de argamassasPublication . Oliveira, Luiz António Pereira de; Santos, Pedro M. S.Este trabalho caracteriza a potencialidade de uso de resíduos, tais como vidro e cerâmica, como componentes de argamassas. Os materiais seleccionados, constituídos por vidro de embalagens e por cerâmica vermelha, foram reduzidos a três intervalos de tamanhos de grãos (0-45μm, 45-75μm e 75-150μm). Após moagem, os resíduos foram caracterizados quanto à forma da partícula, massa volúmica e superfície específica. Foram realizadas argamassas com substituição parcial do cimento por estes materiais (10, 20, 25, 30 e 40%) e determinou-se a resistência à compressão (7, 28 e 90 dias) e o índice de actividade pozolanica e expansibilidade. Os resultados dos ensaios mecânicos, do índice de reactividade, bem como de expansibilidade viabilizam o uso do resíduo de vidro e de material cerâmico como componente de argamassas.