Browsing by Author "Santos, P."
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- Hygrothermal Effect on the Impact Response of Carbon Composites with Epoxy Resin Enhanced by NanoclaysPublication . Reis, Paulo Nobre Balbis dos; Silva, Abílio P.; Santos, P.; Ferreira, J. A. M.This paper presents the results of the hygrothermal effect on the impact response of carbon/epoxy composites and the benefits gained from doping the epoxy resin with nanoclays previously subjected to a silane treatment appropriate for the resin. The nanoclay reinforcement increased the maximum load and the elastic recovery of the composites. The thermal degradation caused by exposure to 60°C for 10 days was insignificant, while the immersion in water at 60ºC for 30 days led to a continuous reduction in the maximum load and the elastic recovery. Multiple impacts resulted in a continuous and nearly linear degradation of the impact response both of dry and environmentally assisted specimens.
- 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.