resumo
The addition of a water reducing admixture like a plasticizer or an air-entraining agent in a cement-based material modified their flow properties, besides the obvious reduction of the kneading water amount. This work presents a study on the effects of these admixtures on the theological properties of a render mortar and its water permeability, which is commonly recognized as important issues either for application but also for hardened mortar final characteristics since they are very dependent on the fresh state behaviour. The studied mortar is a single-coat render mainly based in Portland cement as the binder and in siliceous sand as the aggregate material. These admixtures presented intense effects over the rheological properties, contributing to the reduction of kneading water content without lost of workability, the stabilization of the mortar suspensions and, in some cases, retarding the setting behaviour. In terms of mechanical strength there was a clear increase with the plasticizer use while the air-entraining agent caused the opposite variation due to the porosity increase. Water permeability and capillary absorption was generically reduced with the use of both admixtures.
palavras-chave
CEMENT-BASED MATERIALS; PORTLAND-CEMENT; PORE STRUCTURE; SUPERPLASTICIZERS; CONCRETE; PASTES; PERMEABILITY; ADMIXTURES; STRENGTH
categoria
Archaeology; Architecture; Biotechnology & Applied Microbiology; Chemistry; Construction & Building Technology; History; Physics
autores
Paiva, H; Ferreira, VM; Labrincha, JA
nossos autores
Helena Maria da Costa Paiva
Investigador
João António Labrincha Baptista
Professor Catedrático