Papers by Author: M.P. Seabra

Abstract: We report the preparation of ceramic pigments using industrial wa stes as primary sources. An Al-rich sludge (generated in the wastewater treatment unit of an anodising or surface coating industrial plant), a galvanizing sludge (from the Cr/Ni plating process ), a Fe-rich sludge (generated during steel wiredrawing), a foundry sand and a marble sawing sludge are combined to formulate distinct pigment structures via the solid state reaction method. In particular, a black spinel and a novel blue pigment based on the hibonite structure are detailed. A green olivine, and brown and pink sphenes are also reported. The pigments were fully characterized, and then were tested in a standard transparent bright ceramic glaze. Typical working conditions and colour development are fully described.

Abstract: One of the key characteristics of fresh mortars is their rheological behaviour since it determines the material workability and has a clear influence on the hardened product final properties. Indeed, mortars rheological properties are extremely important since several factors, related with placement, consolidation, durability and strength depend on the flow properties of the mortar paste. In this work, the effect of ageing time on the rheological properties of fresh aerial lime-based mortars was investigated. Mortars having a 1/3 binder/aggregate volume ratio were studied as a function of ageing time. The influence of a water retaining agent (0.1 wt. %) addition in these mortars was also analysed. Mixing and ageing have a clear influence in the water intake process ruling over the rheological behaviour of this type of mortars.