Development of multifunctional plaster using nano-TiO2 and distinct particle size cellulose fibers

The present study reports on the development of multifunctional plaster showing superior thermal insulation, ability to control the indoor RH and NOx photocatalytic degradation. The plaster contains TiO2 nanoparticles (1 wt.%) and 0-4 wt.% fibers of two distinct sizes: 1 mm < d < 2 mm (Fb(1-2mm)) and 2 mm < d < 4mm (Fb(2-4mm)). The formulations were adjusted based on flow table and rheometer tests, aiming to assure a desirable workability. Plasters with similar workability (spread on table) showed distinct yield stress values over time and Fb((1-2mm)) plays an important role on the workability control. Rheological behaviour was governed by Fb((2-4mm)). Binary mixture 2.0Fb(1-2mm) + 2.0Fb(2-4mm)2.0Fb(2-4mm) required less water amount to show the same workability of the single formulation 4.0Fb(1-2mm). However, the control of the rheological behavior over time was found difficult. The apparent porosity, water absorption and capillary index were strongly incremented with the rise of cellulose fiber concentration. Singular and binary samples present similar results and no significant differences were observed by changing the fibers size. Plaster's buffering capacity and NOx uptake was considerably improved by using cellulose fibers, being this increment primarily governed by the fiber concentration. Formulation containing 4.0 wt.% Fb((2-4mm)) revealed the optimal performance. (C) 2017 Elsevier B.V. All rights reserved.