Mechanical evaluation of coating mortars with added nanofibrillated pulp and crystalline microcelulose under thermal shock cycles

ABSTRACT

Rendering mortars are constantly exposed to temperature variations, alternating between heat and cold, sun and rain, which generate thermal shock cycles that can compromise their durability. In this context, this study evaluated the impact of incorporating crystalline microcellulose (MCC) and fibrillated nanocellulose pulp (NFC) on the performance and durability of these mortars, with an emphasis on resistance to thermal shock cycles. In the methodology, the mortars were evaluated in the fresh state through tests for air content, bulk density, and consistency index using the flow table method. After curing, they were subjected to wetting and drying cycles to simulate the effect of thermal shock and assessed for compressive strength and flexural tensile strength. The results indicated that NFC pulp increased air incorporation, reducing density and improving workability, while MCC increased the density of the fresh mixture. In terms of mechanical performance, the addition of 0.2% NFC significantly reduced compressive strength, whereas the other formulations exhibited behavior like reference. The incorporation of MCC and NFC pulp in rendering mortars did not positively influence flexural tensile strength properties. Thermal shock affected compressive strength, with a greater impact on mortars containing MCC, whereas those with NFC pulp demonstrated greater thermal stability. Flexural tensile strength, on the other hand, was not significantly influenced by the tested additions under thermal shock cycles.

Keywords:
Cycling; Nanomaterials; Durability; Thermal stability