Nanocellulose enriched mortars : evaluation of nanocellulose properties affecting microstructure and strength & development of mixing protocols

Abstract

In this work, four different nanocellulose (NCs) aqueous suspensions (two Cellulose Nano-Fibrils-CNF and a pair of Cellulose Nano-Crystals-CNC) were selected for the evaluation of key aspects that potentially affect the final performance of mortars. The main objective was the development of appropriate mixing protocols that will allow the incorporation of cellulose nanoadditives into cementitious blends. Inclusion of two different NC species into mortars will provide a side-by-side performance comparison between CNCs and CNFs leading to a better understanding of particle morphology impact on the properties of cementitious composites. Moreover, preliminary structural and physicochemical NC characterization tests were performed to enlighten the effects of NC intrinsic features on the final efficiency of the materials. Strength tests of as-obtained NC enriched specimens revealed an enhanced performance when compared to respective reference samples. In particular the presence of CNFs – and specifically AVAP® CNFs– in the mortar mixture resulted in an increase up to 43% in flexural strength values, whereas CNCs were more effective in raising compressive strength values (up to 21%). Supposing that this improvement, emanates from evolving interactions between NCs and defects existing in the matrix at the onset of their formation a more detailed study is on-going aiming at the in depth comprehension of all synoptic parameters that will enable a straight correlation between mortars and nanocellulose properties and will facilitate the use of NCs to upgrade cementitious materials into tailored made composites.