Effect of nano Cellulose and nano carbon black on cement paste microstructure

Abstract

Over the last few years, nanotechnology has emerged as a breakthrough in concrete technology exploring new frontiers for engineering multi functional properties towards higher eco-efficiency. Researchers incorporated both reactive and inert nano-materials, and evaluated their effectiveness in tailoring different properties necessary for sustainable cement composites. In this study, nano carbon black is used as the inert inclusion. Due to it's high hydrophobicity, carboxymethyl cellulose (CMC) is used as a dispersing agent into the cement composite. CMC is a cellulose derivative with carboxymethyl groups bound to some of the hydroxyl groups. The polar carboxymethyl end groups enable the cellulose to be soluble and chemically reactive. Carbon black is a very attractive nanomaterial for its contribution in enhancing the mechanical and electrical properties. The micro and nano mechanical properties of the final product were examined along with the properties of the paste made with carbon or cellulose solely. The cellulose by itself had no signicant increase in the mirco-mechanical properties, unlike the carbon black that resulted in an increase in the measured hardness and indentation moduli up to a certain volume addition, regardless of the presence of cellulose. This is attributed to the carbon filler effect.