Optimizing cellulose nanomaterials dispersion in cement-based systems: Effect of mixing sequence and superplasticizer type

This study investigates the influence of three superplasticizer (Sp) types, Polycarboxylate ether (PCE), Polynaphtalene sulfonate (PNS), and Polycarboxylate linear (PCL), and different mixing sequences on the dispersion of cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) in cement-based systems. The three mixing sequences were: O 1 (simultaneous CNM and SP addition at the start), O 2 (Sp addition after CNM and cement incorporation), and O 3 (CNM addition after cement particle dispersion by SPs). To quantitatively assess CNM dispersion across SP types and mixing sequences, a zeta potential-based comparative framework was developed. This framework consisted of four cement paste systems (I–IV) enabling separate evaluation of cement chemistry, CNM, and Sp adsorption contribution. Based on this framework, two novel dispersion indices, δ C for CNC and δ f for CNF, were introduced. Correlations with reflocculation behavior validated that electrochemical variations captured by δ C and δ f correlated with measurable rheological changes. Overall, this work establishes a scalable, reproducible methodology for evaluating and optimizing CNM dispersion in cementitious systems and reveals how Sp chemistry and mixing sequence jointly control CNM behavior.