Evaluation of a novel cellulose-based viscosity modifying admixture in rheological properties of cementitious pastes.

Viscosity Modifying Admixtures (VMAs) are used to increase the viscosity and cohesiveness of cementitious matrices, hence, increasing the stability of cementitious composites, either in self-consolidating concrete and/or under-water concrete. Since currently available VMAs are mostly costly and may increase the concrete production costs, studying new VMAs is of crucial importance. This study investigates the use of cellulose micro and nano fibers as VMA and investigates the rheological properties of cementitious pastes and compares their flow behavior with that of the commercially available VMAs. Different curve fitting methods are applied to model the flow behavior of neat and modified cement grouts. The Herschel-Bulkley model presents the best curve-fitting results in neat cement grouts. It also gives the best results in fitting that of cement grouts modified with cellulose based materials and synthetic copolymers. Steinhart-Hart method fits the rheology of cement grouts modified with diutan gum better. The results show that cellulose based VMA can be manufactured to cover a wide range of viscosity modifying properties.