Kappa (к)-carrageenan as a novel viscosity-modifying admixture for cement-based materials – Effect on rheology, stability, and strength development

Abstract

An experimental investigation was carried out to evaluate the performance of (к)-carrageenan as a novel viscosity-modifying admixture (VMA) in cement-based materials. The effect of different dosages of (к)-carrageenan and their combinations with two different high-range water-reducer (HRWR) types on rheology, forced bleeding, hydration kinetics, and compressive strength of cement suspensions was evaluated. Welan gum was also used for comparison purposes due to its thickening and binding properties. The use of (к)-carrageenan led to higher yield stress and plastic viscosity, shear-thinning response, and greater resistance to forced bleeding compared to the reference mixture. However, when used in combination with HRWR, the suspensions exhibited linear Bingham behavior, lower yield stress, plastic viscosity, and forced bleeding. In the case of cement hydration kinetics, the use of (κ)-carrageenan prolonged the dormant period, regardless of the HRWR type. The mixture containing 0.5% of (к)-carrageenan showed the highest compressive strength.