Rheology of CAC-based cement pastes and the relationship to penetrability through nonwoven fabric reinforcements

In this study, we present an analysis of the rheological behaviour of calcium aluminate cement (CAC) based pastes with variable metakaolin (MK) contents (0-50%), with and without superplasticizer (SP) and at different water/cement ratios. Viscosity tests were performed under variable shear rate to analyze the macroscopic flow behaviour of the pastes. Furthermore, the penetrability of the pastes into natural fiber nonwoven fabric was examined using optical microscopy. The penetrability results were assessed to determine the suitability of the pastes for production of textile-reinforced composites. It was found that increased metakaolin content and decreased water/cement ratio both led to reduced viscosity. The addition of SP led to a reduction in viscosity, although this effect was lessened at high MK contents. Penetrability tests indicated that the paste viscosity significantly influenced the ability of the pastes to flow through the nonwoven structure, with more viscous pastes showing reduced penetrability.