Assessment of scale of the microstructure impact on capillary transport in cement-based composites with polypropylene fibers

The paper presents results of the microstructure and capillarity tests of four cement mortars reinforced with polypropylene fibers with length of 19 mm. The recipes of the particular composites were varied by applying superplasticizer, air-entraining agent and silica fume. In order to identify differences in the internal structures of the mortars as a result of application of selected modifiers, microstructure tests using mercury intrusion porosimetry (MIP) were performed. The capillarity experiments were conducted for two months with reference to each composite. Obtained data of samples mass changes were used to determine values of water sorption coefficient that characterizes the rate of water absorption. The influence of structure modification on the course of capillary flow was assessed. The conducted studies provide some practical guidelines for a controlled regulation of the capillary water transport processes in porous materials with a microstructure modified through appropriate use of selected admixtures and additives.