2.5. Water permeability and capillary rise

To verify the influence of PP strings on water transport properties of concrete the water permeability and the capillary rise tests were performed on both CF and CR samples. The former experiment was conducted according to the standard procedure described in EN 12390–8 [62]. After 28 days of maturing three cubic specimens (150 × 150 × 150 mm³) of each type were stored in air for 30 days. Subsequently, samples were subjected through their lateral surfaces to the waterfront under the pressure of 5 bars for 72 h. After this time cubes were split in a half and the depth of the waterfront was measured.

The capillary rise test was conducted by means of the conventional method presented in DIN 52,617 [63]. The air-dried samples were placed in water so that their surface reached up to 0.5 cm of cubic height. The amount of absorbed water was controlled through the mass change in time intervals for 375 h.