CMA

11 concrete specimens, it was interesting to test absorption of water by “internal surfaces” (so basically the water absorption by the bulk of the specimens). Water absorption by “internal surfaces” was evaluated by removing multiple times a 5mm layer of concrete from the top surface. Said differently, the top surface of the specimens was polished to remove 5 mm at a time from the original or newly created top surface. The test results are shown in Table 4, and Figure 2 shows the water penetration through the external surface but as well from the “internal surfaces” measured using the same testing method. Volume of water absorbed after 24 hours contact with water are plotted as a function of the depth of the tested surface. Specimens of concrete modified with the microencapsulated silicone resin (MIC-RES) or with the silane emulsion (EM-SIL) are showing reduced water absorption even when the tested surface are 4 or 5 cm deep, demonstrating the effectiveness of the concept of integral water repellent. Water absorption is, as predicted, reduced to a greater extend when addition level of the microencapsulated silicone resin (MIC-RES) increases. Concrete specimens modified with the silane emulsion (EM-SIL) do absorb much less water as reference, as well. Table 4. Water absorption of reference and modified concrete specimens (measured at 5 and 50 mm depth) Specimens Depth (mm) Water exclusion (%) Control 5 - 50 - MIC-RES (0.2%) 5 50 50 36 MIC-RES (0.5%) 5 72 50 64 MIC-RES (0.7%) 5 46 50 71 SIL-EM (0.5%) 5 19 50 62 b t : Specimen cross-section length (mm), t is the length of the side in the vibration direction m : Mass of specimen (kg) f l : Primary resonance frequency of deflection vibration (Hz) T : Factor (Table 3) K : Radius of gyration, For prismatic specimens = Table 3. Factor T K — L T *1) K — L T *1) 0.00 1.00 0.09 1.60 0.01 1.01 0.10 1.73 0.02 1.03 0.12 2.03 0.03 1.07 0.14 2.36 0.04 1.13 0.16 2.73 0.05 1.20 0.18 3.14 0.06 1.28 0.20 3.58 0.07 1.38 0.25 4.78 0.08 1.48 0.30 6.07 *1) Calculated with the dynamic Poisson ratio as 1/6 Freeze-thaw test method The freeze thaw test was used to evaluate the resistance of concrete specimens to freeze thaw cycles. The freeze-thaw test was conducted in accordance with JIS A 1148: 2010 “Concrete freeze-thaw test method”. The substrate used were 10 x 10 x 40 cm³ rectangular parallelepiped concrete specimens. As for the freeze-thaw cycle, one cycle was set to +5 to -18°C, and 300 cycles were repeated in about 4 hours. Freezing damage resistance was evaluated from the decrease in the dynamic elastic modulus of concrete. RESULTS AND DISCUSSION Testing of Water Absorption Water absorption by reference and modified concrete specimens was evaluated using the JIS A 6909: 2014 “Water Permeability Test B Method”. In order to assess whether the integral water repellent are distributed homogeneously into the