Issue34

A. Satoh et alii, Frattura ed Integrità Strutturale, 34 (2015) 397-405; DOI: 10.3221/IGF-ESIS.34.44 399 Mechanical properties Fractographic parameters Name of GF (N/mm) Fb (MPa) FRR Hmax Rr1 RRL Sd Type specimen Data Average Data Average (-) (mm) (-) (-) (mm) Repaired H2dC4S10Fa10-1 0.400 3.848 0.853 2.819 0.05 1.070 1.085 mortar H2dC4S10Fa10-2 (0.886) 0.422 4.328 4.359 0.961 2.961 0.06 1.142 0.775 H2dC4S10Fa10-3 0.443 4.903 0.955 1.753 0.06 1.092 0.766 Repaired H2dC4S10-1 0.628 3.583 0.955 3.110 0.09 1.111 1.156 mortar H2dC4S10-2 0.441 0.424 3.616 4.025 0.961 2.591 0.04 1.097 0.759 H2dC4S10-3 0.204 4.877 0.742 4.391 0.04 1.071 1.697 Table3 : Mechanical properties of repaired mortar specimens. M ODELING FROM OBSERVATION OF CONCRETE - REPAIR INTERFACE he authors observed mortar-repair interface with employing SEM (Scanning Electron Microscope) from the sample cut from H2dC4S10Fa10-3 after fracture toughness test. It is the adhered part made of 2 regions: the left side in Fig. 2 is substrate and the right is repair (C4S10Fa10). From Fig. 2(a), black line is recognized along the interface, and white small dots (iron sand) and a large oval (steel fiber) is observed. Fig. 2(b) is a color map of Ca, measured with EPMA, where concentration of Ca is recognized along the interface caused by the bleeding in repair. Fig. 2(c) is a close-up BSI near interface, where the upper right is substrate and lower left is repair. There is a thick layer of CH with the thickness of 50  m. It is judged that the black line in Fig. 2(a) is the layer of CH judged from Fig. 2(b) and (c). (a) BSI near interface. (b) Color map of Ca. (c) Close-up BSI near interface. Figure 2 : SEM observation of Specimen (H2dC4S10Fa10-3) near interface. It is also known that there is a wall effect near an interface where smaller particles gather and large ones are scarce. Then the authors made FEM models according to the above-mentioned observations depicted in Fig. 3. LB and LWE in Fig. 3 are a layer of bleeding and a layer of wall effect respectively. Model M and R are monolithic repair with different material properties: M has the properties for ordinary mortar and R for repair with lower strength and higher ductility from the inclusion of fiber. Model S-N and S-A have two layers of straight interface (LB and LWE), and only S-A has 31 particles of aggregates. Model W-N and W-A have two layers of crooked interface, and only W-A has 46 particles of aggregates. Left side of the interface models is substrate mortar. Figure 3 : Three models for FEM analysis. T Substrate Substrate Repair Repair Interface CH along interface Iron sand Substrate Repair Interface 300µm