Issue34

A. Satoh et alii, Frattura ed Integrità Strutturale, 34 (2015) 397-405; DOI: 10.3221/IGF-ESIS.34.44 404 For repaired mortar with interface Fig. 13 represents the relationship between respondent Ft (or GF) and Ft of interface which is the input used for FEM analysis. X-axis in Fig. 13 represents the input and Y-axis represents the response including the plots of monolithic ones (R, R-S, R-I, R-V, TSD1, TSD2 and TSD3). It is natural that the responses of the repaired mortar (W-N, A and S-N, A) cannot exceed the response of R even though the input Ft for interface is stronger than that of R (See Fig. 13(a)). It agree with the weakest chain model for strength: the weakest part among substrate, interfaces and repair fractures. But for WOF, the responses of the repaired mortar (W-N, A and S-N, A) can exceed the response of R. It derives from the energy dissipation by the existence of the interface. But if the interface is too weak, the respondent WOF is far below that of R. It is clear that the roughness of the interface is very effective when property of interface is TSD2 shown in Fig. 13(a) and (b). But the roughness of interface has little effect in the cases that have higher or far-lower strength than that of R (See Fig. 13(b)). If we compare the experimental results in Tab. 2 and 3, the strength of repaired mortar (4.025 for average) is far-lower than that of repair (7.136 MPa for average). This correspond to the relationship between the case R and the case depicted in the leftmost (W-N, S-N) in Fig. 13(a). Then it is suggested that the strength of the interface should be close to that of the repair to achieve high strength and high ductility. The roughness of the interface is especially effective for the ductility in that case. Even in the case that the interface is stronger than the repair, strength is limited to the repair. But the ductility is high even in the case of flat interface (S-A, N), if the interface is stronger than repair. . (a) Ft-Ft of input interface (b) WOF- Ft of input interface. Figure 13 : Relationship between Ft (or WOF) and Ft of interface for repaired mortar. C ONCLUSIONS he experimental results of repair material and mortar-repair interface are verified with FEM analysis. Also FEM analysis suggests the clues for further enhancing the performance of the repaired interface. The findings are as follows. - High modulus fine aggregates in repair material enhance strength of it especially in the case of brittle matrix. Also they enhance the strength of the interface repaired with it due to the induced crack path into repair. - The strength of the interface should be close to that of the repair or higher than repair to achieve high strength and high ductility. Even in the case that the interface is stronger than the repair, strength is limited to the repair. - The roughness of the interface is effective for the mechanical performance in the case where the strength of interface is close to that of repair. But the ductility is high even in the case of flat interface, if the interface is stronger than repair. R EFERENCES [1] Kamiya, Y. et. al., Performances of a new repair material, Ahma Series. Report of Mitsubishi Material Research Center., 14 (2013) 81–90. [2] Kunieda, M. et. al., Effects of repairing with surface protection liner employing ultrahigh strength strain-hardening mortar, Transactions of repair, reinforcing & upgrade for concrete structures.,12 (2012) 31–38. T