Issue 41

H. Šimonová et alii, Frattura ed Integrità Strutturale, 41 (2017) 211-219; DOI: 10.3221/IGF-ESIS.41.29 218 C ONCLUSIONS he authors focused their attention on the evaluation of the influence of the interfacial transition zone on the stress distribution in the cracked specimen. The crack tip was located at the interface between MTX and ITZ. As the average stress is used for stability criterion suggestion in cases of general singular stress concentrators [21], it can be used for quantification of the severity of the crack with its tip at a bi-material interface. Therefore, the opening stress  yy was observed and the average stress  yy ahead of the crack tip calculated. Not only the influence of the various ITZ thicknesses but also of various elastic moduli of ITZ on the near-crack-tip stress field was studied and discussed. Critical applied stress was evaluated based on knowledge of critical opening stress. Knowledge of the effect of the ITZ on the stress distribution will contribute to better understanding of the toughening mechanisms of the ITZ and aggregate in silicate-based composites. A CKNOWLEDGEMENT his outcome has been achieved with the financial support of the Czech Science Foundation under project No. 16- 18702S “AMIRI – Aggregate-Matrix-Interface Related Issues in Silicate-based Composites”. R EFERENCES [1] Nevile, A.M., Properties of Concrete, Pearson Education Limited, Harlow, (2011). [2] Scrivener, K.L., Crumbie, A.K., Laugesen, P. The Interfacial Transition Zone (ITZ) between Cement Paste and Aggregate in Concrete, Interface Science, 12 (2004) 411–421. ISSN 1573-2746. DOI: 10.1023/B:INTS.0000042339.92990.4c [3] Farran, J., Contribution mineralogique a l'etude de l'adherence entre les constituants hydrates des ciments et les materiaux enrobes, Revue des Matiriaux de Construction, 491 (1956) 155–157, 492 (1956) 191–209. [4] Mori, T., Tanaka, K., Average stress in matrix and average elastic energy of materials with misfitting inclusions, Acta Metallurgic, 21 (1973) 571–574. DOI: 10.1016/0001-6160(73)90064-3. [5] Hashin, Z., Monteiro, P.J.M., An inverse method to determine the elastic properties of the interphase between the aggregate and the cement paste, Cement and Concrete Research, 32 (2002) 1291–1300. DOI: 10.1016/S0008-8846(02)00792-5 [6] Li, C.V., Maalej, M., Toughening in Cement Based Composites. Part I: Cement, Mortar and Concrete, Cem Concr Comp. 18 (1996) 223–237. DOI: 10.1016/0958-9465(95)00028-3 [7] Shah, S.P., Fracture toughness of high strength concrete, ACI Mater J, 87 (1990) 260–265. [8] Wriggers, P., Moftah, S.O., Mesoscale models for concrete: homogenisation and damage behaviour, Finite Elements in Analysis and Design , 42 (2006) 623–636. DOI: 10.1016/j.finel.2005.11.008 [9] Vervuurt, A., Van Mier, J.G.M., Fracture of the Bond Between Aggregate and Matrix: An Experimental and Numerical Study, In: A. Katz, A. Bentur, M. Alexander, G. Arligue, (eds.) RILEM Second International Conference on the Interfacial Transition Zone in Cementitious Composites, E & FN Spon, New York, (1998) 51–58. [10] Klusák, J., Profant, T., Knésl, Z., Kotoul, M., The influence of discontinuity and orthotropy of fracture toughness on conditions of fracture initiation in singular stress concentrators, Eng Fract Mech. 110 (2013) 438–447. DOI: 10.1016/j.engfracmech.2013.05.002 [11] Knésl, Z., Klusák, J., Náhlík, L., Crack initiation criteria for singular stress concentrations, Part I.–IV, Eng Mech, 14 (2007) 399–408, 409–422, 15 (2008) 99–114, 263–270. [12] ČSN EN 196-1:2005, Methods of testing cement – Part 1: Determination of strength, Prague: ČNI, 2005, (the Czech version of the European Standard EN 196-1:2005). [13] ČSN EN 1015-3:2000, Methods of test for mortar for masonry – Part 3: Determination of consistence of fresh mortar (by flow table), Prague: ČNI, 2000, (the Czech version of the European Standard EN 1015-3:2000). [14] ČSN EN 1015-6:1999, Methods of test for mortar for masonry – Part 6: Determination of bulk density of fresh mortar, Prague: ČNI, 1999, (the Czech version of the European Standard EN 1015-6:1999). T T