Document Type : Original Research Paper


Department of mining engineering, Imam Khomeini international university, Ghazvin, Iran


Fracture toughness is an important concrete property that controls crack extension and concrete fracture. Concrete is the most widely used material in civil engineering containing the most conventional and cheapest materials. Accordingly, cracks and fractures may cause irreparable damages. To this end, fibre-reinforced concretes have been recently constructed in order to overcome the aforementioned weaknesses. Crack propagation and fracture toughness of various concrete specimens are analyzed by the straight notched Brazilian disc (SNBD) test. The specimens are conventional concrete lacking micro-silica and limestone powder, and those containing various volume percentages of fibers including the concrete specimens containing 0.35% individual polypropylene (PP) fibers, 0.35% individual glass fibers, concrete specimens containing 0.17% PP and 0.18% glass fibers, and concrete fibers containing 0.1% PP and 0.25% glass fibers. Micro-silica has replaced 10 wt% cement in all fiber-reinforced concrete specimens, and limestone has replaced 5 wt% cement. Crack extension from the pre-existing cracks in the specimens and mode I, mode II, and mixed-mode fracture toughness are calculated. The BD test is performed on the specimens at the crack inclination angles of 0°, 15°, 28.83°, 45°, 60°, 75°, and 90°. The experimental results show the initiation of wing cracks at angles less than 60° (0 < α < 60°) from the tip of the pre-existing cracks. The crack growth and propagation path approach the loading direction by continuing loading. However, the cracks are initiated at a distance of d from the crack tip at angles larger than 60°. The observed distance is larger in the fiber-less specimens than in the fiber-reinforced specimens. The concrete specimens reinforced by 0.17% PP and 0.18% glass hybrid fibers containing micro-silica and limestone powder showed the highest mode I, mode II, and mixed-mode fracture toughness compared to the other concrete specimens.


[1]. Haeri, H., Shahriar, K., Fatehi Maraji, M., and Maraefvand, P. (2013). The use of displacement discontinuity method in analyzing crack propagation mechanism in pseudo-rock materials, Analytical and Numerical Methods in Mining Engineering, Vol. 5, 38-49.
[2]. Payro, P. (2013). Fiber-reinforced concrete, Tehran, Farhand and Danesh.
[3]. Yazıcı, Ş., İnan, G. and Tabak, V. (2007). Effect of aspect ratio and volume fraction of steel fiber on the mechanical properties of SFRC. Construction and Building Materials. 21 (6): 1250-1253.
[4]. Song, P.S. and Hwang, S. (2004). Mechanical properties of high-strength steel fiber-reinforced concrete. Construction and Building Materials. 18 (9): 669-673.
[5]. Karahan, O. and Atiş, C.D. (2011). The durability properties of polypropylene fiber reinforced fly ash concrete. Materials & Design. 32 (2): 1044-1049.
[6]. Choi, Y. and Yuan, R.L. (2005). Experimental relationship between splitting tensile strength and compressive strength of GFRC and PFRC. Cement and Concrete Research. 35 (8): 1587-1591.
[7]. Prathipati, S.T. and Rao, C.B. K. (2020). A study on the uniaxial behavior of hybrid graded fiber reinforced concrete with glass and steel fibers. Materials Today: Proceedings, 32, 764-770.
[8]. AR, T.F. and Soheili, H. (2016). Combined effect of glass fiber and polypropylene fiber on mechanical properties of self-compacting concrete. Magazine of Civil Engineering, (2 (62)), 26-31.
[9]. Aslani, F. and Nejadi, S. (2013). Self-compacting concrete incorporating steel and polypropylene fibers: Compressive and tensile strengths, moduli of elasticity and rupture, compressive stress–strain curve, and energy dissipated under compression. Composites Part B: Engineering, 53, 121-133.
[10]. Patel, K., Gupta, R., Garg, M., Wang, B. and Dave, U. (2019). Development of FRC materials with recycled glass fibers recovered from industrial GFRP-acrylic waste. Advances in Materials Science and Engineering.
[11]. Jorbat, M.H., Hosseini, M. and Mahdikhani, M. (2020). Effect of polypropylene fibers on the mode I, mode II, and mixed-mode fracture toughness and crack propagation in fiber-reinforced concrete. Theoretical and Applied Fracture Mechanics, 109, 102723.
[12]. Ghazvinian, A., Nejati, H.R., Sarfarazi, V. and Hadei, M.R. (2013). Mixed mode crack propagation in low brittle rock-like materials. Arabian Journal of Geosciences. 6 (11): 4435-4444.
[13]. Golewski, G.L. and Gil, D.M. (2021). Studies of fracture toughness in concretes containing fly ash and silica fume in the first 28 days of curing. Materials. 14 (2): 319.
[14]. Abou El-Mal1, H.S.S., Sherbini, A.S. and Sallam, H.E.M. (2015). Mode II Fracture Toughness of Hybrid FRCs, International Journal of Concrete Structures and Materials Vol. 9, No. 4, pp. 475–486.
[15]. Akbardoost, J. and Ayatollahi, M.R. (2014). Experimental analysis of mixed mode crack propagation in brittle rocks: The effect of non-singular terms. Engineering Fracture Mechanics, 129, 77-89.
[16]. Iran Boress Co. Catalogue, 2019.
[17]. Institute of Standards and Industrial Research of Iran. (2015). Concrete aggregates-properties, Standard No. 302.
[18]. Institute of Standards and Industrial Research of Iran. (2013). Mixing room, moist chamber, moist room, and water ponds used in hydraulic testing of cement and concretes, Standard No. 17040.
[19]. Krishnan, G.R., Zhao, X.L., Zaman, M., and Roegiers, J.C. (1998). “Fracture Toughness of a Soft Sandstone”, Int. J. Rock Mech. Min. Sci. Vol. 35, No. 6, pp. 695-710.
[20]. Funatsu, T., Kuruppu, M. and Matsui, K. (2014). Effects of temperature and confining pressure on mixed-mode (I–II) and mode II fracture toughness of Kimachi sandstone. International Journal of Rock Mechanics and Mining Sciences, 67, 1-8.
[21]. Mirzaei Nasirabad, H., Jalali, S.M.E., Shariati, M., and Kakaei, R. (2010). Experimental study of crack growth in notched Brazilian plaster discs and effect of crack slope on failure behavior, Analytical and Numerical Methods in Mining Engineering, Vol. 1.