Effects of alkaline solution to binder ratio on fracture parameters of steel fiber reinforced heavyweight geopolymer concrete

In the current paper, effects of alkaline solution to binder ratio (Al/Bi) (i.e. 0.65, 0.75 and 0.85) on fracture parameters of steel fiber reinforced heavyweight geopolymer concrete (SFRHWGC) with different fiber volume fractions (Vf) (i.e. 0.5%, 1% and 1.5%) are investigated using work of fracture method (WFM) and size effect method (SEM). Moreover, relationship between each of the fracture parameters, the steel fiber volume fraction and the Al/Bi ratio is proposed in the form of a polynomial function. The results show that: (a) with increase in the steel fiber content, the fracture energy, the fracture toughness and the ductility increase significantly. (b) the effects of steel fiber content on the fracture parameters are more significant at higher ratios of the Al/Bi. (c) at Vf = 1.5%, the total fracture energy (GF), the initial fracture energy (Gf) and the fracture toughness (KIC) can be obtained approximately 95, 8 and 3 times that of control samples, respectively. (d) at Vf = 1.5%, the ductility indices such as the characteristic length (Lch) and the effective size of the process zone (Cf) may be obtained approximately 24 and 8 times that of the control samples, respectively. (e) at a given volume fraction of steel fiber, as the Al/Bi ratio increases, the fracture energy and the fracture toughness reduce while the ductility increases. (f) at Vf = 1.5%, the ratios of the values of the fracture parameters such as GF, Gf, KIC, Lch and Cf at Al/ Bi = 0.85 to 0.65 are obtained equal to 0.84, 0.82, 0.71, 2.52 and 1.69, respectively. (g) as both the steel fiber content and the Al/Bi ratio increase, the GF/Gf ratio increases. (h) the GF/Gf ratio for the SFRHWGC is found to be equal to 35.21 +/- 5.91%.