Investigating the fracture parameters of lightweight geopolymer concrete reinforced with steel and polypropylene fibers

Abstract

In this current paper, the effects of different percentages of scoria (70, 80, and 90) replacing coarse aggregates, steel fiber volume fractions (Vsf = 0.5 %, 1 %, and 1.5 %) merely and in combination with polypropylene fiber volume fractions (Vppf = 0.1 %) on fracture parameters of lightweight geopolymer concrete(LWGC) have been studied using WFM(Work of Fracture Method) and SIZEM(Size Effect Method). The results indicate that: (a) increasing the content of Vsf and Vppf increases the fracture energy and fracture toughness. (b) The content of polypropylene and steel fibers has remarkable effects on fracture parameters in compositions containing 70 % scoria. (c)The composition of 70 % scoria instead of coarse aggregates, containing (Vsf = 1.5 %) and (Vppf = 0.1 %) is more significant in the analysis of fracture parameters than other samples in this research. In general, it can be said that the increase of fracture parameters like Gf, GF, KIC, and Cf is more noticeable in samples containing 70 % scoria. Also, in the samples containing 70 % scoria, containing (Vsf = 1.5 %) and (Vppf = 0.1 %), the Gf, KIC, and GF are almost 1.84, 1.44, and 2.08 times the control samples, respectively. It is also to see an increase in parameters such as Gf, GF, and KIC in samples containing (Vsf + Vppf) compared to (Vsf). This shows the positive effect of adding polypropylene fibers (Vppf = 0.1 %) to the samples. When the content of steel fibers increases by 0.5 %, 1 %, and 1.5 %, the increase in the mentioned parameters can also be observed. The positive effect of increasing the content of steel fibers in increasing the fracture energy obtained from the results is determined.