SiC fiber reinforced geopolymer composites, part 1: Short SiC fiber

In this paper, short SiC fiber (SiCsf) reinforced geopolymer composites (SiCsf/geopolymer) were prepared and effects of fiber contents and lengths on the microstructure and mechanical properties of the composites were investigated. In-situ crack growth was carried out to study the fracture behavior and toughening mechanism of the composites. The results showed that SiCsf/geopolymer composite developed weak interfacial bonding state through mechanical interlocking rather than chemical interfacial reaction. The presence of SiCsf not only enhanced both flexural strength and work of fracture, but also prevented the catastrophic failure as seen in neat geopolymer. When fiber content was 2.0 vol% with length of 5 mm, the composite obtained the highest flexural strength and work of fracture, which were 5.6 and 63 times as high as those of neat geopolymer, respectively. In-situ crack growth together with fractographs showed that toughening mechanisms of the composite included formation and propagation of microcracks, crack deflection, fiber debonding and significant pulling-out.