A Real-Time Study on the Cracking Characteristics of Polyvinyl Alcohol Fiber-Reinforced Geopolymer Composites under Splitting Tensile Load Based on High-Speed Digital Image Correlations

The cracking of geopolymer caused by its brittleness characteristics could reduce the stability and durability of the building structure. Studying the cracking behavior of fiber-reinforced geopolymer composites (FRGCs) is important to evaluate the toughness strengthening of geopolymer. This paper presents a real-time study on the cracking characteristics of FRGCs under splitting tensile load based on high-speed digital image correlation (HDIC) technology. The splitting tensile test was conducted on the FRGC with different fiber content. The real-time variation of strain and displacement field during the splitting process was analyzed. The influence of fiber content on the mechanical properties and crack behavior of FRGCs was discussed. Considering the splitting strength and crack width, the optimal fiber content for FRGCs that satisfied the crack resistance requirement was proposed. The results show that the incorporation of fiber can delay the cracking time and reduce strain change during the splitting process. The splitting tensile strength and the deformation increase as fiber content increases, while the crack width decreases as fiber content increases. The FRGC with 2.0% fiber content can maintain a crack width smaller than 0.1 mm, which satisfies the crack resistance requirements of practical engineering for economic consideration.