6. Conclusions and Recommendations

It can be concluded from the present study that fiber-reinforced geopolymer can significantly improve the bending strength of the matrix, which makes the failure mode of the geopolymer change from brittleness to ductility. Fiber acts as a bridge for geopolymer cracks, and transfers stress from cracks to geopolymers, thereby reducing crack propagation. Different fibers have different effects on matrix. Steel fiber is helpful to enhance strength properties, while glass fiber is conducive to eliminating microcracks and the ductility. In order to obtain a composite fiber with comprehensive properties that are endowed with all the benefits of strength, microcrack elimination, ductility, and denser mix, steel and glass fibers can be used in the best proportion of the composite fiber.
At present, the research mainly focuses on the influence of fiber type and content on the performance of geopolymer, but the following factors may also affect the geopolymer performance: the selection of geopolymer matrix, interface strength, fiber extraction method, and fiber treatment. Therefore, the following aspects remain to be further explored:
  1. Most geopolymers are prepared by alkali activation, but it is actually feasible to carry out acid activation as well. Studies on fiber reinforced acid activated geopolymers should be taken into consideration.
  2. The present research focuses on the influence of fiber type and content on the geopolymer performance. Indeed, more emphasize can be placed on the fiber treatment, extraction method, matrix-fiber interface characteristics and pore structure of composite materials.
  3. There are few studies and applications on the influence of unique properties of fibers such as light weight, heat preservation and heat insulation on geopolymer, which requires further exploration.
  4. More academic attention should be paid to the special application of geopolymer, such as 3D printing, insulation wall materials, etc.