Effects of wood fiber on the properties of silicoaluminophosphate geopolymer

Silicoaluminophosphate geopolymer is an important class of inorganic cementitious material, which attracts increasing attention due to the excellent mechanical properties, high thermal resistance and low dielectric properties. However, like most of the pristine or unreinforced cement based materials, silicoaluminophosphate geopolymer still suffers from brittle failure, which seriously limits its popularization and application. Based on the characteristics that sili-coaluminophosphate geopolymer is almost a Ca-free material forming in acidic environment and driving by the demands of low carbon, environmental friendly and low cost, this paper adopts wood fiber as a reinforcing material to improve the toughness of silicoaluminophosphate geo-polymer. Results show that the incorporation of wood fiber can effectively reduce the brittleness and increase the fracture toughness of silicoaluminophosphate geopolymer by the excellent bonding performance between reaction products and wood fiber. However, the addition of wood fiber is unfavorable to the setting and hardening behaviour, reaction degree and compressive strength of silicoaluminophosphate geopolymer. Although the hydrolysis of wood fiber in acidic environment results in some local defects on its surface, these defects have little effect on the improvement of silicoaluminophosphate geopolymers toughness due to the repairing effect of reaction products.