An Experimental Study on Compressive Properties of Composite Fiber Geopolymer Concrete

The production process of Portland cement (OPC) consumes energy and releases carbon dioxide, which affects the environment. It has been found that geopolymer cementing material is a better substitute for it. The strength effect of fiber on geopolymer materials is the basis of the application of fiber geopolymer concrete in structural beams, slabs, and other components. Geopolymer concrete was prepared with fly ash, slag, and water glass as the main raw materials, and the effects of fiber type, quality, and blending method on the compressive properties and elastic modulus of geopolymer concrete were compared to explore the working mechanism of fiber-reinforced geopolymer concrete. Through experimental research, the results showed that in 0.2% flocculent lignin fibers, when the mass ratio of carbon fibers was increased, the strength of the geopolymer concrete decreased. Due to the increased mass ratio of wavy steel fibers, comprising 0.2% flocculent lignin fibers, the strength enhancement effect was not apparent. Moreover, with regard to enhancing the modulus of elasticity of geopolymer concrete, blending fibers exerted the most significant effect. The fiber was added to geopolymer concrete to form a three-dimensional supporting frame system. When cracks occurred under the action of force, the development of cracks was limited due to the fibers, and the bonding slip delayed the propagation of cracks. The composite fiber could make full use of the advantages of each material and improve the strength of geopolymer concrete. The compressive properties of geopolymer concrete could be enhanced by blending single-fiber or mix-fibers, and the effect of mix-fibers was more optimal than that of others. The above research results provide a theoretical reference for the design of geopolymer concrete and a theoretical basis for the application of fiber geopolymer concrete in structural beams, slabs, and other components.