Fiber factor for fresh and hardened properties of polyethylene fiber-reinforced geopolymer mortar

Abstract

The rheology properties of cementitious composites are essential for building materials, especially in fiber reinforced composites. This paper studied two different lengths (6 mm and 12 mm) of polyethylene (PE) fiber reinforced fly ash-slag-silica fume-based geopolymer mortars with two different water-binder ratios. PE fiber reinforced geopolymer mortar (PFRGM) consists of suspended fluid, and fiber particles are divided into three areas according to the fiber factor (FF) theory. When FF is lower than critical FF (Fc) = 70, the distance between fibers is far, so its influence on PFRGM can be ignored. When FF exceeds dense FF (Fd) = 400, the fibers tangle together easily, resulting in balling, which seriously deteriorates the various performance of PFRGM. When FF is between Fc and Fd, the mechanical properties are significantly improved, and the mixture can still flow under its weight, which is the best region for preparing PFRGM. A good quadratic function correlation between the FF and the fluidity is revealed. The relative compressive strength of PFRGM is higher than that of glass fiber reinforced cement mortar. In contrast, the relative flexural strength of PFRGM is lower than that of glass fiber reinforced cement mortar. Generally, 12 mm fibers provide a better improvement in the flexural strength of mortar than 6 mm fibers due to the higher bridging efficiency of the longer fibers.