Effect of Adding Methylcellulose on Mechanical and Vibration Properties of Geopolymer Paste and Hybrid Fiber-Reinforced Geopolymer Composite

The effect of methylcellulose, an organic admixture, on the mechanical properties and vibration characteristics of newly developed geopolymer paste (GP) and hybrid fiber-reinforced geopolymer (FRG) composite is investigated in this study. Fly ash and slag are applied to manufacture both the GP and FRG. Short fibers, including 1% copper-coated micro steel fiber, 1% high-strength polyethylene fibers in volume fraction, and 0.4%, 0.8%, and 1.2% methylcellulose in weight fraction, are added to reinforce the geopolymer matrix to develop a new FRG. The addition of methylcellulose can increase the compressive strength and flexural strength of GP and FRG and the load-carrying capacity and toughness with the deflection hardening for FRG, while slightly decreasing the static modulus of elasticity (SMOE) of GP and FRG. The increase in the toughness of FRG can reach 80% by adding 0.8% methylcellulose. In addition, the dynamic modulus of elasticity (DMOE) and the damping ratio of GP and FRG are investigated by conducting hammer impact forced vibration test. The results demonstrate that the addition of methylcellulose to GP and FRG significantly increases the damping ratio by up to 15% and 25%, respectively, while slightly decreasing the DMOE of both GP and FRG.