Effects of Hybrid Fibers on Lightweight Oil Palm Geopolymer Concrete Exposed to Elevated Temperatures

The study was conducted to investigate the high temperature resistance of hybrid fibers of polypropylene (PP) and polyvinyl alcohol (PVA) fibers using oil palm husk (OPS) as coarse aggregate in combination with palm oil fuel ash (POFA) as binder in geopolymer concrete consisting of alkali activated sodium silicate and solid sodium hydroxide (NaOH) with an activator to binder ratio (AK/B) of 0.6. To investigate the changes in their fresh and hardened properties, nine concrete mixtures of oil palm husk fiber geopolymer concrete (FOPSGCs) were prepared with different mono and hybrid fiber concentrations of PVA and PP fibers (0%, 0.5%, 1% and 1.5%) of volume fractions. For this purpose, the mechanical properties of compressive, flexural and splitting tensile strengths FOPSGCs were produced using a ternary mixture of 25% POFA and 75% fly ash (FA). The high temperature resistances of 200°C, 400°C, 600°C and 800°C for 2 h at 4.4°C/min were investigated using compressive strength and scanning electron microscopy (SEM). For the purpose of determining the residual compressive strength of each mixture, the geopolymer concrete samples were subjected to high temperatures of 200, 400, 600 and 800°C. The test results showed that 1% PVA fibers gave the best mechanical properties. In general, exposure to temperatures above 200°C increases the compressive strength of OPSGC. After exposure to temperatures up to 400°C, the strength of OPSGC began to decrease. The max. reduction in compressive strength was 42.3% for mix PP1.0PVA0 when exposed to 400 °C.

Effects of Hybrid Fibers on Lightweight Oil Palm Geopolymer Concrete Exposed to Elevated Temperatures Keywords:

Geopolymer , Lightweight concrete , Palm oil fuel ash , Polyvinyl alcohol fiber , Elevated Temperature