Compressive Strength and Microstructure of Palm Oil Ash Containing Aluminum Foil Geopolymer Paste

Abstract

This research was to study early compressive strength at 7 days and microstructure from palm oil ash containing aluminum foil geopolymer paste. Palm oil ash was replaced by aluminum foil 0, 2.5 and 5.0 percents by weight. Alkali liquid/binder ratio of 1.0, Na2SiO3/NaOH ratio of 1.0 and concentration of NaOH 12.5 M. All the samples after mixing were cured at 30, 40 and 50 oC in an oven for 48 h after then curing at room temperature for 5 days before compressive strength test. From this test showed that the compressive strength increases with the amount of aluminum foil displacement due to increases the amount of aluminum ions in the system that gave the Si/Al ratio an optimum value, resulting in a large amount of Si-O-Al bonding. But the amount of aluminum foil higher than 5% by weight allows the geopolymer paste to faster setting time as a result difficult forming. The effect of curing at 50 oC gave higher compressive strength due to high temperature catalyzes the geopolymerization. SEM and FTIR were used for analyzing microstructure of the samples.