A Study of Strength Activity Index of Mortar Due to Hydration Reaction, Packing Effect, and Pozzolanic Reaction of Rice Husk-Bark Ash and Palm Oil Fuel Ash

Abstract

The objective of this research is to study the strength activity index of mortar due to hydrationreaction, packing effect, and pozzolanic reaction of rice husk-bark ash and palm oil fuel ash.Pozzolanic materials and river sand were ground into 3 different sizes as retained on a sieve No. 325as 5±2%, 13.5±2% (Portland cement was retained on a sieve No. 325 as 13.5%) and 34±2%.Portland cement type I was replaced by the pozzolanic materials or the ground river sand at 20% byweight of cementitious material. The flow of mortar was maintained between ±5% from the flow ofstandard mortar. Compressive strengths of mortars were determined at 3, 7, 14, 28, 60 and 90 days.

It was found that the strength activity index of mortar due to packing effect increased 2%when the ground river sand retained on a sieve No. 325 as 5±2% was used and decreased 3% whenthe ground river sand retained on a sieve No. 325 as 34±2% was used. Strength activity index due tohydration reaction of mortar containing ground sand with particles retained on a sieve No. 325 asthose of Portland cement was 80%. The strength activity index of mortar due to pozzolanic reactionof rice husk-bark ash and palm oil fuel ash with particle size retained on a sieve No. 325 of 5±2%were 11 and 5% at 3 days, 20 and 18% at 28 days, and increased to 25 and 23% at 90 days,respectively.