An Experimental Study on the Hydration Properties of Nano Palm Oil Fuel Ash

Abstract

This experimental study was conducted with objectives to figure out the material properties and the hydration properties of nano sized Palm Oil Fuel Ash (nPOFA), which was newly invented, and draw the hydration mechanism of nPOFA in cement matrix through experimental results. This study largely consists of 2 series. First series is the material properties of nPOFA. Second series is the hydration properties of nPOFA in cement matrix. The replacement ratio of nPOFA was set at 0 to 90% and specimens containing nPOFA were prepared in order to figure out flowability, compressive strength and hydration products. XRF, BET, XRD, SEM-EDS, TEM and FT-IR analysis indicated that the nPOFA mainly consists of SiO2 and its average size of nPOFA is between 100 ~ 150 nm. It was confirmed that the compressive strength of mortar with 10% nPOFA was higher than that of OPC at the age of 7 days and mortars containing nPOFA showed the higher compressive strength than OPC at the late ages (28 and 56 days) due to the pozzolanic reaction. It was thought that the maximum replacement ratio of nPOFA was 30% from the results. As curing ages increased, microstructure became denser due to hydration products, but at the early age, large pores existed because nPOFA particles hindered cement to hydrate and were adsorbed on the surface of cement. The reduced amount of Ca(OH)2 from the pozzolanic reaction and the formation of C-S-H were also confirmed by TG/DTA, XRD and FT-IR analysis. Through these experiments, schematic hydration mechanism of nPOFA in cement matrix could be drawn.