Potential use of spent mushroom compost ash as an activator for pulverised fuel ash

When added to the PFA/OPC paste mix SMCA had the effect of improving early strength development. X-ray diffraction results showed that, in the mix which contained 20% SMCA, ettringite formation was improved at both 7 and 28 days, whereas thermogravimetric analysis identified depletion of calcium hydroxide levels at both 3 and 7 days for the same sample pastes. It is therefore considered that the increased strength development in SMCA mixes is a result of the presence of large quantities of sulfates in SMCA, which, when hydrated, has activated the glassy phases present in PFA to form ettringite, as well as possibly accelerating the pozzolanic activity.