Mechano-chemical activation of high-Ca fly ash by cement free blending and gypsum aided grinding

This paper presents a laboratory study exploring the pozzolanic reactivity of a calcium rich fly ash by blending and grinding in a cement free system. A synergistic physico-chemical composition was achieved through individual grinding and ternary blending with another alkali sulphate rich fly ash and silica fume. The beneficial role of Flue gas desulfurisation gypsum as a grinding aid as well as a sulphate activator for fly ashes was also reported. The new blend’s parameters sensitivity revealed the physico-chemical features analogous to cement. The dispersion of the ground reactive blend particles by super plasticiser was found more effective than further alkali activation by NaOH. The potential of the developed blend as a new cementitious material is highlighted in this study. Progressive mortar compressive strength up to 90 days and 46 MPa after 28 days of curing was reported by the cement free system of activated fly ashes.