In this study, the possibility of using micro metakaolin (mMK) as a partial replacement of ground granulated blast-furnace slag (shortened as slag) in alkali-activated slag (AAS) paste was investigated. Slag was partially replaced with mMK at levels ranging from 0% to 10% with an interval of 2%, by weight. Workability of different mixtures was investigated. Compressive strength at ages of 7, 28, 91 and 180 days was measured. The behaviour of the investigated paste mixtures after exposure to elevated temperatures ranging from 400^°C to 1000^°C with an interval of 200^°C for 2h was evaluated quantitatively by measuring the residual compressive strength and qualitatively by visual inspection. The various decomposition phases formed were identified using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectra (EDS). The results showed higher workability with the inclusion of mMK. The workability increased with increasing mMK content. The compressive strength significantly decreased with the inclusion of mMK at early ages. This reduction sharply reduced at latter ages. The inclusion of 6-10% mMK showed higher fire resistance than the neat AAS up to 800^°C, whilst the neat AAS showed higher fire resistance at 1000^°C.

activated slag, micro metakaolin, residual strength, elevated temperature.