Tailoring the hydration and physicomechanical properties of fly ash-modified cement through lithium oxide addition

Fly ash was used as an effective supplement for Portland cement during construction industry. However, the problem of slow hydration at early ages of cement mixes containing fly ash worries researchers in this field. This work aims at improvement of early hydration progress of 50:50 wt. % of fly ash: cement mix through addition of limited contents of lithium oxide (0 up to 1 wt. %). Physico-mechanical properties involving setting time, densification parameters and mechanical properties of the hardened cement/fly ash pastes were evaluated in accordance with international standards. XRD, FTIR and TG technique were employed to monitor the mineral composition and hydration behavior of some selected samples. It was concluded that addition of 0.6 wt. % lithium oxide to 50:50 wt.% fly ash: cement mix results in a pronounced improvement of the early ages-hydration and hence densification and mechanical properties since the lithium oxide particles act as seeds which decrease the nucleation barrier and hence initiate early (1,3 and 7 days) hydration process.