This study investigates the effects of alkaline activators and curing method on the compressive strength of mortar for the development of cementless alkali-activated concrete using 100% of fly ash as binder. Results reveal that the compressive strength improved according to the increase of the molar concentration of NaOH. In addition, molar ratio Na2O to SiO2 of 1.12 activated the reaction of fly ash with Si and Al constituents and resulted in the most remarkable development of strength. In the case of mortar requiring high strength at early age, higher curing temperatures appeared to be advantages. Curing at 60°C during 48 hours is recommended for requiring high strength at age 28days. Moreover, performing atmospheric curing after high temperature curing appeared to be more effective for the development of strength than water curing. Based on these results, it has been analyzed that alkaline activators fabricated with proportions of 1:1 of 9M NaOH and sodium silicate should be used and that atmospheric curing should be performed after curing at 60°C during 48 hours to produce high strength alkali-activated mortar exhibiting compressive strength of 70MPa at age 28 days.