The compressive strength of geopolymer-hardened materials such as mortar or concrete shows a linear relationship with the alkali/water content (molar ratio) of the alkali silicate solution used in their production. Geopolymer mortar and concrete have excellent properties of chemical durability such as alkali-aggregate reaction resistance and acid resistance. Potassium increases the fluidity of fresh geopolymer mortar and concrete, and this fluidity enables the creation of a hardened paste featuring higher strength with high alkaline concentrations. In this study, an environmentally friendly geopolymer PC sleeper was prepared using fly ash and alkali silicate solution. The sleeper satisfies the performance specifications of JIS E 1202.