For the purpose of developing a repair material that contributes to decarbonization, a basic study is conducted on an alkali activated material that does not require an alkaline solution. Thin study is characterized by the use of sodium orthosilicate as an alkaline source in order to achieve powder premixing, be ultra rapid hardening. Specifically, a basic study on ultra rapid hardening property and an improvement of the length change performance of the material using only ground granulated blast furnace slag were carried out. As a result, it was clarified that sufficient compressive strength at 3 h can be achieved by increasing the alkaline usage rate, and that the length change performance can be improved by using shrinkage reducing agents and expansive agents.