The repair of mortar-based structures is critically important because mortar-based structures such as buildings, bridges, tunnels, highway and roads are inevitably degraded by deterioration or damage. To save expense during construction and to avoid traffic congestion during repair work, it is very important to reduce construction time as much as possible. In order to reduce construction time, therefore, the setting time of mortars has to be shortened. The mortars which have short setting times are called high early strength cement mortars. These high early strength cement mortars usually have a short working time of under 40 min and a compressive strength of over 24 MPa [1].