Portland Cement I/II is one of key components in making concrete and portland/lime mortars. When mixed with sand and coarse aggregate it produces concrete. When mixed with lime and mason sand it produces mortar. Type I is for general use.
Use portland cement for custom concrete mixes, for both concrete slabs or for repairs where the concrete will be at least 2" thick. Also use for custom mortars where adjusting the portland to lime ratio allows for both higher or lower strengths.