</font><font color="blue" class="small">( powder concrete)</font>
I assume that you mean "Portland Cement" which is made of limestone, clay, and sand cooked together then gypsum is added. This is the "binder" in the concrete and composes 7-15% of the total concrete weight. The rest is aggregate: sand, gravel, etc. When you order concrete delivered by truck, they ask "How many sacks?" This means how many (usually 80 lb.) sacks of Portland Cement do you want mixed into each cubic yard of the concrete. Typical mixes, depending on application, will be 4 sack, 4.5 sack, 5 sack, 5.5 sack, or 6 sack mixtures. In addition to the normal aggregates, for an extra cost you may add flyash or volcanic pumice to increase density and reduce porosity, fiberglass or HDPE fibers to prevent cracking during curing (these can substitute for rebar), coloring, etc. Water content varies depending on outdoor temperature and other factors. Special mixes for special applications include things like Gunnite to build swimming pool walls.
Dry, from the home center, you can buy just Portland Cement in a bag, or you can get "Ready Mix Concrete" which is a small percent Portland Cement already mixed together with the aggregates.
Brick mortar is Portland Cement and a specific grade of sand blended. Again, you can buy "Ready Mix Mortar" if you don't want to mix it yourself.
You can get a number of special mixes at the home center as well as additives such as liquid acrylic to make the product stronger and reduce porosity. Some mixes are designed to be applied dry. An example may be a prepoured concrete anchor that is already in the ground for a metal post. The anchor has threaded rod to which the post is secured with bolts. Then the volume from the bottom of the post to ground level may be packed (as in hard tamp packed) with a dry mix concrete which absorbs moisture from the surrounding environment and then cures.