Q&A for How to Mix Portland Mortar

It depends on the type of surface and its purpose. One possibility is to mix white cement and regular cement. Note, however, that the white cement does cure more quickly as it is designed to be used for instance to place tiles. If it is for finishing a wall or floor, you can also look for polished cement or micro cement.

For pointing, a 3:1 sand to cement mix should be fine. I don't expect pointing will significantly impact the load bearing aspects of the wall.

Additives aren’t necessarily needed unless you have special requirements, e.g. you want to accelerate or decelerate the setting/curing period. The setting rate is temperature dependent; for example, in hot weather, you may want to add an additive to slow down the setting rate, whereas in cold weather, you may want to speed up the setting rate. You also can add pigments to the mortar mix if you want a custom color.

One yard of aggregate will make one yard of concrete. Portland cement and water barely change the volume at all. Mixing coarse and fine aggregate is tricky because the fine aggregate fits in the spaces between the coarse aggregate without increasing the finished volume. So I recommend buying concrete aggregate rather than sand and gravel separately.

The crystals may be sand that was mixed with the cement. Regular Portland cement usually has crystals as one of the ingredients in the production is limestone. Some other cement types used, for instance, to apply tiles have smaller crystals.