The unfortunate side effect of building for a home is that there are so many angles of a project that ordering materials can be an overwhelming process. Take, for example, concrete blocks. While there are some estimates for the average block size, the reality is that custom blocks and numerous other variables can change exactly how much sand you need to order to create the mortar for setting the stones.
The basic mixture for mortar will depend on the individual who is doing the work. Most masons use a mixture of three parts sand to one part cement, or four parts sand to one part cement. It is rare for any mason to go beyond four parts because the mixture can be too sandy and lacks sufficient binder to harden into a mortar phase.
Basic Block Size
The average building block size is 8-by-8-by-16-inches. This means the block is 16 inches long and 8 inches square around the sides. However, there are so many options that the type of stone you have can change the amount of sand you need to order. Your most viable option is to speak with a professional to determine exactly how much you need for your block project.
As a general rule, you can order around 600 to 800 pounds of sand for every 100 blocks you are setting, provided that you are using the standard size cinder block. You will use two and a half to three bags of cement mixed in with that sand. However, the smaller the blocks, the more sand and cement you will need because there are consequently more joints to fill.
Whenever you are ordering for a project you should always order 15 to 20 percent extra. This is doubly true with block projects because if you start trying to mix different batches of sand and cement, you can end up with a completely different color of mortar due to the inconsistencies of color in these natural products. Always order more than what you think you need.