The experts and I agree, that with pre-mix bags available, unless you are on a major jobsite with at least a dozen masons working, it's just not worth mixing yourself. However, if you are inclined to do so, our friends at Superlite Block have provided the industry standard directions below.
There are a variety of mortar mixes that the mason contractor can mix up, depending on the type of material that is being installed:
The different types are achieved by varying the ratio of Portland Cement, Lime and Sand. Type S mortar is the most common for the Arizona market so we will use this as the basis for our comparisons.
There are three primary ways to make mortar:
The Portland Cement, Hydrated Lime, Masonry Cement and Pre-mixed Mortar are available in bags, the Masonry Sand is generally available in “bulk quantities” that are delivered by a truck or can sometimes be purchased in big “super sacks” from the big box retailers.
|Portland Cement||94# bags|
|Masonry Cement||70# or 78# bags|
|Pre-mixed Mortar||60#, 80# or 94# bags|
|Masonry Sand||Usually a pile of sand is delivered to the jobsite by a dump truck. The sand is measured into the mixer by means of a standard square point shovel that is “mounded full”. This is referred to as a “shovel of sand”|
Portland Cement, Lime and Sand
This is the “old school” method, the standard for the industry that all other methods are compared to. In order to make a Type S masonry mortar one would proportion the materials into the mixer in this manner;
|1 bag||94# of Portland Cement|
|½ bag||50# Hydrated Type S Lime|
|28 “Shovels”||Masonry Sand|
|7 to 8 Gallons||Clean Water|
Amount of water required to make good mortar will vary depending on the desired consistency of the mortar. For stiff mortar use less water, for wet mortar use more water. If you do not add enough water the mortar is so stiff that it is unworkable and very difficult to use, if you add too much water the mortar turns to “soup” and you will be unable to use it.
Masonry Cement is simply a product that has Portland Cement and Hydrated Lime already blended together in the proper proportions. In order to make a Type S mortar with Masonry Cement one would proportion the materials into the mixer in this manner:
|1 bag||70# or 78# Masonry Cement|
|18 to 20 “Shovels”||Masonry Sand|
|5 Gallons||Clean Water|
Add water to achieve desired consistency of mortar, less water for stiff mortar, more water for wet mortar.
This is the easiest mortar of all to make. Pre-mixed mortar is a combination of Portland Cement, Hydrated Lime, and Masonry Sand already blended together in the proper proportions to make a Type S mortar. All that is needed is to add sufficient water to achieve the desired consistency, usually about 5 to 6 quarts for an 80# bag. Pre-mixed mortars are a little unique in that they require a slightly modified mixing procedure.
Pre-mixed mortars use a kiln dried sand that has a higher water demand. It takes a few minutes for all of the water to be absorbed into the dry sand, hence the need for a prolonged mixing time. If you do not allow the mortar to set and “slake”, it will feel gritty on the trowel and will be difficult to work with.
All of these mortar may be mixed by hand in a wheelbarrow or “mud tub” for those of us who do not own a mixer. A mortar hoe is a great tool when mixing by hand, as well as the obligatory square point shovel. I have found from past experience that a standard construction grade wheelbarrow is too small to mix a full bag of Portland Cement, ½ bag of Hydrated Lime and 28 shovels of sand. It will just barely fit 1 bag of Masonry Cement and 18 to 20 shovels of sand. A standard wheelbarrow very comfortable fits 3 of the 60# bags of Pre-mixed Mortar, or 2 of the 80# or 94# bags of Pre-mix Mortar. Follow the same mixing procedures as when using a mechanical paddle mixer.