Block mortar

If you are not mixing a yard or more it is cheaper and easier to use bagged mortar mix with sand in it. The pros still use a bag mix on big jobs but the kind without the sand and they get sand dropped loose. It doesn't hurt the sand to get wet but adjust the water you add accordingly. I have never seen anyone actually get the portland and lime. Usually mortar mix will have some "secret ingredient" and the guys do usually have a brand they prefer although the secret may be that it is all the same. ;-)

No way can you measure mixes as accurately as the folks at the bagging plant. If you're talking several cubic yards of mix daily with scales and other specialized equipment, do your own. Otherwise, prepackaged is better like many other products.

Joe Joe

I think the bags of premix are rated 4000 psi.

For a yard or more, you may want to compare the rental price of a mixer against your labor/time, as to using a shovel/hoe to mix a wheel barrow at a time.

Sonny

Years ago we used to mix out own mortar, 3 pails of sand, one pail of Portland cement and 1/2 pail of Sealbond, and additive that was available then. It made a very strong mortar and one that was very sticky so that it stuck well on the ends of the blocks without falling off before you got it in place.

It sounds as if this may be whole new undertaking for you. You don't need to use any mortar. Look at SureWall, actually quite an effective approach. I would still rebar and slush the vertical cells and trough blocks.

Sorry, SureWall is apparently an old name for the material. Quickrete has a version here: