Expert: Dan Griffin - 7/30/2009

Question
QUESTION: I have some N type mortar and would like to use it to pour a slab. Will this N type work and how do I mix it if I can use it. It was give to me and I was thinking I could mix sand and gravel to pour my slab.

ANSWER: Mike, N type mortar is for laying bricks.  It has lime and Portland blended for creating a mortar mix.  It does not make structural concrete and does not have the same ultimate compressive strength required for slabs.  You don't tell just what you are making.  It will set up and get hard, but will be prone to dusting.  I would not use it for something permanent.

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QUESTION: I am wanting to use this pad to drive my pickup on going in and out of my shop and use it for a wash pad to wash my motorcycle on and cars.

Answer
Mike, I'm getting the impression you might not understand much about concrete.  Here are a few facts.

Cement is NOT concrete.
Mortar mix is NOt cement.
Mortar is made from cement, lime, and sand.
Concrete is made from cement, sand, and gravel.

A car would need a slab about 20 feet long by 10 feet wide.
The slab would need to be at least 4" thick.
This would equal 66.67 cubic feet of concrete.
Each cubic foot weighs 150 pounds, so the slab will weigh about 9,999 pounds.
There are different design mixes, but there will be about 20 pounds of Portland in each cubic foot, the rest being sand and stone.
This slab would require about 1340 pounds of Portland cement, Portland weighs 94 pounds per bag (your type N is much lighter), so you would need about 14 bags of Portland cement to mix with about 4 1/2 tons of sand and gravel.  If you think about a 1/2 ton pickup truck, you cannot haul the cement in one trip.  The sand and gravel will take 8 to 10 trips.

I hope this has put concrete into perspective for you.