Ok I admit it, almost all of the masonry i have done has been with premixed bagged, just add water motar mix.
So this week I am taking a missions group to Peru to lay a bunch of concrete block for a school down there. And you guessed it. down there they don’t have any sort of premix. Just sand and portland.
So what’s the recipe? I seem to remember making some mortar with a 1 to 3 portland to sand mixture but I’m a little cloudy on that.
Also I heard that throwing a shovelfull of lime into the batch makes it good and sticky….?
And grout for filling the cavities….the same mix, just with more water or what?
Can a good mason give me a couple recipes and also mixing tips? We will have a 2 1/2 bag mixer down there.
Thanks a bunch, Jason
Replies
You've basically got it- 1 part masonry cement to 3 parts sand. masonry cement can be anything between 1:1 lime to portland cement to pure portland cement. I've actually used mortar without p-cement, just lime and "pozzolan clay", a volcanic ash with cement like qualities. I wouldn't recommend that unless you're doing restoration work.
However, using 1/3 lime and 2/3 portland cement is a good mix. I.e., 1 shovelful lime, 2 shovelfuls portland, 9 shovelfuls sharp sand. If you're using rounded sand, like riverbed sand, you'll want to decrease the amount of sand in the recipe.
Traditional way to make it is to slake the lime in water, then add the other ingredients, but most people just mix it all together dry, then add water. That seems to work fine.
zak
"so it goes"
Ok, so what about the grout for filling the cavities? just use the same mix and add more water?
When in doubt, get a bigger hammer!
I use concrete, or concrete and sand and rocks. you could use the mortar recipe, but leave out the lime, and add some larger aggregate if it will fit in the cavities.
It depends if the fill is going to be structural or just filler. In a double sided wall for a building, I would go with concrete. a little decorative wall, I wouldn't worry much about throwing extra gravel and rock in there.
I'll assume that you don't have premixed concrete either. 1 cement, 2 sand, 3.5 gravel is a place to start for making concrete, but there are others here that will give you a specific mix design for your needs, if you know what they are.zak
"so it goes"
we use 9 shovels to one bag“Our country! In her intercourse with foreign nations, may she always be in the right; but our country, right or wrong.”
mortar is
portland and sand (any sand below 1/8")
not beach sand....
cleaner the better... and clean drinkable water
depends what you are building...
lime (you can use just lime & sand for lime mortar about 500psi and it's self sealing and really what you want to use for sun dried or lite fired bricks... it drys vs cure'n for portland)
more portland= stronger harder
more lime= weaker softer but longer working time and easier to work usually
more sand=weaker softer
so you need balance
my standard mix to look like old work is 94lb portland 30lbs lime 350lbs dry masons sand thats pretty close to a weak type n mortar i believe, gives you about an hour working time... that usually takes about 10gals of water (thats a guess)
p