Why does nobody talk about how much sand you actually need for mortar...

I was mixing up a batch for a little retaining wall project in my backyard last weekend, maybe 80 bricks total. Looked up the ratio on a bag of cement and it said 3 parts sand to 1 part cement... but I piled up what I thought was enough sand and ran out halfway through. Turns out I needed almost 200 pounds of sand for that small job, not the 50 I grabbed. Does anyone else always underestimate the sand or is it just me messing up the math?

3 comments

3 Comments

olivia_white9320m ago

@fiona_kim97 you nailed it with the sand type thing honestly. Play sand and masonry sand are totally different beasts volume wise, a 50 pound bag of play sand is like half the actual sand you get with masonry sand. And yeah bricks drink water like crazy, so your mix consistency changes real fast. Mortar math is just one of those things you gotta learn the hard way, nobody warns you about it.

wren23015h ago

Hang on, you ran out halfway through 80 bricks with 50 pounds of sand?

fiona_kim9714h ago

Actually never thought about it that way but that sand weight probably threw the whole batch off. 50 pounds is pretty standard for a concrete mixer but if you're hand mixing that much sand with bricks the water ratio gets real touchy. Bricks suck up water totally different than concrete blocks do too, they're way more porous. So your mix could dry out faster than you expect and you're scrambling to add more water which just messes up the sand to cement ratio even worse. And depending on what kind of sand you got, like play sand versus masonry sand, they pack differently so a 50 pound bag might not actually be as much volume as you think. That plus the bricks themselves probably being different sizes, no wonder you ran short.