Read about repointing mortar in freezing temps, wish I knew this years ago

Saw a post from a guy up in Minneapolis about repointing when it's below 40 degrees. He mentioned using Type S but heating the sand first so the mortar doesn't set up too slow. I always just mixed normal and worked faster, ended up with weak joints on two garage jobs. After reading that, I started keeping a bucket of sand in my truck cab overnight during cold snaps. Anyone else run into frost issues with their mortar on early spring jobs?

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elliot_miller221mo ago

Yeah the heated sand trick is solid, I do the same thing but I'll also wrap the freshly struck joints with a thermal blanket if we're hovering around freezing overnight. Learned that one the hard way doing a walkway in April where the mortar turned to powder by the next spring. Another thing that helped me is adding a splash of hot water to the mix instead of cold, just enough to get the temp up without making it too wet. And I always check the forecast for the next 36 hours, not just the day I'm working, because a surprise dip at night will wreck all your effort. Had a buddy skip that once and he was chipping out crumbly mortar for a whole weekend.

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