harperschmidt•4d agoProlific Poster

Why does nobody check their concrete cure times before pouring?

I was on a job site last month in Austin and watched a crew pour a slab for a strip mall when the forecast had temps dropping to 40 that night. They didn't put down any insulation blankets or heaters and the top layer cracked by morning. I've seen this happen at least 4 times in the last 2 years on different projects. It's basic stuff - concrete needs to stay above 50 degrees for the first 48 hours to cure right. Why are so many crews skipping the simple prep steps for cold weather? Has anyone else had to deal with this on their sites?

2 comments

2 Comments

ray_mitchell3d ago

I read somewhere that the Portland Cement Association did a study and found something like 80% of cold weather concrete failures happen because nobody checked the actual ground temperature, not just the air temp. Idk if that's exactly right but it stuck with me. That ground can stay cold for days after a cold snap even if the air warms up a bit during the day. Probably explains a lot of those slab jobs where the top looks fine but the bottom edges start crumbling a month later.

the_daniel4d ago

Why do you assume every crew has the luxury of waiting for perfect weather? Sometimes the schedule is set by the GC or the developer and you pour when they say pour, not when the concrete guy wants to. I've been on jobs where the foreman told us to pour at 35 degrees because the building permit was about to expire and delays would cost more than fixing cracks later. Not saying it's right, but in the real world you deal with the cards you're dealt. Plus a lot of these crews are working with cheap concrete mixes that don't have the additives for cold weather, and nobody wants to pay for the extra cost. You can preach about blankets and heaters all day but if the boss says "just get it done" then that's what happens.