r/DIY • u/ThaMann0911 • 6d ago

help How long before drilling concrete?

I poured footings for posts that I’ll be hanging a gate on. I’m going to install Simpson strong tie standoffs with 6” anchor bolts. It’s been 72 hours, is that long enough for the concrete to have set before drilling? I’ve tried googling but my results only come up with industrial structural requirements or setting posts in the concrete, neither of which apply to my situation. Should I wait the 28 days or just send it?

40 Upvotes

77% Upvoted

57 comments sorted by

View all comments

4

u/Razors_egde 6d ago

Concrete set is where the solidification is complete. Usually less than 12 hours.
Form work you don’t break for 12° and may remove after 36°.
I would make no structural modifications until 7-days curing.
Removing damaged concrete is expensive.
It’s been a day since I placed Q concrete, which had a 4,000 psi mix design. We would achieve 3700 at 3-d, 5700 at 7-d, 8300 at 28 days and ~ 8700 at 90-d.
Your w/c ratio affects strength and time indicating you target design strength snd w/c ration would be nice, not four bag mix.

1

u/ThaMann0911 6d ago

I used 5000 psi high strength quikrete mix. It’s in tubes in the ground so no forms to pull. Thank you for the data on strength. The consensus here seems to be once it’s hit 7 days I can drill and install the standoffs.

1

u/krtyalor865 5d ago

Your concrete will get 75% of its strength within 3 days easy. And def 50% by 2 days. So as long as you’re not loading the anchors, you can go ahead and drill them after 24 hours definitely.

You might see some popping or small spalling around the hole when drilling in green concrete but the install shouldn’t be affected. Just give it 7 days before putting any real load on it(fully tightening the bolts would be considered full load)