I set 6 4x4 fence posts yesterday using that quickrete for setting posts. You just pour it into the hole then pour water in and it sets. 4 of them hardened up well but 2 just didnt. I can wiggle the post like the concrete didnt get hard enough or something. i removed one and it just wasnt dry, so i re dug out the hole and re-did it. Better this time but still not solid like the others were. Wonder if the sackrete brand would have done better..anyone had this problem with this?
Thanks

Maybe a bit too much water. That and temperature makes a difference. The concrete might take longer to set up. See if letting them sit for a while longer sets them better.

Here's a couple of Youtube videos where they set posts with plastic foam. No more concrete.

i have never used this plastic foam stuff.

looking at the pics tells me the foam is open cell foam.
from my experience from repairing late model rusty cars tells me open cell foam traps moisture that is extremely difficult to evaporate. moisture next to wooden posts creates rotting wood.
my guess is using this foam your post will rot away faster when using this foam to set wooden fence posts.

I've never had consistent luck with the 'pour and then water' post setting concretes. Initially I had worse luck with pouring a concrete mix into the holes. The posts seemed to swell a bit from the water while the concrete was curing and cracked the concrete. The last one I did, I soaked the bottom of the posts before I put them in and then poured concrete into the holes. That worked well.

I set several posts for a deck project a while back...

One thing I also do is to make sure the bottom of the holes are flat and the dirt is least 5-6" clear around the post...

I also run a couple 8" lag bolts through the posts and then add in the concrete...

In my experience one day is not long enough to let them set up...

Sometimes the ground around them is still saturated and it moves the post and concrete around making the dirt hole larger...

The other thing that makes a big difference is the depth the poles are set into the ground...

I never liked setting treated posts in concrete, saw too many over the years that were that were rotted off at the top of the concrete.

Same here.
I always just mix it in a wheelbarrow then pour . That way I KNOW the consistency of the mix

Last June I put in a new mailbox post and four 4x4 posts for a "snow plow" and "vandal" defense and used the Quikrete RED fast set. It set up in about 15 minutes but left the finish of the work for another 24 hours or the next day. Solid as a rock. I would think with the regular Quikrete or similar product you would need at least a day if not more time for it to really be firm or solid. The temp when I used the Red fast set was in the upper 70's F so I know that helped also, and for some dumb reason I used hot water too

I am thinking about getting more of this quickset and mixing it BEFORE dumping it in the hole so i know the mixture is correct. Im behind on this project now because of this so i still would like to use the quickset if it will work.

Just make sure to mound whatever you use to set it so water drains away from the post, doesn't take much slope.

You're going to have to be "quik" (pun intended) because it really does set up quickly. You shouldn't have any problems doing it per the instructions or the YouTube videos.

I agree and although you'll likely never have this problem, but in cold temperature areas winter frost can heave the concrete thus causing the poles to rise a bit.
I put lots of rocks in beside these cedar 6 x 6's that were sunk two feet in the ground, pounded the rocks in and around and then put smaller rock/stones in, levelled everything and nothing has moved even 1 inch in 2 years now.
All is level and even, photo causes poles to look angled.

I've put a couple wood replacement posts in by using just the same dirt that came out of the hole and tamping it back in super hard all the way back up to the top with a wood dowel. They don't move at all. Time will tell how well they hold up being in soil vs putting them in concrete.

when i worked on a farm we just put the dirt back in the hole. pounded the dirt with a metal bar. then pounded rocks against the pole. we continued this alternating method until the hole was filled.

I put in some galvanized poles in the ground and used some brackets to mount the 2x4's to for the fencing horizontal runners. I used an auger to make the holes, dropped the poles in, beat the snot out of rocks and gravel around them, and covered the top with compacted dirt. Hasn't budged yet. Posts were 10' tall and they are about 4' in the ground. Fence is the typical 6" dog ear planks.

The concrete and the four 4X4's got the test this winter by being hit with high speed snow blasts by the snow plow several times. I just checked and they are still solid. Had the mail box damaged many times when we would get a "stand in" snow plow driver (usually young and first timer) that didn't get the phone calls yet from neighbors that lost their mail boxes too. Even the regular driver(s) sometimes couldn't avoid doing some slight damage to our or other's mailboxes when trying to keep up with heavy "lake effect" deep snows. Even had what we think were bore kids take out mailboxes with stolen large trash cans thrown from the bed of a pickup "just for kicks". Put up the 4X4's in hopes to at least minimize the snow plow damage and so far it helped. Had an older neighbor and his wife walking their dogs and overheard the wife question why the four posts? Husband stopped and then said "Hmmmm that's a good idea, remember how we've had to replace the mailbox a couple of times from the snow plow, I guess that's what they are for?"

The snowplow gets going at a pretty good clip out here and being a large "country" mailbox takes a pretty good hit........well before it did, now not so much.

When I fenced in our back yard I used some sort of gravel cement mix from home hardware in the holes covered with dirt. I couldn't go too deep because we have a lot of rocks under the surface but 12 years later it's still holding up alright. I've heard that filling the holes with plain gravel doesn't cause the rot problems that cement does and holds the posts sturdier then filling back in with dirt.

The best way to set a wooden post and have it last is to set it in rock. Dig the hole 6" deeper then tamp in 6" of rock in bottom of whole install post and then fill to ground level with rock. Post in concrete will rot off just below ground level due to water not being able to drain out of post.