mixing concrete - or not?

[bdog]

I just got through setting 46 posts and builing a fence around my place. We used 2 sacks of quickcrete per hole and mixed it up first and poured it in the holes. I had a buddy stop by and tell me that I was doing a lot of uneccessary work. He said to put the posts in the holes, pour in dry concrete mix, then add water and it will be fine, no mixing required.

I am going to be setting 25 more posts this weekend and am contemplating doing this as it will save a lot of work, but I am not sure if it is a good idea or not?

 

[EddieWalker]

Your friend is right.

The real question is wether you need to add water or just put it in dry and leave it. Lots of folks do it either way with good results.

I like to add a bucket of water myself, but the most important thing is to build up the mix along the post and angle it down and away. You want to create a path for the water to drain away.

Eddie

 

[bugstruck]

Most put it in dry. I'd guess wet dries to a little better compressive strength if you ran the test. I have done it before in a different application and it wasn't as hard as full wet might have been, but it was way beyond what a fence post needs. Still took a sledge to break it up.

 

[gsganzer]

IMO,mix it. You've already gone through all the trouble of digging holes. Why risk not getting the posts set firmly if the concrete isn't right? With that many posts, I'd rent a gas powered mixer that you can tow behind your truck/tractor.
My neighbor installs fences for a living. When he replaces peoples fences, he can tell which ones did the dry hole method.

 

[TwinWillows]

The Civil Engineer in me just can't deal w/not fully mixing concrete before putting it around the post so that's what I do. I also put several shovels of gravel under the post so it won't sit directly on wet ground & soak up moisture & rot fast.

Others dump quickcrete in dry & pour water on top. 2 different schools of thought, as long as the posts don't move I guess it does not matter.

 

[Bird]

My neighbors and I did it the other way around. We dumped a bucket of water in the hole, then dumped in the sackrete after the water instead of before, then "mixed" it with just an up and down motion with a steel rod, usually a piece of half inch rebar.

 

[ALBALD1]

I've set a lot of poles dry if the ground was moist. when the ground was really dry & i had a water source nearby, i poured in a little water on top. can't tell any difference. they all seem tight.

 

[SPIKER]

what you didn't say is what type of post?

PT, std lumber, wood species (aka cedar ect.) or steel.

some absolutly no concrete others work OK with concrete in hole. most times as a decrotive fence crete is not neded if compacting the posts base some with some gravel under em.

anyhow storming here & have to shut down.

markM

 

[wroughtn_harv]

I mix it in a concrete mixer for a couple of reasons.

1. It's cheaper. Of course I do hundreds of cubic yards a year. But when you figure my holes are one foot by three and a half to four foot deep minimum and an eighty pound sack of sacrete provides six tenths of a cubic foot, well, six to seven bags per hole. /forums/images/graemlins/blush.gif

2. I've pulled a lot of posts in my time. If they're sacreted the first thing I do is hit the post with the sledge. Nine times out of ten if they were dry set a couple of hits with the hammer and I can lift the post while leaving the concrete.

3. Dry setting is like painting a car with today's paint and then not applying a clear coat. It's hard to tell the difference......for awhile. /forums/images/graemlins/grin.gif

 

[texredneck]

Nice analogy there Harv,
I agree with mixing. Although Im definately guilty of doing it the cheap way, I guess you know theres the right way to do it, and theres that way that gets you by. Its like saying, hey can I change my brakes and not change my fluid? Well yes you can but youd really miss a good oppurutuntiy to do it right

 

[CurlyDave]

...but the most important thing is to build up the mix along the post and angle it down and away.

I agree here. Crowning the concrete will greatly increase the life of the post. I prefer wet set, just because I am an engineer and that produces a stronger result. But then, I also buy about 1 bag of Portland cement for every 10-12 bags of fence post mix and add a heaping garden trowel of pure cement to the concrete while I am mixing it.

I have seen the no-mix method done & it is "good enough" for most purposes. Certainly better than just back-filling with dirt.

If you decide to go that way, crown the concrete (you can still go back & crown the first set, by the way--just add more mixed cement over the top of what you have), and mix the cement for the corner posts and ones that will hold a gate.

 

[DannyD]

With all we have seen Harv do on here with concrete, can anyone truly not go along with every word he says. If he told me to stand on my hands while mixing it, I would believe him.

 

[Builder]

Concrete won't dry the right way if you put it in dry. Concrete cures properly with exothermic action when water is added in the right quantity.
Take the time to do it right and you'll have a better concious over a job well done. Plus if you have cattle or horses banging into them, they'll last longer.

If your posts are wood, dunk the azz-end of 'em in a barrel of wood preservative for a while, then bury 'em.