This is a somewhat different topic from my fence thread. I'm going to be mixing concrete soon for setting fence posts. Any advice on how to mix it, what goes in the mix, where to get the stuff from? Or any good websites on this topic?
Concrete=Aggregate(sand and gravel)+Water+portland cement I would just use Quickcrete or any other premade concrete mix. Just unload bag in a wheel barrel add water and mix with hoe. Just be sure not to add to much water. The more water you add the weaker the concrete becomes.
Unless you have a LOT of posts, the best bet for me has been to use a product called "Sakrete" concrete mix. This is a pre-mix of Portland cement, sand, and gravel. Come in 80# bags with mixing instructions (how much water, etc.).
I like to mix things up in a old empty 5 gallon taping bucket, or something like that. Easy enough to handle, but having a wheel barrow to move things around on is especially helpful. Mix as per instructions on the bag, pour in hole around post, true the post up, and that is it.
Available at most good hardware stores, Home Depot, Lowes, etc.
There are a lot of websites, but the basic mix for concrete is this:
2 parts "1/2 inch" stone or coarse gravel, 3 parts sand, 1 part portland cement, and just enough water to make it workable. The sand should not be beach sand, as the salt will mess things up.Portland cement is available, usually in 94lb bags, at any home center or farm store. If you are making a lot of concrete, get a local sand and gravel company or landscape company drop off a load of each. If you are only making a small amount (setting one or two posts) just buy the bags of premix, otherwise you'll have a partly used bag of portland cement left over, and once openned, it doesn't really keep (though I have had some luck using a 5 gallon bucket with lid). If you are making a lot of concrete, buying or renting a mixer is a good option, but it's not really needed for only a couple of posts..
If you are using a regular square shovel and a wheelbarrow, put 4 heaping shovels of stone, 2 shovels of portland cement, and 6 shovels of sand in the wheelbarrow, and mix while still dry. You can use the shovel to mix with, but a hoe probably works better. If you don't have space to store a wheelbarrow, there are also plastic mixing tubs, usually in the same aisles of the home center as the concrete.
If your ingredients are bone dry, they will use about 2 gallons of water, but they will probably already have some water in them, so start by adding one gallon and then mix thouroughly. Measure it, don't just guess with the hose. It can help if you make a hollow in the middle of your dry ingredients to add the water, and gradually work the dry ingredients into the wetter center as you mix. You should have a very dry stiff mix at this point. Add a little more of the water, like maybe a quart or so. Continue to mix. From here on out, the amount of water makes a huge impact on the consistency. Even a cupful can make a huge diffference. You're shooting for a mix about the thickness of canned stew--something that just pours well enough to get it where you want it, but isn't runny or soupy.
Bag mix is made the same way, but use the recommendation on the bag for
the amount of water. Again, don't add it all at once, you might not need all of it, only get it wet enough to be workable.
And last but not least, rinse all your tools off right away, or you will have crusty tools until you gradually (if ever) wear the concrete off of them again. --Glenn Lyford
"news:IcednVvrIJe92GrZnZ2dnUVZ snipped-for-privacy@giganews.com... Last time I used concrete I used a "pre-mix". Dug hole, poured half bag in hole added water, mixed stuck in pole. That was 8 years ago fence still there. Xeno
just dig the hole, pour the mix in dry, pee in the hole.. kick a little dirt in the general direction of the post, move on to the next.
Hmmm. You forgot the "drink 2 beers" before "pee in hole". I might get 4 holes done. Dig hole. Drink beer. Put post in hole. drink beer. pee in hole. Mix. Repeat.
And after 3-5 holes, I might stay in bed the next day and do nothing but hate life :P
Excellent advice everyone, thanks. I'm going to set 25-30 posts, but not all at once. I expect it to be an ongoing project for several weeks. Any thoughts on how many holes a 80# bag will do? Or how many bags per hole? The bags are cheap enough, and it sounds like it might be my best bet to just do it a bag at a time.
you get about 2/3 of an 80lb bag of crete in an 18"-24" deep hole (about 6 - 8" diameter )
or... the math would be, 60 lbs per post
I used to run my own fence and gate company, i got this thing down to a science
for concrete, I used to pour one gallon of water into a 5 gallon bucket, and top off with concrete (that's all the hole would get.. one 5 ga buckets worth is going to be a little more than one hole needs) then I used a shovel to chop the mix in the bucket.. it doesnt take much to get the mix you need... more mixing gets done on the pour and on the stabbing.
it's also good to stab the wet concrete while you are plumbing the post
I hate setting posts anymore, it's alot of shoulder work
depending on the ground you are digging in, for 35 posts, you might think about renting an auger. for 40-50 bux, it is sooo worth the cost! trust me. you can drill all the holes in one day, then set them in a couple days.
our home supply shop sells 60lb bags of concrete (perfect for one hole)... and oh so nice on a fella's back
Those bags are very heavy. Invite friend or teenager with strong back, weak mind.
Are you sure you really need any concrete? I have some wind break fences that lived through 2 hurricanes and a half dozen close calls and they are just 4x4s in tamped dirt holes. If you use a 2x2 and tamp the dirt back in around the post on 3 or 4" "lifts" they get real solid right away and immovable in a year or two. I made a nice tool with the 2x2 by knocking the corners off with a hatchet (rounding off about 6" of it) and wrapping the "handle" part in hockey tape.
The above poster is absolutely correct. Better yet, get some inexpensive 'pea' gravel or similar product. Place the post in the hole and while slowly pouring the gravel around the post, give the post a small wiggle in each direction. Advantages:
1) Absolutely solid post. Evey time the post moves just a little the gravel drops down and gets tighter. 2) Posts do not rot at the ground line. Concreted posts are guaranteed to rot right at the top of concrete. The water cannot drain away. Most posts are rotted out within 8-10 years. At that point you have to get heavy equipment to pull out the concrete slug along with expensive trips to the dump for disposal. 3) Gravel is a lot cheaper and less labor intensive than concrete.BTW, I've set tall regulation basketball posts with gravel only. Absolutely solid with no rocking whatsoever.
Ivan Vegvary
It rains a lot here. Lots and lots. Soil is a bit soft, I'm afraid that without the concrete the posts would be likely to wobble. Don't really know for sure, as most people sink their posts in concrete. I think a post in concrete lasts longer then a post in web muddy soil, but again I'm guessing.
Will a post in concrete last longer then a post sunk in the dirt? What is the life expectancy of a post in dirt or concrete? I'm using 4x4 pressure treated, ground contact rated.
Rains a lot here too (SW Florida). My soil is basically fine sand and it holds a post just fine., The other poster pointed out that you can firm it up with gravel but I would try the dirt first. "Mud" implies clay and that will pack in very tight.
It may last a bit longer, but it certainly will be more difficult to replace when needed. Could be 10, 20, 50 years, but it will need replacement.
I don't know about the new stuff. Used top be rated something like 20 years.
That is a good system. For fence posts, the probably weaker concrete will be plenty strong.
Also, I suggest you dig the holes slightly deep and put a little gravel in the bottom. Then insert the post and add the concrete while plumbing the post. The idea here is that water that seeps down between the post and the concrete should drain out -- not be trapped at the bottom of the post. Such trapped water hastens decay of the post.
SJF
Slight correction.
"That is a good system" -- But the post goes in the hole first ( after the gravel) then the ready mix, then the water.
I watched the "pro" fence installers and all they did was dig a fairly shallow hole, drive the post in the dirt at the bottom until all the tops were level and toss enough concrete in to fill the hole. I think the only function of the concrete was to make it look sturdy, maybe help control grass growing around the post
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