The alternative energy posts have been so helpful, informative and so much fun that I thought we might consider several of these how-to topics that everyone could contribute to or profit from. I'm obviously not as gifted a mechanic as some of you, but I am a concrete pouring fool--when it comes to concrete I've 'been there, done that' in some wildly varied applications.

Several folks on the forum have talked about moving, building houses, building barns, renovating houses and so on. Concrete is a good topic to start with because it's the first thing you do when you build a new building.

This can be a place to tell instructive concrete related stories--tales of humor, hardship, woe, and triumph.

What does a yard of 'crete cost in your neck of the woods and what's the minimum? What have you used for rebar and what sort of finishing tricks have you learned?

-- Rags (nobody@nowhere.org), February 26, 2002

Answers

Boy, do I have the questions! I will be getting my Dad's cement mixer next spring and the project list is growing. I will be doing cement fence posts, raised beds, hypertufa planting containers.......

I have an old foundation that I would like to build on, but....it is chunked up from being run over by a CAT. Can you pour new concrete onto old and how would you make them bond?

-- Laura (Ladybugwrangler@hotmail.com), February 26, 2002.

Hello Rags,

Melitza (my wife), Margo, (my oldest daughter-14) and I slipped form our cellar before we built our house. We used Scott and Helen Nearing's (Authors of, Living The Good Life) method of slipforming by using the rocks that grow on our land. We built a small form and filled the front and back with rocks by turning them sideways and poured concrete in the middle. When the concrete was cured (about 24 hours), we removed the form and set it up at another spot. This worked out well for us and we built the entire cellar in about three weeks. We could have probably done it quicker but, we did not have a mixer and did all out mixing by hand in my wheelbarrow.

The only part where I used rebar was when we built the footer. We laid three pieces the length of the entire footer.

We built the piers for out house next. First we dug the holes and poured the footers. We put the rebar so that it was sticking out of the footer the length of the intended pier. The form for the pier was sona tubes that we just cut to length and slipped over the protruding rebar. Again, we pour them by hand just like the cellar.

Our cost was just the bags of Portland cement and the gravel. The bags of cement were around $6.00 per bag and a dump truck of gravel was $130.00.

The house was built on top of all of this and it worked out pretty good. It has been about a year since we poured the concrete and I have yet to see a crack anywhere.

Sincerely,

Ernest

-- http://communities.msn.com/livingoffthelandintheozarks (espresso42@hotmail.com), February 26, 2002.

Way to go, Ernest, you've got a good start. A little used barbwire along through that slipform stuff can really toughen it up. Sonic tubes can open up a brave new world: they are also cool for piers under water or in flowing water.

Laura, there are several ways to patch 'crete, but whether or not you can use a crushed footer depends on what you want to build on it-- garden wall, OK--railroad trestle,maybe not. Hydraulic cement, Tap- con pegging, chipping away to sound material, and pouring a 4" or thicker cap over the whole broken footer, or several other possibilities could be called for depending on what you want to build.

And Ernest shows where it begins: first the wheelbarrow; then maybe a home made mortar trough made from 2x12's and sheet metal; then graduating to a 1/3 hp electric mixer! I would buy one of those 1 bag 5 hp rental machines but I'm afraid I would work myself to death with it.

Maybe we'll get some more folks to testify before we break out the hard science. How about it?

-- Rags (nobody@nowhere.org), February 27, 2002.

It will be a small barn. The foundation out there is three equal sections with a concrete pad in the middle. I think it was an ammo or supply bunker. There is plenty of rebar in it.

You figured out exactly why my Dad is bringing me his mixer. He is working himself too hard with it, and Mom keeps coming up with new projects. It sounds like she doesn't want to walk on hardpack anymore. Do they REALLY need a sidewalk to the woodpile?!?

-- Laura (Ladybugwrangler@hotmail.com), February 27, 2002.

Just a word of advice; don't scrimp on rebar. Concrete has very high compressive strength, but low tensile strength. Steel has high tensile strength. It's very cheap for what it gives you.

-- joj (jump@off.c), February 27, 2002.

Right you are, JOJ, but let's hold off on coefficient of expansion, tensile geometry in loaded beams, and the other grandeurs of concrete theory for a bit--at least until we get a report from the rest of the crew. When we do get to the nitty gritty, JOJ, and some of you other whizzes like the two Johns(sorry Doofus don't mean to slight you just because you're not a heavy duty 'John') will sure be welcome to weigh in on slump rate and mix rate and all the fine points we can find.

Come on gang, let's get the 'crete stories rolling!

-- Rags (nobody@nowhere.org), February 27, 2002.

I guess I am not one of the "heavy duty Johns", I know nuffink about concrete. :)

-- john hill (john@cnd.co.nz), February 27, 2002.

I really don't have a lot of experience with concrete, post holes and one of those patios with he rock looking form. The only "unusual" thing I did was to mix regular bags of Ready Mix with half as much sand to make a firm but somewhat porous floor in my chicken coop. That worked out just fine. My property has a gradual slope and heavy clay soil so when it rains very hard that area was always pooling up with water, and I didn't want my chickens to be swimming birds!

Also one thing I learned from a fellow is that if the temp is 40 and going up it is fine to pour, but if it's 40 and going down you are better of not pouring as cracks will occur. That's if you don't add something special like some kind of silica which is what they do in the far north so that they can continue to work through much of the year.

-- Doreen (bisquit@here.com), February 28, 2002.

A "heavy duty John" would be one made of concrete! (Is that kinda like a "brick S***house"?) ;-)

Poured lots of walls, flatwork, steps. Have set prestressed panels, but know not a thing about the engineering behind them. I'm a lousy finisher, mostly because my Dad was so good at it.

-- John in S. IN (jdoofus@hotmail.com), March 01, 2002.

All Right! Jdoof, sounds like you'll have a lot of 'crete stories to tell. Good finishing depends on proper water in the mix, good compaction and settling by shaking,tamping, vibrating, a smooth, clean screeding job, and waiting to just the right moment to trowel and then trowelling until the trowel blade rings. Another way to put it--good finishing depends on good help. Do you remember any of your dad's finishing tricks you could tell us about?

Pouring walls, huh? Not bad. And prestressed panels, too, pretty heavy duty after all. Like my old friend Jim used to say, "You NEVER know."

Doreen brought up another good topic--bagged premixes like Sackrete. Most of these premixes have small aggregate size (poor for mixers, easy on wheelbarrow mixing) and are cementiously rich mixtures(hence Doreen could cut hers with sand to make a light duty floor. These premixes don't go far, but for setting a post or a tower base or patching a garden wall or some other small task they can be very handy.

-- Rags (nobody@nowhere.org), March 01, 2002.

This is a good site that deals with ferro cement. http://www.ferrocement.net/ There is good archives and you can sign up and get on email list. You can also ask questions and get several answers from experts so you do your project right. Here is another one http://planetaryrenewal.org/ipr/ultralc.html And here is one more that is a cool site with good photos. about:blank

http://www.geocities.com/flyingconcrete/index.htm I hope to get some free time to play with ferro cement soon. A good small project would be dog house or chicken coop. Might be good for raised beds.

-- ed (edfrhes@aol.com), March 01, 2002.

Well, since someone else had to bring up the concrete outhouses, I actually used one, in Peru, of all places--on an island in Lake Titicaca, called Amantani; one the closest places to heaven I''ve ever experienced.

Oh, yeah. Back to the outhouse; the folks I stayed with (Quechua "Indians") built it, and it was a "regular" outhouse, except it had a flat concrete floor with a hole in it; the hole stayed full of water, like a toilet bowl. When you needed to use it, you carried a bucket of water down the hill to the outhouse, and after you were done, dumped the water from the bucket into the hole. This "flushed" it.

There was no toilet seat; you just squatted. It had no odor, and was very clean. I ASSUME the effluent went into some sort of septic tank, though I never asked. Should have, I guess, but my hosts' Spanish was worse than mine, so we did a lot of sign language.

I'd sure build something like this, if I still had an outhouse.

-- joj (jump@off.c), March 01, 2002.

Ed, it IS good for raised beds. That's what mine are, and they are super!

-- joj (jump@off.c), March 01, 2002.

I've been looking for block for my beds........I inherited a mixer when I bought this place. I moved it into the barn to get it out of the weather and haven't touched it in the year since then. HHHMMMMMMM. Maybe I need to check this idea out.

Most of my work was housing. Footers and basements. I had a stronger back then and humped a lot of panels.

The craziest pour I was ever a part of was a smokestack for a big power generating station. I was building scaffold, Tube stuff, and we moved with the concrete. It was an neat system. The forms and all were integrated. I only did it for a day and a half. Went down for lunch and told the boss I didn't want to go back up. It was 330'. they ended up going 300' more. I moved over to the cooling towers and felt better at only 60 - 80'. Yeah, I know, you'd be just as dead.

-- John in S. IN (jdoofus@hotmail.com), March 02, 2002.

A little tip for all of you resurrecting old mixers is to be sure to take the belt off carefully, before it has a chance to break, and take it down to a hardware or car parts store and get a couple of spare ones. It's a lot easier to measure a utility belt for a replacement while it is still in one piece. Also make sure the drive pinion and rings gears are clean and then heavily grease them. If the pivot shaft or the tilt bearings have zerk fittings, grease them heavily.

Another mixer trick: to clean buildup off the inside of the drum and the mixing paddles, pour a gallon or two of vinegar into the drum and leave the mixer running all day. The next day break a couple of bricks into small, sharp shards, put them in the mixer with the vinegar mix and run that an additional day. When this process is through, you can take a small hammer and peen away most of the buildup. Be careful to wear eye protection. Once the drum is as clean as you can get it inside, rinse it out thoroughly, then paint the inner surface with white anti rust primer. Make sure the metal is bone dry before you paint it and do the painting on a hot day with the mixer in the full sun.

-- Rags (nobody@nowhere.org), March 02, 2002.

Some more things to think about w/ concrete....It's not like working w/ wood. If you do a crappy job, your stuck w/ it for the most part. And everything that will be built on it will be a problem.

So start right and make sure your forms are LEVEL and SQUARE! From the footer up. If the foundation is out of whack, it will be a source of aggravation all the way up to the roof. A transit for level and squaring up things w/ proper batter boards are essential.

Get those footers deep if you live in colder areas. Find out what the recommeded depth is from an architect or city/county engineer.

Concrete is HEAVY! even for a 4" thick sidewalk, make sure the forms are staked in well.

-- John in S. IN (jdoofus@hotmail.com), March 03, 2002.

Something else I just thought of when pouring flatwork. Water drainage, as in, where is the rain runoff going to go? Sidewalks and patios up close to the house should be pitched enough to allow water to run away from the house. How much pitch? I've never found it needed much, as in a 1/4" in a 4' wide sidewalk. Too much pitch would be bad for the balance and have someone falling down.

Driveways carry a lot of water, especially if there are gutter downspouts dropping on them. Look at the lay of the area and figure out which way is best to follow the natural flow. Don't try to go against gravity.

It's been quite a while since I did any concrete work. Rags, maybe you could explain how to use wire & expansion joints in flatwork, or pouring a drive in sections. Thanks for the mixer tips BTW.

-- John in S. IN (jdoofus@hotmail.com), March 03, 2002.