Concrete building questions

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I priced premixed (bagged) concrete at several stores and, after pushing my mouth back up to my chin, went home with no conrete. 4 bucks a bag is outrageous! So, I decided that I will mix my own concrete, and my questions are pointed in that direction on HOW TO. A breif rundown: I am constructing a large chimney and several supports for a porch. I am pouring a 12 inch thick footer under the chimney, 5' by 3 foot. The supports are getting 6 inches of concrete in a 2 by 2 area as footers and stone work (using Flaggstone type building) will rise above that footer. Most of the work is a bit her, a bit there, so hiring a concete truck to pour is not an option. Ok, heres the Q.s: Can I buy crush and run driveway gravel for use in the concrete, or is a different type of stone used? If I did use crush and run, but screened (washed) all the fine particles out for use in walkways/ etc, would it work then? Is there a recommended type of cement to use? The rest I think I have covered- I will be using barbed wire fence and rebar for interior strength on the chimney and footers. Still need to find a source for chimney flues. I am going to use white quartz, found on the land, for the stone work.

-- Kevin in NC (Vantravlrs@aol.com), March 25, 2002

Answers

Around here it's called concrete gravel, it's a washed sand and gravel mix not just gravel, or even crusher run. I'm sure it's riverbed gravel at that! I'd think washing out the particles would be bad but I'm no expert! I can almost garuntee there will be regional differences in agrigate, but a sand and gravel mix is what you start with for concrete from my experience.

-- Ross (amulet@istar.ca), March 26, 2002.

Kevin, I am sure you can use just about any available rock as the bulk of your concrete but good strong concrete requires appropriate materials. There should be a range of sizes as the smaller particles of gravel and sand fill in the spaces between the bigger bits. Around here we call the desired stuff "builders' mix", it typically costs as much to transport as it does to buy!

As for type of cement, I didn't know there was a choice! I think what we use is properly known as 'portland cement'

Any steel is going to reinforce your concrete so maybe barbed wire would be OK. Although I have seen it used for just about everything else I have never seen barbed wire used in concrete.

-- john hill (john@cnd.co.nz), March 26, 2002.


Hi Kevin, Along with your barbed wire and rebar, you should consider some type of fiber reinforcement. Do not know what is available or the cost in your part of the country, but the fibers does add strength and helps with the cracking problem. It probably will cost about $4 to $10 for enough to do a cubic yard of concrete (27 cubic feet). There is a whole field devoted to concrete applications and techniques. Good pouring!

-- ken (you@surfbest.net), March 26, 2002.

The strength of the concrete depends on the strength of the aggregate. The river gravel is stronger than the crushed limestone they sell around here. Even limestone strength can vary. The quartz you have on your land might be a stronger aggregate than the stuff from suppliers unless it's the rounded river gravel which is also I believe quartz.

There are different types of cement but unless you need really high strength or protection from constant immersion in water, the stuff your supplier normally has will do fine. Depending on the type soil you have you might want to consider making the foundation wider than the base of the chimney. The greater surface area spreads the weight over a wider expanse of soil and will help prevent settlement.

Another factor in the development of strength in finished concrete is proper curing. Keep it moist and don't allow it to dry out during the curing period. The fact that your foundations are underground as compared to a driveway that is on the surface will help.

-- Darren (df1@infi.net), March 26, 2002.


Try this site it will probably answer most of your questions:

http://www.kent.net/home-hardware/tips/concretemixing.html

Talk to you later.

-- Bob in WI (bjwick@hotmail.com), March 26, 2002.



Kevin,

Around here Portland cement is $6.00 a bag, but mixed four to one with a gravel and sand mix, it goes pretty far. Gravel and sand mix cost about $125.00 a dump truck load, delivered. That's in Southern Missouri.

Sincerely,

Ernest

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


$4/bag is highway robbery. I pay $2.50/80# bag and I'm in the middle of no where MT. And that's from Ace Hdwr which usually has the highest prices around. Go find a Home Depot, Lowes or Ziggys for better pricing.

This is the best site I've found on this subject

http://www.concretenetwork.com/concrete/homes/

-- al (yr2012@hotmail.com), March 26, 2002.


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