RV parking cement pad question

[CUMMINZ]

Sometimes it does not matter how much reinforcing you do or good grading, concrete will crack. The best thing to do is to saw a cut or two at the right spots and allow the concrete to expand.

 

[GFritsch]

Sometimes it does not matter how much reinforcing you do or good grading, concrete will crack. The best thing to do is to saw a cut or two at the right spots and allow the concrete to expand.

Excellent point. We have a saying that there are two types on concrete, concrete that is cracked and concrete that will be cracked. Your point about expansion joints is a good one. Control or tooled joints every 8 feet on center will allow the cracking (hopefully) to be controlled.

 

[Grizzly]

I like to place expansion and or construction joints in approximate squares, such as 10x10 or 12x12. If you cut concrete in 10 x 20 sections, you can count on it cracking near down the middle. One of the most important things to do to freshly placed concrete is to apply two coats of curing compound.

 

[gonzo2]

Here's what I've been doing for the last year or so, about 100,000 cubic yards on this one (concrete that is). Lots of cracks!

 

[Grizzly]

Interesting, what's the project Gonzo? Is it near Vancouver?

 

[jjdiesel]

There are only three guarantee's you need to remember about concrete..... 1)it won't burn, 2) they won't steal it, and, 3) it will crack.

 

[Grizzly]

There are only three guarantee's you need to remember about concrete..... 1)it won't burn, 2) they won't steal it, and, 3) it will crack.

And the most important thing you need to know about concrete is, "It won't wait for you when you are finishing it".

 

[gonzo2]

Interesting, what's the project Gonzo? Is it near Vancouver

Yes it's a new water treatment plant/reservoir for greater Vancouver, it will process about a half billion gallons a day when completed.



Sorry BGlidewell, I got excited at the word concrete and shouldn't have hi-jacked your thread. To answer your question, extra bar never hurt!

 

[BGlidewell]

Sorry BGlidewell, I got excited at the word concrete and shouldn't have hi-jacked your thread.

NO PROBLEM, it's a forum ...

 

[frankram]

I can't believe that no one has mentioned FIBERS. The floor of my shed has

steel and fibers, yes that is over kill, but for a few dollars more all is good.

4 years no cracks. I look at the cost over the life of the structure, a little thicker concrete, a little more steel and fibers the cost is really low over the next 20 years.

 

[BGlidewell]

I can't believe that no one has mentioned FIBERS. The floor of my shed has

steel and fibers, yes that is over kill, but for a few dollars more all is good.

4 years no cracks. I look at the cost over the life of the structure, a little thicker concrete, a little more steel and fibers the cost is really low over the next 20 years.

I asked the contractor about fiberglass in the mix and he frowned. I remember looking at my brothers slab and it had the fiber mix. You could see the fibers through the skim and I thought that might not work well with an exposed concrete surface like a driveway

 

[robertyoke]

I can't believe that no one has mentioned FIBERS. The floor of my shed has

steel and fibers, yes that is over kill, but for a few dollars more all is good.

4 years no cracks. I look at the cost over the life of the structure, a little thicker concrete, a little more steel and fibers the cost is really low over the next 20 years.

I have fibermesh in my shop, it still will crack. it will shrink and crack but hopefully at the control joints only. I have one nasty crack that happened outside of the control joint when the foundation settled down from having an undersized footing and expansive soils.

-robert

 

[Prairie Dog]

My contractor gave me the turd sniffer look too when I asked about fibers. He pointed out that it would still crack but with steele, it wouldnt seperate.

 

[Grizzly]

Concrete and the soil that lies under it can be a very complex issue, that's why some people have degrees in the subject. Before you place any concrete, the first thing you have to do is find out all you can about underlying soil. This can effect the strength of concrete, how much steel if any and many other admixtures you decide to put in the concrete mix. If you have doubts of questions about the underlying soil, have some holes drilled and sampled. Then get it analyzed. If you have CH clay (fat clay), expansives soils, peat in the soil, gumbo or other unsuitable foundation soils, you may be required to remove it or part of it and replaced with something more suitable such as granular material. If on the other hand you have granular soil (sand and graver), your lucky, because granular soil provided good drainage. On a small slab the least I would do is dig postholes as deep as you can. If you need help in analyzing the soil, get it. It doesn't necessarily have to be a Civil Engineer, it can be a Soils Lab Technician or a concrete Contractor with many years of experience, such as our own TDR, GFritsch.

Once you have determined the underlying soil and what to do about it, you design the sub-base and the concrete for the load you plan to put on it. There is so much to know about the foundation and the properties of concrete. Then you have all the additives you can put into the mix, such as rebar, 6x6 mesh, fiber, as mentioned, air, accelerators and many more. If I am doing outside concrete, I'll use 5% "air". It helps control surface spalling in freezing weather. Some use more then 5%, but it becomes too difficult to finish. Again the most important thing to do to concrete is proper curing.

 

[bighammer]

Now, is cement. . er. . I mean Concrete poured or placed?

Depends on how you mix it-- Dry side to just right, you place it. Add to much water and you pour it.

 

[Byershome]

My garage that is 34 by 24 has nothing but fiber and 2 metal keyway control joints... ... ... . 10+ years and counting with no cracks. It was a monolithic slab so the exterior footing did have a couple of # 5 's all the way around.

 

[cwsoules]

I needed a building permit, and the city engineer told me that for a 10K 5er I needed a 6" steel reinforced slab. It has worked very well for us.

 

[BGlidewell]

The "landing strip" is being poured tomorrow. 40'x60' 4" with 12"x12" beam surround and 2, 40'x12"x3' deep beams to support the wheels and jacks. All my trailers and truck will have a home soon Oo. #ad


#ad

 

[DFranks]

First of all it's a concrete pad, not a cement pad. Cement is an ingredient that goes into concrete. 4" thick, 3500 lb, well cured concrete over 6" compacted granular base is more then enough. I would in addition place a 2x6x2' under each jack. I built mine that way some 15 years ago and still have no cracks. I'm a retired civil engineer and a general contractor and it kills me when someone calls concrete, "cement". Cement is to concrete as flour is to bread.

I agree 4" is plenty enough, but order the concrete "Aerated" the surface will hold up to plummeling rain/weather beating, much longer.

 

[Midnight]

Be sure and post pics of your finished product.