Structural Slab for new WFO

[mikku]

Re: Structural Slab for new WFO

Tscarborough -/ Stonecutter-

Thanks, I will check out the forum and join when I have time. Just put in a 17 hour day and having a little refreshment.

2) I'm asking about SP concrete because I want to use it for my own application and I want to do it right--if it doesn't come out right the first time, I'll do it until it does!

3) My stand is 1000% overkill--so what! It is a hobby--next time I'll lighten it up a little.

4) I like what I see from BASF- no vibration concrete.

5) Tscarborough--your comment "The professionals already know how to use SP, or at least when to use it, and the DIY guys (and girls) are not well served by making it an option."

"On a lighter note"- you can substitute SP with "condom" or countless other things. I'd rather determine what is important to me by access to information--than to have it decided by someone else -- like an 1984 society.

Please take no offense-- I really like the response generated by this topic and personal opinions given!

[david s]

Re: Structural Slab for new WFO

Yes you are right. A 4" slab, properly vibrated with adequate and well placed reinforcement will be quite adequate. I was not advocating the use of SP in the design.

[Tscarborough]

Re: Structural Slab for new WFO

I would say that 100% of all slabs and stands built on this site are around 3-400% overbuilt for their use, not even counting using SP.

[david s]

Re: Structural Slab for new WFO

Yes it will, key words being, "if you use it correctly". Again, for the construction of a WFO it is simply not needed, period.

The topic arose about the mixing of concrete for a project that did not involve an oven. The strength of a supporting slab for a WFO is a crucial factor because of the extreme weight involved, also as the stand design often requires a fairly wide span. Adequate strength can be provided by a combination of concrete strength, reinforcement and its placement as well as thickness. In my case I need a light thin slab so rely on reinforcement and concrete strength to reduce thickness.
The Imperial Neanderthal comment was meant as a friendly jibe.

[stonecutter]

Re: Structural Slab for new WFO

Mikku,

I am on the CT forum as well, and wrote a complete walk through about a hand pressed concrete project, in which polymers and admixes are discussed. You can get them in gallon sized jugs here ( sorry for the very offensive use of our imperial unit of measure) and they work well. And while I agree that a highly engineered concrete mix is pretty much over kill for most DIYers, there is a value to learning about it if counters or other pieces are being made.

[Tscarborough]

Re: Structural Slab for new WFO

When my Dad built this, we used an SP to facilitate pumping the concrete. It was in 1979-82 when commercial SP use was relatively new, and we dosed up to 100 trucks a day onsite. After dosing, each batch was tested and either sent on to the pumps or rejected. In the beginning, we lost 2 of 10, and even after thousands of trucks, we still lost one in 15.

https://maps.google.com/maps?hl=en&ll=29.655775,-95.276125&spn=0.003679,0.003449&t=h&z=18

[Tscarborough]

Re: Structural Slab for new WFO

Yes it will, key words being, "if you use it correctly". Again, for the construction of a WFO it is simply not needed, period.

[david s]

Re: Structural Slab for new WFO

Unfortunately this is true. However the fact remains that adding additional water to a concrete mix in order to achieve the desired flow , leads to a weaker product. The additional water increases the volume resulting in looser bonding.All concrete that is delivered by truck contains superplasticisers.

Sorry, I was wrong. It is also only added by the concrete batchers on special order here too. Still doesn't alter the fact that its use will give you a superior product if you use it correctly.

[Tscarborough]

Re: Structural Slab for new WFO

Mikku, if you want to talk about SP and related products, join this board and you will get all the discussion you want about construction beyond the scope of this forum:

Contractor Talk - Professional Construction & Remodeling Forum, News, Reviews, and Blogs | ContractorTalk

I am there as Tscarborough, same as all boards.

[Tscarborough]

Re: Structural Slab for new WFO

It is not offlimits, it is just counter productive. The professionals already know how to use SP, or at least when to use it, and the DIY guys (and girls) are not well served by even making it an option. When you are building a one-off personal project, the risk of failure is not worth the benefit, even though they may be considerable when it is used correctly in the correct application. Building a WFO does not have any area in which the risk or cost is worth the reward regarding the use of SP.

[mikku]

Re: Structural Slab for new WFO

This topic came up when I described mixing bag mix concrete with a plaster's drill and adding water in excess of bag instructions. I do not know the ratio of professionals to DIYers who use dry mix but it is a convenient product.

The point that I was making was you do not need a huge mixer to make concrete, but the drill I use is the price of a mixer. It is important to add your ingredients consistantly to maintain ratios between batches--regardless the batch size.

This forum is a mix of professionals and week-end DIYers. The topic of SP concrete should not be off limits because it takes accurate measurements to achieve proper results.

The minimum quantity for the BASF product is also 20 liters so you must justify its use before purchasing.

[Tscarborough]

Re: Structural Slab for new WFO

All concrete in the US does not contain SP, it is very much a special order, and on the large projects I have worked on it is added at the jobsite, not at the plant. Bad concrete with no plasticizer is still usually better than incorrectly dosed SP concrete, which is why it is not and will not be a DIY product.

[david s]

Re: Structural Slab for new WFO

Super plasticizers are not really a DIY product.

Unfortunately this is true. However the fact remains that adding additional water to a concrete mix in order to achieve the desired flow , leads to a weaker product. The additional water increases the volume resulting in looser bonds. If you try to buy the stuff you can only obtain it in commercial quantities. I had to get 20 L which was the smallest quantity I could buy. It is enough to treat LOTS of concrete when addition is around 1ml/ litre, (that's 1/1000 for the imperial Neanderthals.) if you know people in the building trade you may be able to score a smaller quantity from them.

[Tscarborough]

Re: Structural Slab for new WFO

Super plasticizers are not really a DIY product.

[mikku]

Re: Structural Slab for new WFO

Has the topic of super plasticizers been addressed before? Somehow, I feel like I am stepping into an old discussion that was left to die along the road...

I've searched but user posts do not go back that far and I don't want to waste the time to dig further...so if there is "old info" point me in the right direction.

NO TIME TO BURN WOOD THIS WEEKEND! SAD STATE OF AFFAIRS FOR A WFO!