Concrete Chairs

[paulsharvey]

Oh, one thing that some people don't know, but some accelerates used in cold environments and or "high early" concrete can attack the rebar. In theory, wire (i mean WWF, not #2 smooth rods) does nothing long term, once curing is complete; however, it does hold cracking concrete together better, and it's a son of a B when it comes time to demo it.

 

[newbury]

they could do it cheaply and come back in two/five/ten years and redo it, depending on actual usage, and degradation.

So if a contractor builds a road cheaply, and he is the only local bidder, then he can probably plan on coming back and get paid to do it again.

 

[paulsharvey]

Post tension down sides; the engineering, the cost of the cables, tensioning equipment, and a testing guy to document the pull force; and then once done; you can't just core or cut that slab. Now, I've ran a GPR on open ground/asphalt, looking for utilities, and maybe? you can GPR the cables in a slab, but if you have conduit, plumbing, HVAC chases in the slab, and how shallow the cables would be, I dont know if the cables would show on a GPR?

If you've never seen them, it's a cable inside a greased pvc sleeve, and once pour if complete, it is tensioned with a hydralic 'jack' and a split nut installed to hold the tension. It virtual eliminates cracks; and you typically don't saw control joints. They aren't just laid out willy-nilly, they are designed and spaced to an engineered plan. They Can float a bit in a pour, and I've seen where a cable was actually at the surface of the concrete, but it was in a tile area, so it was able to be hidden.

 

[paulsharvey]

Ultra runner fiberglass is significantly more expensive than steel. Only used in highly corrosive environments or where magnetic properties are issue

Even in most corrosive environments, cathodic protection is probably a better route than fiber bars.

 

[paulsharvey]

We did a 'lumber tree' at a conclusion supply house once; me and one helper; 10" thick on top of 10" limerock, #5 rebar mat, 3" up, then a WWF layer, then another set of #5 bars in top 3". All that, with fiber in the mud too; it was like a 36 yard pour each (2 foundations) and finish, and a pain in the butt. I think those two slabs will outlast mankind, but it was what the engineer designed.

 

[paulsharvey]

So if a contractor builds a road cheaply, and he is the only local bidder, then he can probably plan on coming back and get paid to do it again.

Almost anywhere, a road will have an engineered design, and an inspector to ensure they build it to spec, on any publicly funded project. Developer or private; most of them don't want to pay for the inspecting costs. Public, you have to think, your thinking 10/15/25 years down the road, for development, your only concerned with the 12 month warranty period, unless it's a developer who plans to keep ownership (the small minority).

When I was working on some 'shovel ready stimulus' jobs, building sidewalks to nowhere (that the county could never afford to maintain after the fact...) the concrete guys were telling me how; when they did house slabs, they would "move forward" the visqueen, wire, and rebar, once inspected; to the next house... there is a lot of shady stuff in the home building business.

If I left any doubt on what I meant by Move Forwards; they would take the rebar, plastic, and wire, after inspected and just use that in the next slab for inspection; and not use any when it was poured. I'll bet there's a neighborhood somewhere south of Ocala, where homeowners are arguing with insurance about "sinkholes" cause their slabs to crack, and foundation problems. These guys thought it was smart/funny, and where borderline bragging about it... I will admit to cutting some corners through the years, but never anything like that.

 

[paulsharvey]

Not concrete; but when I was an acting super, I had a job interview with a home builder. Interview, they said, take us step by step every process in building a home. Anyways, got all the way to drywall, and I stop myself, and say, 'crap I forgot to insulate'.
After the interview, I'm talking to a friend who was a Project Mananger, and told him about that. He say, that's not funny, we forgot to insulate a house one time at a previous company. I asked "what did you do". He say, what do you mean, we caught it too late, and never insulated it, someone is wondering why their power bill is 3x their neighbors.

 

[jjeff]

Geez, companies like that give construction workers a bad rap. Makes me grateful I never worked for companies like those examples and diy everything when it's time and cost effective.

 

[jjeff]

Worst thing I ever did working for a company was when I got taken off the framing crew (surgery, light duty) put on finish crew, finishing out a small closet putting ledgers for shelves on painted textured drywall, still had my framing hammer on my obnoxiously large tool belt put a nice hammer head sized hole in the drywall. That shelf ended up with about 1.5" closer spacing to the shelf above it and I considered it personally customized cuz of my bull in a china shop f-up.

 

[lilranch2001]

Did you go to confession after that?