Post frame building slab.....

[BHD]

I graded formed and had a 40' X 65' slab poured. I got the "With fiber you don't need rebar" sales pitch.
WELL obviously they never go back and look at the slab 11 years later!
I've got areas that have heaved up or dropped an inch and cracks! And these are areas that I scraped down to level, no fill what so ever!
I think fiber is BS just so the concrete co can get $4. more a yard and the drop and finish crew doesn't have to work around rebar or wire! With rebar and or mesh there is no guessing if will it crack and lift later.

if you have had that much problem your base and preparation was faulty.

if the soil moves under the slab it is going to break the concrete up,

I have seen 75 year old slabs with out any steel mesh or wire, of any type nearly (and hand mixed to boot), with out any major problems and I have seen new that is a disaster in just months, (it like road) if the base is not done properly the top is not going to last long,

and a proper base is not nessarly no fill, but building up the proper bed with the correct soils, (sounds like you have expansive soils or a lot of organic in your soils or both).

all top soils should be removed, and a base built up of non expansive soils and properly compacted,

I worked in Wyoming for a time and in this one location, and there they would dig down 4 or 5 foot, and start with placing up to 12" rocks and then other smaller and then gravel type fill, and properly compacting it as they went and then in theory they would not lift and shift, and even then it was not fool proof. very expansive soils.

saw another thing done from a builder that had worked in expansive soils.
when they did basement frame walls they would cut the frame wall about 3 inches short. and then add a 2x4 to the floor leaving about the distance of tall trim, then they would drive nails between the "Bottom" plate and the plate that was on the slab and the space was so the floor could float up and down and not push the house up an down, the trim was to attach on the bottom plate and the dry wall stop at the bottom of the wall plate, so there the idea was let it float,

one way to have less problem is more small slabs they may not stay even to each other tho, a series of 10 x 10 foot pours,

 

[Tractor Seabee]

Most problems with slabs on grade are the result of poor construction methods and practices. Most contractors that due primarily residential work are the least informed as to all the proper methods and procedures. Quite often 3-4 different sub contractors and/or tradesmen are involved. Success starts at how the total site preparation is done. Un-compacted filled areas are a disaster in the making if that is where the slab is going to be, worse is slabs spanning both unfilled and filled areas. Reinforcing of either type is useless if it is walked on by the spreading methods. Adding water at the site to the truck so it is easy to spread will give poor results in strength and shrinkage cracks and can effect the surface appearance. Yes concrete cracks but you have to tell it to crack where you want it. Control joints cut the next day after placement are a waste of time and money as the concrete has already cracked where it wants. I have done large 4" fiber concrete slabs with no mesh or rebar and 20 years later, no cracks and have even run concrete trucks over it. I didn't do my garage and driveway but after 15 years there are no cracks anywhere.

This whole subject is two complex and technical for a forum like this. There are many many variables that need to be considered and it starts with coordination by the prime contractor to keep all the players following the play book.

The American Concrete Institute are the experts and publish all the standards, procedures, and methodology. The building codes reference their standards. Large commercial/industrial/government projects require various levels of ACI certified testers, inspectors, supervisors, and finishers to assure the project specifications and the codes are complied with by all players. Small projects don't warrant that level of effort or cost but the principles are the same. Otherwise you get what you pay for.

Ron

Ron

 

[deerseeker001]

Compact it well and you will be ok

 

[kolwelding70]

good luck on the project