project update... If only!!!! Long

[EddieWalker]

Eddie:

I hate to disagree with you, but in every reinforced concrete structure I have ever seen engineering plans for, the strength is derived from the bar, not from the concrete.

The reason bar is placed a certain distance from the edge of a pour is usually to prevent rusting. While I agree that the job is sloppy to the point of being inexcusable, I think that this area could be salvaged by being grouted, especially if a consciencious contractor took care to assure bonding between the grout and the existing pour.

Hey Dave,

I've always been led to believe that concrete has a certain level of strength based on it's mix and the materials used. Adding rebar to that mix increases the strenghth of the concrete by spreading out the surface area and allowing the concrete something to bond to. Haveing exposed rebar doesn't accomplish anything from my understanding. If it's just that one area, than a patch over it will keep it from rusting and make things pretty, but that will always be a week spot.

I fully admit to not being qualified to make these statments and I cannot defend or support them in any way. It's just what I've always been told and thought I understood.

You make an excellent point on the dirt used to build up the pad. I missed that because I just assumed it would have been compacted to pass the building inspection. One of the first jobs I had after the Marines was runnning a water truck, which dealt with building up pads in California for residential and commercial jobs. Every inspection involved testing for the level of compaction. Nothing else was done until that test passed.

If it's like you say, and I believe you're right, that pad will be moving for the next 30 years. I predict it will crack and split between the beams. They are huge and will tend to stay put, but the week spot will be those thin areas.

Again, I wonder what the inspector was inspecting? The fact that it was inspected on numerous times led me to believe that some sort of code was met. Obviously there's more wrong here than we can ever imagine.


Jim,

You have a nice building there in a nice setting. How close to Pine Grove or Jackson are you?

Eddie

 

[CurlyDave]

I've always been led to believe that concrete has a certain level of strength based on it's mix and the materials used. Adding rebar to that mix increases the strenghth of the concrete by spreading out the surface area and allowing the concrete something to bond to. Haveing exposed rebar doesn't accomplish anything from my understanding. If it's just that one area, than a patch over it will keep it from rusting and make things pretty, but that will always be a week spot.

Concrete has strength in compression. It has almost no strength in tension.

While steel has strength in both tension and compression, the long, thin pieces of rebar would easily buckle if subjected to any significant compressive forces.

Reinforced concrete is a composite material which uses the strengths of both components to achieve its properties.

The way an engineer designs a reinforced concrete structure is to examine the tensile forces developed under the anticipated loads, apply a safey factor, and then specify enough bar to withstand the tensile forces. For most instances, unless you have a completely rediculous amount of bar (ever see a bank vault being constructed?), the area of the concrete times its compressive strength is so much greater than that of the steel that no calculation is ever done for compressive strength. The common term for this is "designing for the bar" or "designing for the steel".

Clearly, the structure is stronger if the bar is completely surrounded by properly compacted concrete, but I expect that the right grout would fill in the exposed voids in this pour. If I owned it, I would mix epoxy with sand, and force that into the exposed voids. Expensive and probably labor-intensive, but the epoxy-sand mixture would adhere well, and make a decent repair. Another possibility would be mixing up a grout with the concrete-adhering emulsions I have seen.

No it wouldn't be as good as doing the job right in the first place, but it could be "good enough".

If it's like you say, and I believe you're right, that pad will be moving for the next 30 years.

Probably longer. The house I live in had areas of uncompacted fill under concrete slabs. It was originally built in 1928. In 1988-89 I completely remodeled and rebuilt it. I had noticed some of the concrete slabs settling before I tore them out, and when I did, the dirt under them was still not fully compacted, 60 years later.

 

[Egon]

My reply is kinda late but:

For any type of action the pad will have to be inspected by a Licensed Engineer and then go from there.

For this job the three man crew needs an additional 4 or more competent men. That's why the water was added. They may also not have had a vibrator or known how to use it properly.

There are voids and the bolts had to be added into partially set concrete. Chances are they may pull out under the right circumstances.

The fellow on the chute was not very experienced and I'm betting there was a lot hand work moving concrete around. Means segregation and real problems on the final finish bull floating and power floating.

I'd also suggest the consistency of the pour will vary all over the place with a lot of future spalling and a slab unable to withstand freeze thaw cycles.

Looking at the bolt placement suggests the form work was not done properly
to ensure they were in the right place and placed vertically. They were placed almost as an after though in partially set concrete.

It's not a nice thing to say but for properly built structure a new start may be in order.

The fixes may cost more in the final tally than starting over.

 

[Buckeye_Jim]

Eddie,

My property is 11 acres 15 miles east of Grass Valley which is 55 miles NE of Sacramento and 82 miles North of Jackson. Whole area is often referred to as the mother load, for all the gold mining which across the region. Grass Valley is about the same elevation (2500’) as Pine Grove, while my property is about 3700’ elevation. It’s a kind of a vacation place where we have a 5th wheel trailer to stay in and we are way beyond the grid, so it’s solar power and propane appliances, and a generator.

BTW I have a good friend named Chuck Thomas who moved up to Tyler from Houston in 2000. I think he’s a volunteer firefighter in the area. I was stationed in Sheveport in the Air Force back in the late 60’s.

Take care,

Jim

 

[EddieWalker]

Hey Jim,

My parents live in Pine Grove and I grew up in the Bay Area is the reason I asked. I've camped and skied over allot of the Sierra's, but can't say I know Grass Valley very well.


Dave,

Thanks for the explination. You have the gift of making these things make sense for me. I always enjoy your posts and learning from you. Thanks.

Eddie

 

[tile]

Sorry for not replying sooner, I've been busy.

I've spoke to a couple professional concrete guys who don't really know what to think of this guy and say that I got a really crappy deal.

I've spoke to 2 engineers, who are fully capable and I trust without a doubt.
I also spoke with a completely capable contractor again who I trust without a doubt. They have seen the slab first hand and are giving me very similar answers. One thing they told me is that it does not look as bad in person as it does on the pictures that I have. However it is not perfect and still has it's obvious problems. This will be a fix in progress for a little while as we are going to allow it to cure a while longer before finalizing our plans.



I do know that most of the guys here will be disappointed in the route I am taking however my goal is to get this barn up and this mess behind me. The contractor who did this is not worth suing as I'll never get anything out of him. He is NOT going to pay for any of the fixes and the most I could get is the labor I WAS going to pay him anyways. That would only be because I wouldn't pay him not that that was all he was liable for. So we are not going to be calling a lawyer. Next is the inspector who is well not going to make life easy for me. There is a good chance the project will be shut down indefinately and that is not going to help me. The inspectors here can be very difficult usually when it's not neccesary. With the help of an engineer/architect and a real GC we have devised a new plan of attack for the project and will be fixing the missing concrete and the areas where the base plates sit. We will be repermitting the project as he is no longer part of the project and has been terminated. For liability issues the manufacture will be reengineering a fix for the base plates that have been drilled. The slab will never be good but it will be enough. I will be calling the licensing board to report him and I will be calling the concrete manufacture if nothing else but to make them understand they are not doing themselves a service by allowing this to happen.


Where this all goes I do not know only time will tell. Hopefully not too much time.

BTW the finished slab top is fairly flat considering. I have seen worse as far as flatness goes. We do tile and epoxy and deal with floors day in and day out. There are no slab cracks as of yet but I've seen 18 yr old slabs crack. There are expansion joints at the north and south end of the building and there are 4 saw cut joints, 2 in either direction. The concrete is still soft but the feeling is that with the extra engineering that is really not required here in Florida and the added fibre along with the rebar we should be ok. There is a discussion of doing a topping but we need to work out a few details as to what materials we will be using.


At this point nothing is set in stone ( not even my slab) and are subject to change at anytime. I'll keep you posted about the progress of the building or non progress.


Thanks

 

[Egon]

Thanks for the update.
I am glad you have good advice on hand locally.

 

[EddieWalker]

Thank you for keeping us updated. If anything, you'll find that we're a concerned group that only wants the best for you guys.

Your solutions are better than we've come up with and in the end, you'll have a buildng to be proud of. It's never the problems that come up that matter, but how you overcome them. Tiles shouls be very proud of his wife.

Thanks,
Eddie

 

[tile]

Hi all
Since it's been a while I just wanted to say,
Hope everyone had a great Holiday and New Year.

For an update on the progress here. After some discussions and a few arguements we finally have gotten somewhere with this situation. Even though I had wanted to just fire the builder and deal with fixing the slab it hasn't happened that way. I took it one step further and had the slab tested. The tests came back very low, 1780, 1770,1440 & 1290. Keep in mind this was a 2500 psi mix which is the lowest psi any concrete plant in this area makes. You could get lower if you ordered it but really why would you. After seeing the results and kicking around our options we really didn't want to live with the slab as it was. One of the superintendents that we work with also knows the contractor and he interveined on our behalf and spoke with the builder. He did some sqwaking and has been some what slow at coming around but the ultimate decision has been to allow the contractor to fix his mistake. SO........

It is gone!

The contractor is going to replace the slab at no additional cost to me. He has removed it and has schedule to form it up and repoured it. I am having the testing company stay onsite while the new slab is placed to avoid any future problems. We have also decided to NOT place the bolts during the pour but have them epoxied in later. Using the J-Bolts seems better to me but since it didn't work the first time we have opted to do it the fool proof way.

 

[BayouMan]

Tile,

I have been following your post and I have to say, that is the worst job for a slab I have ever seen. I am truely amazed at your perseverence to stay the course and come to a great resolution. May God continue to Bless you.