Verifying quantity of concrete
Verifying quantity of concrete
(OP)
I have suspicions that my concrete supplier may be leaving us short changed on concrete. How much tolerence should we allow before we get annoyed. We have never been given too much.





RE: Verifying quantity of concrete
RE: Verifying quantity of concrete
RE: Verifying quantity of concrete
RE: Verifying quantity of concrete
RE: Verifying quantity of concrete
If you are using good quality forms and the concrete is not for a slab at grade then it should be easy to accurately calculate the concrete required compared agaibst delivered. Why not send the truck to a weigh bridge.
RE: Verifying quantity of concrete
Do a batch plant inspection for compliance to the National Ready Mix Concrete Association (NRMCA). This is a detailed review of their storage, batching, and transit mixing operations. It gets their attention. In almost every case where I've done a batch plant review inspection, the consistency of the concrete immediately improved (for that project at least!). Keep in mind that whomever does the inspection will have to crawl inside a transit mixer! (I've done it in Florida in the summer...not fun!) It will require confined space entry procedures.
Secondly, have a yield done at the site by the testing laboratory (third recommendation on this one!!). Make sure the technician is ACI certified (assuming you are in the US).
Third...make sure everyone in the process is aware of the requirements and the standards. A pre-placement conference with all parties is invaluable.
RE: Verifying quantity of concrete
Yes, the rebar displaces concrete and reduces the total volume of concrete to complete the work. My point was, along with another post indicating the method of obtaining quantities in-place, the displacement of steel needs to be accounted for before you accuse the contractor of shorting you on the concrete.
Some folks may be surprised but we have had bridge projects where the concrete in the bolster above the beams was significant. Contractors have challenged our quantities in the past because they believed the bolster had not been included. In some cases they were correct.
My agency has plant inspectors and field inspectors for major concrete pours. If there is a disagreement, we will shoot elevations and verify the in-place quantities. It is routine for our bridge folks to account for rebar; they use much more than the other folks. We have to remind the other designers to address this before accusing the contractor of shorting the order. The real problem is what to do when it is found that he has. There is usually an adjustment for payment but does this reflect the consequence of getting a short order?
RE: Verifying quantity of concrete
RE: Verifying quantity of concrete