Testing FF/FL Prior to Saw Cutting

[alyon4]

I apologize if this has been covered but I was unable to find anything after doing a quick search.

A problem I have faced several times with contractors onsite is that we are often "bullied" and eventually cater our schedule to test FF/FL prior to saw cutting operations, even though the specifications only call for testing within the first 48-72 hours of placement.

My question is: as long as we use a Dipstick (some that is able to "walk" over saw cuts) and do a good job of sweeping the surface clean of any debri prior to testing, is there any significant difference testing when the slab is finished and ready, as opposed to hopping on first thing the following morning (no more than 12 hours later)? We are in a constant battle right now of just making sure we have techs available to cover various sites, so it's easier sometimes for us to come out first thing the following day.

And if we could maybe turn this into a generic FF/FL thread with other generic tips, that would be great. Thanks!

 

[SlideRuleEra]

alyon4 - I understand your concern. However, if I had to negotiate a settlement on this issue, I would go with the Contractors' position. Concrete curing behavior dictates when saw cutting should be performed... IMHO, this overrides specification wording that may have been inappropriate for a project that includes FF/FL testing. In fact, as an Owner's representative, I would be (silently) impressed that the Contractor cared enough to insist on performing the saw cutting at the proper time. On this issue, suggest that you adjust the testing schedule to accommodate the saw cutting... for the overall benefit of the project.

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[darthsoilsguy2]

the 72 hours is a consensus position by the committee who drafted the ASTM. 72 hours is a reasonable time period to ensure the opportunity to test occurs as job sites are sometimes closed and inaccessible on the weekend. I would suspect that Allen Face wrote most of that ASTM. More and more specs require testing within 24 hrs.

Contractually, you'll probably need to just do it to their schedule. The Contractor controls the site and if they schedule for testing to be done at a time, you should cover it at that time (assuming it is still a valid test at that earlier point). The Contractor is required to provide work that confirms to the projects specs, but you do not want to put yourself in the position of "Owning" 2 days that you could have informed the Contractor earlier had you staffed when they asked. I haven't hit a Contractor that wanted it done before cuts for curling issues, but i have hit quite a few that want it done because they load up the slab with all kinds of stuff for staging and you can't draw a straight line over the slab. There has been plenty of times that i have told the contractor it wasn't going to happen until the next day because we just physically could not staff it since only a few in the office had the ability to correctly do the test, troubleshoot the equipment, and write the quality of report needed.

I've had at least 1 project where the Owner told the contractor we would not be floor profiling on saturdays or sundays because of the overtime rates in our contract for nights & weekends. When the Owner supports you, the Contractor will let it go.

 

[yaschief]

Your obligation to perform FF/FL verification does not override the contractors obligation to perform saw cutting within 12 hours as per code. I have been on both sides of this issue as an Inspector and as a Contractor.

Saw cutting should not affect FF/FL Verification as the saw cuts only go 1/4 depth or less into the slab.

 

[alyon4]

Thank you for the replies, everyone. I guess my question is, regardless of who is supposed to do what and when, will saw cutting affect the FF/FL numbers? Would there be any difference testing as soon as the slab is ready, and before they saw cut as opposed to the following morning after saw cutting operations? Sometimes we just don't have the guys available to perform testing in the afternoon, or at least not until the evening if the site is open.

 

[darthsoilsguy2]

"Will saw cutting affect the FF/FL numbers?" NO. and why entertain the theory that it does.....
The ASTM allows for 72 hours and it was developed primarily for slabs-on-grade which usually get saw cut. If you wait until hour 60, saw-cutting always happened before that.

You are correct to use the term "Bully". Don't overthink this on behalf of the Contractor. When they object and say that cutting changes it.... you don't have to personally prove the Contractor wrong.... Just say "Look... there are a lot of smart industry leaders who have been doing this much longer than you and me who put this test together at the American Society of Testing Materials and the American Concrete Institute.... and i'm not just going to throw them under the bus on a gut feeling...."

this doesn't change any of the points i made before. i still think the contractor controls the site and the scheduling of testing services

 

[alyon4]

Thank you, darth. I have only tested a few dozen slabs but there has yet to be a time when everyone didn't beg for it to be done ASAP. I do respect the fact that some projects have things scheduled for certain reasons. But if given the option, I have much better things I'd rather do in the evening hours than to have a group of contractors breathing down my neck every step with the Dipstick asking "Did it pass?" lol.