Can tape over the probe cause erroneous readings?

[CC Solutions]

Do you think duct tape over the probe cap will cause erroneous readings?
I am believing it can so I have quit doing this. I used to put a piece of duct tape over the cap to keep the dang cap in place because you know how people love to rip that cap off and fill the hole with dirt!

But I think the tape will cause the slab to dry more slowly than it normally would. So I won't use tape on a long term test.

Thoughts?

[eaadams]

I think it would do the same thing as putting a puddy on the sleeve to hold it in place.

I am unsure if they affect anything, perhaps do a few side by side tests on some jobs?

[CC Solutions]

(10-12-2011 04:07 PM)eaadams Wrote:  I think it would do the same thing as putting a puddy on the sleeve to hold it in place.

I am unsure if they affect anything, perhaps do a few side by side tests on some jobs?

You mean like a puddy cat?

I'm sure it doesn't have an effect on a 72 hour reading, but how about a 4 month test? I think anything suppressing the natural release of moisture form the slab would be of concern...

[eaadams]

I wonder if that big pile of drywall gets moisture on the bottom....

[eaadams]

Well I have two testers doing this now. I have not seen a difference. I have seen one set of tests start around 99 and they got down to the low 90's

edit ....

over three months
99 to 86
94 to dead probe
90 to 80
99 to 90
96 to 81
99 to 85
99 to 91
99 to 85

[CC Solutions]

Very interesting.

I need to find out how Wagner has redesigned the test probes now that the requirement for a full sleeve is in effect. The previous probes would breathe, they have holes in them, but are they designed to breathe a certain percentage to mimic porous concrete?

If they allow moisture to escape from the test hole, how will 3 month old tests correlate with new tests?

[CCR]

Interesting stuff.

Because of problems I've had with sensor contamination or flat out destruction (from water) after placement, I caulk the orange caps after initial place AND cover the caps with bright color tape. I also use a marker and write "TEST IN PROGRESS DO NOT DISTURB" on the tape. I also ask the GC to ask workers to do their best to not disturb my test locations. This seems to work, but I never thought of the tape having an adverse affect on my results.

[CC Solutions]

I have not tested or seen test results regarding the taping of sensor caps. I have seen test sights with several pieces of duct tape placed over the caps and I would suspect that this would be an issue on long term testing.

The concrete needs to emit vapor to dry. Any barrier to emissions will create an abnormally high reading area (such as an area where pallets of materials were stacked for several months). We know moisture vapor doesn't travel sideways through a slab, so I wonder how much a small amount of tape, say 4" by 6" over the sensor, could effect the reading.

My gut feeling is that it could throw it off quite a bit on long term testing.

[CCR]

Would be helpful to hear what Ray Thompson says.

[rthompson]

No, It doesn't matter if you put tape over the hole or not
The reading is at the 40% depth and not the gradient of the hole.
Rayt