air meters 1

[bb29510]

as a concrete inspector, i have always used the roll meter, its in good shape, I gget a new one about every five years, I like the roll meter.

The pressure meter, is bulky for my small truck and people do like to take them, when they in the bed. leaky oring, stuck valves etc. nothing abnormal. I just like the roll meter.

my question is; I been kick off at least three jobs because i use a roll meter instead of a pressure meter, when did contractor have the right to tell me what equipment i must use if the equipment are ACI certified ?

 

[Ron]

Either method is acceptable in accordance with ASTM. Unless the specification requires pressure method (which it shouldn't if the specifier knows anything about materials testing), you can use either acceptable method.

I agree that the Roll-O-Meter is a better, more repeatable method. Pressure meters can be quirky and they are hard to maintain.

 

[darthsoilsguy2]

Most contractors don't understand your industry. if you do something different from what they perceive is the norm, they point that out. If something is out of tolerance, they use whatever they can grab for a distraction so they can pile more materials on the work. when i started, the CMT manager stocked all rollameters (except 1 shiny airpot for CCRL visits) so its not completely abnormal either. i personally wouldn't roll... as i like my back, but there is nothing wrong with it if that's your preference.

There are some contractors out there that "kick off" an inspector/tech because they are really just looking for one they feel they can control to replace you. I've been requested not to return to at least 5 sites by the GC all while holding a PE license, ACI 1, AWS-CWI, and a ton of ICCs, so don't think that getting red-carded isn't par for the course.

Correct me if i'm wrong, but i think there is something more than just the equipment you are using at play here. There are plenty of technicians out there who will test the air from the first wheelbarrow load out of the truck to "Check the air and the slump". They then tell the contractor it is in spec and they proceed to discharge. They then collect their strength sample mid-load to finish the test (assuming a savvy GC, concrete foreman, or QC from the plant is there... all who know the concrete strength is best from the mid-load mix). Of course we all know that doesn't meet ACI/ASTM, but if the GC you are dealing with assumes they must include waiting for you to finish testing in their means/methods.... you will continue to be kicked off because rollameter is slower. Bottom line is unless specified otherwise (very rare) initial testing should be done by the Contractor QC and assuming you work for the Owner your testing should be middle of load.

 

[emmgjld]

Also keep in mind with the Entrained Air Chemistry producing smaller 'bubbles' the pressure meters now appear to be measuring slightly low. It may actually be to the producer/contractors benefit to use the rollameter. I know we have been experiencing mixes with the measured Air Content (Pressure Meters) on the low to slightly failing range for quite a while, yet the batch plant tickets do not indicate this amount of skinning-up is actually occurring. Just trying to be mid to slightly under the spec range (a good place to be with exterior slabs to minimize surface problems).