Grinding Concrete Ends 1

[pinoyce]

So, we are using concrete grinders but we also have capping compound. The thing is one of the six cylinder grinders broke down and I'm left with just one and on after winter we do break 80-120 cylinders a day.

My question is what is the ASTM standard for grinding cylinders prior to breaking. I want to manage my time well and grind ahead if I'm not that busy. Will there be issue with ASTM standards?

 

[Ron]

First, if you are testing concrete specimens, you should have copies of the ASTM standards that would apply to that testing. There is currently no approved ASTM standard that allows grinding only; however, you could interpret the standards to perhaps include preparatory grinding for capping methods or if you meet the planeness tolerance, then no capping. Get copies of the ASTM standards and be familiar with them. Your company is open to liability and criticism for not doing so.

I would suggest that if you are testing a lot of cylinders, and it appears that you are, you should consider using unbonded polymer lined caps. This is an acceptable ASTM method and will save you considerable time. You will need to develop a protocol for inspecting the caps and replacing the polymer lining on a regular basis because of wear. I would also suggest that you do companion testing with sulfur caps for a while to see the differences in results, if any.

 

[pinoyce]

Thanks for the reply Ron. And yes we do have all the ASTM standards in place, plus my company developed a guideline that has to be checked and filed everyday or whenever needed.

I just cant seem to find anything about grinding. The only thing I can find related to this is the capping section which tells about the planeness. Other than that, nothing.

I have a heavy day 9days from now and want to grind ahead but I dont want to do that unless I could find something from ASTM saying I'm allowed to do so. Right now, we are grinding and breaking on the same dates with the break dates.

Thanks Ron.

 

[Ron]

pinoyce...as noted, there is currently no ASTM standard for grinding as a means of test preparation, except minimally to prepare for capping. There has been research done on grinding as a viable method of preparation, and it holds promise for high strength concretes, but I would be hesitant to use it because of potential sample disturbance and induced micro-cracking, particulary on lower strength specimens.

 

[pinoyce]

I've noticed that as well and is using capping for low strenght concrete.

I guess I have to stick to grinding and breaking at the same day.

 

[Ron]

pinoyce...you're missing my point. I'm not sure you can justify using grinding as a preparation method. I doubt that it is legally defensible and could cause you liability problems.

 

[pinoyce]

Ron, thank you for your concern. Regarding legality I'll let my employer deal with it and my supervisor. I'll mention it to them.

 

[bb29510]

i been testing clyinder for 29 years and has never grinded a sample. either cap the cylinder with compound, neet cement the sample or use the neo caps. You can alway cut the sample with a lapping saw, but that takes time.

ICC Master Special Inspector, Structural Masonry, Reinforced Concrete, Soils, Structural Bolted Joints, Structural Welding, AWS CWI D1.1