Experience with ASTM C157 (Length change measurements of Concrete)
Experience with ASTM C157 (Length change measurements of Concrete)
(OP)
Wondering of anyone has experience with ASTM C157, and if so I would love to hear a simplified explanation. Here is a link to the standard for reference: ftp://ftp.ecn.purdue.edu/olek/PTanikela/To%20Prof....
I have the molds, gage studs, reference bar and digital comparator. What confuses me is the de-molding process. I can see how I can get the specimen out of the main mold, however the two 3x3 steel plates holding the gage studs will still be attached to the removed specimen and I do not understand how to get those off. I'd assume if I oiled the inside of those 3x3 plates then I could just take them off by hand, but I do not want to disturb the gage studs.
Furthermore, I want to take a reading immediately after de-molding, then at 7 days and 28 days. I don't mind not following the standard to a tee.
Thanks
I have the molds, gage studs, reference bar and digital comparator. What confuses me is the de-molding process. I can see how I can get the specimen out of the main mold, however the two 3x3 steel plates holding the gage studs will still be attached to the removed specimen and I do not understand how to get those off. I'd assume if I oiled the inside of those 3x3 plates then I could just take them off by hand, but I do not want to disturb the gage studs.
Furthermore, I want to take a reading immediately after de-molding, then at 7 days and 28 days. I don't mind not following the standard to a tee.
Thanks





RE: Experience with ASTM C157 (Length change measurements of Concrete)
After marking the specimens, submerge them in a lime-saturated cure tank @ 73 +/- 3.5 for 1/2 hour to equalize the temperature in the specimen. Then take the initial, zero readings. Then put them back in the tank until 28-days, or otherwise specified. Once started drying, reading are typically taken as a minimum at 0, 4, 7, 14, 28-days and onward as described in ASTM C 157. We usually stop measuring at the specified age depending on the project.
Hope this helps.
Greg
RE: Experience with ASTM C157 (Length change measurements of Concrete)
RE: Experience with ASTM C157 (Length change measurements of Concrete)
To follow up - I de-molded by unscrewing the threaded plates by hand. With a good oiling, it was no problem at all