Early strength testing method of Shotcrete! (urgently need help)
Early strength testing method of Shotcrete! (urgently need help)
(OP)
Hello all,
I have to carried out the 8hrs strength test of the shocrete as the contract specification. As the time is tight, it is not possible to send the sample to laboratory for testing.
As such, I could like to ask is there any insitu testing method can do for that?
The specification requirement on the 8hrs compressive strength should be min. of 5MPa.
I was think of Schmidt Hammer Testing before, however, I try to search in the internet and noted that it seems only applicable for min. of 10MPa.
I am not sure whether Schmidt Hammer Testing really can't working for the 5MPa concrete. Does any of you have the idea?
Many thanks!!!
I have to carried out the 8hrs strength test of the shocrete as the contract specification. As the time is tight, it is not possible to send the sample to laboratory for testing.
As such, I could like to ask is there any insitu testing method can do for that?
The specification requirement on the 8hrs compressive strength should be min. of 5MPa.
I was think of Schmidt Hammer Testing before, however, I try to search in the internet and noted that it seems only applicable for min. of 10MPa.
I am not sure whether Schmidt Hammer Testing really can't working for the 5MPa concrete. Does any of you have the idea?
Many thanks!!!






RE: Early strength testing method of Shotcrete! (urgently need help)
RE: Early strength testing method of Shotcrete! (urgently need help)
It is best if you just do the testing properly, then you'll know.
Use the "basket method" to fabricate specimens as you shoot the shotcrete. Carefully transport to the lab or have the lab bring a portable machine to the site for testing, since you will not have any appreciable curing to replicate.
RE: Early strength testing method of Shotcrete! (urgently need help)
Actually, I am working on a tunnelling project, and 24hr working with 2 shifts will be carried out. As such some shotcrete may applied in the evening time and 8hrs after will be in the mid-night which result in really difficult to test at the laboratory.
The 8hrs smaple may not have to cored. The contract simply stated testing method "AS APPROVED" and that is why I am finding the "correct" way to test it.
yes, shoot panels will be used for the testing purpose and sample will be cored from the panels for 3/7/28days testing.
Ron, I think Windsor Probe is the similar method as "Hilti bolt peneation method" (not really remember the name), but as it is consumable and we have to carry out a lot, the implication on the cost will be a lot. As such, it could be prefer to adopt the cost in "one-go" e.g. Schmidt Hammer Testing.
do you have any idea?
Thanks!!!!
RE: Early strength testing method of Shotcrete! (urgently need help)
RE: Early strength testing method of Shotcrete! (urgently need help)
It only determines a rebound number, from which you can judge the consistency of the concrete, but not its strength. In fact, if you use it to test the roof of the tunnel, that is the worst possible position for it (vertical, up).
It's not a big deal for a laboratory to have a technician on site at midnight...I've done it many times.
RE: Early strength testing method of Shotcrete! (urgently need help)
An expert is a man who has made all the mistakes which can be made in a very narrow field
RE: Early strength testing method of Shotcrete! (urgently need help)