Altering ceiling

My roller door is stuffed. Its mounted below the carport ceiling and I want to raise a new one up into a boxed-out roof space which is fairly straight forward, however I have to cut the eaves lining with an angle grinder so Im hoping its fibre cement.

Ive read up on the asbestos posts here, but Im not sure when my home was built, Im guessing in the 70's and there are no warning stickers on the back of the sheet. Ive broken a small piece off which seems to be layered in its construction. When rubbed between my fingers in bright sunlight I can see some fragments of what appears to be fibreglass and the rest of the material crumbles into a fine gritty powder. So I think its hardiflex fibre cement sheet. Do you agree?


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