What is the proper way to seal a tub trap hole through a slab. Its the worst area to leave an opening in a termite infested region.(water and wood framing=)and why is it left open anyway,if there is no access provided? is it just easier than having to wait for someone to refill it with concrete.
Personally I would fill it up with plaster rather then CEMENT as the cement would be a heck of a job to chopout in the future when repairs/replacement is needed
Also plaster wont harm brass tubing like concrete can ( lime )