"shedmeister" wrote in message
om...
The basement floor and walls of my new house (in Indianapolis) were
poured with a 3500 lb mix = 5.5 bag mix. This sounds normal. So my
question is, what could cause this concrete to be harder and more
brittle than any other concrete I have ever drilled? Moisture starved
while curing?
Looks like it, curing in cold weather will do that to, water evaporates
easily and the concrete never hardens enough. But you don't really care what
caused it, you want to fix it. If it is moisture starved adding water will
fix it. I would try to keep a spot (2' by 2' at least) wet for a few weeks.
A wet rag and keeping it wet will do that, than see if it still chips so
easily. How to fix the whole basement ? Ever wanted an inside swimming pool
?
Curing in the winter? Here are 2 phenomena that did
not occur in my last 3 homes:

1) When I drill and install standard wall anchors, and screw in
standard zinc-plated screws, about 40% of the screws break.
Try a new drill bit and be sure the hole is deep enough. This has nothing to
do with the concrete I think.

2) When I drop something hard and heavy on the concrete, it chips out
a significant chunk.

Thanks,
Jim