Masonry bit and ice block questions...

[clawhammerdan]

This past weekend, I began framing my basement (to finish it) I wanted to anchor some 2x4s to the floor, and drilled through the wood with a wood bit, and then into the concrete with a masonry bit (5/16). I then placed some expandable anchors in the hole that bulge as you tighten the nut, above the 2x4. My question is why did my masonry bits seem to go so dull so quickly? I probably only got to drill 3 holes with each bit before they became ineffective. The package said for block or brick, and this was in a concrete floor. Was that the problem? Do they make 5/16 bits that will go through concrete more easily? I still have 36 more linear feet to go, next weekend.

Second question: Do any of you have experience with ice block? (Styrofoam where rebar and poured concrete form walls)? I want to hang sheetrock, but it's kinda "iffy" hitting the metal strips (supposedly every twenty inches). :-/

[Ozarks_1]

??? Cheap bit, maybe?
I've used masonry bits on concrete and rock without a problem. I'm tempted to give the quick answer that even some of the "famous name brand" bits are made in China - with a wide range of quality - but I've got a set of Chinese-made 'no-name' masonry bits that still work well after drilling literally hundreds of holes.

Are you using a regular drill or a hammer drill?
A hammer drill - even a cheap one - makes drilling concrete and rock much easier.