Rant: I swore by silica sand for years until last month's job near the river

Been laying block for 12 years and always used silica sand for the mix, but on that flood wall project in Nashville the concrete started cracking on me. An older contractor pointed out the crushed limestone aggregate was causing expansion issues in the wet conditions, and now I'm rethinking my whole supply order before my next job.

2 comments

Log in to join the discussion

Log In

2 Comments

holly7091mo ago

Crushed limestone aggregate was causing expansion issues" - yeah that's just nature's way of telling you your block wall wanted to grow a few feet taller on its own, free of charge.

0

jordan_hill1mo ago

Isn't that basically what happens with any reactive aggregate though? You pour the concrete, wait a few years, and suddenly your retaining wall looks like it's trying to turn into a Roman aqueduct. I've seen a driveway heave up a solid 4 inches from pyrite in the fill underneath, looked like a skate ramp. At least with limestone expansion you can blame the rock itself and not the guy who mixed the batch on a rainy Tuesday.

1