TIL most guys are using way too much water in their mix

Watched a 20-year veteran finish a 300 square foot driveway with barely wet mud last week, and I finally saw the light on how much better the surface holds up. Has anyone else noticed that drier mixes just seem to float out smoother and resist cracking longer?

3 comments

3 Comments

charles8368d ago

Gotta disagree hard here. You're asking for shrinkage cracks and delamination issues pushing that dry of a mix, the water helps it actually bond to the slab underneath.

wood.uma8d ago

My crew tried a 0.40 water-cement ratio on a 30,000 square foot warehouse slab a couple years back and we ended up with hairline cracks showing up in about 15 percent of the control joints within six months. That extra water might seem like it helps with bonding but it just adds more movement when the concrete dries out. We switched back to a standard 0.45 mix and haven't had those same issues since. The bonding problem comes from poor surface prep or not enough moisture at the interface, not from the mix being a little on the dry side. If your base is graded right and you wet the subgrade a bit before pouring, a drier mix will grip just fine. Charles you're right to call out the risks because I've seen plenty of guys blame the mix when it's really their process.

stellat468d ago

Start checking your base prep before you blame the mix. A dry mix will crack if your subgrade is uneven or you didn't compact it right, but if you get that part solid it bonds just fine. I've been running a little tighter on water for years and only had issues when I got lazy on the prep work.

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