greening concrete

[dchan]

Originally Posted by scalziand

Salt needs to be dissolved into water to penetrate the concrete. If the water can't get in, then the salt can't either.

That's right, good point. If it works as well as advertised, I'm wondering whether it can durable cost-effective enough to be used in large scale.

There's a sidewalk section in my neighborhood that can really use this hydrophobic concrete. Several years ago, the city DOT decided to create a dead-end at the end of a diagonal street that had previously ended at an intersection between two normal grid streets. At the dead-end, they plopped in a garden and sidewalk bulbout. The first time they poured in the sidewalk, they used normal concrete. When winter came around, the snowplows pushed the snow and salt directly onto the bulbout. So by the time spring came around and all of the snow had melted, the sidewalk emerged very deteriorated and pockmarked, with spalled concrete chips everywhere.

This phenomenon isn't limited to new concrete sidewalks. This year's large snowfall amounts and extended below-freezing periods did a number on sidewalks which normally don't see that much snow and salt. But it does affect newly-poured sidewalks much more than older sidewalks that have mostly cured already.

After seeing the badly damaged concrete surface, the DOT decided to replace the deteriorated sidewalk bulbout with new concrete, this time putting on a shiny coating or paint of some sort (not sure what it is) that I'm guessing is meant to seal the concrete. Long story short: it didn't work this winter. It's not as badly damaged as the previous concrete sidewalk, but it's still pretty badly pockmarked and has exposed concrete that hasn't been coated.