A portion of the porous concrete sidewalk in front of East Germantown's Waterview Recreation Center was replaced yesterday; the surface of the sidewalk was spalling, or breaking apart. The porous pavement at Waterview Rec Center is designed to absorb stormwater from the walkways and surrounding land and infiltrate it through a gravel bed (shown in the photo above) beneath the sidewalk surface.
Why was the sidewalk breaking apart in the first place? PWD's materials testing lab is currently analyzing specimens of the old concrete to determine the cause. One theory is that an excess amount of deicing salt was applied to an area of the sidewalk during the winter, damaging that portion of the concrete. (Deicing salts can have damaging effects on conventional concrete and asphalt as well—not just porous paving.)
Click here to learn more about porous paving. After the jump, a photo of the porous concrete surface being installed over the gravel infiltration bed.