Concrete Light Reflectance Value

[PT999]

Concrete gurus
Anybody know where I can find light reflectance value for standard concrete (or know the answer)

I need to figure this for ADA requirements governing detectable warning devices which require a contrast of 70%
between the concrete and the detectable warning buttons

 

[epoxybot]

Master Builders or Euclid can probably tell you. You would want to talk to somebody regarding their light reflective floor toppings. Seems I recall that they (MB) use to be able to give you an indication of ROI for the topping, so they would have to have a base LUX for concrete to start.

On the otherhand there is some interesting info here;

http://proxima.astro.virginia.edu/infoshts/is125.html

 

[Ron]

Concrete, in most areas, is between a photo-neutral gray (18%) and close to white (100%). Depending on water-cement ratio, additives such as fly ash (darkens the concrete), the range for most concrete will likely be in the 50-70 percent range.

What you are looking for with ADA compliance is the CONTRAST percentage, based on two different reflectance values adjacent to each other. For this application, you usually need to provide some coating or coloring to achieve.

 

[PT999]

Thanks
I want to use standard safety yellow detectable warning truncated domes as the contrast at the bottom of a handicap accessible vehicle ramp.

For some strange reason the contractor has installed grey colored domes. I don't think there is any chances that this meets the 70% contrast requirement, although the new concrete is a clean white at the moment. It looks like I'll have to order him to remove the grey domes, but I want to be sure that I am on firm ground before I have him redo.

This happens to be in New York City. Does anybody know if NYC has different rules than the USDOJ ADA requirements.