It looks like technology is making a perfectly good insult obsolete.
From an Article in The Christian Science Monitor...
Another modification to the built environment is the carbon fiber-reinforced concrete of Deborah Chung, a materials scientist at the State University of New York at Buffalo. By running an electrical current through concrete, Dr. Chung says, tiny deformations caused by minute pressures can be detected. "You can monitor room occupancy in real-time, controlling lighting, ventilation, and cooling in relation to how many people are there," says Chung.
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Other things she suggests elsewhere (Google using "Deborah Chung concrete") are weighing trucks as they pass by at highway speeds, monitoring roads/bridge surfaces, de-icing, etc. .
Concrete is not a rock in a geologic sense so this doesn't pertain _sensu_stricto_.
"Rock is a naturally occurring aggregate of minerals and/or mineraloids" ^^^^^^^^
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or any basic geology or high school natural sciences text.
When a geology student picks up a piece of weirdly weathered concrete and asks the prof what kind of rock it is with the hope of tripping her/him up, a good answer is " A piece of insubordination".
FWIW, the electrical properties of concrete have been recognized as important since at least the 1950's
Just how conductive is concrete? Can its conductance be improved? I'm thinking of UFER grounds where the rebars or mesh in concrete in contact with earth can be used as a ground electrode.
Here is to those that get their technical info "From an Article in The Christian Science Monitor...". The World Weekly News at the supermarket checkout line has some good info too! Ever see those photos of BatBoy?
a "scholarly" site cite that suggests it's all about slag:
Abstract Electrical conductivity measurements were made on concrete systems containing blast-furnace slag. It was found that the slag content significantly influenced the concrete conductivity. A linear relationship between the concrete conductivity and the slag content and the volume fraction of aggregate was established by experiment. The relationship can be expressed as follows sc = ka·fa + ks·(?slg&den;c) + kowhere sc is the concrete conductivity; fa is the volumetric fraction of aggregate; (slg/c) is the relative content of slag by weight of cementitious materials; and ka, ks, and ko are empirical coefficients. This relationship provides a basis for the determination of slag content in hardened concrete by electrical conductivity methods.
This technology has been developing for _at least_ a dozen years. Apparently Dave and CSM jist picked it up for whatever reason,
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Pu-Woei Chen and D D L Chung Dept. of Mech. & Aerosp. Eng., State Univ. of New York, Buffalo, NY, USA Print publication: Issue 1 (March 1993)
Abstract. Electrically conducting concrete, as provided by the addition of a short carbon fibers (0.2-0.4 vol.%) to concrete, can function as smart structure material that allows non-destructive electrical probing for the monitoring of flaws.
Lisa Randall had an interesting op ed in Sunday's NYT that deals, among other things, with piecemeal extraction and popularization of the latest scientific "breakthrough" -- well worth the read. Reprinted here:
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