The Model 4370 Concrete Stressmeter comprises a short vibrating wire load cell in series with a longer cylinder of concrete. This concrete cylinder has the same properties as the surrounding concrete but is de-bonded from it by means of a smooth-walled, porous plastic tube. It’s coupled at its ends to the surrounding concrete by means of two flanges equipped with sections of rebar to provide a better grip. The vibrating wire load cell measures the load imposed on the inner concrete cylinder by stresses in the surrounding concrete. This load, when divided by the cross sectional area of the inner cylinder, gives the stress in the surrounding concrete.