Kneas Bar Hammer???

Mwhite,

we use a clegg hammer at our company to test the quality of finished subgrade. not sure if this is even close to what you have mentioned. i will describe it to see if it sounds similar to what was used in your case. the clegg hammer is a proctor hammer outfitted with an accelerometer. the maximum deceleration is measured when the hammer is dropped from a set height onto the finished subgrade. the read out is digital (termed the clegg impact value [CIV]) in units of g's/10. the CIV can be roughly correlated to CBR values. when used enough you can build up a local database of values with other testing methods. our firm is currently using the clegg hammer on jobs with cone penetrometer tests and CBR's to develop our own correlations. hope this is helpful.