Kneas Bar Hammer???

[Mwhite]

I recently had a testing lab use one of these for bearing capacity checks in the field. I cannot find any reference to this device. What is it? Who makes it? What is its reliability? This is being used on structural fill in central PA.

 

[tylermacleod]

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.