Kenneth C. Clear, Inc. has had significant
  success in the past seven years using the
  three electrode linear polarization (3LP)
  technique to define and monitor the rate of
  corrosion of steel in concrete.
  The technique is based upon the fact that
  the D.C current required to alter the natural
  electrical half cell potential of the steel
  a few millivolts, is proportional to the natural
  corrosion rate of that steel.
  If a high current is required, the corrosion
  rate is high; and vice versa.
  The goal of the testing is most often to
  predict the future durability and
  maintenance requirement of a reinforced
  concrete structure,
  or to define the benefit of a repair
  technique as a means of reducing future
  expenditures for rehabilitation.
   3LP Package
KCC INC 3LP Device (Model 3LP - NBSI) :
KCC INC 3LP Instruction Manual which includes the Measuring Rate of Corrosion Paper :
Complete portable probe set up with sufficient cable to allow about 19 feet between
   the portable probe and the rebar ground connection :
AC cable for recharging battery :
Pencil cell (copper-copper sulphate) :
Vice grip with banana pin connection :
Screwdriver for zero adjust :
Software package for use on IBM PC's :