Grout Sample Collection 101

Accurate grout thermal conductivity testing results for geothermal applications start in the field with proper sampling procedures. Here is a quick guide to getting the best sample possible.

Sampling from the Paddle Mixing Tank

When obtaining a grout sample from the mixing tank, first ensure that the mixing system is at a complete stop. Then, take the sample from the center of the tank (top to bottom). This will guarantee that the test results will be representative of the installed grout.

Taking the sample by skimming grout off of the top of the tank will probably result in a thermal conductivity test value that falls below target. GeoPro makes a grout sample collector available for purchase that has been specifically designed to take an appropriately-sized sample from the center of the mixing tank (without requiring the sample-taker to get his hands dirty).

Sampling from the Tremie or Cleanout Line

When obtaining a grout sample directly from the end of the tremie or from the cleanout bypass (side discharge), take the sample in the middle or near the end of pumping the batch. In most cases, a bore will be completely filled when there is additional grouting material left in the mixing tank.

It will be easiest to take the sample when the tremie line is at the top of the bore and there is material left in the line. Taking the sample at the beginning of the pumping process will likely result in a tested thermal conductivity value which falls below target.

Sampling from the Completed Bore

Never attempt to take a grout sample intended for thermal conductivity analysis from the completed bore.