Testing the Compaction of Frozen Ground

[raburris]

My firm typically conducts some foundation installation and back-fill in the winter in order to meet schedule and at times the temperatures are well below zero. We have had some internal and external discussions regarding the testing of the material within these sub-zero temperatures. The material that we are placing is thawed imported fill and we are placing it in lifts of 12". We have been told by some of the testers that the machines that our testers are using are good to temperatures of -20°F but we would like some verification of this claim. Also we have have compacted a lift and not tested it till the day after placement and saw densities that were higher but with a lower moisture than what we had seen with the same effort testing it immediately after placement. My question here is: Do ice particles read on the machine like a solid or will they still be read as moisture and why? Thanks in advance for any insight.

 

[oldestguy]

My experience with radium-berillium source of neutrons is that the percentage or density of water is the same whether frozen or not. That experience was not with the current nuc gages however.

 

[darthsoilsguy2]

um... wasn't the import is thawed cut..? ice is still water on a molecular level, just a lot more organized... i can't see why the neutron radiation would know the difference with the water structure. the frozen water crystals will prevent the lubrication of the soil to achieve compaction.... definitely should make sure any field proctor samples are well above freezing before pounding out.

Everybody knows the cold affects batteries. There are many electronic devices that are affected by the cold too (is it the capacitors? i don't know.. i hate electricity).... anyway, might have more trouble with that part.

 

[BigH]

Are you just using the nuclear gauge or are you also using sand cone or water replacement? This might help in determining the problem you are having at the time of placement/testing or a day later/testing.