Why do I not have good luck with trench packer

[Shimmy1]

Just looking for anyone else out there who has used one of those small, articulated trench packers. Have rented one a few times for packing in over culverts and never been satisfied with the job. Have tried all sorts of different strategies as far as very small lifts, pre-packing with excavator bucket, etc.

At end of day can always get it better by packing with jumping jack, making hole huge and using loader, or beating down with hoe bucket. Salesmen always brag "These things will pack 2 feet no problem". What a joke or do I just expect too much out of a 3500 pound machine?

 

[clintm]

think about it an 814 cat or 84" vibratory roller won't pack over a 1' and the feet on those are 8"to12" tall I use to have a rex pactor that had open spoke wheels that wouldn't pack no more than 11/2' so there no way a rammax with dimples on steel drums can pack 2' for trench compacting it's hard to beat a pac wheel on a excavator it will do 12" to 16"no problem

 

[old-iron-habit]

There is a good reason most project specs call for 8" lifts. It's all real dependent on soil type also.

 

[CM1995]

Clint beat me too it.

What kind of pipe are you laying?

 

[Shimmy1]

Metal pipe 18, 24, 36" mostly. Sometimes bigger.

 

[JDOFMEMI]

The key to those is thin, uniform lifts, and well graded material. If you have lots of lumps and clay balls, you will get bridging, and no compaction.

Put a couple of guys with shovels smoothing in front of the roller, or a really good operator striking off the lift with the bucket, and then still some handwork to fill voids before running the roller over it will go a long way.

They are good tools, but they are small and will not fix poor material or poor practices. Salesmen telling you they will pack 2' are trying to sell you something, and have probably never had to use one in the real world.

If your pipe is that big, and you have space, once you get over the pipe, bench your trench out wide enough for a 48" ride on, and you will double the speed of your backfill, even though you are compacting more material.

 

[CM1995]

That's the same size pipe I normally lay in concrete. We dig our main trench and then bench the sides, keeping the first bench at the same elevation more or less of the top of the pipe we are laying. Bed and backfill with stone either up to the spring line or to the top of pipe, whatever the specs are. The 1st bench at this point is wide enough to get an 84" pad foot (533E) to fit in. Place the first fill lift 12" and use the hoe to place another 6" directly over the pipe, like a ridge. Roll it in and then finish the backfill 8" at a time. Done a lot of pipe this way and never had a problem.

If the line runs through an existing parking lot or road, solid stone backfill is the norm. I try my best to stay away from jumping jacks and shovels.

 

[buddy605]

I use to test sub grade all the time and contractors would tell me that machine is good for 2 feet. Look on the bomag site and there is compaction brochure this is the best cast scenario at ultimate moisture pushing against solid material. For the types of materials here I use to suggest halving it sure it is a little more excavator work but less compactive effort is required. With a lot of resistance some local guys started doing it and the compaction bonus went up. For pipe work there is no bonus but the material is not usually near optimum moisture. So maybe the backfill material should have water added to it.

 

[OMB]

Ever try a excavator based plate compactor such as a Ho-Pac by Allied? It can be run on a tired hoe without the nut to run a bucket but enough hydraulic output to run a "thumper".