Plastic planks for retaining wall?

Hi, all

We're in the process of landscaping our back garden and will need to drag some of the soil back towards the house to raise the ground level. However, our house is on stumps, so I'l going to have to clad the stumps to hold the soil.

My father in law thinks that there's some kind of plastic planks that I could use rather than wooden sleepers, but he can't remember what they're called and my Google-fu is failing me. Does this ring a bell with anyone?

Thanks in advance for any help.

Plastic is a bad idea as under the load of retaining soil it will tend to creep over time.

I would be going for concrete planks as a first choice, or timber as 2nd Choice.

Check out Aussie concrete products. They have 2m sections of concrete sleepers.