SRW block replacement

[WallEGuy]

I'm trying to develop an insert for a segmental retaining wall that will replace one of the blocks during install. Dimensions approximately 10" deep, 10" wide at face, 6" tall. It is to be made of metal and have void space exposed at the front end of the wall. Therefore, I am trying to get the thickness that I will need if I were to make a sleeve that is both structurally sound enough to meet astm standards of 2,500 psi and thin enough to allow the biggest void space. Does anyone have a material suggestion and thickness that I would need?

Thank you for your time!

 

[thaidavid40]

A piece of 10x10x1/2 tube steel maybe (HSS 10x10x1/2 x 6"-long)?
Dave

Thaidavid