Specifications of fill behind basement walls of RC Building

[Robert-32]

Dear Colleagues,
What is the best material to fill behind basement walls? Is it compacted granular fill @25cm layers? or another type of fill?

 

[TigerGuy]

You should get as many opinions on this as there are different possible scenarios and site soil conditions.

 

[EireChch]

if you have drainage either weep holes or a perforated pipe then granular backfill would be preferred.

If you are only compacting a small width of backfill behind your wall then granular would again be better since its easier to work with and compact in smaller areas.

Cohesive fill maybe better if you want to reduce the potential for ingress of water into your basement wall.

Like TG said, there are many different scenarios.

 

[dik]

Clean 1" crush is what I specify, with drainage tile and a geofabric between the fill and the native soil and topsoil cap.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JedClampett]

Your Geotechnical Consultant should have given you active, passive and at rest pressures on this wall. What did they base these loads on? In other words, his/her design, his/her backfill guidance.

 

[EireChch]

Dik - you material is for the 0.3m or so thickness of drainage material behind the wall. I think the OP is talking about the bulk backfilling.


and good point by Jed - that should be your first port of call.

 

[dik]

There could be a metre thick at the top... The backfill space is generally what is required for construction of the foundation wall. They normally replace the excavated soil with clean backfill. I also use Miradrain with foundation walls. and an impervious clay cap and topsoil (we have lots of clay) to cover the granular fill.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik