Structural Backfill 2

[JohnTerry4]

Hello,

I am wondering if anyone has experience utilizing structural backfill for a retaining wall? Is it reliable, effective in draining water, etc.?

I heard about it from block manufacturers and the system is incorporated in design programs.

Here is the design mix:

1. SPECIFICATIONS
1.1. 28-DAY STRENGTH 1,500 PSI NON-AIR
1.2. WATER/CEMENT RATIO 0.41
1.3. AIR VOIDS 25%
1.4. SLUMP 1-2 INCHES
2. CEMENT PORTLAND TYPE 1 CEMENT 400 LBS
3. AGGREGATES
3.1. CONCRETE SAND 0 LBS
3.2. COARSE AGGREGATES #6, #, OR #57 (UNIT WT. 98.88 LBS/FT3/) 2,540 LBS
4. WATER 166 LBS
ADMIXTURE POZZOLITH 100X RETARDER 8.0 OZ/YD3/


TIA!

 

[r13]

Is this for basement wall? If so, I think there are cheaper and better way for water proofing.

 

[PEinc]

Feras Ayoub, structural backfill is usually well graded, granular, compacted backfill. You listed a concrete mix which is not usually considered structural backfill.

http://www.PeirceEngineering.com

 

[r13]

He is using a lean concrete mix to replace conventional structural backfill, that consists of well selected/graded and compacted soil.

 

[cvg]

concrete can be used for backfill.
it is fast and requires no compaction.
but the material is expensive.
it would be reliable.
it would not promote drainage of water
nor will it waterproof the wall.
if done properly, it will reduce the pressure on the wall,
but if poured in high lifts will exert a lot of pressure on the wall until it sets.

you might go with a low strength flowable fill rather than the very stiff coarse aggregate mix that you proposed. that would eliminate the need for vibration and might be cheaper.

 

[MTNClimber]

it would not promote drainage of water

Cellular concrete can be designed to be lightweight and pervious.

 

[cvg]

cellular is more expensive, most contractors will not use it - requires a specialty contractor that are not readily available. but otherwise, I agree that cellular would also work

 

[cmoreride]

As others stated "structural backfill" is a class of backfill material where there will be loads placed on back fill (roadway) . Also a specific pay item. LCC light weight cellular concrete can be used as backfill material to reduce, structural requirements, footing sizes, piles and imported material. We're using LCC on a large design build project. Where a 3/4 cut might work for an excavation. Typical LLC fills are 2:1 and must be stepped to key into adjacent materials. Also have there own sub drain systems Many factors were considered to evaluate the use of LCC.

 

[Settingsun]

Also known as no-fines concrete. It does drain unless it gets clogged by fines, as for conventional granular fill. Pay the same attention to preventing that as usual or your wall will join the many others that fall down after heavy rain when they're >10 years old.

 

[r13]

With lean concrete backfill, the wall becomes more of a gravity wall. Recheck the stability with full hydrostatic pressure and effective earth pressure.