Reinforcing Cellar Retaining Walls

The exposed parts of the cellar retaining walls were in dire need of attention:

1. The lime finishing experiment was informative but not holding up to the elements.
2. The incomplete water-shed umbrella meant that water was collecting into the retaining walls and together with the clay soils exerting pressure on the retaining walls. That pressure met the weak curvature of the walls (where one wall also was out of plumb) and caused the earthbag walls to push outward.

We decided to build a secondary concrete wall alongside the exposed parts of the earthbag retaining walls. This will hopefully reinforce the earthbag walls and weather proof them and prevent further degradation. We also decided to use concrete blocks (that would be filled with rebar and concrete) instead of attempting to build formwork to support heavy concrete walls.

The first step was to dig the trenches into which the concrete walls would be set. We did this when the excavator was here to work around the summer kitchen.

The next step was to find construction materials: concrete blocks, cement and rebar. We have construction material shops in the village that do delivery. But they do not have a truck with a crane for offloading. On a good day, I do not look forward to manually offloading 120 concrete blocks and 20 sacks of cement. My spine was healing from a back strain so manual off-loading was unimaginable. We did some internet hunting and found a supplier (further away) with better prices for the items which compensated for the additional expense of long-distance delivery with an offloading crane:

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The first step was to complete and level the trench.

Next was lining it with geotextile and covering it with a drainage layer of sand and gravel:

… and then seeing how the blocks would fit and how far they would go:

and then running into the extension of the ventilation intake pipe and figuring out how that should meet the wall:

This gave me a first opportunity to shape concrete blocks … roughly possible but not a good idea.

I soon realized that it was not possible to continue dry stacking because it would not be possible to elaborately fill concrete around the pipe. So it was already time to finalize the placement of the pipe … some cob “joined” it to the existing pipe (which had been deformed by the weight of the earthbag walls):

… and backfilling (this felt like a point of no return):

A bit of improvised form work to complement the poorly-shaped concrete blocks:

… and the first vertical rebar … added initially just around the pipe where I intended to poor concrete:

… and then a first concrete pour … at the time it felt more dramatic then it may look:

… then more vertical rebar and a continuing cycle of concrete, block laying, back-filling … and a wall grew:

… and the cat discovered the pipes and playfully enjoyed hiding from the dogs … not really hiding because she is being indoctrinated as a member of our dog pack:

… until the (first phase) of the first wall was completed:

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Iulia joined me for some of the work on second wall:

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… until it too was “firstphase completed” (forgot to take a picture!). This was already a relief since now the earthbag walls were protected from further collapsing. We now had massive retaining walls made up of a core earthbag wall, some backfilling (where there were gaps) and a concrete wall.

We deliberated quite a bit about options for the top of the wall. We ended up deciding to “cap” the wall with a concrete top that would lean slightly away from the cellar entrance area. And so began another adventure. Finding a way to keep in place formwork, backfilling (with earth and bricks) to reduce the amount of concrete that would be needed … and putting in some lengthwise rebar that would lock it all together (I think it may have been good to put in some short rebars set into the width of the top … but I cut that corner):

I tried to mix a thicker concrete (with less slump) so that it would build up and hold its form better:

I worked my way up in segments:

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… and then moved to the second wall (though between the two walls we seeded another recovery project, also related to the cellar … more on that in a future post) to apply the same strategy to its slightly different shape:

This is where we are now:

The concrete work needs to be continued, but to do that we first have to interface between the ends of the concrete wall and the cob walls:

We will do this with cob … and that will lead us to the final form of the wall and allow us to complete the vertical parts of the concrete and the “cob bridge” that sits on top of the entrance.

Nights and mornings are getting cold and the days are getting shorter … curious to see how much further we’ll be able to go this season. I am content with where we have arrived and feel it will hold up well in winter. I do look forward to reaching a state of completion where we can let the place settle and help it transform back into an undisturbed green space with a passage into the earth.

I’ve come to (somewhat) better appreciate the qualities and potential of concrete.