Pool remodeling – demolition of the old retaining walls
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The pool remodel in our backyard is still in full swing. The steel wall pool is to be converted into a stone pool. For this purpose, the oval steel-walled pool, which is sunk into the ground, must first be dismantled.
I had already removed the foil, the skimmer, the inlet nozzles and also the LED underwater spotlight in the previous weeks. The steel wall was also removed in one piece.
Last week I built back the terrace around the pool. I took down the BPC decking boards and also removed the freestanding substructure, on the east side of the pool. Now before I can build the new pool, I need to remove the retaining wall on the east side as well.
Retaining wall by the pool – for what?
The steel wall pool had an oval shape with dimensions of 6.23 x 3.60 meters. On the long lateral sides, the steel wall was supported by a wall of shuttering blocks. The formwork blocks were reinforced and filled with concrete. These walls form the new outer walls of the pool.
On each of the short sides of the steel wall, the pool was semicircular. In this area, the steel wall had held on its own. Nevertheless, I have additionally stabilized these areas.
On the west side, it was relatively easy. The area between the steel wall and the soil behind it was filled with lean concrete. So I was able to remove the water from the pool without the soil slipping.
On the east side, this was already more difficult. Here the skimmer and the LED lamp were installed. Both are built-in parts that must be accessible at all times. Due to the slope of the pool, it made sense to build the terrace freestanding around the pool and to banish the technical area under the terrace.
In order to have enough bearing surface for the substructure of the pool terrace, and at the same time to further stabilize the steel wall of the pool, I had shuttered the complete rounding and filled it with concrete. Reinforcement made of reinforcing grids and iron pipes should make this retaining wall even more stable. Which she did.
How to remove a reinforced retaining wall?
I already asked myself this question in preparation and came up with a plan. In addition to a 3Kg sledgehammer, hammer and chisel, my compressed air chisel and a large hammer drill, I had also brought my father for reinforcement.
Together we wanted to remove this wall within a day. The rounding on the west side could remain. Here, I only wanted to remove part of the curvature to be able to install the new wall flush with the side retaining walls.
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Is the hammer enough?
To make a long story short: No! Only the upper part of the retaining wall could be removed with the sledgehammer. This part had significantly less reinforcement and was easier to smash through the opening in which the skimmer and LED underwater spotlight had been located.
After some time, however, it was clear that this could not be a permanent solution. The wall was too solid and too stable to destroy with a sledgehammer alone.
Heavy technology always goes – hammer drill in use
The hammer drill was of a completely different caliber. The Hilti blew the wall into many small pieces. The amount of force required for us to do this was significantly less than with the sledgehammer.
Unfortunately, however, it was not possible to knock larger pieces out of the wall with the device. True to the motto “The squirrel feeds with difficulty,” we proceeded to pick off many smaller pieces.
- Leistungsaufnahme
- Leerlaufschlagzahl 1.100 - 2.650 min-1 Einzelschlagstärke 8,1 J Passend für SDS-MAX
- Makita
- DRILL
Pool remodeling project video
The entire project to convert our pool, from steel wall pool to stone pool, I accompany with my camera. In my Youtube playlist “Projekt Pool umBAU” you can watch all videos about the rebuild. I also captured the demolition of the retaining wall in a separate film.
Remove retaining wall with angle grinder?
Somehow that was already clear to me beforehand. Not for nothing have I got my big angle grinder, my flex, ready. With this machine I wanted to simplify my work.
So I cut vertically with a diamond blade, from top to bottom – and as deep as I could – into the retaining wall. Every 20 to 30cm I set a new slot.
Then we went to the other side of the retaining wall. Exactly opposite the previously drawn slits I set again. Again from top to bottom and as deep as it could go.
Due to the wall thickness, it was not possible to saw the wall completely in the middle, but I was able to reduce the stability enormously with this measure.
After I had slit everything, I set to work again with the sledgehammer. This time there was clearly more movement. Large parts of the wall could thus be removed.
Compressor and compressed air chisel remove the wall
With my duo of compressed air chisel and powerful compressor I could already report some successes. Most recently, I was able to remove the reinforced basement slab within 3 days.
Here at the retaining wall of the old steel wall pool, the compressed air chisel also performed well. Although the decisive power was missing and I could only break out small pieces, as with the hammer drill, the chisel was much more precise and accurate.
This was especially useful at the connection to the two side shuttering walls. I wanted to continue using these walls. So it was important to me to minimize any damage.
Detach retaining wall from concrete floor
At the beginning of the demolition, I was very concerned that I would not be able to cleanly detach the retaining wall from the concrete floor. The wall was not anchored to the ground, but the concrete was poured in a liquid state several years ago.
To my astonishment, however, the retaining wall could be detached from the ground almost without damage. The concrete had not set with the soil. After a good 3 hours it was done. The demolition, which was originally supposed to take all day, was completed in no time.
After the remains of the wall in the middle of the excavation pit had been backfilled, I could devote myself to the excavations on the west side.
Notch round retaining wall – The angle grinder helps
In order to get the recess clean and straight, I first marked the rounding at the corresponding point with a vertical line. Then I used the flex to make a clean cut from top to bottom in the wall.
Since this wall was not freestanding, I could not use a hammer. So I had to pick out that edge. Here, too, the small compressed air chisel showed enormous strength. After only 30 minutes, the two edges on the left and right sides of the western retaining wall were removed.
- Winkelschleifer mit sehr robustem Gehäuse für den harten Baustelleneinsatz
- Gummiauflagen schützen das Gehäuse
- Mit Sanftanlauf
- Mit Superflansch vormontiert am großen Winkelschleifer
- Anti-Restart-Funktion verhindert ungewolltes Anlaufen nach Spannungsunterbrechung
Construction waste from the pit
A weekend later, hard work was again the order of the day. A good 4t of construction debris had to be hauled out of the excavation pit and loaded into the container 50 meters away.
With the help of many hardworking (and strong) helpers, this was also done within 2 hours.
Remove hard foam boards from the stone wall
Now all I had to do was remove the XPS rigid foam panels on the side walls. I had glued these panels to the formwork blocks with construction foam. The plates should decouple the steel wall from the stones and thus protect it.
This was relatively easy with a large spatula. Only removal of the remnants of the construction foam was much more tedious. Neither the Bunsen burner nor the chemical variant brought any success here. I was only able to scrape off the construction foam with a painter’s spatula.
Eventually, however, that was also done and I could finally start building the new pool.
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