Tuesday, 9 July 2013

A Smashing Good Time

I present the next installment in the backyard chronicles... At this point I am finally ready to work on the pool proper. its kindof like Indiana Jones finally reaching the Arc of the Covenant.the first task in this phase is to cut back the concrete deck from the pool. I marked a cut line 10" back from the coping, and set to work with a rented walk-behind saw... The water is lovely, dive right in...

There was hardly any dust, but the saw was very noisy, and the mix of water and concrete grindings left a slick slurry on the deck. After about 5 or 6 hours, I had cut through the concrete deck all the way around the pool, and made a couple extra passes on the side of the pool with all the hardware and the worst slope.

This slab was poured in 1978, which puts it at 35 years old. It is over fine sand. Wire mesh was laid on the sand for the pour, but the wire mesh / concrete interface is patchy. in some spots the wire mesh is embedded in the concrete by about 1" in others it is lying in the sand just below the concrete.

The concrete itself is actually quite good with few cracks. I believe the 'chemistry' in the pour was good. Today a colony of chipmunks has moved in under the slab and is vigorously tunneling  They need to be eradicated, but the neighbour's bird feeder is a good food source for them so I don't see them moving along without a pile of encouragement from my side.

The failure mode of the concrete appears to be that the sand washed out from under the slab. On 3 sides of the pool there is a gap between the bottom of the slab and the sand ranging from  2" to 8" or more. These gaps run the full length of the pool (16' X 32') and extend back from the pool wall by 18" to 2 ft. The edge of the slab away from the pool has settled by 4" over 3 ft on the worst side. Adjacent to the pool, the slab is sitting on the pool wall.

After I was done with the saw, I pulled out my sledge hammer and mattock, and set to work removing the concrete.

You can see a 'cave' under the slab in the last photo above. It turns out that the entire deck was being held up by the pool wall since the sand had all washed out from underneath. Here is what it looks like of you stick  a camera in there:

After about 12 hours with the sledge and mattock I have only another 20 sf of concrete to remove. Yay. All of this had to go so the pool company could come in and remove the coping and liner to replace it all. Once they are done their work, it will be time to really get excited. In the meantime, here is what it looks like on each side of the pool...

North side:
South side:

East side:

And my favourite... West Side:

I think I drank my body weight in water, and sweated it all right back out again. Busting up concrete is some hard work!For my next job, I need to get some wood to use as form boards, and set up what the edge of the pool deck will look like, all ready for backfilling with gravel.

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