Date:21/02/2016 18:33

We started building the back wall of the swimming lane today! We managed to
do 43 blocks with 3 mixer loads of mortar before it got dark. Each row of
the wall contains 50 blocks and we are doing 5 rows at this stage.

It was quite difficult in keeping consistent with the mortar gap between the
concrete blocks and not let it “run” ahead! We had to keep it down to 10mm
or less because we got our steel rods going up through the hollow cores,
meaning keeping the rods fairly clear of the edges of the blocks.

And the other discovery we learnt, is the sloppiness of the mortar mix. Each
concrete block are much heavier than house bricks so they press down with
27kg of force, on their narrow edges, which means they squeezed out the
mortar if it is too sloppy.

We make a strong mortar mix using 1 bucket of sharp sand with 2 buckets of
soft sand (a “Builder’s” bucket is about 13litres) which gives a total of
40litres of sand, together with a 10litre bucket of cement (a complete 25kg
bag fills just about 2 10litre buckets).

Currently, we are working with 4litres of water (plus 100ml of plasticiser)
and this produces a slightly sticky and sloppy mix which just about holds up
the block.

It takes a little while for our electric mixer to produce the “flop”
consistency, and it seems that the plasticiser then starts creating
microscopic air bubbles which makes the mix even more sloppy after another
couple of minutes. We think we will reduce the plasticiser down to 50ml in
our next mix.

We will inspect our build in the morning to judge the quality of our current
mortar mix!!

Only 207 blocks to go!!



By Shaun

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