One of the last groundwork tasks finished. We laid paving slabs from the front door to the loke. The wonder of a diamond saw allowed us to make a neat mitre joint at the bend and V cut at the front door. The gravel is part of the drainage for the drive and storage areas and is up to 600mm deep.
Yes we mean that literally! Over 8 tons of timber has been delivered today. Some of it was special ordered so we got a whole pack of it, which is enough of that size for the main house as well. Most of the rest will be used in the garage construction.
We have covered all of it with tarpaulins and strapped them down.
Shaun noticed that there was a high contrast between the wax covered slab (nearly white) and the asphalt drive (dark grey)!
As advised we cut saw slots in our nice pristine concrete slab, this is to allow the concrete to crack in a predefined place if the ‘plastic shrinkage’ exceed the tensile strengthof the concrete. When laying standard concrete it is normal to leave breaks between sections to allow this shrinkage, but as our slab was poured in one piece other arrangements has to be made.
We cut two slots, the first from left to right under the dividing wall (2.5m from Mass wall) and the second from front center back to the first line.
We finished off the materials storage area today. This where we will put all the bulk deliveries of timber and other building supplies.
A week ago we flattened the triangle between the storage shed, school field hedge and the loke (about 70m²). Today we laid geo-textile over it and placed 50-70mm of granulated asphalt covering and compacted.
We also filled in some of the ruts caused by the concrete trucks yesterday…
As requested by Kevin we removed the formwork from the slab this morning. The slab as set hard already and can be walked on… though it is very slippery where it still wet!
Slab has a nice smooth finish and you can see the fibres!
After the problems bailing out the actual pour went smoothly!
There were 3 loads of concrete (Agilia Force) delivered between 11:00 and 12:15. Each load only took 3-4 minutes to pour into the formwork! The mix was quite fluid and only need gentle encouragement to spread out evenly, we only had to walk around pushing with our boots to get a good level.
When we were satisfied we had a even distribution of concrete the Lafarge rep (Kevin) brought out his agitator bars. These are round poles held horizontally with two handles rising up to hold. These had to be used in two passes, 1st pass involved moving up and down about 50mm then advancing by the width of the pole and repeating (this releases any traped air). 2nd pass was a light dabble over the surface to give a smooth finish.
The rain continued to fall in showers (even hail) while we were working and Daphne bailed out some of the excess water from the corners where it had been pushed by the concrete.
Finally Kevin sprayed a wax based agent all over the finished concrete to help the slab cure properly.
Here is an edited and speeded up (16 times) video of the pour.
Well we had 10.9mm of rain since we finished the DPM Yesterday. That’s over 800 litres of water to get out of the garage slab DPM.
The job was not as easy as we thought when we started at 9 o’clock. First we tried the submersible pump – no go, the water was not deep enough. Then we used the drill pump successfully for 1/2 an hour before it overheated! At this point probably half the water had been removed. Third try was using sponges and towels! – this worked but was very slow. Then Shaun remembered the wet and dry vacuum cleaner – this worked well, better than any of the other things.
By this time it had started to rain again! and Kevin (Lafarge man on the spot) said we had got rid enough water! So it time for the concrete.
According to the weather meter we have had 3.5mm of rain in the last hour…
This is nearly 270 litres of water in our slabs DPM ‘tank’ . We will have some bailing to do in the morning.
The Damp Proof Membrane is lying flat and relatively smooth !
We started early again (8:30am) to get the job done before the Building Control inspector came! Phew!
We put down three separate strips, cutting holes where the conduits and pipes comes through and taped all the overlapping joints (at least 500mm!)! We folded like a parcel around the doorways which was a bit fiddly but plenty of duct tape and small pieces of DPM did the trick!
We also drilled a side hole in the manhole chamber (to the rain water tank) and stuck a short piece of conduit in, to allow the pumped water pipes, electrical cable and perhaps data sensor cables into the rain tank. The height of the chamber was adjusted so that the lid will come just above the finished surface of the concrete slab!
After lunch, we mixed some high ratio concrete, one and three quarter bags chucked into the mixer, a splosh of water until it was nice and creamy and then gradually put in four buckets (100Kg in total) of sharp sand and stones ballast, mixing all the while until the mixture is just a lovely texture!!
This works out at a 2:1 ratio mixture which will provide a water tight and seal all the bases of the conduits and pipes to the DPM.
This is important as the Agilia Force concrete from Lafarge is so liquid that it can find those loose joints and flow like water underneath the plastic and produce problems! !
We finished off the afternoon by banging in plenty of stakes to hold the formwork and weighed it down with loads of concrete blocks. There is after all quite a weight of material in there and its acts much like a liquid with some sideways loading so we are making sure we don’t have a dam burst!
And finally we finished off by roughly smoothing out the remaining portions of the driveway asphalt chippings and compacted it thoroughly ready for 3 24tons lorries to deliver the concrete !
We finished about 6:30pm ! In the dark again ! O Boy!
