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.
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!
Our inspector from the building control department came at lunch time and inspected the integrity of our DPM, ready for the floor slab of the garage and as long as we carry on and mix high cement concrete and push it in and around all the conduits and pipes to seal the DPM down solidly, he is happy!
Well, that’s another box ticked !
As we are on a tight schedule we started work at 9:00am and finished at 6:40pm, this is the longest day we have done so far!
The morning was spent completing the sand fill up and compaction. Then I went round all the concrete edges and removed any sharp parts. Meanwhile Shaun was preparing timber for the form work.
After lunch we constructed the formwork for the slab from 300mm high x 18mm thick OSB (recycled from the foundations) screwed to the edge of 150mm x 50mm timber planks. These formed a continuous structure for the sides. After positioning and aligning the sides we fixed then by banging stakes into the soil against the planks.
We finished by making the front of the slab with the two doorways inset by 100mm, which ment forming four corners. By this time we were working by floodlight!
This morning we pulled up the foundation’s formwork and it wasn’t too difficult thank goodness! Very nice smooth finishes with just a hint of a textured surface picked up from the OSB sheet wood. We are planning to reuse the formwork to build the floor slab tomorrow!
Then the next job was to bring up to the correct level the sand inside all the foundations so we can lay down the DPM (Damp Proof Membrane) right across the whole garage without any dips or bumps!
So far we have done the back portion which was rather fiddly with all the pipes, conduits and man hole chamber sticking out of the ground! We scraped the surface to make a smooth finish. We double compacted the area to make sure it is fully settled and ready for the concrete!
Tomorrow we finish off the front portion of the garage and then we can build the formwork with the DPM cut and stuck together to form a water tight envelope ready for the liquid free flowing special concrete from Lafarge called Agilia Force! It is so liquid that there is a potential chance that if the DPM wasn’t stuck down properly along the joins, then the concrete could find an edge and flow under the plastic DPM sheet and push it up!! Not nice!
This is also why we are going to mix some concrete of our own and cover all the bases of the sticking out objects to make sure the DPM is well securely stuck and water tight on each conduits and pipes!
Another early start ! phew!
Yesterday we put up the guttering on the front of the wooden temporary shed and our new front door. It was something we were meaning to do for a while now. The immediate area just below the roof overhang was getting very soggy and very muddy! We needed to make sure this area and the driveway surface was bedded on solid ground before laying the asphalt chippings, so we needed to collect the rain water and divert it to a soak away module.
So yesterday we went to B&Q to get the guttering, brackets, downpipe and bits and pieces. Got it up so it slopes down towards the playing field end of the shed. We then dug a one metre square by over half a metre deep to take two AquaCell modules side by side. We wrapped them up in geotextile fabric. The downpipe was connected into the top of them and chucked the dirt back in on top!!
This morning we finished spreading the remaining soil around and compacted it all nice and smooth!
Now we wait for the rain to come !