The great slab pour

In March 2010, we were finally finished the footings and the penetrations were complete so I had arranged for concrete to be delivered for the 6th.  We called in any favour we thought we might have owing to us and racked up a debt to others but managed to gather a strong team of people to assist us with the slab.

Again, in an attempt to save money, we decided that we could purchase the concrete and manage the pour ourselves.  We'd spoken to a number of concrete contractors and done some research (by this stage Google was our new best friend.  To be honest, it was pretty much our only friend as we were dedicating all our free time to building) and decided that the slab, at 10m by 7m, was right on the cusp of as big as you'd want to pour without professional help.  Optimism overflowing, we decided to save the $8K and go for it.  How hard could it be?

Well, as it turns out, it was pretty exhausting but pretty doable, actually.  I wouldn't want to do a slab any larger than what we did but we managed it.

We hired the formwork which consisted of straight boards, star pickets and some bright yellow plastic safety caps.  The concreter from Leongatha was a really good bloke and gave us some great tips and even let us borrow a couple of long screeds for levelling.

We used some off-cut pieces of timber secured with star pickets to brace the formwork on the outside of the slab to ensure the formwork would hold up against the weight of the wet concrete.

As you can see the ground was not as level as we had hoped, so we were shortly to be back on the end of shovels and carting dirt BACK to where we had just removed it.

We spent a couple of days flattening the tops of each of the six squares on the waffle slab to make sure that the concrete calculations were correct and so that none of the bedrock penetrated through the waterproof membrane.  Then we shoveled in the packing sand and compacted it:

 

 

 

Packing sand complete

Bar chairs, waterproofing and trench mesh at the ready

We then laid the waterproof membrane and sealed up the penetrations to ensure that no concrete ended up in our pipes.

Grandpa provides some advice

Silver tape became my friend as I was put in charge of sticking all the pieces together while my darling hubby lugged the trench mesh around and put it in place:

Little Miss helps out with the tape

The trench mesh was placed into the trenches on bar chairs to ensure that the metal is embedded in the concrete.  This avoids rust forming.  We used wire to tie the sections of trench mesh together.

While my muscle man laid the trench mesh, I went around and tucked all the loose plastic around the formwork and started shovelling dirt to backfill any deviations from 'flat' that had resulted from months of weather while I was acutely sick.

The mesh was then put in place on the bar chairs and tied together.  We had to make some cuts around the penetrations.  The angle grinder would have been great here but the sparks would have burnt the waterproof membrane so we used bolt cutters which were terribly hard to work with, considering the tight corners.

My parents came down from Melbourne to entertain the kids and provide technical assistance (my Dad is extremely talented and has a lot of handyman experience so has been an invaluable resource).  Mum has a real green thumb and kindly brought us some roses from her garden.  We improvised and stored them in a plumbing pipe off-cut.

The preparation was complete around dusk and we all enjoyed fish and chips in the early autumn evening before heading home ahead of an early start the following day:

I was at the block early on March the 6th while my hubby, Master Padawan and Little Miss slept in, had breakfast and packed for the day.  We had the BBQ up at the block and I had made a whole heap of various tasty treats to get us through the day.  Dad had agreed to man the BBQ and Mum was going to look after the kids so we could concentrate on concrete and know the kids were safe and happy.

Thankfully, for once, the weather was on our side and I had the pleasure of watching the sun rise before using an old towel to sponge out dew that had gathered on the plastic overnight before the concrete was delivered.

We were very lucky to have brothers and brothers-in-laws provide some muscle on the day and were delighted that the majority of the crew arrived before the concrete did.

Once again, we were lucky to have great contractors who dispensed plenty of useful and appreciated advice to us amateurs.    As soon as the concrete began to be dispensed from the truck it was all hands on deck. 

Gumboots were a must and old clothes essential.  I thoroughly recommend gloves, too, as concrete burns are NOT fun.  My poor hubby touched the slab at one point to check the rate of cure and burnt the palm of his hand.

We started by roughly levelling with the shovels, trying to make sure that the concrete was evenly distributed.  We jiggled as much as we could while we were shovelling to reduce the number of air pockets.  We then used a vibrator with a nozzle attachment, especially in the trenches.  We were lucky that the guy that delivered the concrete had seen a great many pours and was happy to dispense advice. 

 At this point (while everyone else was shovelling) my hubby used a screed to make sure the slab was level.

The concrete sets surprisingly quickly, especially in 20+ degrees.  We levelled against the formwork initially and then used the levelled sections and the formwork to provide a level as we moved across the length of the slab.

Management

We worked solidly for a couple of hours and then hit a bit of an issue.  The lead delivery guy called me over and told me that there was a delay in getting the last cement truck (we needed three to deliver the required quantity of cement). 

Negotiations seem to have failed

 As such, we had some downtime before the final load which was potentially going to be quite a significant issue as dry and wet concrete do not tend to bond together well.  While we welcomed the break (shovelling concrete is heavy work), we were significantly stressed that the bond would be weak and therefore affect the structural integrity of the slab.

As it turns out, we were lucky.  Clouds rolled over and the final load was delivered while the underlying layer was still damp.

Once the concrete was in place, we took a brief break for some lunch.

It was then time to start watering and helicoptering the slab to smooth it over

By the end of the day we had a slab:

There was a (very) small amount of concrete left over so we made use of it to provide protection over the trench for the plumbing pipe