Thursday 10 May 2012

Concrete Poured

Tuesday the concreters were back on site laying the plastic under the slab, followed by the Styrofoam Waffle Pods and the steel reinforcement. I was not familiar with the Waffle Pod system, but it appears to be quite popular of the South Coast. I was initially concerned about the environmental impact of using all that Styrofoam, however the Styrofoam will provide some insulation to my concrete slab, which I intend to use as thermal storage. In addition the Waffle Pods create a series of integral beams across the slab, stiffening it and theoretically these beams mean that the slab can use less concrete in other areas. To me it still seemed like a lot of concrete. The Pods did raise the slab up a bit, which was particularly useful on the side that had been cut in to level the block, since no additional fill had been used to level the block. This means that the whole of the slab will be above natural ground level, useful to prevent flooding.

Waffle Pod installation - photo sent to me by me concreters

Steel reinforcing installed - photo sent to my by my concreters

 The Termimesh installer put the stainless steel mesh around the pipe penetrations and across the control joints. This is to provide a physical barrier against termites entering the house unseen through these areas. I preferred to use Termimesh over a chemical barrier. 

Because we are having a polished concrete slab the Engineers specified additional steel mesh reinforcement and stiffer concrete (32MPa). Where the hall joins the middle and back pavilions together there was a weak point and so control joints were put in. The hall will be poured tomorrow. The other possible weak section is where the front and middle pavilions join, so extra steel was specified here.

Early in the morning- Formed up ready for the pour
Lots of steel in that tricky join
The formwork was all in and ready to go. the concreters had put additional timber on the formwork to create the step down at the edge of the slab, as well as additional set ins for each of the sliding glass doors and the lowered sections in the bathrooms and laundry, so that when they are tiled they will be flush with the polished concrete slab.

Early this morning I heard the rumble of the concrete pump arriving. It was like something out a Bob the Builder episode, and the concrete pump was enormous - and bright yellow.

My car and the garage look tiny next to the huge concrete pump
The concrete pump had a long reach - right across the block
The concrete was pumped into place, shovelled a bit and vibrated, before being levelled, screed and floated. Today's pour used about 30m3 of concrete - that is five concrete trucks. No very good for my carbon footprint, but I hope that the thermal mass provided by the concrete combined with the solar passive design of the house will mean that we do not need any heating or cooling, reducing our carbon footprint in the use of the house.

Starting with the front pavilion
Moving on to the middle pavilion - excavator in the background is
providing bracing for the formwork where the soil was soft from
the removal of the tree roots
Levelling and screeding
Finishing up at the back pavilion

The concrete had a little bit of colour added, so that when it is polished it does not have that typical light grey concrete colour. But we did not go too far from the natural colour of concrete, choosing Onyx 3% from the Concrete Colour Systems colour chart, which is a dark grey. We will not be able to see how it will look until the concrete is polished and sealed.

All finished - except the hall - A job well done

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