Pouring the concrete bench tops

Entry no. 99 and 101 shows the beginning of what is now our kitchen. Building the cabinets was something we decided to do ourselves, mainly due to the amount of money we could save, and the fact that we wanted to use structural ply, rather than melamine for the walls. It was put up in less then two days, including all the cutting and the installation, so not too bad at all.

When it came to the pouring of the concrete bench top we decided to bring in a little bit of help, mainly as we really wanted it nice and level and we weren't sure if we would manage this ourselves. Now, the normal way of making concrete bench tops is to to make moulds, pour it in the mould and then turn it upside down before polishing. This ensures that you get a really nice smooth surface on top (the original bottom). However, due to our curved walls and the share size of the benches we decided that it would be easiest to pour it in-situ. But as we said, then deciding to get a helping hand in.

As we had been very happy with the guys who did our slab for the house, we contacted them again, and Albert (picture below) was more then happy to give it a go, even though he had not done it before either. But at least he knew what he was doing.

Geir did the mixing of the concrete and we used wheelbarrows to get it into the kitchen and the laundry. The mix consisted of 5 parts of sand, 3 parts of 7mm blue metal and 2 parts of cement, which had already been premixed with a black oxide. The hard part was then getting the right moisture level. You don't want it too wet, but not too dry either as it then becomes hard to work with, especially getting it all nicely down into the corners. There are a couple of methods normally used to vibrate the concrete on the edges, either using an electric sander (without sanding paper) and run this along the edge, or using a small hammer to knock on the side until it stops falling. Our concreter preferred the latter and the end result was reasonably good. More about this further down. First some pictures to show how it was done.

Introducing Albert - our concreter.

Hard at work - basically, we used shovels to put the concrete in place, Albert then made it nice and level and then floated it.

After the floating and letting it set for between 30-60 minutes, we spread pebbles in different colours all over it, to make it a bit more interesting when it was finally polished. Here you can use more or less whatever you want - pebbles, shells, glass, etc.

Jodie hard at work, putting pebbles on the bench top.

The second bench floated and ready for pebbles.

After the pebbles were put on top, Albert then knocked them all down into the concrete, and floated it again. Unfortunately we don't have any pictures of this, but at least this shows the bench top when it was finished. It also shows the boxing we put around to create the height we wanted for the "slab". We decided to let the edges come down a bit further then the actual top, so the concrete on the middle of the bench is about 40mm, but on the edges it is about 60mm.

After the pour, this time seen from inside the kitchen. The black edge you can see is form ply that was used to hold the concrete in place.

And finally, a picture too of the laundry bench top that we decided to do the same with.

After the pour was completed, we let it dry for 5 days before starting to polish it. The polishing process was something that took some time to decide, especially when it came to which method to use. Most concrete is polished wet, meaning that you need a special sander/polisher that you can use with water. These cost around 500-600 Australian dollars and for a one time job we thought it was quite a bit of money to spend. When researching options for diamond pads to use, we found that you can now also get diamond pads that are made for dry polishing, thus no need for water. By going for this method, it meant that we could buy a cheap sander polisher for $100 instead of going the expensive way. We bought the pads over Ebay from Hong Kong. It also came with the pad holder to fix to the sander/polisher and it was delivered in the mail in 5 days.

So, cost wise, we ended up spending $100 for the sander/polisher, $130 for diamond pads/pad holder, $100 for labour, $35 for cement, $ 25 for oxide, $20 dollars for two big bags of pebbles and $140 for the water based epoxy we used on top of the benches after they had been polished (more about this later). We already had the sand and the blue metal on site, but the estimated cost of this would be about $20 dollars, if that much. So, overall, the total cost was around $550 which is not bad, considering a quote we got to do it professionally was $600 per linear metre of bench top - of which we have about 10 metres !

Anyway, back to the polishing. Having let the concrete dry for 5 days, we used the 50 grit diamond pads to start grinding down the surface to expose the pebbles. As we were doing this dry, and inside, it got really, really dusty, but there was not much we could do about that. As mentioned before, in an ideal world, you would do the pour in moulds and then either polish them outside or in a work shop, but we had to do it in the kitchen and in the laundry. The first 50 grit grinding took most of a day to complete and left a few small holes in the concrete top. What we did then, which we had read in a book about all this (reference later) was to make up a slurry of cement, oxide and water and put this on top of the bench top. This was then grinded back again, using 50 and 100 grit pads, before we increased the grit on the pads, going through 200, 400, 800 and 1500.

One thing that we wouldn't do again is using the slurry. This really did not work very well - possibly due to our handy work (who knows). What we actually found to work better was using a tile grout that had a very similar colour. This was just mixed to normal grout consistency and then put into the small holes using our fingers. It stayed in place really well and hardly needed any polishing after. So if we ever do it again, this is what we would do. We also had a small problem with concrete in front of the sink in the kitchen. As this was really narrow, it actually broke off and was only held in place by the steel. We ended up gluing it back together, using a 2 part araldite glue and then using the tile grout to seal up the cracks. In the end you can hardly see that it actually came off, so we are happy with the end result, though it gave us a bit of extra work.

Once the polishing was completed, we sealed the surface with a 2 part water based epoxy manufactured locally by a company called Tasmanian Paints (or Tas Paints for short). After mixing the two components it gives a working time of around 60-90 minutes. We mixed up 0.25 litres at the time, and manage to put it on before it got too dry. Overall, one coat for all the benches required 0.5 litres. We did 3 coats on the bench tops and then did one coat on the recycled bricks in the kitchen. This really brought out a nice colour in the bricks and we are very happy with the result.

So what does it look like? A few pictures taken recently:

Bench that separates the kitchen from the living room

Kitchen bench with sink - with window to the west.

Bench that separates kitchen and dining area

The whole kitchen, as seen from the living area

The laundry, before tiling the splash back.

Now, so where do you start if you want to do this yourself. Well our recommendation is to first look at the following website:   http://www.concreteexchange.com/

The owner of this website also has published a book which is very good for owner builders. We found this in our local library, so check that out before you go and buy it.

Concrete Countertops. Designs, Forms and Finishes for the New Kitchen and Bath. By Fu-Tung Cheng with Eric Olsen. Published 2002 by Taunton Press, ISBN 1-56158-484-3, # 070599

However, there is a lot of information out on the net regarding doing your own bench tops in concrete, so it is just to start searching.

Any problems, please email webmaster. This page was last updated 24/07/2008