Now that the concrete has fully cured, we had to finish it to a standard that we are happy to leave exposed as the finished floor. The term polished concrete is actually a little deceiving. The concrete is not so much polished as 'ground' through various grades of 'polishing stones'. Starting with a diamond grinding stone and progressing through to fine grinding stones which are a bit like sanding concrete with sandpaper. The aim for us was to create a concrete surface with a uniform grey colour and some small aggregate exposed.
The shot above shows the grinding in process. Slow and laborious with many passes across the concrete as one moves through the 'polishing stones'. The grinding can be done dry or wet, we chose to grind it wet purely because the cement dust is a health hazard that we could do without.
The image below shows the concrete surface once we had finished 'polishing' the concrete. You can see the uniform colour as well as the exposure of some smaller aggregate...perfect.
From a negative perspective, concrete polishing has the effect of wearing the finished concrete surface, thus leaving the concrete exposed to staining from anything that might be dropped on it. So a sealer needs to be applied to provide a barrier that prevents the spilt red wine from leaving a stain!
Our choice of sealer is a water based sealing compound manufactured in Australia by a paint company called Murobond. We love both them and their stuff. They have a strong environmental bent both in the products they make and their company attitude. All of their paints and finishes are either low or zero VOC, perfect for anyone planning to building green.
After curing the sealer for a week, we will be straight onto the slab and erecting the timber wall frames. Watch for the next post.