Ground and polished first sample

Today I used the grinder that arrived yesterday to grind and polish the first sample. It is good to get a few practice runs in so that I can learn to use the tool, see how messy it is and see how various amounts of grinding look. The troweling gives the surface a smooth, mottled look. Grinding actually takes away material and exposes the aggregate (pebbles) in the concrete mix. It also removes the troweling marks and mutes the color to a more greyish tone. When we were shopping for supplies at Home Depot, we were surprised to see knee-high rubber boots in the concrete section. After griding, I know why they are there! The grinder is a wet grinder, meaning it sprays water as you grind (the grinder is like a big, powerful rotary sander). I bought a big heavy plastic apron the wear that came to my ankles (I'm only 5'3"). The water sprayed on the front of me and rolled right down to my feet. A lot of water. The lower part of my pants and my shoes were soaked. My shoes took 3 days to dry out in very dry weather. I was sloshing around all over the place with water spilling our with every step. I also found out that people use the boots when they have to walk into large pours - like a patio or foundation slab.

I'm very happy with how this sample turned out - it's going to be hard to decide which look I like best. I love the feel of it - it's very tactile. I could picture people standing by the countertop and idly running their hands over it. I certainly will be doing a lot of this!

Here is a shot showing the effects of grinding. On the right, I ground away more material. The color is a little more greyish, and more aggregate shows. On the left, I ground away less material. The color is a brighter, more orange shade and very little aggregate is visible. You can also see the mottled color cause by the troweling.



This is the end where I ground away a lot of material. This effect is called terrazzo. These pebbles came in the concrete mix, but you can use decorative stones in combination with these or instead of.


Here is a shot of the concrete with very little grinding. The color is very intense, and just a few small grains of aggregate are visible. The troweling pushes down the aggregate, so the more you grind the more you expose. The mottled color caused by troweling is also visible. I really like the variations in the color. The small holes are caused by air bubbles and can be fixed with a mix called slurry. It mixes to the consistency of toothpaste and you smooth it on and remove it with a squeegie.