Decorative Aggregate

 

Decorative aggregates, such as colored glass or crushed stone, can add a great uniqueness to a concrete countertop. Aggregate is not very difficult to use and it creates a total custom look. However, it does require more work that just pouring the concrete because you need to expose the aggregate through careful grinding and optional polishing.

Here are three basic ways (ranked from easiest to most difficult) of getting the decorative aggregate into a pour-in-place concrete countertop:

         1: Mix all of the decorative aggregate in with the concrete.

         2: Placing aggregate in the bottom of the mold when precasting (pouring upside down)

 

First easiest method is mixing the aggregate into the concrete for more consistancy. Since the decorative aggregate is mixed into the concrete, all surfaces will look the same. In addition, the average spacing of the aggregates is more uniform. It does take the most aggregate though, up to 10 pounds per 50 lb bag.

Second easiest method is placing the decorative aggregate into the bottom of the form (only if pouring upside down). This method is very useful when you want a specific pattern or look to the finished design. The aggregate is usually held in place at the bottom with a bit of spray glue so it does not move when the concrete is poured in.

Third easiest method is seeding aggregate into to top of the concrete. This method is similar to the bottom seeding except you need to time it right so that you can float the aggregate carefully into the surface (actually push it just below) so that when it cures, you can expose it through grinding. The key here is that you must be quite good at floating and finishing the concrete to be very flat so that when you grind, you are not dealing with undulations in the surface. This method only requires 1-2 lbs of decorative aggregate per bag.