Exercise balls have become a staple in most home gyms. However, have you ever thought about casting a series of these balls in concrete to create an interesting outdoor decorative piece? Concrete exercise balls can be used by businesses as a landscaping element or even as an interior art piece, or they can be cast and sold to customers interested in having their own unique concrete exercise ball decoration. Fortunately, regardless if you want to use them for personal use or if you want to sell them, the casting process is fairly simple.
Blow up your exercise ball using an air pump. Most exercise balls now come with their own air pump.
Mix 4 gallons of Portland cement, 1 gallon of fine grain sand, 1 gallon of concrete admix, 1 gallon of colored latex paint and 2 cups of poly fibers. To this mixture, add just enough water to create a thick, moist paste.
Trowel on a layer of the mixture onto a part of your exercise ball. Press in a strip of your metal mesh into the cement mixture. Repeat until you have covered the entire ball. You will need to overlap the mesh strips by 1/2 inch. Allow this layer to set.
Apply a thin layer, about 1/8 inch thick to the surface of one side of your exercise ball. Allow the cement mixture to dry, then turn the ball and repeat until the entire ball is covered by at least an 1/8 inch of cement. If you plan on sitting on these balls, you will want to make the layer at least 1/2 inch thick. Allow the concrete exercise ball to cure for about 1 week.
Leave your concrete ball rough, or you can polish the surface. If you will be leaving the ball outside, you will want to seal the surface with a cement sealant such as VSeal. If you want a smooth surface, you will need to sand the cement finish until it is smooth. If you want a polished look, you will need to spend about 1 hour per square foot sanding with progressively finer grained sand paper.