How to Mix PET Plastic With Concrete

Measure out the dry ingredients for your PET concrete. Basic concrete may contain 7 to 15 percent cement, 14 to 21 percent water and 60 to 80 percent gravel and “fines,” or total aggregates. Assuming a blend of 10 percent cement and 20 percent water, the remaining 70 percent would be aggregate -- let’s say equal volumes of sand and pea gravel. Substitute PET for all of the gravel, or half the total aggregate, for 35 percent plastic by volume. Mix all dry ingredients together in the tub.

Place the water in the wheelbarrow. Start with a small amount of water, about 10 percent or 15 percent instead of 20 percent, to avoid a soupy, weak mix. You can always add more later. Slowly and gradually add dry ingredients to the water, dragging the hoe through all ingredients to mix them.

Add more water if the mix is too dry or if the concrete is crumbly and won’t hold together when disturbed. The ideal texture has some “flow,” such as a gritty cake batter, and holds together well. Pour the PET plastic concrete into forms or molds, depending on your intended use, and let it set and cure.

Wash out and clean up the wheelbarrow and hoe immediately -- while the concrete is still wet -- using running water and the scrub brush to clean all surfaces.