From the last plastic shredder machine post, we cast the walking stone (30 x 30 x 5 cm) by  mixing concrete ready-mixed mortar and plastic.We experimented with 2.5%, 5%, 10% plastic by weight. We cast it all by put the pure ready-mixed mortar (about 1 cm height) and then put plastics-mixed mortar until the mold was full. For reference, at 10%, this is roughly the plastic in 16-18 600ml bottles inside 1 stone. (Note! It is better to recycle your plastic bottles. We will be using this for unrecyclable scrap plastics. We use these bottles only for testing and for reference numbers.)

The texture of all stones are the same. we plan to test it by put some weight on it. We found a reference journal article in the Journal of Sustainable Development that found that 11% plastic flakes by weight composite stone can support 10 MPa compressive strength (101 kgf/cm2). With no plastic, this number is only X MPa. So not only is this keeping plastic out of land fills, but it should mean the stepping stones are stronger and will last longer before breaking.