Because the top is a plastic, a general purpose PVC Cement from any Lowe's, Home Depot or Wal-Mart or hardware store is all that you basically need. (Always follow the instructions on the product first!)

For hairline cracks, take the swab and "squish" the cement into the crack well. Have a paper towel ready to wipe the excess from the surface. Hold the crack together for 30 seconds and then let it cure for 24 hours before using the tile.

For larger cracks or complete fractures use the same method as above butt open the crack as much as you can before applying cement. This will allow more of the cement to enter and seal the seam. For cracks or punctures that "pop up" from the surface - sand, scrape or trim it flush first then follow with PVC cement treatment. These cracks generally can't be "opened up" like hairline cracks or fractures to aid in cement penetration, so just be extra generous and forceful in the "swab squishing" stage. If the fracture is a depression, you can try filling in the area with hot glue and then sanding flush.