Concrete planter urns add decorative interest to any outdoor garden or indoor plant display. Concrete urns have been used for centuries because of their classic aesthetic and resilient construction. However, despite being resilient to severe weathering and outdoor deterioration, urns can be damaged when dropped or tipped. Luckily, cracked planter urns can be repaired at home with a few simple products and proper concrete mending steps.
Thoroughly clean the broken surface, using a scrub brush and soap and water.
Rinse the surface and let it air dry. Concrete surfaces harbour holes or smaller cracks that fill with water when the surface is wetted; you must wait for all the trapped water to evaporate before continuing with the next step---evaporation may take up 1 to 2 hours.
Make sure the broken pieces fit together. If they do not fit, then you'll need to find small gravel pieces to fill the gaps. The gravel can be glued right to the broken piece prior to attaching the two ends together; the piece of gravel will be fairly obvious, so don't expect a seamless repair if most of the pieces don't line up properly.
Apply PVA glue to two broken surfaces. (Glue two pieces at a time and wait for for the glue to cure before moving onto the next piece. If you try to glue too many pieces at once, holding them all together with tape or clamps becomes very difficult.) Press the pieces together and wipe off any excess glue with a damp cloth.
Securely hold smaller glued pieces together with duct tape or use a sturdy bar clamp for larger pieces.
Allow at least 24 hours drying time in a clean, moisture free environment.
Repeat Steps 4 through 7 until all the pieces have been glued together and all the glue has thoroughly dried.
If you're dealing with dozens of shattered pieces, chances are good that many pieces won't line up. Replacing the urn may be more feasible than repairing it.