Hi @TD1,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you join us.
Unfortunately, the Dy-Mark Epoxy Kits cannot be applied over sealed concrete. If you wanted to use this product, you will need to remove the sealer. Depending on the product that was used, you may have some success using DIGGERS Xylene Solvent to strip and remove the sealer, but if it is a penetrative sealer, this would not be 100% effective.
For the best result, you will likely need to have the concrete ground back. Due to the risks involved in concrete grinding, I'd suggest this is a job best left to the professionals. You might like to use a service such as HiPages or True Local to find a concrete grinding specialist in your area.
If you didn't want to go to this extent, I could suggest using the Dulux Concrete & Paving Range. When the appropriate products, such as the Sealed Surface Cleaner and Sealed Surface Primer are used, it can be applied over sealed concrete to achieve a similar result to the epoxy.
Let me know what you think and if you have any further questions.
Jacob
