as discussed yesterday, I'd like to summarize our recomendation for the existing floor joints each 25 m2 (= each 5 x 5 meter). As I understood from our conversation, the current specification for filling this joints ask for a flexible PU sealant. And on the othter hand, owner and contractor ask you to give a warranty that - when overcoating this joints with epoxy coating - the joints shall not crack.
Our recommendation: You can only give a guarantee on this joints, when you change the filler (from flexible PU sealant) to be filled with epoxy mortar or a specific epoxy grout. The reason is that these so-called construction joints are done by saw-cutting 5-10 mm deep and therefore they cannot move anyway.
However, please be aware that for so-called "movement joints" (expansion- or contraction joints) you cannot fill with (rigid) epoxy mortar and you need to fill it with a flexible PU sealant.
Therefore, you should get following answers from the contractor:
1. Wich joints are designed to be movement joints? (This you still need to fill with flexible PU and you cannot overcoat with epoxy later in order to ensure the
required movement capacity.
2. For all construction joints (saw-cut joints) you can offer to close it with epoxy mortar or epoxy grout.
3. What is the current specification for the floor coating material? Example: Epoxy self-leveling 2 mm , or .... PU self-leveling 2 mm
4. How many sqare meter? when to be done? how long curing time of concrete (after casting) before application of flooring system, etc.
Remark: Detailed information on proper installation of epoxy mortar or epoxy grout into the joints and overcoating with epoxy, you shlll receive later.