Used same stuff (identical container) about 5 years ago but the recent purchase went off far quicker than the first one. Had a word with Everbuild technical dept, very helpful and suggested using at a lower temperature. Therefore, I got cold water where it comes into the house and is much colder than the cold supply in kitchen or enen outside taps. The tub of Febtank plug was kept in coldest part of the house. So, I made multiple small mixes and eventually all cracks were filled in and seemed very satisfactory. The cracks were undercut slightly as advised and pressure hosed to clean them out. Also kept using hand sprayer to keek areas wet immediately prior to application. I wait to see if the cracks remain water- tight. But am cautiously optimistic!