A very old mason's trick for accelerating the set of concrete is to dissolve ordinary household soda in the mixing water. Is this in any way detrimental?
The addition of household soda (anhydrous sodium carbonate) will accelerate the setting process to a very great extent when mortar is to be used for plugging leaks and similar applications where very rapid set is essential. On the debit side, workability will be seriously limited and thorough compaction becomes difficult.