Important Cold Weather Installation Note
Water expands when it freezes.
All grouts are mixed with water. If the outdoor temperature is cold enough to freeze the water before the grout cures the water will expand. This could cause the surrounding concrete, stone, or block to crack.
Water contracts like all liquids as it is cooled, until it reaches approximately 38 degrees Fahrenheit. As it continues to cool it expands slightly until it reaches 32 degrees Fahrenheit when it freezes. At that point it expands 9%. The force of water expanding can cause cracks like those shown in the picture.
For this reason all grouts should be used carefully in cold weather.