I'd like to use plastic cement as a mortar (typical lime-free brick and stone mortar) to secure rocks in my new pond. The pond quot;shellquot; is 4 to 6 inch reinforced concrete with a fish safe epoxy sealant. The rocks would line the wall of the pond shell.
White Portland cement is lower alkalinity than regular Portland. You can get it at most brickyard and stucco suppliers. Plastic cement may have a different expansion/contraction coefficient from concrete and mortar. It is very likely to pop off as temperatures change in the pond if that coefficient is too different.
