WJE Primer: Deleterious Expansion of Gypsum-Containing Grout


Grouts used to secure railing posts to concrete elements are expected to be volumetrically stable and durable after their installation. Far too often, the chemical composition of proprietary rebagged grout typically used for this application creates an environment ripe for volumetric expansion that occurs within the grout after installation. This expansion can cause significant damage to the grout and the surrounding concrete, resulting in falling debris hazards and/or instability of the embedded railing.

This primer written by structural engineer Gary Wentzel is intended to educate designers, contractors, and others in the building and real estate industries about the destructive potential of this material as well as successful approaches to remedy its deleterious effects.