Kinetics of moisture expansion in fired clay ceramics: a (time)(1/4) law.

We report the results of experiments to estimate the moisture expansion of several modern and ancient clay brick ceramics from the time of manufacture. From these data we propose a new expansion law, in which the expansive strain increases as (age)(1/4) approximately. Such time dependence is consistent with a mechanism in which expansion arises from a diffusion-controlled rehydration reaction on a linear or low-dimension structure. Our results provide new guidance for the engineering design of masonry and suggest a possible new method for archaeological dating of ceramics.