Instrumentation

A custom-built, outdoor exposure device to impose dynamic strain on the seal­ant, based on the differential coefficient of thermal expansion between the PVC pipe and wood, was used in this study. The details of this apparatus are found elsewhere [11], but a short summary is included here. This device imposes a strain on the sealant sample based on the relative expansion of the PVC pipe relative to the wood frame to which the PVC pipe is attached. The applied strain is designed to be ±25 % of the sealant joint height based on the expected temperature range in Gaithersburg, MD. There are two versions of this appa­ratus, one that imposes a compression strain on the samples with increasing temperature and one that imposes a tensile strain on the samples with increas­ing temperature.