Elastomeric Adhesives in Wood Connections: Short-Term Behavior

Three hundred eighty-five joints made with elastomeric construction adhesive were tested in short-term loading in shear. The ultimate stress and slip were recorded for each specimen. The purpose of this study was to evaluate the two previously evaluated mechanical properties as a function of: chemical formulation of the adhesive (acrylic-, urethane-, and rubber-base); treatment with chromated-copper-arsenic preservative; and moisture condition at the time of joint fabrication and testing (fabricated tested = dry dry, wet/dry, and wet/wet). Application of the elastomeric construction adhesives was performed according to manufacturer's specifications. The mean and standard deviation were collected for all specimens ( 13) evaluated for each combination of the aforementioned variables. In addition, analysis of variance statistical procedures were used to determine if mean properties varied as a function of the experimental variables. It was found that the inherent variation between test specimens contributed substantially to the total variation of the joint mechanical behavior. In addition, joints that were dry at testing had superior properties to those that were wet. Rubber-based (styrene-butadiene rubber) adhesives generally demonstrated poorer mechanical behavior than those made from acrylic and urethane bases. The latter two had somewhat similar behaviors. The effect of chromated-copper-arsenic treatment was somewhat masked by the large variation in joint fabrication, although no definitive effect of this variable was apparent.