Discussion

The test results given in Figs. 3 and 4 suggest that the maximum tensile stress and maximum shear stress of the ALC panel surface onto which sealant was applied and used in this study was approximately 0.7 N/mm2. In order to ensure the long-term durability of sealed joints, the sealant must be designed such that the maximum stress in either tension or shear does not exceed 0.7 N/mm2 over its designated service life. In addition, the movement capacity of the joint is an important factor when assessing sealed joint performance. Shear movement capacity is especially important for ALC panels. Figure 5 indicates the average amount of movement achieved at the maximum shear stress for two-sided and three-sided adhesion test specimens of the five different sealant products. The degree of permissible movement (deformation) of sealed joints of two-sided ad­hesion test specimens tends to be higher than that of three-sided adhesion test specimens. However, product specimens No. 3 through No. 5, each having a “higher" sealant modulus, showed extremely low values for movement accom­modation with the two-sided adhesion test specimen, and product specimen No. 5 had a degree of movement capability less than twice that of the value for the corresponding product specimen with three-side adhesion.