Test Specimen and Test Method
Test Specimens—In this study, the sealant product modulus was varied with the use of a two-component polyurethane sealant that hardened via the reaction between the base material and the curing agent. The formulation ratio of base materials to curing agent was adjusted in order to produce five types of sealant, given in Table 1, with each expected to yield a different modulus.
Figure 1 shows the configuration and relative sizes of the two types of test specimen: a two-sided adhesion joint and a three-sided adhesion joint. The ALC substrate had dimensions of 50 mm in width, 100 mm in length, and 37 mm in depth. The two-sided adhesion joint specimen had a 10 mm joint width and an 8 mm joint depth, whereas the three-sided adhesion specimen had a 7 mm joint width and a 7 mm joint depth; there was a 1 mm space at the base of the threesided joint. The method for producing the test specimens was as follows: After applying polyurethane resin primer on the surface of the ALC substrate forming the joint (as is typically done to ensure long-term adhesion), sealant was applied to the joint in order to reach the designated joint width and joint depth. In order to comply with JIS A 1439 , the specimens were cured in a thermostatic chamber at a temperature of 23°C for two weeks and then further cured in a thermostatic chamber at a temperature of 50°C for another two weeks.
Test Method—Two sets of static tests were conducted: (i) a tensile test to evaluate the degree of material expansion and contraction that can accommodate the expected panel dilation due to temperature changes, and (ii) a shear test to determine the degree to which sealant products can tolerate relative story-to-story displacement brought about by an earthquake event. Figure 2 shows the test setup and test jigs for the tensile and shear tests. Both tensile and shear tests were conducted at a deformation rate of 50 mm/min. The 50 % modulus, maximum stress, and elongation at maximum stress were measured, as well as the elongation at rupture; fracture modes were also examined. For both
TABLE 1—Sealants and respective formulation ratios.
Tensile test jig
FIG. 2—Static tests.
tensile and shear test sets, three test specimens were evaluated for each test condition.