ADHESIVENESS OF Z-S TREATED STEEL AND DOU GLAS-FIR (PSEUDOTSUGA-MENZIESII) AND A CONVENIENT JOINT METHOD AT A BUILDING SITE

Z-S treatment is a mechanical plating process to improve adhesiveness. Minute steel balls, which have a diameter of 0.5 mu m, and are covere d with zinc films, are projected onto the basic material. Then a zinc- iron alloy is laid on the surface of the basic material, and a special chemical treatment is applied. Z-S treated steel and Douglas-fir (Pse udotsuga menziesii France) glued with API (aqueous vinyl polymer solut ion-isocyanate) resin showed exellent results in block shearing tests and in cold water soak delamination tests of Japanese Agricutural Stan dards (JAS). However some improvement was necessary in some aging test s, such as the vaccume-pressure delamination test of the Standard meth od for manufacturing structural glued laminated timber with large dime nsions, and resistances of adhesives to cyclic laboratory aging condit ions for exterior, and marine purposes which are similar to ASTM D1183 . On the other hand, zinc plated steel and non-treated steel showed po orer results, especially in the tests for exterior, and marine uses. R F (resorcinol formaldehyde) resin was not suitable for Z-S treated ste el. Before adhesion, all of the steel was washed slightly with a deter gent for home use. The joint method, which can be done at a building s ite using Z-S treated steel, was investigated, and shear-tests by tens ion loading were made. The methods of manufacturing specimens and test results were as follows: Two Douglas-fir laminae were adhered on both faces of Z-S treated steel using API resin. The laminae and steel had bolt holes, and pressure was applied by tightening the bolts. After c uring, all bolts were removed, and a long brass pin whose diameter was less than that of the bolt hole was inserted instead of a bolt. Speci mens made by this method had average shear strengths up to 26 percent of that of bonded specimens without pins, and average displacements at the ultimate strength increased to 60 percent. After breaking at the glue line, adhered specimens with pins showed similar load-displacemen t curves as those of specimens jointed with only pins.