STRUCTURAL ADHESIVE JOINTS FOR CIVIL ENGINEERING USE

Abstract

The paper reports on an experimental analysis focused on determining the mechanical characteristics of two types of acrylate adhesives applied in double lap connection loaded by shear. The study comprises two basic substrate materials often used in facades both for cladding and for substructure – aluminum and galvanized steel. Both materials are applied with a smooth and mechanically roughened surface to compare adhesion in relation to laboriousness of surface preparation. Except for blank aluminum, anodized aluminum was also used. Material and surface treatment has a great influence not only on adhesion and hence strength of the joint but also on failure mode, behavior and safety of a particular joint. Moreover, every necessary surface treatment creates higher labor intensity, higher time consumption and thus increased costs. Our results showed different behavior of both chosen acrylate adhesives in spite of their similar chemical base. The first acrylate, two-part structural methacrylate, showed shear strength from 12 to 17 MPa in dependence on substrate material with shear strain between 0.6 and 1.2. The best adhesion was observed at roughened galvanized steel substrates. The second acrylate adhesive, two-part structural adhesive based on acrylic double performance polymer technology (ADP), proved shear strength from 8 to 9 MPa for aluminum substrates and less than 6 MPa for galvanized steel substrates. ADP adhesive also showed higher shear strain values (approx. 2.8). The experimental study proved that a choice of the adhesive has a great influence on mechanical properties of adhesively bonded joint as well as on adhesion to a particular substrate even in the case of the similar chemical base of adhesives.