Considerations for Prolonging the Working Life of Sealed Exterior Building Joints

摘要

The working life of a sealed joint depends on its inherent durability-determined by joint design, sealant selection, and installation-and on its regular maintenance. Considerable work in the past has focused on the durability of building joint sealants, while less emphasis has been placed on detecting seal failure, particularly in respect to water- and air-tightness, and on suitable preventive measures that allow prolonging the working life of sealed joints. Recent research suggests that wind-driven rain water readily enters cracks in both extended and non-extended joints. Loss of adhesion is the predominant failure mode observed with sealed joints in field studies. Simple visual inspection may not allow detection of this failure mode in non-extended joints and, even more so, in compressed joints. The most commonly used industry protocol to check joint sealant adhesion has been the destructive "pull test" procedure as described in ASTM C1521-13. The ASTM C1521 discontinuous method allows checking the adhesion of the sealant at discrete locations along the joints; however, this inspection procedure is not suited for the evaluation of the continuity of the seal. Recently, a method suitable for continuous inspection of sealed joints has been published: ASTM C1736-11. ASTM C1736 describes a non-destructive procedure that induces a depression in the joint seal via a rolling device. The force-controlled ASTM C1736 method allows an evaluation of the health of sealed exterior building joints as part of the regular preventive maintenance process and, consequentially, an identification of opportunities for minor repairs, which can have a remarkable effect on prolonging the working life of the sealed joint.