A Panel Discussion: ASTM Introduces C1736 Standard Practice for Non-Destructive Evaluation of Adhesion of Installed Weatherproofing Sealant Joints Using a Rolling Device

ABSTRACT: The panel discussion was originally conceived as a discussion on sealant warranty issues, but became a spirited conversation regarding the impact of the newly developed ASTM C1736 Standard Practice with partici­pation by the panelists, ASTM C24 members, as well as presenters and guests of the international symposium. The panel consisted of three mem­bers of ASTM C24 committee, who had direct involvement with the creation, oversight, and/or passage of C1736, plus one panelist representing a sealant applicator. In order to provide context to the discussion, the editor has pro­vided a short introduction to the topic.

Introduction

Considerable work has focused in the past on the deterioration of building joint sealants (see, for instance, information provided in the RILEM State-of-the-Art Report [1]), while less emphasis has been placed on understanding the conse­quences of seal failure, particularly in respect to water-tightness. Deficiencies in the water-tightness of weather seals in building envelopes may indeed be induced by the effect of weathering on sealants, as the climatic factors may cause the sealant to deteriorate by hardening, softening (reversion), cracking, or losing adhesion to the substrate. However, deficiencies that affect the water­tightness of weather seals may also come about from design faults or improper installation. Water penetrating into the joint and into the building envelope via these deficiencies may lead to deterioration of the building fabric or premature failure of the joint sealant or of other envelope components.

By the early 2000s, a practical means of assessing adequate sealant per­formance in the field in terms of the quality of the sealant-to-substrate bonding following initial installation as well as during inspections carried out over the life of the sealed joint had become of considerable interest in the construction community. Since 2003, ASTM has sponsored this “Durability of Building and Construction Sealants and Adhesives (DBCSA)" Symposium Series. The need

Copyright © 2012 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

Copyright by ASTM Int’l (all rights reserved); Tue May 6 12:07:08 EDT 2014

Downloaded/printed by xxxi

Rochester Institute Of Technology pursuant to License Agreement. No further reproductions authorized.

for a field practice to facilitate the inspection of sealed joints such that the conti­nuity of the seals can readily be determined was highlighted by various presen­tations during this symposium series. Work presented by Lacasse, Miyauchi, and Hiemstra at the 2008 symposium demonstrated that substantial amounts of water, i. e., up to several liters per minute, can be penetrate through very small interfacial “cracks" along the bond line of the sealed joint with the crack lengths ranging between 2 mm and 16 mm [2]. Not surprisingly, water readily enters open cracks along the sealant-to-substrate interface when the joint is extended; however, the study also demonstrated that water from wind-driven rain may penetrate through cracks of non-extended (apparently “closed") joints. Loss of sealant adhesion in non-extended joints (and, even more so, in com­pressed joints) may not be detectable by simple visual inspection.

The most commonly used industry protocol to check joint sealant adhesion has been the destructive “pull test" procedure as described in ASTM Standard Practice C1521-09e1 for Evaluating Adhesion of Installed Weatherproofing Seal­ant Joints [3]. This method allows checking the adhesion of the sealant at dis­crete locations along the joints; however, it is not suited for the evaluation of the continuity of the seal.

In the 2003 Symposium of the DBCSA series, a method of in-field testing of sealed joints using a rolling device was presented [4]. Every symposium in the se­ries thereafter has had one or more presentations on the topic of continuity of joint seals in terms of suitable inspection methods as well as consequences of fail­ure. Putting words to action, in 2001, ASTM C24 Committee on Building Seals and Sealants began to look seriously at the rolling device methodology for consid­eration as a standard practice. Starting in 2008, work item WK21464 “Standard Practice for Non-Destructive Evaluation of Adhesion of Installed Weatherproofing Sealant Joints Using a Rolling Device" came under development by ASTM C24.30. By the time the 4th DBCSA Symposium began on June 16th, 2011, the committee had granted final approval for WK21464 just the day before, on June 15th, and subsequently gave it the designation ASTM C1736. ASTM C1736-11 Standard Practice for Non-Destructive Evaluation of Adhesion of Installed Weatherproofing Sealant Joints Using a Rolling Device has recently been published [5].

The ASTM C1736 Standard Practice describes a non-destructive evaluation procedure which induces a depression in the joint seal via a rolling device. Sub­jecting the sealant bead to a strain by moving the rolling device continuously over the sealed joint causes a stress on the bonding at the sealant-to-substrate interface that moves along the bond line. Controlling the amount of stress induced along the bond line allows an assessment of the quality of the adhesive bond of a joint seal in a particular installation. This practice, therefore, can be used to verify the continuity of building seals and its primary purpose is to reveal sealant adhesion anomalies that may affect air or water infiltration resistance or both of the sealed joint. It is expected that this practice will be used for quality control, forensic investigations, and repair programs. Users may include sealant manufacturers, consulting engineers and architects, test agencies, and construction contractors.

This paper is a summary of a panel discussion, originally conceived as a dis­cussion on sealant warranty issues, but which evolved into a spirited conversa­tion regarding the passage of C1736. The thematic thread that developed during

Copyright by ASTM Int’l (all rights reserved); Tue May 6 12:07:08 EDT 2014

Downloaded/printed by

Rochester Institute Of Technology pursuant to License Agreement. No further reproductions authorized.

the discussion was what impact will this standard have on the industry, in the context of historical and current industry standard practice?

The following is a summary of that discussion, with C24 members, guests, and audience participation represented generically. The panel consisted of three members of ASTM C24 committee, who had direct involvement with the crea­tion, oversight, and/or passage of C1736, plus one panelist representing a seal­ant applicator. One audience member represented a Consultant in the content and total amount of comment that was offered. For clarity, additional contribu­tory comments and questions from audience members have been woven into the responses made by the panelists. Note that names, personal comments and issues, and all otherwise off subject material have been removed.