Canadian Broadcasting Corporation Building, <a href="//commons.wikimedia.org/wiki/Toronto" title="Toronto">Toronto</a>, <a href="//commons.wikimedia.org/wiki/Ontario" title="Ontario">Ontario</a>, <a href="//commons.wikimedia.org/wiki/Canada" title="Canada">Canada</a>: Shrinkage cracks in <b>AD Firebarrier Mortar</b> that was used to <a href="//commons.wikimedia.org/wiki/Firestop" title="Firestop">firestop</a> electrical through-penetrations (a <a href="//commons.wikimedia.org/wiki/Cable_tray" class="mw-redirect" title="Cable tray">cable tray</a> in this case) in electrical closets and service rooms in the broadcast centre. This mortar was applied too thinly in many locations, below the thickness required by the certification listing. Thinly applied mortars are more vulnerable to shrinkage. Applying the mortar too thinly can result in lower firestopping costs as well as code violations. Chemical shrinkage compensation mechanisms are not understood equally well by all makers of firestop mortars. Apart from that, installers need to be sure to apply the correct thickness and wet down dry concrete surfaces before applying mortars whose effectiveness is strongly affected by the bond between the mortar and the concrete. Avoiding dry, windy conditions across the curing surface also helps. The use of curing compounds as well as keeping a seal wet for a few days after placement are well proven compensatory measures to avoid dangerous seal shrinkage such as is shown in these two pictures.
<a href="//commons.wikimedia.org/wiki/User:Achim_Hering" title="User:Achim Hering">Achim Hering</a>
2007-09-10
<span class="int-own-work" lang="en">Own work</span>