Updated Guidance on Dealing with Redundant Cast-in Channels in Close Proximity

Here, masonry support specialist, Leviat, provides details of how redundant cast-in channels should be treated when located in close proximity to post-fixed anchors.

This guidance is based on using Ancon 30/20 or 38/17 cast-in channels where a post-fixed anchor is to sit within 100mm of the redundant channel. Anchors that are greater than 100mm away from redundant cast-in channels can be designed in the normal way, treating the cast-in channels as the concrete edge.

Case 1

For applications where the redundant channel is at least 50mm above the new post-fixed anchor.

In such applications, the filling of cast-in channel locally is not required. A bolt with a 20mm greater embedment depth should be used.

Case 2

For applications where the redundant channel is less than 50mm above the new post-fixed anchor.

Where post-fixed anchors are to be used in close proximity to cast-in channels, it is essential that the channel is filled locally (see below for recommended infills) in order to maintain the compressive resistance of the structure around the anchor. This infill should be at least 100mm wide (centred on the bolt).

The post-fixed anchor must be installed with 20mm greater embedment.

Case 3

For applications where the redundant channel is a minimum of 50mm below the new post-fixed anchor.

In such applications, it is again essential that the channel is filled locally (see below for recommended infills). This infill width should be at least twice that of the dimension away from the channel (centred on the bolt). Therefore:

• Installing the anchor 50mm below the channel would require an infill of at least 100mm wide
• Installing the anchor 75mm below the channel would require an infill of at least 150mm wide

The post-fixed anchor must be installed with 20mm greater embedment.

Case 4

It is not recommended to install a new post-fixed anchor in applications where the redundant channel is to be less than 50mm below the new post-fixed anchor.

Suitable Filling Materials

Where infilling of the channel is required, Leviat recommends the use of the following.

• Max Power Multiuse Epoxy Putty
• Sylmasta AB Original Epoxy Putty
• Fosroc Conbextra GP

For more information on their preparation and use for this application, please contact our masonry support specialists on 0114 238 1222 or tech.ancon.uk@leviat.com.