Honeycombing

Summary

Honeycombing - is where coarse aggregate is exposed at the surface of a formed joint in a concrete element.

Technical Information

In a floor slab, honeycombing can lead to a significant decrease in the load transfer capacity of dowelled joint. It can decrease the effect cover to the dowel, potentially leading to the dowel bursting out of the slab.

It can be caused by:

Inadequate compaction.
Insufficient fines in the mix.
Paste and fines leaking out of the formwork.

Plate dowels increase the chance of honeycombing as they partially restrict the concrete’s access to the space beneath them. Therefore, when using plate dowels, it is important to take extra care to compact the concrete properly around the dowels and use a mix workable enough to easily flow beneath them.