Honeycombs are hollow spaces and cavities left in concrete mass on the surface or inside the mass where concrete could not reach. These look like honey bees nest. Improper vibration and workability of concrete are main causes of honeycombs in concrete.
Causes of honeycomb and voids include the following reasons
Stiff or unworkable concrete.
Over vibrating the poker the concrete.
Improper vibration during concrete.
Addition of more water.
Improper placing practices such as pouring or releasing the concrete from a height.
The normal water cement ratio that should there is within the range of 0.4 to 0.6, but if more water is been added the workability of the concrete mixture increases. This will cause problems when the vibrator is been inserted.
The grout will start to leak through the small voids and from the bottom voids of the formwork.
It will also cause the plywood to swell and will also change the dimensions and the cross- section area of the structural elements.
