Honeycomb repair is an art of work that has to be done with much care and with technical assistance.
Lack of compaction, leakage of grout, reinforcement congestion, etc. causes the honeycombs in concrete. Most of the honeycombs are discoverable as they occur close to the surface. However, in large structures, there are changes having created cavities that do not fill with concrete.
Honeycomb is a rough and stony concrete appearance with air spaces between aggregates
Depending on the size of the honeycomb, they can be categorized as minor and major honeycombs.
Minor honeycomb can be rectified with much difficulty by approved construction grouts.
Construction ground could be mixed as directed by the manufacturer adequately and it could be applied in the area after applying the bonding agent and anticorrosive as per the approved method statement.
When the honeycomb is very small, the application of anticorrosive may not be required.
All types of honeycomb repair shall be rectified by using nonshrink construction grout and which has very very low volume reduction.
When the size of the honeycomb becomes larger, special attention shall be made during the rectification. The following steps could be followed in the rectification process.
Concrete Honeycomb Repair Method
- Loads on the structural elements. If it is a column and if several floors have been constructed, depending on the size/depth of the honeycomb, vertical supports could be provided if necessary or make necessary arrangements as advised by the structural engineer.
- Initially, the loosened material shall be removed and concrete shall be exposed. Extend of the cavities if any shall be observed and they shall be cleaned adequately by removing loosen material manually. All the rectification shall be done manually and the use of machinery could cause the development of cracks.
- Depending on the shape of the honeycomb formwork arrangement shall be finalized.
- Construction grout shall be used for the rectification and mix proportions shall be as per the manufacturer’s specification. In general, when the depth of the honeycomb is smaller, no aggregate will be added. However, if the dimension is around 100mm or more, an aggregate could be used. Metal chips could be used as mostly does as the aggregate and generally, the mix proposition will be 1:1. However, it shall be as per the manufactures specification.
- Anti-corrosive could be applied to the reinforcements before the rectification as an additional precaution.
- Approved bonding agent shall be applied on the concrete surface before adding the concrete and the time frame shall be as per product specification.
- Some times honeycomb repair is done in two-stage when depth is higher. There is a maximum thickness that could apply at once. If the construction ground supplier specifies two stages of rectification, shall be followed.
- Curing shall be done as recommended by the manufacturer.
As indicated in Figure 02, this honeycomb can be considered to be a one that required greater attention. Rectification shall be done by taking into account the points discussed above in addition to the following project specification.
Source: structuralguide
