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Honeycomb: Area containing primarily coarse aggregate olds: Areas containing no concrete
Causes
Honeycomb forms when mortar fails to fill voids between coarse-aggregate particles. The defect may be purely,cosmetic or, depending on the location and extent of honeycombing, may be structural and require repair. For instance, honeycombing behind posttensioning anchors may require repair so the posttensioning forces don't cause compressive failure of concrete in the bearing area.
Voids form when concrete fails to fill areas in a form, typically those under large blockouts, in very deep placements, or that are heavily reinforced. Voids are almost always structural defects requiring repair.
Causes of honeycomb and voids include stiff or unworkable concrete, segregation, congested rebar, insufficient consolidation, and improper placing practices.
Prevention
Preventing honeycomb and voids starts with attention to concrete mix proportions. Proper techniques for forming, rebar placement, and concrete placement also are important.
Concrete proportions:
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