Rocking slab A rocking slab is a concrete slab that moves or rocks when weight is applied because it no longer has uniform support underneath. The movement indicates instability beneath the pavement.
Rocking slabs often develop when erosion, settlement, or voids form beneath the concrete, leaving portions of the slab unsupported. Repeated movement can worsen cracking and create unsafe walking conditions. Effective repairs generally involve restoring proper support before reinstalling or replacing the slab.
Frequently Asked Questions About Rocking slab
What is a rocking slab?
A concrete slab that moves or tilts when weight is applied because it has lost uniform support underneath.
Why does a slab start rocking?
Erosion, settlement or voids beneath the concrete leave part of the slab unsupported, so it pivots under load.
Is a rocking slab a violation?
Yes. An undermined or rocking flag is one of the substantial-defect categories DOT cites.
What is the correct repair?
Restoring proper support beneath the slab through base repair and compaction, then resetting or replacing the flag. Simply re-bedding the top will not last.