Overlay is a concrete layer constructed on a hardened concrete base slab to provide a wearing surface. Floor slab overlay construction is commonly used to improve the surface quality of existing floor slabs. Overlays commonly take the form of bonded or unbonded construction.
- Bonded Overlay; for thickness ≤ 80mm (a bonding agent is used to bond the old and new concrete along with proper surface preparation) and
- Unbonded Overlay; for thickness ≥ 100mm (Double layer of slip membrane of the thickness of 200 to 300 μ along with proper surface preparation is used to un bond overlay with the base slab.
Making use of both deformed bars (Mesh, Say 6 mm in Φ @ 150 mm C/C spacing) or Steel Fibre reinforced concrete (SFRC) of dosage say between 12 to 18 Kg/m3 as per manufacturers recommendations.
Consideration of construction tolerances is needed to define finished floor levels as per FM/ DM areas meeting today’s surface regularity requirements for the movement of modern MHE.