What is the minimum grade of concrete specified for these precast units?

M20 for reinforced concrete units and M35 for prestressed concrete units (Clause 4.1.1).

What is the minimum required bearing of the slab units on a support?

A minimum of 75 mm on masonry or concrete walls, and 40 mm on steel joists (Clause 5.10.1).

Is a structural concrete topping required?

Yes, an in-situ structural topping of at least 40 mm thickness is required to ensure monolithic action and distribute loads (Clause 8.4.1).

What are the dimensional tolerances for manufacturing these units?

Length: ±6 mm; Depth/Width: ±3 mm; Straightness: Deviation not to exceed 3 mm per 3m length (Clause 9.2).

IS 10297

: 1982

Code of practice for design and construction of floors and roofs using precast reinforced/prestressed concrete ribbed or cored slab unit

CurrentSpecializedCode of PracticeBIMStructural Engineering · Planning, Housing and Pre-fabricated Construction

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This code provides guidance on the design and construction of floors and roofs using precast reinforced or prestressed concrete ribbed or cored slab units. It covers materials, design criteria for bending and shear, manufacturing tolerances, handling, erection, and the placement of in-situ concrete toppings. This standard has been officially 'Withdrawn' by BIS, but its principles are still useful for the assessment of older structures.

Code of practice for design and construction of floors and roofs using precast reinforced/prestressed concrete ribbed or cored slab unit

Quick Reference Values

Minimum grade of concrete for precast RC unitsM20

Minimum grade of concrete for precast PSC unitsM35

Minimum thickness of in-situ structural topping40 mm

Minimum end bearing for units on masonry/concrete75 mm

Manufacturing tolerance in length of unit±6 mm

Manufacturing tolerance in depth/width of unit±3 mm

Minimum clear cover to reinforcement (factory conditions)15 mm

Practical Notes

This code is 'Withdrawn' by BIS. For current general precast practice, refer to IS 13990 and IS 16700, though this code's principles for ribbed/cored slabs remain informative.

Handling and erection stresses (Clause 8) are critical design considerations, as units are most vulnerable during construction before becoming part of the composite floor system.

Strict adherence to manufacturing and erection tolerances (Clause 9) is essential for achieving proper fit-up and the intended composite action with the structural topping.