What is the maximum permissible tolerance in the length of an 8-meter long slab?

±8 mm, as L/1000 (8000/1000 = 8 mm) is less than the absolute limit of 15 mm (Table 1).

Does this standard cover structural design?

No, it is a product specification for manufacturing and quality. Structural design must comply with IS 456 and IS 1343.

What is the minimum cover to reinforcement specified in this code?

Minimum cover should be 20 mm, but also must satisfy the durability requirements of IS 456 or IS 1343, whichever is greater (Clause 7.1).

IS 15478

: 2004

Precast Concrete Hollow Core Slabs - Specification

CurrentSpecializedSpecificationBIMStructural Engineering · Precast and Prefabricated Concrete

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This standard specifies the requirements for materials, manufacturing, dimensions, tolerances, and quality control for precast concrete hollow core slabs. It covers both reinforced and prestressed types of slabs used in floor and roof construction.

Specifies requirements for precast concrete hollow core slabs, including materials, manufacture, dimensions, tolerances, and testing.

Quick Reference Values

Minimum grade for pre-tensioned slabsM35

Minimum grade for reinforced slabsM25

Maximum water-cement ratio0.45

Minimum cement content340 kg/m³

Permissible length tolerance±15 mm or ± L/1000, whichever is less

Permissible width tolerance±5 mm

Permissible depth tolerance±5 mm

Minimum clear cover to reinforcement20 mm (or as per IS 456/IS 1343 for durability, whichever is more)

Practical Notes

Dimensional tolerances (Table 1) are critical. Non-compliance can lead to major issues during installation, affecting floor levelness and connection details.

Verify the supplier's documentation, which should include design criteria, concrete grade, strand details, and handling instructions as per Clause 10.

The code focuses on the product specification. The overall structural design of the floor/roof system using these slabs must be carried out as per IS 456 and IS 1343.