What are the standard grades of ARCC slabs as per IS 6073?

The code specifies two grades: Grade I (min. avg. compressive strength 3.0 N/mm²) and Grade II (min. avg. compressive strength 2.0 N/mm²) as per Table 1.

What is the minimum clear cover for reinforcement in these slabs?

For slabs up to 200 mm thick, the minimum clear cover is 15 mm. For slabs thicker than 200 mm, it is 20 mm (Table 3).

What is the maximum allowed deflection during a load test?

The maximum deflection under the specified test load should not exceed the span divided by 250 (Clause 8.3.1).

What is the standard width for these prefabricated slabs?

The standard width is 600 mm, with a permissible tolerance of ±3 mm (Clause 5.2 and Table 2).

IS 6073

: 2006

Autoclaved reinforced cellular concrete floor and roof slabs

CurrentSpecializedSpecificationBIMStructural Engineering · Planning, Housing and Pre-fabricated Construction

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This standard specifies the requirements for materials, dimensions, manufacture, physical properties, and testing of autoclaved reinforced cellular concrete (ARCC) slabs for floors and roofs. It covers two grades of slabs and outlines procedures for quality control, sampling, and acceptance, including the crucial transverse load test.

Autoclaved reinforced cellular concrete floor and roof slabs

Quick Reference Values

Minimum average compressive strength (Grade I)3.0 N/mm²

Minimum average compressive strength (Grade II)2.0 N/mm²

Maximum drying shrinkage0.08 percent

Standard width of slab600 mm

Minimum clear cover for reinforcement (slabs <= 200mm thick)15 mm

Maximum permissible deflection in load testSpan / 250

Maximum permissible crack width after load test0.2 mm

Key Formulas

Test Load W = 1.5 (DL + LL) or 2.0 DL, whichever is greater

Practical Notes

ARCC slabs are significantly lighter than traditional RCC, reducing dead load on the structure and foundation, but possess lower strength and require careful design integration.

Handling and erection require special attention to prevent chipping, cracking, or damage to these prefabricated units, which are more brittle than standard concrete.

The anti-corrosion coating on the reinforcement cage is critical for the long-term durability of the slab and must be verified as per Clause 4.5 before casting.