What are the strength grades specified in IS 12440?

Two grades are specified: Grade A with an average compressive strength of 5.0 N/mm² and Grade B with 3.5 N/mm² (Table 2).

What is the maximum permissible water absorption for these blocks?

The average water absorption for a sample of blocks shall not exceed 10 percent by mass (Table 2).

What are the standard dimensions for these blocks?

Standard lengths are 390, 290 or 190 mm; standard heights are 190 or 90 mm; and widths are as required (Table 1).

Has this standard been updated?

Yes, IS 12440:1988 has been superseded and its contents have been amalgamated into IS 2185 (Part 3):2008.

IS 12440

: 1988

precast concrete stone masonry blocks

CurrentSpecializedSpecificationBIMMaterials Science · Cement Matrix Products

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This standard specifies the requirements for materials, dimensions, manufacture, and physical properties like compressive strength and water absorption for precast concrete masonry blocks with a natural stone facing. It provides two grades of blocks based on strength and outlines the necessary testing procedures.

precast concrete stone masonry blocks

Quick Reference Values

Minimum average compressive strength (Grade A)5.0 N/mm²

Minimum average compressive strength (Grade B)3.5 N/mm²

Maximum average water absorption10 percent by mass

Maximum drying shrinkage0.06 percent

Minimum thickness of stone facing20 mm

Dimensional tolerance (length/width/height)±3 mm

Practical Notes

This standard is now superseded by IS 2185 (Part 3):2008, which covers precast concrete blocks, including those with stone facing. For new projects, IS 2185 should be referenced.

The bond between the concrete backing and the stone facing is a critical performance parameter; ensure proper manufacturing and handling to prevent delamination.

These blocks are intended to provide the aesthetic of stone masonry with the manufacturing efficiency and dimensional consistency of concrete blocks.