What lightweight aggregates are typically used in this plaster?

Expanded perlite and exfoliated vermiculite are the most common lightweight aggregates used (Clause 4.1).

Is this plaster suitable for exterior walls?

No, gypsum-based plasters are generally intended for internal applications where they are protected from weather and continuous moisture.

Which code details the testing procedures for this material?

IS 2542 (Part 1) provides the detailed methods of test for gypsum building plaster.

IS 2547

: 2000

gypsum building plaster, Part 2: Premixed lightweight plaster

CurrentSpecializedSpecificationMaterials Science · Building Limes and Gypsum Products

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This standard covers the specification for premixed lightweight gypsum building plaster used for internal plastering. It incorporates lightweight aggregates like exfoliated vermiculite or expanded perlite to reduce dead weight and improve thermal insulation.

gypsum building plaster, Part 2: Premixed lightweight plaster

Quick Reference Values

minimum setting time60 minutes

maximum setting time180 minutes

maximum dry bulk densityUsually ranges up to 900 kg/m³ depending on coat type

minimum compressive strength1.2 to 3.0 N/mm² (varies by plaster type)

minimum transverse strength for finish coat1.0 N/mm²

Practical Notes

Lightweight gypsum plaster significantly reduces the dead load on building structures compared to conventional sand-cement plaster.

It provides better thermal insulation and enhanced fire resistance.

Ensure the application surface is adequately prepared, dry, and free of moisture ingress, as gypsum degrades rapidly under continuous dampness.