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IS 12654:1989 is the Indian Standard (BIS) for low-grade gypsum use in the building industry-code of practice. This standard outlines the code of practice for utilizing low-grade gypsum in the building industry. It specifies the requirements, testing, and application methods for gypsum plaster, partition blocks, and other building components derived from gypsum with a purity of 70% or more.
Low-grade gypsum use in the building industry-code of practice
Overview
Status
Current
Usage level
Specialized
Domain
Materials Science — Building Limes and Gypsum Products
Specifies requirements for raw gypsum, including a minimum purity (≥70%) that aligns with the IS code's 'low-grade' definition.
EN 13279-1:2008CEN (European Committee for Standardization), Europe
MediumCurrent
Gypsum binders and gypsum plasters - Part 1: Definitions and requirements
Defines requirements for finished gypsum plasters, a key application for the low-grade gypsum discussed in the IS code.
ASTM C842 - 19ASTM International, USA
MediumCurrent
Standard Specification for Application of Interior Gypsum Plaster
Provides a code of practice for applying gypsum plaster, overlapping with the application guidance in IS 12654.
EN 12859:2011CEN (European Committee for Standardization), Europe
HighCurrent
Gypsum blocks - Definitions, requirements and test methods
Specifies requirements for gypsum blocks, a primary product application detailed in the IS code of practice.
Key Differences
≠IS 12654 uniquely focuses on promoting the use of 'low-grade' gypsum (70-80% purity) and by-product phosphogypsum, whereas international standards typically set minimum quality thresholds for general use rather than creating a specific code for lower quality material.
≠The Indian standard has a very broad scope, combining raw material guidance, calcination process, and manufacturing/application for multiple products (plaster, blocks) into one document. International practice segregates these into separate standards (e.g., one for raw gypsum, one for plaster, one for application).
≠IS 12654 is more prescriptive in its guidance, suggesting specific calcination temperatures (140-160°C) and mix proportions. Modern European standards like EN 13279-1 are more performance-based, focusing on the final properties (strength, setting time) of the product.
Key Similarities
≈Both the IS code and its international counterparts recognize the same primary end-use applications for calcined gypsum, including interior plastering and the manufacture of masonry blocks and panels.
≈All standards are based on the same fundamental chemical process: the calcination of gypsum (dihydrate) to form plaster of Paris (hemihydrate) and its subsequent rehydration and setting.
≈Key quality control parameters for the finished products, such as setting time, compressive strength, and fineness, are specified in both the IS code and relevant international standards to ensure performance and usability.
≈The principles behind the standard test methods for properties like setting time (Vicat apparatus) and compressive strength (testing of standardized specimens) are fundamentally similar across Indian and international standards.
Parameter Comparison
Parameter
IS Value
International
Source
Raw Gypsum Purity (CaSO₄·2H₂O)
70% to 80% (recommended for low-grade)
Minimum 70.0%
ASTM C22 / C22M - 21
Plaster Compressive Strength (28-day)
Minimum 6.0 N/mm²
Minimum 2.0 N/mm² (for standard building plaster, Class B1)
EN 13279-1:2008
Plaster Initial Setting Time
Minimum 20 minutes
Minimum 20 minutes (for building plasters)
EN 13279-1:2008
Fineness of Plaster (Residue on 150 µm sieve)
Maximum 5%
Maximum 2% (for gypsum neat plaster passing No. 100 sieve)