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IS 658:1982 is the Indian Standard (BIS) for magnesium oxychloride composition floors. This code covers the preparation, laying, finishing, and maintenance of magnesium oxychloride (magnesite) composition floors. It is used by engineers and contractors when installing heavy-duty, seamless, non-sparking indoor flooring in industrial or specialized commercial buildings.
Code of Practice for Magnesium Oxychloride Composition Floors
Overview
Status
Current
Usage level
Rare
Domain
Architectural — Flooring, Wall Finishing and Roofing
BS 776:1963British Standards Institution (BSI), UK
HighWithdrawn
Specification for materials for magnesium oxychloride (magnesite) flooring
Covers the material requirements for magnesite flooring, which are referenced by the IS code.
CP 204: Part 2: 1970British Standards Institution (BSI), UK
HighWithdrawn
Code of practice for in-situ floor finishes - Part 2: Metric units
A code of practice that included a detailed section on laying magnesite flooring.
DIN 272:1951Deutsches Institut für Normung (DIN), Germany
MediumWithdrawn
Magnesia binder for building purposes; Steinholz, composition flooring (Sorel cement)
Specified the binder ('Steinholz') used for magnesite flooring, analogous to the material specs in IS 658.
ASTM C275-61American Society for Testing and Materials (ASTM), USA
LowWithdrawn
Standard Specification for Oxychloride Magnesia Cement (for Exterior Use)
Covered oxychloride cement materials but was specifically for exterior use, unlike the interior focus of IS 658.
Key Differences
≠IS 658:1982 is technically still a 'Current' standard, whereas its direct international equivalents (BS 776, CP 204, DIN 272) were withdrawn decades ago, reflecting the decline in use of magnesite flooring.
≠IS 658 explicitly permits the use of 'asbestos fibre' as a filler material, a practice that is now banned in most countries and makes that part of the Indian standard obsolete by modern health and safety regulations.
≠The Indian standard is developed for tropical climates, with specific guidance on protecting the floor from direct sun and rain during curing, a consideration less emphasized in British or German standards for temperate climates.
≠IS 658 specifies compressive strength as a key performance metric for the wearing coat, whereas some material-focused counterparts like BS 776:1963 prioritized transverse (flexural) strength and did not specify compressive strength.
Key Similarities
≈All standards are based on the same fundamental binder chemistry: the reaction of calcined magnesite (MgO) with a magnesium chloride (MgCl₂) solution to form a hard, durable magnesium oxychloride cement matrix (Sorel cement).
≈The core constituent materials are consistent across all standards, comprising calcined magnesite, magnesium chloride, and a range of organic or inorganic fillers and pigments.
≈The methodology of a two-coat application (a resilient undercoat and a hard-wearing topcoat) is a common practice detailed in both IS 658 and historical codes like the British CP 204 for achieving a high-quality finish.
≈All related standards strongly emphasize the vulnerability of magnesite flooring to moisture, requiring a thoroughly dry sub-base and often recommending the use of a damp-proof membrane (DPM).
Parameter Comparison
Parameter
IS Value
International
Source
Transverse Strength (Modulus of Rupture) at 7 days
Minimum 3.0 N/mm²
Minimum 450 lbf/in² (~3.1 N/mm²)
BS 776:1963
Fineness of Calcined Magnesite
Minimum 90% passing 150-micron IS Sieve
Maximum 10% retained on a 152-micron (BS No. 100) sieve
BS 776:1963
Compressive Strength (Wearing Coat) at 28 days
Minimum 7.0 N/mm²
Not specified; focus was on transverse strength.
BS 776:1963
Minimum Wearing Coat Thickness (Two-Coat System)
10 mm
8 mm
CP 204: Part 2: 1970
Minimum Undercoat Thickness
10 mm
Not distinctly specified; part of a recommended total thickness of 12 mm to 25 mm.
CP 204: Part 2: 1970
Density of MgCl₂ Solution for Mixing
Typically 1.18 to 1.20 sp. gr. (22° to 24° Baumé)
Typically specified in a similar range of 20° to 26° Baumé.
CP 204: Part 2: 1970
⚠ Verify details from original standards before use
Can magnesium oxychloride floors be used in wet areas like bathrooms?+
No, they deteriorate rapidly under continuous dampness and are restricted to dry, indoor areas.
What materials make up the binder?+
The binder is formed by the exothermic reaction of calcined magnesite (magnesium oxide) and a gauging solution of magnesium chloride.
Is there a corrosion risk to embedded steel?+
Yes, due to the high chloride content, direct contact with structural steel or embedded conduits must be avoided or properly insulated to prevent corrosion.