Code of practice for laying bitumen mastic flooring
1978 Edition

Per IS 1196 (Clause 4.2 and Table 2), for heavy-duty industrial applications such as engineering workshops and loading areas, the recommended bitumen mastic thickness ranges from 25 mm to 30 mm or more. The thickness selection depends on traffic intensity and impact load, with floors installed in one or two layers based on thickness requirements. A robust base is essential to support both the mastic and imposed loads, and special mastic grades should be chosen when chemical or temperature exposure is anticipated to ensure longevity.

IS 1196, particularly Clause 4.1.2 and Table 1, outlines the chemical resistance profile of bitumen mastic floors. Standard grades are susceptible to attack by acids, alcoholic substances, and alkalis at elevated temperatures and concentrations. Special grades are necessary for dilute acids, breweries, distilleries, radioactive environments, and oily conditions. The standard also recommends metal armouring in dairy applications to prevent fat accumulation and suggests high-temperature grades for frequent hot water exposure. These specifications help tailor the material selection to resist chemical deterioration effectively.

IS 1196 advises a sturdy and sound base capable of supporting expected loads, with specific treatment based on the substrate. Metal bases require cleaning and priming with bitumen paint, while concrete surfaces should be free from contaminants. An isolating membrane (Type 1 as per IS 1322-1970) is recommended for bitumen mastic thicknesses up to 20 mm, laid loosely to act as a thermal and moisture barrier. Glass fibre felt (IS 7193-1974) may be used when the base is in direct contact with the ground. Membranes are essential over timber, porous or cracked bases, chemically contaminated surfaces, and thermal insulation layers to prevent defects and premature cooling.

The repair process per IS 1196 involves cautiously softening the damaged area using hot bitumen mastic to avoid further harm. Once softened, the defective section is carefully removed without hammer or blow lamp damage. The area must be cleaned thoroughly to eliminate dirt, oils, and grease. Fresh bitumen mastic is then placed, spread to the appropriate thickness based on traffic conditions, and leveled using hand tools and floats to achieve a smooth, even finish. This method ensures the repair maintains the floor’s durability and performance.

Immediately following installation, the surface must be protected until the mastic cools to ambient temperature to prevent damage. This includes restricting exposure to construction traffic, spills, and avoiding the mixing of concrete or mortar on the floor. Use of an isolating membrane beneath mastic layers up to 20 mm thick is recommended for certain base types to prevent rapid cooling and surface defects. Priming on metal bases should be fully dried before laying mastic. Controlling moisture and temperature conditions during curing minimizes issues such as 'blowing,' ensuring a durable and properly cured flooring system.