bitumen felts for waterproofing and damp-proofing
1993 Edition

IS 1322 defines two main base fabric categories for bitumen felts: Type 1 felts use fibre or hessian fabrics that are saturated with bitumen after moisture removal, primarily for underlay purposes. Type 2 felts also utilize fibre or hessian bases but are finished with a bituminous coating that may include mineral fillers, serving waterproofing applications. Moisture content is minimized before saturation to ensure proper impregnation, using bitumen conforming to IS 702 and IS 73, and mineral fillers meeting specific sieve requirements as per IS 460.

Per IS 1322 Clause 7.2 and Table 1, minimum bitumen content in kilograms per 10 square meters is specified as follows: Type 1 underlay felts require at least 3.6 kg; Type 2 self-finished felts need 12.0 kg; Type 3 self-finished hessian felts have minimums of 12.1 kg for Grade 1 and 20.2 kg for Grade 2. These measurements comply with IS 13826 (Part 7), with total finished weights including mica dusting powders except for Type 1. The bituminous coatants for Types 2 and 3 must adhere to IS 702:1988 standards and contain no more than 42% mineral filler by weight.

IS 1322 mandates several tests to confirm bitumen felt compliance: Breaking strength (warp and weft directions) and pliability tests apply to Types 1 and 3 as per IS 13826 Parts 1 and 2. For Type 3 felts, additional tests include storage sticking (Part 3), pressure head (Part 4), heat resistance (Part 5), and water absorption (Part 6). Total bitumen content is also assessed following Part 7. Tests ensure felts do not crack upon unrolling, resist surface rupture beyond 5 mm, show no bitumen leakage or melting, and meet absorption limits, thereby guaranteeing quality and performance.

Sampling under IS 1322 involves randomly selecting rolls that have passed dimensional inspections, from which 5-meter-long, full-width samples are cut, avoiding damaged sections. Test specimens are prepared according to Figure 1’s layout and subjected to tests such as breaking strength, pliability, storage sticking, heat resistance, pressure head, and water absorption. Conformity is confirmed if no cracks appear on unrolling, ruptures do not exceed 5 mm, no bitumen leakage or melting occurs, and water absorption remains within prescribed limits. Testing is performed not earlier than two days post-manufacture to ensure accuracy.

IS 1322 Clause 10.2 requires that each bitumen felt roll or package be distinctly and permanently marked with the manufacturer’s name or origin, type and grade of the felt, roll dimensions including length, width, and weight, as well as batch identification codes and manufacturing date. While detailed packing methods are not explicitly described, felts are generally wrapped in moisture-resistant materials to protect against damage during transit and storage, ensuring product integrity and traceability throughout distribution.