Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D173 – Standard Test Method Technical Guide
🧵 Materials and Manufacture Requirements
The ASTM D173/D173M standard specifically covers woven cotton fabrics that are saturated with either asphalt or coal-tar pitch. These fabrics are designed for use in built-up roofing and waterproofing systems, working in conjunction with specific bituminous plying cements or solvent-bearing compounds.
As outlined in the standard’s scope, asphalt-saturated cotton fabrics must be paired with asphalt-based plying cements conforming to ASTM D312/D312M or D449/D449M. Similarly, coal-tar-saturated fabrics require coal-tar-based plying cements conforming to ASTM D450/D450M.
| 🟦 Fabric Type | 🟫 Saturant | ⚙️ Compatible Plying Cement |
|---|---|---|
| Asphalt-Saturated Cotton | Asphalt | D312/D312M, D449/D449M, or solvent-bearing asphaltic compounds |
| Coal-Tar-Saturated Cotton | Coal-Tar Pitch | D450/D450M or solvent-bearing coal-tar compounds |
During manufacture, the dry cotton fabric must be thoroughly and uniformly saturated with bitumen via passing through or spraying with the saturant, followed by heat calendering and cooling before winding. The fabric must be woven entirely from cotton fibers, with customary sizing materials limited to a maximum of 8% by weight of the moisture-free cotton. If a selvage is employed, its width must not exceed 16 mm [5/8 in.].
📏 Key Dimensions and Performance Properties
To ensure reliability in the field, the standard imposes strict limits on the dimensions, material composition, and physical performance of the saturated fabric. The product must be capable of being unrolled without cracking, sticking, or tearing across a defined temperature range.
⚠️ Unit System Independency: The standard requires that SI and inch-pound units be treated separately. Combining values from the two systems may render the product non-conforming to the specification.
| 📐 Property | 📏 Requirement / Limit |
|---|---|
| Selvage Width | Not more than 16 mm [5⁄8 in.] |
| Customary Sizing Materials | Not exceeding 8% by weight of moisture-free cotton |
| Unrolling Temperature Range | No cracking, stickiness, or tearing between 10 and 60 °C [50 and 140 °F] |
| Mesh Condition after Saturation | Meshes must not be completely closed or sealed |
💡 Workmanship Note: The meshes of the fabric must remain partially open after the saturation process. This ensures adequate inter-ply adhesion and bitumen flow during application in the roofing or waterproofing assembly.
In addition to these specific requirements, the finished product must conform to the full physical requirements, dimensions, and masses outlined in Table 1 and Table 2 of the standard. Workmanship, finish, and appearance are also evaluated to ensure uniformity and quality.
📋 Referenced Standards for Testing and Compliance
This specification relies on several related ASTM standards for detailed testing procedures and material definitions. Sampling and testing of the saturated fabrics must be conducted in accordance with Test Methods D146/D146M. Key referenced standards include:
- D146/D146M: Test Methods for Sampling and Testing Bitumen-Saturated Felts and Woven Fabrics for Roofing and Waterproofing
- D312/D312M: Specification for Asphalt Used in Roofing
- D449/D449M: Specification for Asphalt Used in Dampproofing and Waterproofing
- D450/D450M: Specification for Coal-Tar Pitch Used in Roofing, Dampproofing, and Waterproofing
- D1079: Terminology Relating to Roofing and Waterproofing
- D3775: Test Method for End (Warp) and Pick (Filling) Count of Woven Fabrics
This standard was developed in accordance with internationally recognized principles on standardization and has been approved for use by agencies of the U.S. Department of Defense, replacing the former Federal Specification SS-C-450.
❓ Frequently Asked Questions
🔍 What types of bitumen are used to saturate the cotton fabric under D173/D173M?
The cotton fabric may be saturated with either asphalt or coal-tar pitch, depending on the intended application and compatibility with the associated plying cement.
💡 What is the maximum permissible width for the selvage on the fabric?
If a selvage is present, it must not exceed 16 mm, which is equivalent to 5/8 of an inch.
📌 At what temperature range must the finished product unroll without sticking or cracking?
The product must be capable of being unrolled without cracking, stickiness, or damage at temperatures between 10 and 60 °C (50 and 140 °F).
⚡ What are the limitations on sizing materials in the dry cotton fabric?
Customary sizing materials are permitted, but their weight must not exceed 8% of the weight of the moisture-free cotton fabric.