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D2628-91 – Standard Test Method Technical Guide
📜 Scope and Material Composition
ASTM D2628-91 (Reapproved 2016) establishes the material requirements for preformed polychloroprene elastomeric joint seals intended for concrete pavement applications. These seals feature a multiple web cross-section and are designed to function purely through compression between the joint faces, with the top folding inward to facilitate this compression. Per Section 3.1, the material must be a vulcanized elastomeric compound using polychloroprene as the exclusive base polymer. This specification is strictly a manufacturing and purchasing standard and does not cover installation or size selection.
🔧 Physical Properties and Dimensional Tolerances
The seal material must conform to the physical properties outlined in Table 1 of the standard. All deflections during testing must be based on the nominal width of the seal as specified in Section 4.2. Dimensional tolerances for the cross-section are not rigidly defined in the standard; instead, they are agreed upon by the purchaser and the producer to accommodate specific joint designs. Seals must also be free of defects that could impair serviceability.
| 🔍 Property | 📐 Requirement | 📏 Test Method |
|---|---|---|
| Durometer Hardness (Type A) | 55 ± 5 | D2240 |
| Tensile Strength, min | 12.4 MPa (1800 psi) | D412 |
| Elongation at Break, min | 300% | D412 |
| Compression Set (22 h @ 100°C), max | 35% | D395 Method B |
| Ozone Resistance (100 pphm, 20% strain) | No Cracking | D1149 |
| Oil Swell (No. 3 Oil, 70 h @ 100°C), max | 20% | D471 |
| Heat Aging Change (70 h @ 100°C) | Hardness Δ: +10 max Tensile Δ: -15% max Elong. Δ: -40% max |