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D2828-96 – Standard Test Method Technical Guide
ASTM D2828-96 specifies the requirements for nonbituminous, sawable inserts used to create contraction joints in portland cement concrete airfield pavements. These inserts are placed while the concrete is unhardened and are partially or totally removed after hardening to form a space for sealant.
🧱 Material Composition and Manufacturing
According to ASTM D2828-96, the product must consist of precut strips formed from bonded natural or man-made fibers or granules. A critical manufacturing requirement is the complete absence of bitumen in the composition. The strips must be robust enough to withstand handling and placement in concrete without deforming or breaking; any damaged pieces are subject to immediate rejection.
⚙️ Physical Properties and Performance Requirements
The specification sets strict physical property limits to ensure the insert performs effectively. These properties are verified through standardized tests, as summarized below.
| 🟦 Property | 📐 Test Condition & Specimen | 🎯 Specified Limit |
|---|---|---|
| Water Absorption | 4 x 4 in. specimen, submerged horizontally under 1 in. of water, 24 hours | ≤ 45.0 mg/cm² through six faces |
| Expansion | 4 x 4 in. specimen, submerged horizontally for 24 hours | Final thickness between 100% and 110% of initial thickness |
| Stiffness (Modulus of Elasticity) | Specimen cross-section 3 in. x t in., tested on a 24-t span | E ≥ 80,000 psi (552 MPa) in bending |
| Bending Strength (Modulus of Rupture) | Specimen with long dimension same as used in the insert | ≥ 600 psi (4.14 MPa) |
💡 Sawability Requirement: The material must readily cut and disintegrate under a power-driven diamond-tipped or silicon carbide water-cooled blade at a peripheral speed of 11,000 ± 1,000 ft/min (3,350 ± 305 m/min). This ensures a clean, sealable groove.
📏 Dimensional Tolerances and Sampling Protocol
The preformed strips must match the groove dimensions specified on the project plan. Strips failing to conform within the following permissible variations must be rejected. A standardized sampling plan ensures quality control.
| 📏 Dimension | ⚡ Permissible Variation (in.) | ⚡ Permissible Variation (mm) |
|---|---|---|
| Length | ± ¼ | ± 6.3 |
| Depth | ± ⅛ | ± 3.2 |
| Thickness | ± 1/16 | ± 1.6 |
Sampling Requirements: One representative sample must be taken from each shipment of 1,000 ft² (100 m²) or fraction thereof, for each thickness ordered. Each sample must yield at least five test specimens measuring 4.5 by 15 in. (120 by 380 mm). Samples must be packed to prevent deformation or breakage during transportation.
⚠️ Historical Status: The responsible ASTM committee voted to withdraw this standard. Users should verify its current approval status before application in new projects.
❓ Frequently Asked Questions
🔍 What is the primary composition of a nonbituminous insert?
The insert must be formed from bonded natural or man-made fibers or granules. The addition of bitumen is strictly prohibited.
💡 What blade speed is required for the sawability qualification test?
The sawability test specifies a water-cooled diamond-tipped or silicon carbide blade operating at a peripheral speed of 11,000 ± 1