IS 17571:2021 is the Indian Standard (BIS) for durability design and detailing of concrete structures. This code provides a comprehensive framework for durability-based design of concrete structures, introducing service life design principles and detailed environmental exposure classes. It moves beyond the prescriptive durability rules of IS 456 to a performance-based approach, aiming to ensure structures achieve their intended service life by considering long-term degradation models.
Provides guidance on designing and detailing concrete structures to ensure long-term durability and resistance to degradation.
Code of practice for durability design and detailing of concrete structures. Service life, exposure, cover.
| Reference | Value | Clause |
|---|---|---|
| Service life — ordinary buildings | 50 years | Cl. 4.1 (Table 1) |
| Service life — important buildings | 75 years | Cl. 4.1 (Table 1) |
| Service life — bridges, dams, marine | 100 years | Cl. 4.1 (Table 1) |
| Exposure class XC1 — dry / permanently wet | low corrosion risk | Cl. 5 (Table 2) |
| Exposure class XC2 — wet/rarely dry | carbonation moderate | Cl. 5 (Table 2) |
| Exposure class XC3 — moderate humidity | carbonation high | Cl. 5 (Table 2) |
| Exposure class XC4 — cyclic wet/dry | carbonation severe | Cl. 5 (Table 2) |
| Exposure class XS1 — airborne salt, no contact | moderate chloride | Cl. 5 (Table 3) |
| Exposure class XS2 — permanent submerged seawater | low oxygen, lower risk | Cl. 5 (Table 3) |
| Exposure class XS3 — tidal/splash | extreme chloride | Cl. 5 (Table 3) |
| Minimum cover — XC1 (50-year life) | 20 mm | Cl. 6.4 (Table 6) |
| Minimum cover — XC4 (100-year life) | 45 mm | Cl. 6.4 (Table 6) |
| Minimum cover — XS3 splash zone | 65 mm + corrosion-resistant rebar | Cl. 6.4 (Table 6) |
| Maximum w/c — XC4 | 0.45 | Cl. 6.5 (Table 7) |
| Maximum w/c — XS3 | 0.40 | Cl. 6.5 (Table 7) |
| Minimum cement — XS3 | 360 kg/m³ | Cl. 6.5 (Table 7) |
| Crack width limit — XS3 (RCC) | 0.15 mm | Cl. 7.2 (Table 8) |
| Crack width limit — XC1 (RCC) | 0.30 mm | Cl. 7.2 (Table 8) |
| Permeability test — RCPT charge limit (XS3) | ≤ 1000 Coulombs | Cl. 8.3 |
| Surface treatment — XS3 marine | silane / epoxy coating | Cl. 9.4 |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Standard Design Service Life | 50 years (Category S2 for Normal Structures) | 50 years (Indicative design working life, Category 4) | EN 1992-1-1 |
| Min. Cover for RC, Moderate Carbonation (XC3), 50-yr life | 25 mm (c_min) | 25 mm (c_min,dur for Structural Class S4) | EN 1992-1-1 |
| Max. Water/Binder Ratio, Marine Splash Zone (XCl3/XS3), 50-yr life | 0.40 | 0.40 | BS 8500-1 |
| Min. Cement Content, High Chemical Attack (XA3), 50-yr life | 360 kg/m³ | 360 kg/m³ (Recommended value) | EN 1992-1-1 |
| Max. Crack Width for RC in Corrosive Environment | 0.20 mm (for XCl2, XCl3) | 0.30 mm (for XD, XS exposure classes) | EN 1992-1-1 |
| Min. Concrete Strength, Very Severe Exposure (e.g., Freeze-Thaw) | M40 (for XF3) | C30/37 (Recommended for XF3) | EN 1992-1-1 |