IRC 36:2010 is the Indian Standard (IRC) for recommended practice for the construction of earth embankments for road works. This IRC code outlines best practices for constructing stable and durable earth embankments, crucial for road infrastructure. It emphasizes material selection based on soil properties, particularly plasticity and shear strength, and details rigorous compaction requirements to achieve specified densities and prevent future settlement. The code also addresses construction techniques such as layer thickness, moisture content control, and placement methods, along with essential quality control measures like field density tests and moisture content checks. Adherence to these guidelines is vital for ensuring the long-term performance and safety of road networks.
This IRC code provides recommended practices for the construction of earth embankments for road works. It covers materials, compaction, construction methods, and quality control to ensure the stability and durability of embankments.
Key material properties, compaction standards, density requirements, and construction tolerances for building stable and durable road embankments.
| Reference | Value | Clause |
|---|---|---|
| Min Compaction (Subgrade)— For top 500 mm of embankment and earthen shoulders. | 97% of MDD | Cl. 7.3 |
| Min Compaction (Embankment)— For general earth fill. | 95% of MDD | Cl. 7.3 |
| Max Compacted Lift Thickness— For soil/granular material. | 250 mm | Cl. 7.2.2 |
| Compaction Moisture Content— For normal soils. Varies for expansive clays. | OMC ± 2% | Cl. 7.2.3 |
| Min Soaked CBR for Subgrade— For new National/State Highways. | 8% | Cl. 3.2.2.3 |
| Max Particle Size (Subgrade)— For top 500 mm of embankment. | 50 mm | Cl. 3.2.2.1 |
| Max Particle Size (Embankment)— For general embankment fill. | 75 mm | Cl. 3.2.2.1 |
| Unsuitable Soil: Max Liquid Limit— Soils with LL > 70 are generally considered unsuitable for fill. | 70 | Cl. 3.2.2.2 |
| Unsuitable Soil: Max Plasticity Index— Soils with PI > 45 are generally considered unsuitable for fill. | 45 | Cl. 3.2.2.2 |
| Max Organic Content— For embankment and subgrade fill material. | 2% | Cl. 3.2.2.2 |
| Max Soluble Sulphate Content | 0.5% | Cl. 3.2.2.2 |
| Min CBR for Top 500mm Fill— Material with CBR < 3 should not be placed in the subgrade portion. | 3% | Cl. 3.2.2.3 |
| Compaction for Expansive Clays— Compacted at moisture content of OMC to OMC+2%. | 90-95% of MDD | Cl. 7.3 |
| Max Lift Thickness (Rockfill)— May be increased with specific approval and vibratory rollers. | 500 mm | Cl. 8.3 |
| Surface Level Tolerance— Value from MoRTH Spec Table 900-1, referenced by this clause. | ± 20 mm | Cl. 9.3 |
| Formation Width Tolerance— Value from MoRTH Spec Table 900-1, referenced by this clause. | +50 mm / -25 mm | Cl. 9.3 |
| Crossfall Tolerance— Value from MoRTH Spec Table 900-1, referenced by this clause. | ± 0.5% | Cl. 9.3 |
| Field Density Test Frequency— Value from MoRTH Spec Table 900-2, referenced by this clause. | 1 test per 1000 m² | Cl. 9.2 |
| MDD/OMC Test Frequency— For each type of borrow material. Ref: MoRTH Table 900-2. | 1 test per 3000 m³ | Cl. 9.2 |
| Material Property Test Frequency— For borrow material (LL, PI, Gradation). Ref: MoRTH Table 900-2. | 1 test per 3000 m³ | Cl. 9.2 |
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Compaction Energy (kJ/m³) | |||
| Minimum Dry Density (% of MDD) | |||
| Maximum Plasticity Index (PI) | |||
| Optimum Moisture Content (OMC) Tolerance | |||
| Layer Thickness (Compacted, meters) |