Guidelines for Use of Geosynthetics in Road Pavements and Associated Works (First Revision)

IRC SP 59 - Introduction: Key Points & Specifications

• Scope: Covers geosynthetics in highway pavements for separation, filtration, reinforcement, drainage, moisture barrier, and erosion control.

• Performance:

  • Vertical strain at subgrade interface with geocells: 309.1 x 10⁻⁶ micro-strain (vs. 100.7 x 10⁻⁶ for conventional).
  • Design life: 115 msa (million standard axles) at 90% reliability as per IRC:37 rutting model.

• Reference Codes:

  • IRC:34, IRC:37, IRC:115 for pavement design and evaluation.
  • IS:13162 series for geotextile testing (tensile, puncture, UV resistance).
  • ASTM and ISO standards for geosynthetics testing (tensile strength, permeability, puncture resistance).

• Geocomposite Properties (Table 2.9):
  | Property | Standard | Unit |
  |---|---|---|
  | Pore Size (AOS) | EN ISO 12956 / ASTM D4751 / IS 14294 | mm |
  | Tensile Strength | EN ISO 10319 / ASTM D4595 | kN/m |
  | Thickness (2 kPa) | EN ISO 9863-1 | mm |
  | CBR Puncture Resistance | EN ISO 12236 | N |
  | Mass per Unit Area | EN ISO 9864 / ASTM D3776 | g/m² |
  | In-plane Flow Capacity | EN ISO 12958 | l/m·sec |

• Design Methodology: Follow IRC:37 for pavement layers; drainage per IRC:SP:42; geosynthetics enhance structural performance and durability.

flowchart LR
    A[Geosynthetics in Pavement] --> B[Separation]
    A --> C[Filtration]
    A --> D[Reinforcement]
    A --> E[Drainage]
    A --> F[Moisture Barrier]
    A --> G[Erosion Control]
    D --> H[Improved Load Distribution]
    E --> I[Water Flow Management]

Summary: IRC SP 59 integrates geosynthetics with established pavement design codes, ensuring improved strength, durability, and drainage using

Key Formulas, Tables & Specifications for Physical & Mechanical Properties of Geosynthetics (IRC SP 59)

1. Geocell Properties (Clause 2.6, Table 2.6)

2. Geomembrane Properties (Clause 2.4, Table 2.4)

3. **Geotextile Properties (Clause 2.

IRC SP 59: Design Considerations & Applications for Drainage (Clause 3.4 & Table 2.9)

Key Design Points for Drainage Applications:

• Design depends on traffic loads, material properties, and pavement structure.
• Surface and subsurface drainage must comply with IRC:SP:42.
• Pavement layer thickness and materials follow IRC:37 and related codes.
• Geocomposites are used for efficient drainage and filtration.

Important Properties & Test Methods for Geocomposites (Table 2.9):

Design Formula Highlights:

• Vertical Strain at Subgrade Interface:
  [ \varepsilon_v = 309.1 \times 10^{-6} \text{ (with geocell)} \quad vs. \quad 100.7 \times 10^{-6} \text{ (conventional)} ]
• Standard Axle Load Capacity (with geocell):
  [ N = 115 \text{ msa at 90% reliability (per IRC:37)} ]

Summary:

• Use geocomposites with verified tensile strength, permeability, and puncture resistance.
• Design must ensure adequate drainage capacity under expected load pressures.
• Follow referenced IRC and IS standards for material testing and performance evaluation.

flowchart LR
    A[Traffic Loads & Pavement Conditions] --> B[Material Properties]
    B --> C[Geocomposite Selection]
    C --> D[Design

IRC SP 59: Performance Requirements & Specifications Summary

1. Asphalt Reinforcement (Clause 4.13, Table 4.13)

2. Geocomposite Properties (Clause 2.9, Table 2.9)

3. Design Methodology Highlights (Chapter 3)

• Design depends on traffic loads and material conditions.
• Follow IRC:37 for pavement layer thickness and material specs.
• Ensure surface and subsurface drainage per IRC:SP:42.
• Reinforcement design includes separation, filtration, drainage

IRC SP 59: Construction and Installation Guidelines - Key Points

1. General Guidelines (Clause 5.1)

• Follow manufacturer-specific installation and quality control guidelines.
• Engineer-in-charge approval is mandatory.
• Adapt to project-specific requirements.

2. Subsurface Drainage (Clause 5.2)

• Use geocomposites as per Table 2.9 for drainage properties.
• Key geocomposite properties include:
  • Pore Size (AOS): EN ISO 12956 / ASTM D4751 / IS 14294 (mm)
  • Tensile Strength: EN ISO 10319 / ASTM D4595 (kN/m)
  • Thickness at 2 kPa: EN ISO 9863-1 (mm)
  • CBR Puncture Resistance: EN ISO 12236 (N)
  • In-plane Flow Capacity: EN ISO 12958 (l/m/s) at various pressures (20-400 kPa)

3. Design Methodology (Chapter 3)

• Pavement layers follow IRC:37 and related codes.
• Surface & subsurface drainage must comply with IRC:SP:42.
• Reinforced road structure design depends on material conditions and traffic loads.

4. Asphalt Reinforcement (Clause 5.7)

• Follow specific construction guidelines for asphalt reinforcement (not detailed here).

Summary Table: Geocomposite Key Properties

flowchart TD
    A[Start: Construction Planning] --> B[Review Manufacturer Guidelines]
    B --> C[Engineer-in-charge Approval]
    C --> D[Material Selection (Geocomposite per Table 2.9)]
    D --> E[Subsurface Drainage Installation]
    E --> F[Pavement Layer Construction (

IRC SP 59: Site Handling and Quality Control - Key Points

Site Handling (Clause 6.3)

• Proper handling of geosynthetics on-site is critical to maintain material integrity.
• Avoid exposure to direct sunlight, moisture, and mechanical damage during storage and installation.
• Use protective covers and handle rolls carefully to prevent tears or punctures.

Quality Control Specifications

• Test sections must be constructed with varying subgrade CBR values to simulate different soil strengths.
• Target permanent deflection: ≥ 25 mm at centerline before reaching target ESALs.
• Uniform compactive effort on all pavement layers (surface, base, subbase).
• Use local materials (BC, DBM, WMM, GSB, subgrade soils) to maintain realistic conditions.
• Rigorous QA/QC with measurements of as-constructed properties.

Relevant Tests & Standards

Key Formula: Rutting Model (IRC:37)

• Number of standard axles (msa) with geocell reinforcement calculated using modified moduli.
• Example: 115 msa with 90% reliability for geocell-reinforced pavement vs. 100.7 x10⁻⁶ micro-strain for conventional.

Summary Diagram: Site Handling & QC Workflow

flowchart TD
    A[Material Delivery] --> B[Inspection & Storage]
    B --> C[Protection from UV & Moisture]
    C --> D[Careful Handling & Installation]
    D --> E[Construction of Test Sections]
    E --> F[Compaction & Layer Uniformity]
    F --> G[QC Tests (CBR, Tensile, Thickness)]
    G --> H[Performance Evaluation (Deflection, Rutting)]

**Ensure strict adherence to

Testing Methods for Geosynthetics (IRC SP 59)

Key Test Properties & Standards

Layer Coefficient Ratio (LCR) - IRC SP 59 Key Points

1. Definition:

• LCR quantifies the improvement in structural contribution of a geogrid in a flexible pavement layer.
• It modifies the layer coefficient ( a ) of the reinforced layer:
  [ SN = a_1 D_1 + LCR_2 \times a_2 \times D_2 \times m_2 + \cdots ] where ( LCR > 1 ).

2. Formula for Layer Coefficient ( a ) based on CBR (Clause 29.14):

[ a = (29.14 \times CBR - 0.1977 \times CBR^2 + 0.00045 \times CBR^3) \times 10^{-4} ]

3. Structural Layer Coefficients (Example from Clause 1.784):

• (MR) = Resilient modulus of the layer (in MPa)

4. Determination of LCR:

• Empirical/back-calculated from full-scale traffic tests comparing reinforced vs. unreinforced sections.
• Provided by manufacturers or via agency-specific evaluation.
• Typical LCR values depend on geogrid type, layer, and local conditions.
• LCR reflects thickness reduction factor (BCR) for base/subbase layers while maintaining traffic capacity.

Summary:

• Use CBR formula for unreinforced layer coefficient.
• Modify with LCR for reinforced layers.
• Obtain LCR from tests or manufacturer data.
• Incorporate LCR in design for improved pavement life and reduced

Full Scale Traffic Testing Procedures (IRC SP 59)

Key Specifications:

• Loading Vehicle: Commercial truck modified to apply 80 kN axle load with "super-single" tires at 0.56 MPa tire pressure.
• Test Track Layout: Oval shape (Fig. II-1) with:
  • Test lane width: 4.6 m
  • Test strip width: 2.3 m
  • Test area length: 30.5 m
• Traffic Application: Channelized, minimal wander; vehicle runs multiple passes until 25 mm permanent centerline deflection is reached.
• Surface Measurement: Laser profiling using a stiff beam and laser distance meter (accuracy ±1 mm).
• Pavement Materials: Local subgrade, base, and surface layers (BC, DBM, WMM, GSB).
• Deflection Measurement: Falling Weight Deflectometer (FWD) for layer moduli and strain analysis.

Test Procedure Summary:

• Modify truck to apply 80 kN per axle, aligned tires for consistent wheel paths.
• Run continuous traffic on oval track.
• Measure rut depth and transverse profile periodically.
• Use FWD data to evaluate pavement stiffness and improvement by reinforcement.
• Repair failed sections by adding base aggregate and smoothing.
• Normalize data to remove section variability; interpolate near 25 mm rut threshold.

Typical Test Section Cross-Section (Fig. II-2):

Key Formula:

• Equivalent Single Axle Load (ESAL): Used to quantify cumulative traffic load until 25 mm rutting.

flowchart LR
    A[Modify Truck Load to 80 kN Axle] --> B[Run Traffic on Oval Track]
    B --> C[Measure Rut Depth & Deflection]
    C --> D{Rut < 25 mm?}
    D -- Yes --> B
    D -- No --> E[Repair & Normalize Data]
    E --> F[Analyze FWD Data for Modulus

Erosion Control Mat Installation - IRC SP 59 Key Points

1. Anchoring Specifications (Clause 5.6.1)

• Anchor trench: 150-200 mm deep × 150 mm wide at mat edges.
• Slope anchoring: Upstream edge anchored in trench for slopes.
• Pin spacing:
  • Along length: 0.5 to 1 m intervals
  • Across width: staggered 400-600 mm
• Pin depth: Long enough for firm soil penetration, flush with surface.
• Slope crest anchoring: For slopes > 1V:3H, anchor trench ≥ 1 m from crest.

2. Pin Density by Slope Gradient

3. Geotextile Material Requirements (Clause 4.11 & 4.9)

Geotextile Permittivity & Opening Size by Soil Fines Content:

Material Specifications & Certificates per IRC SP 59

Key Tables & Test Methods