Recommendations for Road Construction in Areas Affected by Water Logging, Flooding and/or Salts Infestation

The scope of IRC 34 covers guidelines and specifications for road construction in water-affected areas, including water logging and flooding. Key standards referenced for materials and testing include:

• Mass per Unit Area of geotextiles: EN ISO 9864
• In-plane permeability: EN ISO 12958
• Apparent Opening Size of geotextiles: EN ISO 12956
• Tensile Properties of geotextiles: EN ISO 10319
• Water Permeability by Permittivity: EN ISO 11058
• Thickness of composite materials: EN ISO 9863

Annex-1 provides equivalences between ISO, ASTM, and IS standards for these tests. For drainage design, IRC SP-42 and IRC SP-50 are recommended references. The code emphasizes site-specific design and specialist consultation for flood-prone embankments (Clause 8.1).

These standards ensure proper selection and testing of geotextiles and drainage composites used as capillary cutoffs and waterproofing layers in road embankments.

Sources: Clause 2.2, Clause 7.2.2.1, Clause 8.1, Annex-1

IRC 34 provides detailed recommendations for road construction in areas affected by water logging, flooding, and salt infestation, particularly in subsoil or groundwater. Key points include:

• Use of suitable capillary cutoffs to prevent upward movement of water and salts (see Clause on Suitable Capillary Cutoffs, p. 22).
• Construction methods adapted to prolonged flooding conditions (Clause on Recommendations for Flooding, p. 18).
• Specific remedial measures for salt-affected soils to mitigate detrimental effects on pavement materials (Clause on Detrimental Salts, p. 20).

Unfortunately, the exact formulas or tables are not included in the retrieved context. However, the code emphasizes:

• Proper drainage design to avoid water logging.
• Selection of materials resistant to salt damage.
• Layered construction with protective sub-base and capillary barriers.

For detailed formulas, tables, and specifications, refer to the sections starting at page 18 (Flooding) and page 20 (Salt Infestation) in IRC 34.

Sources: Recommendations for Road Construction in Areas Where in Addition to Water Logging, Flooding for Prolonged Periods is Also Expected, Recommendations for Road Construction in Areas Where in Addition to Water Logging, Detrimental Salts are Present in the Subsoil or Ground Water, Suitable Capillary Cutoffs

The IRC 34 code provides general recommendations primarily focused on remedial measures for road construction in water-affected areas. Key points include:

• Clause 1.2 states remedial measures for various water-related problems are included.
• Clause 8.1 and Table 8.9 address solutions for road embankments overtopped by high-velocity flood water, emphasizing that combinations of solutions may be adopted per site needs and specialist input is recommended.
• For drainage design, refer to IRC:SP-42 (Road Drainage) and IRC:SP-50 (Urban Drainage).
• Annex-1 (Clause 4.5.2.5.1) lists relevant test standards for geotextiles used in road construction, including IS 14294 for apparent opening size and IS 14324 for water permeability.

These guidelines serve as a framework; site-specific design and specialist consultation are essential for effective implementation.

Sources: Clause 1.2, Clause 8.1, Annex-1 (Clause 4.5.2.5.1)

For drainage design and capillary cutoffs per IRC 34, key specifications and formulas include:

• Capillary Cutoff Positioning (Clause 4.7.3 & 4.7.4):

  • The cutoff should be placed at least 0.15 m above the ground or standing water level, whichever is higher.
  • It shall not be positioned higher than 0.6 m below the top of the subgrade.
  • When using polyethylene sheet (geomembrane) as cutoff, cover it with a 0.15 m thick granular layer (sand) for drainage and protection.
  • For drainage composite (geomembrane + geonet + geotextile), no additional granular cover is needed as geotextile protects and filters, and geonet provides drainage.

• Drainage Composite Properties (Clause 7.2.2.1):

  • Geotextile: Apparent Opening Size (EN ISO 12956), Tensile Strength (EN ISO 10319), Permittivity (EN ISO 11058)
  • Drainage Net: Mass per unit area (EN ISO 9864)
  • Composite: Widewidth Tensile Strength MD (EN ISO 10319)
  • Impermeable geomembrane: Polyethylene waterproofing film

• Embankment Surface (Clause 4.7.3):

  • Should have sufficient camber and crossfall to ensure gravity drainage and prevent ponding.

• Illustrations (Fig. 4.7):

  • Show cutoff location relative to water table and embankment for effective moisture control.

These ensure effective prevention of capillary moisture rise and proper drainage in embankments.

Sources: Clause 4.7.3, Clause 4.7.4, Clause 7.2.2.1, Fig. 4.7

Key specifications and formulas for embankment construction and protection per IRC 34 include:

• Sand Blanket Thickness (Clause 7.1): To intercept capillary action, the sand blanket thickness t (cm) is given by:

  [ t = 2d_1 \times d_2 / (d_1 + d_2) ]

  where d is mean particle diameter (mm), d1 is sieve aperture size through which fraction passes, and d2 is sieve aperture size on which fraction is retained.

• Wave Action Protection (Clause 5.1.2): Stone pitching of designed thickness over graded filter or geotextile is required to protect embankments from flood wave action.

• Embankment Height (Clause 4.1): When deep drainage is impractical, embankment height should ensure the subgrade bottom is at least 1.5 m above highest water-table/flood level.

• Geotextile Testing (Annex-1, Clause 4.5.2.5.1): Relevant IS and international standards for geotextile properties include IS 14294 (apparent opening size), IS 14324 (water permeability), and others for tensile and mass properties.

• Drainage Design: Refer to IRC:SP-42 and IRC:SP-50 for detailed road and urban drainage guidelines.

These combined measures ensure embankment stability and protection against water-related damage.

Sources: Clause 7.1, Clause 5.1.2, Clause 4.1, Annex-1 (Clause 4.5.2.5.1), Clause 8.1

According to IRC 34, harmful salts in subgrade soil or groundwater affect road construction mainly through physical and chemical actions (Clause 2.3, 2.3.1, 2.3.2). Sulphates of calcium, magnesium, sodium, and sodium carbonate are critical salts causing damage, especially to cement-based pavements and stabilized soil layers. Safe concentration limits are: sulphates below 0.2% (as SO3) in soil and groundwater, sodium carbonate below 0.2% in soil and 0.02% in groundwater (Clause 6.1). No special measures are needed if these limits are met. For concentrations above these limits, special mitigation measures (beyond Sections 4 and 5) are recommended. Testing methods for salt concentrations follow IS 2720 Part XXIII and Part XXVII. Also, dissolved CO2 or bicarbonates are not harmful if pH > 5 (Clause 6.1).

Sources: Clause 2.3, Clause 2.3.1, Clause 2.3.2, Clause 6.1

As per Clause 4.7.2 of IRC 34, suitable capillary cutoffs consist of layers of coarse or fine sand and graded gravel. The recommended minimum thicknesses of these granular layers for different subgrade situations are given in Table 4.7.2. For subgrade 0.6 - 1.0 m above the High Flood Level (HFL) with Plasticity Index (PI) > 5, the minimum thickness is 350 mm for fine sand (425 micron to 2 mm), and 150 mm for both coarse sand (2 mm to 4.75 mm) and graded gravel (4.75 mm to 20 mm). For sandy subgrade soil (PI < 5, sand content ≥ 50%), the thickness reduces to 300 mm for fine sand and 100 mm for coarse sand and graded gravel. These thicknesses ensure effective capillary cutoff to prevent moisture rise in pavement layers.

Sources: Clause 4.7.2, Table 4.7.2

IRC 34 provides guidelines and remedial measures for specific problems related to road construction in water-affected areas, detailed in Clause 8. Key points include:

• Clause 7.2.3 refers to the use of granular material cutoffs as a remedial measure (see para 4.7.2 for details).
• Section 8 covers various specific problems with recommended solutions, such as water logging, flooding, and presence of detrimental salts.
• The document includes tables and recommendations for suitable capillary cutoffs (Page 22) and detailed remedial measures starting from Page 23.

Unfortunately, the exact formulas and detailed tables are not provided in the retrieved context. For precise formulas and specifications, refer directly to Clause 8 and related paragraphs in IRC 34.

This section is essential for addressing water-related subsoil issues and ensuring road durability through appropriate construction techniques and materials.

Sources: Clause 7.2.3, Clause 8, Page 22, Page 23

For drainage between road and rail track as per IRC 34, Clause 8.7, the key approach is to provide effective drainage to prevent water accumulation affecting pavement and track stability. Clause 8.3 details drainage for roads in cutting, recommending aggregate drains on either side of the road to lower the underground water table, as shown in Fig. 8.3. These include V-shaped edge drains combined with subsurface aggregate drains. The specifications for aggregate drains are given in Table 4.5.2.5 (not reproduced here). Fig. 8.7 illustrates drainage zones A and B between road and rail track, emphasizing proper water flow management. The typical cross-section with drainage composite is shown in Fig. 4.6. The design ensures water is diverted away from both road and rail track foundations to maintain structural integrity and serviceability.

Sources: Clause 8.7, Clause 8.3, Table 4.5.2.5, Fig. 8.3, Fig. 8.7, Fig. 4.6

Key specifications for materials in IRC 34 include grading requirements for aggregate filter materials and properties for drainage composites. Per Clause 4.5.2.5, the grading of filter materials is classified into Class I, II, and III with percent passing by weight on various sieve sizes as follows:

For drainage composites (Clause 4.6.2.2 and 7.2.2.1), key properties are:

• Widewidth Tensile Strength ≥ 3000 N
• Mass per Unit Area ≥ 710 g/m²
• In-plane permeability at 100 kPa hydraulic gradient (i=1) ≥ 0.45 to 0.55 l/m·s
• CBR Puncture Resistance per EN ISO 12236

These properties are measured as per EN ISO standards (e.g., 9864, 10319, 12958).

This drainage method applies to all road types and is preferred where economically feasible.

Sources: Clause 4.5.2.5, Table 4.5.2.5, Clause 4.6.2.2, Clause 7.2.2.1

As per IRC 34 Clause 5.2, when flood water is expected to pass over the road with heavy traffic and prolonged flooding, a cement concrete surfacing of appropriate thickness should be provided for at least two lanes. This pavement must rest on a 15 cm thick dry lean concrete or cement/lime stabilized soil base. For flexible pavements at water crossings, a 50 mm thick bituminous concrete wearing coat is recommended. When asphaltic concrete surfacing is used, the mix should be dense graded and flood-resistant. Wider paved surfaces are preferred to distribute traffic loads better under flooding conditions.

Sources: Clause 5.2

Key points for Monitoring and Maintenance of Drainage Systems per IRC 34 are:

• Darcy's Law governs subsurface water flow (Clause 4.5.2.1a).
• Perform field observations and discharge measurements on completed drainage works to assess performance (Clause 4.5.2.1b).
• Based on measurements, adjust subsurface drain depth or spacing as needed (Clause 4.5.2.1b).
• Use solid pipes with open joints or perforated pipes with free draining filter material to ensure effective drainage (Clause 4.5.2.1c).
• Filter material must prevent soil particle ingress and be more permeable than surrounding soil for stable flow (Clause 4.5.2.1c).
• For design and maintenance details, refer to IRC:SP-42 (Road Drainage) and IRC:SP-50 (Urban Drainage) as per Clause 8.1.
• Relevant test methods for geotextiles and drainage composites include:

• Composite drainage materials should have:
  • Widewidth tensile strength ≥ 3000 N
  • Mass per unit area ≥ 710 g/m²
  • In-plane permeability ≥ 0.45 to 0.55 l/m.s at 100 kPa hydraulic gradient (Clause 4.6.2.2).

This ensures effective monitoring, maintenance, and performance of drainage systems in road embankments and pavements.

Sources: Clause 4.5.2.1, Clause 8.1, Annex-1 (Clause 4.5.2.5.1), Clause 4.6.2.2, Clause 4.5.2

Key specifications and references in IRC 34 include standardized test methods and guidelines for road construction in water-affected areas. Annex-1 (Clause 4.5.2.5.1) provides a table linking ISO, ASTM, and IS standards for geotextile testing, such as mass per unit area (EN ISO 9864), water permeability (EN ISO 12958), and apparent opening size (EN ISO 12956). Clause 8.1 references guidelines for drainage design: IRC:SP-42 for road drainage and IRC:SP-50 for urban drainage. The document also notes that official amendments are published in 'Indian Highways'. The preamble outlines the scope and topics covered, including construction methods for water logging, flooding, and salt-affected soils. These references and annexures serve as essential tools for design and testing in water-affected road construction.

Sources: Clause 2.2, Clause 8.1, Annex-1 (Clause 4.5.2.5.1)