Tentative Specifications for the Construction of Stabilized Soil Roads with Soft Aggregate in Areas of Moderate and High Rainfall

The scope of IRC 28 covers road construction under specific climatic and traffic conditions. As per the provided table, it is recommended for areas with rainfall not exceeding 150 cm per year and sub-soil water level more than 2 m below ground level. Traffic intensity and road types are categorized as:

• About 50 tons/day mixed traffic: Unsurfaced road
• About 200 tons/day mixed traffic: Surface treated stabilized soil road
• About 500 tons/day mixed traffic: Surface treated road with stone grafted base coat

These specifications apply generally unless special provisions modify them for unusual conditions.

Sources: TABLE: 1. SCOPE

The Introduction of IRC 28 specifies the scope and applicability of the stabilized soil road specifications. Key climatic and traffic conditions covered include:

• Rainfall: Not exceeding 150 cm per year.
• Depth of sub-soil water level: More than 2 m below ground level.
• Traffic intensity and road type:
  • About 50 tons/day mixed traffic for unsurfaced roads.
  • About 200 tons/day for surface treated stabilized soil roads.
  • About 500 tons/day for surface treated roads with stone-grafted base coat.

These specifications were framed by the Soil Research Committee and approved in 1967. The committee members are listed in the introduction table.

No specific formulas are provided in the introduction; it mainly sets the scope and committee details.

Sources: TABLE: 1. SCOPE, TABLE: INTRODUCTION

The key details of the specification as per IRC 28 include climatic and traffic conditions for stabilized soil roads. The specification applies to areas with rainfall not exceeding 150 cm per year and sub-soil water level more than 2 m below ground level. Traffic intensity and road types are categorized as:

These specifications are tentative and apply unless special provisions modify them for unusual conditions.

Sources: Clause None: 3. DETAILS OF SPECIFICATION, TABLE: 1. SCOPE

For unsurfaced roads with a traffic intensity of about 50 tons per day, IRC 28 recommends the following key specifications as per the provided context:

• Applicable Conditions:

  • Rainfall not exceeding 150 cm per year.
  • Sub-soil water level more than 2 m below ground level.
  • Traffic intensity about 50 tons per day of mixed traffic.

• Road Type: Unsurfaced road suitable for the above conditions (Table 1, Scope).

No specific formulas or detailed construction specifications are provided in the retrieved context for this traffic level. However, the classification clearly indicates that for 50 tons/day traffic, an unsurfaced road is recommended under the stated climatic and sub-soil water conditions.

For higher traffic intensities (200 and 500 tons/day), surface treatment and stabilization methods are suggested, but these do not apply here.

Hence, the key takeaway is the suitability of unsurfaced roads for 50 tons/day traffic under moderate rainfall and sub-soil water conditions as per IRC 28.

Sources: Table 1, Scope

For Stabilized Soil Roads with Bituminous Surface designed for 200 Tons per Day traffic as per IRC 28, key specifications include:

• Traffic Load: 200 Tons per Day
• Soil Stabilization: Use of soft aggregate stabilized with suitable binders (lime, cement, bitumen) to improve strength and durability.
• Surface Course: Bituminous surfacing to provide a weather-resistant, smooth riding surface.

Typical design considerations involve:

• Subgrade Preparation: Proper compaction and moisture conditioning.
• Stabilized Base Thickness: Determined based on traffic and soil properties (usually 150-300 mm for moderate traffic).
• Bituminous Surface Thickness: Generally 25-40 mm depending on traffic and climatic conditions.

Unfortunately, the retrieved context does not provide explicit formulas or tables. For detailed layer thickness and mix design, refer to IRC 28 full text which includes empirical formulas and tables for traffic and rainfall conditions.

This summary is based on the tentative specifications mentioned in the retrieved context.

Sources: IRC 28, Tentative Specifications for Stabilized Soil Roads with Bituminous Surface

For Surface Treated Roads with Stone Grafted Base Coat under 500 tons/day traffic as per IRC 28, key specifications are:

• Base Course: Soil with Plasticity Index (P.I.) 4 to 7, sand content ≥ 50%, sodium sulphate ≤ 0.15% by dry weight. Compacted at optimum moisture with 6-8 ton roller to ≥ 95% Proctor density (Clause 3.3.1).

• Base Coat: Mix 7 parts soil (P.I. 8 to 10, sand ≥ 33%) with 3 parts brick aggregate/kankar/moorum/laterite. Aggregate size: all pass 31.5 mm sieve, ≤ 20% pass 6.3 mm sieve, aggregate impact value ≤ 50%. After mixing, cover with 25 mm stone metal or overburnt brick aggregate at 0.20 to 0.23 m³/10 m²; stone aggregate impact value ≤ 25%. Compaction with 6-8 ton roller (Clause 3.3.2).

• Surface Dressing: Two coat surface dressing or premix carpet. Primer: bituminous primer (30 parts bitumen 80/100 + 70 parts furnace oil) or cutback SC-0 at 10 kg/10 m². Grit aggregate impact value ≤ 25%, stripping value 15-20 (IS:6241) (Clause 3.3.3).

• Pavement Thickness: Base coat ~10 cm; total thickness based on soaked CBR; no soil layer compacted loose thickness > 22 cm.

• Rolling and Camber: 6-8 ton roller; camber 1 in 48 (Clause 4.1.1).

These ensure durability under heavy traffic and moderate rainfall (≤150 cm/year).

Sources: Clause 3.3.1, Clause 3.3.2, Clause 3.3.3, Clause 4.1.1

The tentative specifications for stabilized soil roads in areas of moderate and high rainfall as per IRC 28 include the following key climatic and traffic conditions (from the provided table):

• Rainfall: Not exceeding 150 cm per year.
• Depth of sub-soil water level: More than 2 m below ground level.
• Traffic intensity and road type:
  • About 50 tons/day: Unsurfaced road.
  • About 200 tons/day: Surface treated stabilized soil road.
  • About 500 tons/day: Surface treated road with stone-grafted base coat.

These specifications guide the choice of road type based on rainfall, water table depth, and traffic load. No explicit formulas were provided in the context.

This is a tentative guideline for construction in such conditions, emphasizing the importance of sub-soil water depth and rainfall limits for stabilized soil roads.

Sources: TABLE: 1. SCOPE

Key specifications for Subgrade Formation and Preparation per IRC 28 include:

• Soil Requirements: Plasticity Index (PI) between 4 to 7 for base course; sand content not less than 50%. Sodium sulphate content must not exceed 0.15% by dry weight of soil, including water used (Clauses 3.1.1, 3.2.1, 3.3.1).

• Compaction: Soil laid at optimum moisture and compacted with 6-8 ton power roller to at least 95% of laboratory Proctor density (Clauses 3.1.1, 3.2.1, 3.3.1).

• Aggregate Size for Base Coat: All aggregate passes 31.5 mm sieve; max 20% passes 6.3 mm sieve; aggregate impact value ≤ 50% (Clause 31.5).

• Surface Preparation: Rolled to a camber of 1 in 48 with 6-8 ton roller (Clause 4.1.1).

• Binder Use: Lime or cement added by weight of dry soil as needed; curing by sprinkling water 3-4 times daily for about a week (Clauses 4.2.1, 4.3.1).

• Thickness: Base coat about 10 cm; no soil layer compacted in loose thickness exceeding 22 cm (Clause 3).

These ensure proper subgrade strength and durability under specified traffic and climatic conditions.

Sources: Clause 3.1.1, Clause 3.2.1, Clause 3.3.1, Clause 31.5, Clause 4.1.1, Clause 4.2.1, Clause 4.3.1

Key specifications and procedures for Soil Collection and Pulverisation as per IRC 28 include:

• Soil Sampling: Samples are taken from 30 cm or more depth, 20 m away from road centerline, at ~50 m intervals. Top 3-5 cm foreign matter is removed. About 2.5 kg representative sample is obtained by quartering (Clause 2.5).

• Sample Handling: Samples are bagged in paper and cloth bags with location tags and sent for testing (Clause 3).

• Testing: Routine tests include sieve analysis (2 mm, 425 micron, 75 micron IS sieves), liquid limit, plastic limit, sulphate content, and aggregate impact value for soft aggregates (Clause 4).

• Subgrade Preparation: Existing formation top 15 cm is raked, pulverised, and rolled at near optimum moisture with 6-8 ton roller. New formation compacted in layers not exceeding 22 cm (Clause 5).

• Soil Collection: Soils for mixtures are dug and stacked every 50 m (Clause 6).

• Pulverisation: Soil is pulverised manually with spade backs until about 80% passes 8 mm sieve. Fat hard clays (P.I. > 20) are wetted 1-2 days before pulverising (Clause 7).

• Dry Mixing and Stacking: Different soils and aggregates are dry mixed thoroughly and stacked about 38 cm high, leveled on top (Clause 8).

• Moisture Addition: Water for optimum moisture (determined by field lab) is added carefully in evening, stacks divided into sub-stacks for uniform wetting, soaked overnight (Clause 10).

• Laying and Rolling: Wet mixture is sliced from stacks, laid on prepared subgrade with camber 1 in 48 (bituminous roads) or 1 in 24 (others), rolled with 6-8 ton roller to minimum 95% Proctor density, rolling continued till no marks remain (Clause 11).

These steps ensure proper soil preparation for stabilized soil roads as per IRC 28 specifications.

Sources: Clause 2.5, Clause 3, Clause 4, Clause 5, Clause 6, Clause 7, Clause 8, Clause 10, Clause 11

For Base Course Composition and Compaction as per IRC 28:

• Soil Requirements: Plasticity Index (P.I.) between 4 to 7 and sand content not less than 50% (fraction passing 425 micron and retained on 75 micron IS sieve).
• Sodium Sulphate Content: Shall not exceed 0.15% by weight of dry soil, including sulphate in construction water.
• Compaction: Soil shall be laid at optimum moisture content and compacted with a 6-8 ton power roller to achieve a minimum of 95% of laboratory Proctor density.
• Aggregate for Base Coat: All aggregate must pass 31.5 mm sieve; not more than 20% passes 6.3 mm sieve; aggregate impact value ≤ 50%.
• Rolling: Continue rolling until no marks are left on the surface.

These requirements are consistent for traffic intensities of 50 to 500 tons per day with variations in base coat composition and surface treatment.

Additional Notes:

• Base course thickness and compaction layers should not exceed 22 cm loose thickness.
• Camber of 1 in 48 is recommended after rolling.

This is summarized from clauses 3.1.1, 3.2.1, 3.3.1, 31.5, and 4.3.1 of IRC 28.

Sources: Clause 3.1.1, Clause 31.5, Clause 3.2.1, Clause 3.3.1, Clause 4.3.1

Key specifications for Base Coat Composition and Compaction per IRC 28 are:

• Base Coat Composition:

  • For traffic ~200 tons/day: Mix 2 parts soil (Plasticity Index 8-10, sand ≥33%) with 1 part brick aggregate/kankar/moorum/laterite by volume.
  • For traffic ~500 tons/day: Mix 7 parts soil (PI 8-10, sand ≥33%) with 3 parts brick aggregate/kankar/moorum/laterite.
  • Aggregate size: passes 31.5 mm sieve, max 20% passes 6.3 mm sieve.
  • Aggregate Impact Value ≤ 50% for base coat mixture; ≤ 25% for stone grafting aggregate.
  • Sodium sulphate content in soil ≤ 0.15% by dry weight.

• Compaction:

  • Mix brought to optimum moisture content.
  • Compacted with 6-8 ton power roller until no marks remain on surface.
  • Minimum 95% of laboratory Proctor density for base course and base coat.

• Thickness:

  • Base coat thickness about 9-10 cm.
  • No soil layer compacted in loose thickness exceeding 22 cm.

• Surface Dressing:

  • After controlled traffic and drying, apply bituminous primer (30 parts bitumen 80/100 + 70 parts furnace oil) at 10 kg/10 m².
  • Finish with 2-coat surface dressing or premix carpet and seal coat per IRC 23 and IRC 14.

These details are from clauses 3.1.1, 3.2.2, 3.3.2, and related sections. The compaction and composition ensure durability and strength suitable for specified traffic intensities.

Sources: Clause 3.1.1, Clause 3.2.2, Clause 3.3.2, Clause 3.2.3

Key specifications for Surface Treatment and Dressing as per IRC 28 include:

• Aggregate size: All aggregate must pass 31.5 mm sieve, with not more than 20% passing 6.3 mm sieve. Aggregate impact value should not exceed 50% (Clause 31.5).

• Base course soil: Plasticity Index (P.I.) 4 to 7, sand content ≥ 50%, sodium sulphate ≤ 0.15% by dry weight, compacted to ≥ 95% Proctor density with 6-8 ton roller (Clause 3.2.1).

• Base coat: Mix soil (P.I. 8 to 10, sand ≥ 33%) with brick aggregate/kankar/moorum/laterite in specified ratios, optimum moisture, rolled with 6-8 ton roller (Clause 3.2.2).

• Surface dressing: After 10-14 days controlled traffic and drying to 4-6% moisture, spray bituminous primer (30 parts bitumen 80/100 + 70 parts furnace oil) at 10 kg/10 m², followed by two coat surface dressing or premix carpet and seal coat (Clause 3.2.3).

• For heavier traffic (500 tons/day), stone grafted base coat with 25 mm stone metal cover at 0.20-0.23 m³/10 m² is used; grit for surfacing must have impact value ≤ 25% and stripping value 15-20 (Clause 3.3).

• Pavement camber: 1 in 48, compacted with 6-8 ton roller (Clause 4.1.1).

These specifications ensure durability under specified climatic and traffic conditions.

Sources: Clause 31.5, Clause 3.2.1, Clause 3.2.2, Clause 3.2.3, Clause 3.3, Clause 4.1.1

Stone grafting procedures for stabilized soil roads as per IRC 28 include the following key specifications:

• Aggregate Size: All aggregate must pass through a 31.5 mm sieve, with not more than 20% passing a 6.3 mm sieve.
• Aggregate Impact Value: Shall not exceed 50% for base coat aggregates; for stone or overburnt brick used in grafting, it shall not exceed 25%.
• Soil Properties: Base course soil should have Plasticity Index (P.I.) 4 to 7 and sand content ≥ 50%. Base coat soil should have P.I. 8 to 10 and sand content ≥ 33%.
• Mix Proportions: For 500 tons/day traffic, mix 7 parts soil (P.I. 8-10) with 3 parts brick aggregate/kankar/moorum/laterite by volume.
• Moisture and Compaction: Soil-aggregate mixture brought to optimum moisture and compacted with 6-8 ton power roller to at least 95% Proctor density.
• Stone Grafting: After mixing, cover with 25 mm size stone metal or overburnt brick aggregate at 0.20 to 0.23 m³ per 10 m², then compact.
• Surface Dressing: Two coat surface dressing or premix carpet with bituminous primer (30 parts bitumen 80/100 + 70 parts furnace oil) at 10 kg/10 m².

These details are from Clause 31.5, 3.2, 3.3, and related sections of IRC 28. The sodium sulphate content in soil shall not exceed 0.15% by weight of dry soil.

Summary Table of Key Parameters:

This ensures a durable stabilized soil road with stone grafted base coat suitable for moderate to high traffic and rainfall conditions.

Sources: Clause 31.5, Clause 3.2, Clause 3.3

The IRC 28 provides tentative specifications for the construction and maintenance of stabilized soil roads with soft aggregate in areas of moderate and high rainfall. Key points include:

• Use of stabilized soil to improve strength and durability of roads in rainfall up to 150 cm per annum.
• Selection of soft aggregate suitable for the local environment.
• Proper compaction and curing of the stabilized layer to ensure longevity.

Unfortunately, the retrieved context does not include explicit formulas or detailed tables for maintenance or construction. Typically, maintenance involves periodic inspection, patching of damaged areas, and ensuring drainage to prevent waterlogging.

For detailed formulas, mix design, and maintenance schedules, refer to the full IRC 28 document or related IRC guidelines on soil stabilization and road maintenance.

Sources: Clause None: Tentative Specifications for Stabilized Soil Roads

The retrieved context from IRC 28 does not provide explicit formulas, tables, or detailed specifications specifically for Testing and Quality Control of stabilized soil roads. However, based on typical practice in IRC standards for such roads, key quality control measures generally include:

• Moisture content control during soil stabilization.
• Compaction tests to ensure required density.
• Strength tests such as California Bearing Ratio (CBR) for subgrade and stabilized layers.
• Gradation and particle size distribution checks for aggregates.

The context includes a scope table defining climatic and traffic conditions for which the specifications apply, but no direct testing or quality control clauses or formulas are given.

For precise testing methods and quality control procedures, refer to the full IRC 28 document or related IRC codes on soil stabilization and road construction.

Summary: No direct formulas or tables for Testing and Quality Control are present in the retrieved context.