Tentative Guidelines for Repair of Concrete Pavements Using Synthetic Resins

Scope of IRC 77: Resin Mortar-Cement Concrete Composites

• Purpose: Covers materials, formulations, testing, and durability of resin mortar and resin mortar-cement concrete composites.
• Materials: Epoxy and polyester resin systems with specified components and proportions.
• Tests & Properties:
  • Bond Strength: Shear test on composite interface; loading rate 140 kg/cm²/min; average of 3 samples.
  • Shrinkage: Mortar bars 2.5×2.5×28.5 cm; measure length change after 2 days curing at 30±2°C.
  • Thermal Expansion: Same size bars; measure expansion with thermal apparatus; coefficient calculated from average of 3 samples.
  • Durability: Accelerated weathering cycles (hot, cold, combined) per CRRI; 30 cycles; monitor bond cracking.
• Typical Properties Table (Epoxy vs Polyester):

• Typical Resin Formulations: Detailed in Appendix 3, including hardener types and proportions.

flowchart TD
    A[Prepare Resin Mortar] --> B[Apply Resin & Sand Layer (2.5 cm)]
    B --> C[Cure 2 days at 30±2°C]
    C --> D{Tests}
    D -->|Bond Strength| E[Direct Shear Test]
    D -->|Shrinkage| F[Length Measurement]
    D -->|Ther

Key Specifications & Tables for Materials (IRC 77)

1. Resin Mortar Preparation & Testing

• Bond Strength Test:

  • Apply resin on clean dry surface.
  • Add 2.5 cm resin-sand layer, compact in 10 cm mold with 1 cm² steel rod.
  • Cure at 30 ± 2℃ for 2 days.
  • Shear loading rate: 140 kg/cm²/min.
  • Take average of 3 specimens.

• Shrinkage Test:

  • Mortar bars: 2.5×2.5×28.5 cm.
  • Cure at 30 ± 2℃ for 2 days.
  • Measure length change using microscope between pins at ends.

• Thermal Expansion Test:

  • Same bar size as shrinkage test.
  • Use thermal expansion apparatus with telescope.
  • Cure 2 days at 30 ± 2℃.
  • Calculate coefficient of thermal expansion from length change.

• Accelerated Weathering Test:

  • Three cycles simulating hot, cold, and alternating climates.
  • 30 cycles at specified temperature/time regimes.
  • Monitor bond cracking after each cycle.

2. Typical Properties of Resin Formulations

3. Typical Strengths of Resin Mortars (kg/cm²)

Key Mix Proportions & Specifications from IRC 77 for Resin Mortar & Concrete

1. Resin Formulation Proportions

• Polyester Resin Accelerator: 0.5 ml to 1.5 ml per 100 g resin (10℃ to 40℃)
• Epoxy Resin Hardener (Tertiary Amine): 4 g to 10 g per 100 g resin (10℃ to 40℃)

2. Resin Mortar & Concrete Mix Ratios

• Coarse aggregate max size < 1/3 patch depth & ≤ 25 mm.
• Sand grading should be uniform (see Table 1).

3. Recommended Sand Gradings (Table 1)

4. Typical Strengths of Resin Mortars

Key Specifications & Formulations for Resin Preparation, Mortar, and Concrete (IRC 77)

1. Resin Formulation Preparation

• Accurately weigh all components; mix in a hemispherical container to ensure homogeneity.
• Manual mixing limit: 2 kg per batch due to short pot life.
• Mechanical mixing possible for larger quantities.
• Pot life varies with temperature and accelerator/hardener type (e.g., epoxy at 25°C: ~90 min).

2. Resin Mortar & Concrete Mix Proportions

• Resin mortar: 1 part resin formulation : 3-5 parts medium/fine sand by weight.
• Resin concrete: Aggregate to resin ratio up to 8:1 (weight basis) for coarse aggregates.
• Mix coarse aggregate first with resin, then add fine aggregate gradually to prevent "balling".

3. Typical Properties of Resin Formulations

4. Mechanical Properties of Resin Mortars

5. Testing & Curing

• Cure at 30 ± 2°C for

IRC 77: Temperature Conditioning for Hot and Cold Weather Repairs

Key Specifications & Guidelines:

1. Temperature Conditioning of Pavement Surface & Repairs (Clause 5.2):

2. Temperature Conditioning of Materials (Clause 5.3):

• Resin components & aggregates must be conditioned to 25°C to 35°C before mixing.
• Methods:
  • Store indoors in heated rooms overnight.
  • Use heated enclosures or hot water baths.
  • For cooling, use shade or cold water baths.
• Avoid heating beyond 60°C or cooling below 15°C.
• Prevent condensation on aggregates.

3. Mix Proportions for Resin Mortar & Concrete (Clause 2.5):

4. Pot Life & Mixing Quantities:

• Manual mixing batch: max 2 kg (due to short pot life).
• Mechanical mixing: larger batches possible.
• Use hemispherical-bottom containers for thorough mixing.

5. Curing Time (Clause 5.2 Table 7.6):

• Cold weather or slow curing resins require longer or artificial heat curing.

Summary Diagram: Temperature Conditioning Workflow

flowchart TD
    A[Check Ambient Temperature] --> B{Temperature Range}
    B -->|<10°C| C[Heat Pavement & Materials to 25-35

Surface Preparation and Application Procedures (IRC 77)

1. Surface Preparation

• Concrete surface must be:

  • Freshly exposed, clean, dry, and free from loose/unsound material.
  • Temperature controlled (preferably 25°C to 35°C).
  • Moisture-free at interface to avoid bond failure.

• Removal of unsound concrete:

  • Use chisels/hammers; form grooves with slightly slanted sides (wider base).
  • Edges must be neat; use joint cutting machine if available.
  • Avoid fine cracks by careful pneumatic hammer use.

• Cleaning methods:

  • Sand blasting, iron brushing, detergent wash for oil, sodium hydroxide for animal fat.
  • Acid treatment (4 kg HCl/10 m²) if other methods not possible; rinse thoroughly.

• For cracks:

  • Clean and remove unsound concrete.
  • Form trapezoidal notch 3-4 cm deep, 4-5 cm wide at top.

• Final cleaning:

  • Use compressed air with oil trap; surface must be dry before resin application.

2. Application Procedures

• Tack coat:

  • Apply resin formulation on prepared surface with brush/spray.
  • Ensure full wetting; apply second coat if surface is porous, while first is still tacky.

• Resin Mortar Mix:

  • Resin to sand ratio: 1:3 to 1:5 by weight.
  • For resin concrete with coarse aggregate: aggregate to resin up to 8:1.
  • Mix resin thoroughly before adding aggregates.
  • Compact in mould (10 cm cube) using 1 cm square rod.
  • Finish with steel trowel.

• Curing:

  • Air cure at 30 ± 2°C for 2 days before testing bond strength.

3. Key Formulas

• Bond strength (shear):

  [ \text{Shear Strength} = \frac{\text{Maximum Load}}{\text{Area of Interface}} \quad (kg/cm^2) ]

• Shrinkage (%):

  [ \text{Shrinkage} = \frac{\Delta L}{L_0} \times 100 ]

  Where:

  • ( \

Key Formulas, Tables & Specifications for Resin Repair Procedures (IRC 77)

1. Curing & Opening to Traffic (Clause 5.2, Table 7.6)

• Normal curing resins:
  • Summer: Min. 4 hours
  • Winter: Min. 6 hours
• Cold weather / slow curing: Use artificial heat to reduce curing time.
• Resin bonded cement concrete overlays:
  • Wet hessian curing immediately after laying.
  • Ponding water curing from day 1 to 28 days.
  • Rapid hardening cement overlay: 7-day curing adequate.

2. Fixing Mild Steel Shear Pegs (Clause 7.7)

• Peg diameter: 20-25 mm mild steel bar
• Plate size: 10 cm × 10 cm × 10 mm
• Hole diameter: 15-20 mm larger than peg diameter
• Hole depth: 15-20 cm embedment
• Minimum pull load capacity:
  • 20 mm bar: 650 kg
  • 25 mm bar: 900 kg
• Maintain 5 cm concrete cover at hole bottom to prevent splitting.
• Use resin sand mortar to bond pegs.

3. Surface Preparation (Clauses 6.2 - 6.5)

• Remove unsound concrete with chisels or pneumatic hammers.
• Form grooves with slightly slanted sides for better keying (Fig.1 & Fig.2).
• Clean surfaces by sand blasting, acid treatment (4 kg HCl/10 m²), or detergent wash.
• Final cleaning with compressed air (oil-free).
• Light chiselling (up to 1 mm) recommended if no sand blasting.

4. Tack Coat Application (Clause 6.6)

• Use same resin formulation as repair mortar.
• Apply with brush or spray ensuring full surface wetting.
• Apply second coat if surface is porous, while first coat is still tacky.

5. Bond Strength Minimum Values (Clause 9.2.1)

Key Specifications for Curing and Opening to Traffic (IRC 77):

• Minimum Overlay Thickness: 75 mm (Clause 7.5.5)

• Curing Period for Resin Bonded Overlays (Clause 7.6):

  • Normal curing resins:
    • Summer: Minimum 4 hours
    • Winter: Minimum 6 hours
  • Cold weather or slow curing resins:
    • Use artificial heat to reduce curing time (see paras 5.2 & 7.1.4)

• Curing Method for Cement Concrete Overlays:

  • Start wet hessian curing ASAP after laying
  • Ponding water curing from day 1 up to 28 days
  • For rapid hardening cement, 7-day curing is adequate

• Before Opening to Traffic:

  • Clean pavement surface thoroughly
  • Seal joints properly

Summary Table: Curing Time for Resin Repairs

Important Notes:

• Bond coat must remain tacky when placing fresh concrete.
• Avoid resin flow into joints to prevent warping.
• Early curing is critical to prevent bond failure due to shrinkage stresses.
• Use rapid hardening cement if time constraints exist.

flowchart TD
    A[Apply Bond Coat] --> B{Is Surface Tacky?}
    B -- Yes --> C[Place Fresh Concrete]
    B -- No --> D[Reapply Bond Coat]
    C --> E[Start Wet Hessian Curing ASAP]
    E --> F[Ponding Water Curing (Day 1 to 28)]
    F --> G[Clean Surface & Seal Joints]
    G --> H[Open to Traffic]

This ensures proper bonding and durability as per IRC 77 guidelines.

IRC 77 - Testing Procedures for Resin & Resin Mortar

Key Test Procedures (Appendices 1,4,5)

1. Pot Life of Resin

   • Mix 500g resin + hardener.
   • Apply on surface every 5 min.
   • Pot life = time until resin is hard to spread.

2. Compressive Strength of Resin Mortar

   • Cast 3 cubes (5 cm).
   • Cure at 30±2°C.
   • Test at 140 kg/cm²/min; average strength of 3 cubes.

3. Moisture Susceptibility

   • 6 cubes: 3 air-cured, 3 water-immersed at 30±2°C.
   • % Loss = [(Air cured strength - Water cured strength) / Air cured strength] × 100.

4. Bond Strength (Resin-Cement Concrete)

   • Prepare 10×10×7.5 cm blocks.
   • Acid treat surface or use saw-cut face.
   • Apply resin + 2.5 cm resin-sand mortar.
   • Cure 2 days at 30±2°C.
   • Direct shear test at 140 kg/cm²/min.

5. Shear Peg Pull-Out Test

   • Apply load in increments (600 kg for 20 mm dia; 800 kg for 25 mm).
   • No slip → adequate bond.
   • Slip before load → record max load before slip.

6. Resin Content in Hardened Mortar

   • Loss on ignition at 1000°C for 1 hour.
   • Resin % = [(W_before - W_after) / (W_before - W_dish)] × 100.

Typical Values (Appendix 2)

Safety and Handling Precautions for Resin Materials (IRC 77)

• Contact Actions (Table 2.1.4):

  Item of Contact	Action Required
  Clothing	Remove soiled clothing immediately.
  Body	Wash with soap and water immediately.
  Eye	Flush with large quantities of water, then seek medical attention.

• Handling Guidelines:

  • Keep resin components in shade, avoid direct sunlight especially in hot weather.
  • Follow manufacturer’s handling instructions strictly.
  • Ensure adequate fire protection during mixing and placing.
  • No smoking, sparks, or flames near resin operations to prevent fire hazards.

These precautions minimize health risks and fire hazards during resin handling and repair work.

flowchart TD
    A[Resin Handling Start] --> B{Contact Occurs?}
    B -- Clothing --> C[Remove Clothing Immediately]
    B -- Body --> D[Wash with Soap & Water]
    B -- Eye --> E[Flush with Water + Medical Aid]
    B -- No Contact --> F[Continue Handling]
    F --> G[Keep Resin in Shade]
    G --> H[No Smoking/Sparks Nearby]
    H --> I[Ensure Fire Protection]
    I --> J[Safe Handling Complete]

Durability and Weathering Tests (IRC 77)

Key Tests & Procedures

1. Bond Strength Test (Clause 2.5)

   • Apply resin on clean, dry surface.
   • Top layer: 2.5 cm resin-sand mix, compact in 10 cm mould.
   • Cure at 30 ± 2°C for 2 days.
   • Shear loading rate: 140 kg/cm²/min.
   • Calculate average shear strength from 3 specimens.

2. Shrinkage Test

   • Mortar bars: 2.5×2.5×28.5 cm.
   • Cure at 30 ± 2°C.
   • Measure length difference with travelling microscope after 2 days.
   • Calculate average shrinkage from 3 bars.

3. Thermal Expansion

   • Same specimen size as shrinkage.
   • Use thermal expansion apparatus.
   • Heat to steady state, measure length change.
   • Calculate coefficient of thermal expansion (CTE).

4. CRRI Accelerated Weathering Test

   • Three cycles based on climate:
     • Type-I: Hot (80°C/6h, 30±3°C/18h)
     • Type-II: Cold (Freeze -12±2°C/6h, Thaw 30±3°C/18h)
     • Type-III: Severe alternating hot/cold/freezing cycle.
   • 30 cycles on resin mortar-cement concrete composites.
   • Monitor bond cracking and durability.

Typical Properties of Resin Mortars

IRC 77: Key Resin Formulations & Properties (Appendices Summary)

1. Typical Resin Formulation Properties

2. Resin Mortar Mechanical Properties

3. Typical Epoxy Resin Formulations (Parts by weight)