Specifications for Dense Graded Bituminous Mixes

IRC 111: Introduction - Key Formulas, Tables & Specifications

1. Maximum Theoretical Specific Gravity (Gmm) - ASTM D2041

Used to calculate air voids and compaction targets:

Formula (Vacuum Bowl)	Description
	A = dry sample mass (g) <br> D = lid & bowl + water mass (g) <br> E = lid, bowl, sample + water mass (g)

2. Marshall Compaction

• Air Voids Target: 7.0 ± 0.5%
• Compaction: Adjust blows per side (start ~10 blows)
• Specimens: 6 total; split into 2 subsets for dry & conditioned testing

3. Indirect Tensile Strength (ITS)

Calculate tensile strength (St) in kPa:

[ St = \frac{2000 \times P}{t \times d} ]

• P: Max load (N)
• t: Specimen thickness (mm)
• d: Specimen diameter (mm)

4. Tensile Strength Ratio (TSR)

[ TSR = \frac{S_2}{S_1} ]

• (S_1): Avg tensile strength of dry specimens (kPa)
• (S_2): Avg tensile strength of conditioned specimens (kPa)

5. Mix Requirements (Table 8 Summary)

Scope of IRC 111 - Dense Graded Bituminous Mixes

Key Points from Clause 2.2 (Scope):

• Dense graded bituminous mixes consist of mineral aggregates and bituminous binder.
• Mixed in hot mix plants and laid with mechanized pavers.
• Used mainly for binder and wearing courses on highways.
• Binder course lies between base and wearing course.

Types of Dense Graded Bituminous Mixes (Table 1):

Aggregate Grading and Bitumen Content (Summary from Table 7):

• Nominal maximum aggregate sizes vary by mix type (e.g., DBM: 37.5 mm, SDBC: 13.2 mm, BC: 19 mm).
• Bitumen content ranges approximately 4% to 5.4% depending on mix.

Summary Diagram (Mermaid.js):

graph TD
    A[Dense Graded Bituminous Mixes] --> B(DBM)
    A --> C(SDBC)
    A --> D(BC)
    B --> E[Base/Binder Course]
    C --> F[Wearing Course]
    D --> G[Wearing Course]
    E --> H[Layer Thickness: 50-100 mm]
    F --> I[Layer Thickness: 25-40 mm]
    G --> J[Layer Thickness: 25/40/50 mm]

Use this scope to select mix types, layer thickness, and number of layers for highway pavement design per IRC 111.

Key Materials Specifications from IRC 111

1. Fine Aggregate (Clause 3.3.1)

• Passing 2.36 mm sieve and retained on 0.075 mm sieve.
• No natural sand in binder/wearing courses; ≤50% natural sand in base courses.
• Clean, hard, durable, dry, free from dust & deleterious substances.
• Sand Equivalent ≥ 50 (IS: 2720 Part 37).
• Plasticity Index ≤ 4 for fraction passing 0.425 mm sieve (IS: 2720 Part 5).

2. Coarse Aggregate Properties (Table 5)

3. Maximum Specific Gravity (Gmm) Formulas (Clause 24.2.2010)

• Using Bowl Method:

[ G_{mm} = \frac{A}{D + A - E} ]

• Using Flask Method:

[ G_{mm} = \frac{A}{D + A - E} ]

Where:

• (A) = Mass of dry sample in air (g)
• (D\

IRC 111 - Design of Mix: Key Points & Specifications

1. Fines to Bitumen Ratio (Clause 3.5.4)

• F/B ratio by weight of total mix: 0.6 to 1.2 for all mixes in Table 7.

2. Job Mix Formula (Clause 4.3 & 4.3.1)

The Job Mix Formula (JMF) includes:

• Material details:
  • Source and location of all materials.
  • Proportions of all materials.
• Binder:
  • Type and percentage by weight of total mix.
• Aggregate:
  • Percentage by weight of coarse aggregate, fine aggregate, and mineral filler (including mineral filler).
  • Single definite percentage passing each sieve for the combined mix.
  • Individual grading of each aggregate fraction and proportion in combined grading.
• Batching:
  • Weight of each aggregate type and binder per batch (for batch mixers).
• Test results: Aggregate properties.
• Temperatures: Mixing and compaction temperatures.

3. Aggregate Blending (Clause 4.3.1)

• Blending of two or more aggregate sizes is done by weight to achieve the ultimate gradation.
• The laboratory mix design provides proportions by individual sieve sizes.
• This blending ratio is essential for field implementation.

Summary Table: Fines to Bitumen Ratio

flowchart TD
    A[Laboratory Mix Design] --> B[Determine Proportions by Sieve Sizes]
    B --> C[Calculate Blending Ratios (Weight %)]
    C --> D[Job Mix Formula]
    D --> E[Field Implementation]
    E --> F[Batch Mixing & Compaction]

This process ensures the mix meets gradation and binder content requirements for durability and performance.

IRC 111: Construction Operation - Key Specifications & Quality Control

Construction Operation Overview (Clause 5)

• Focus on laying dense graded bituminous mixes for base, binder, and wearing courses.
• Ensure proper temperature control, mixing, laying, and compaction procedures.

Quality Control Tests & Frequency (Table 13, Clause 6.4.1)

Important Notes:

• Maintain temperature control during mixing and laying for workability.
• Conduct stability and voids analysis to ensure mix durability.
• Frequent sampling ensures consistent material quality and compaction.

flowchart TD
    A[Material Sourcing] --> B[Quality Tests]
    B --> C[Mix Design]
    C --> D[Mixing & Heating]
    D --> E[Laying & Spreading]
    E --> F[Compaction]
    F --> G[Quality Control Tests]
    G --> H[Final Acceptance]

This flow ensures systematic construction operation per IRC 111 standards.

IRC 111 - Controls for Dense Graded Bituminous Mixes

Key Specifications & Control Measures (Clause 6 & Table 13)

Permissible Variation from Job Mix Formula (Table 9)

IRC 111: Test Method for Moisture Susceptibility — Key Points

Specimen Preparation & Conditioning

• Compact 6 specimens with Marshall compactor to 7.0 ± 0.5% air voids (adjust blows, start ~10 blows/side).
• Divide into 2 subsets (~equal air voids):
  • Dry subset: Room temp, then 25°C water bath for 2 hrs before testing.
  • Conditioned subset: Saturate → wrap in plastic + 10 ml water in sealed bag → freeze at -18 ± 3°C for ≥16 hrs → thaw in 60 ± 1°C water bath for 24 hrs → 25°C water bath for 2 hrs → test.

Indirect Tensile Strength (ITS) Test

• Measure specimen thickness (t, mm).
• Load diametrically at 50 mm/min using Marshall testing machine.
• Calculate tensile strength (St):

[ \boxed{ St = \frac{2000 \times P}{t \times d} } ]

Where:

• (St) = tensile strength (kPa)
• (P) = maximum load (N)
• (t) = specimen thickness (mm)
• (d) = specimen diameter (mm)

Tensile Strength Ratio (TSR)

[ \boxed{ TSR = \frac{S_2}{S_1} } ]

• (S_1) = average ITS of dry specimens (kPa)
• (S_2) = average ITS of conditioned specimens (kPa)
• TSR indicates moisture resistance; higher TSR = better resistance.

ASTM D2041: Theoretical Maximum Specific Gravity (Gmm)

• Used to calculate air voids and compaction targets.
• Procedure involves vacuum saturation of loose mix submerged in water at 25°C.
• Calculate (G_{mm}) (using vacuum bowl under water):

[ \boxed{ G_{mm} = \frac{A}{A - (C - B)} } ]

Where:

• (A) = mass of dry sample in air (g)
• (B) = mass of bowl under water (g)
• (C) = mass of bowl + sample under water (g)

Equipment Summary

• Marshall compactor

Outline of ASTM D2041 for Specific Gravity and Density (per IRC 111 Annex B)

Purpose:

• Determine Theoretical Maximum Specific Gravity (Gmm) of loose bituminous mixtures at 25°C.
• Used to calculate air voids, bitumen absorption, and compaction targets.

Equipment:

• Vacuum bowl or vacuum flask (capacity ~4000 ml).
• Vacuum pump (residual pressure ≤ 4.0 kPa).
• Balance (accuracy 0.1 g).
• Water bath at 25 ± 1°C.
• Manometer or pressure gauge.

Key Formulas:

Method	Formula	Parameters
Bowls Under Water		A = mass dry sample (g) <br> B = mass bowl under water (g) <br> C = mass bowl + sample under water (g)
Bowls in Air		A = mass dry sample (g) <br> D = mass lid & bowl with water (g) <br> E = mass lid, bowl, sample & water (g)
Flask Determination		A = mass dry sample (g) <br> D = mass cover & flask with water (g) <br> E = mass flask, cover, sample & water (g)

Test Procedure Summary:

• Sample (~1500-2500 g) placed in vacuum container.
• Water added at 25°C to cover sample.
• Vacuum applied to remove air bubbles (residual pressure ~3.7 kPa).
• Vacuum maintained with agitation for 15 ± 2 min.
• Weigh container + sample either submerged or in air as per method.
• Use formula to calculate Gmm.

Application: