Bitumeninous mix consumption calculations

Bituminous Mix Consumption on Site

Important Formulae

$$\text{Density} = \frac{\text{Mass}}{\text{Volume}}$$

$$\text{Volume} = \text{Width} \times \text{Loose Thickness} \times \text{Length}$$

For loose thickness calculation from desired compacted thickness of Bituminous Concrete, refer: Loose Thickness Calculations

$$\text{Volume} = \frac{\text{Mass}}{\text{Density}}$$

$$\text{Length} = \frac{\text{Volume}}{\text{Width} \times \text{Loose Thickness}}$$

Examples: Length Covered per Truck Load & Loads per Km

Example 1

• Density of mix: 2.2 MT/m³
• Mass in truck: 22 MT
• Volume = 22 / 2.2 = 10 m³
• Loose thickness: 30 mm (0.03 m)
• Road width: 3.75 m
• Cross-sectional area = 3.75 × 0.03 = 0.1125 m²
• Length covered per load = 10 / 0.1125 ≈ 88.89 m
• Loads required per km: 1000 / 88.89 ≈ 11.25 loads

Example 2

• Density: 2.2 MT/m³
• Mass: 30 MT
• Volume = 30 / 2.2 ≈ 13.64 m³
• Loose thickness: 25 mm (0.025 m)
• Width: 3.75 m
• Area = 3.75 × 0.025 = 0.09375 m²
• Length per load ≈ 145.45 m
• Loads per km: 1000 / 145.45 ≈ 6.875 loads

Example 3

• Density: 2.2 MT/m³
• Mass: 30 MT
• Volume ≈ 13.64 m³
• Loose thickness: 25 mm
• Width: 5.5 m
• Area = 5.5 × 0.025 = 0.1375 m²
• Length per load ≈ 99.17 m
• Loads per km: 1000 / 99.17 ≈ 10.08 loads

Effective Bitumen Content After Seal Coat

Problem: Carpet mix has 3.3% bitumen (by volume). Seal coat of 1 kg/m² is applied. What is the effective bitumen % in a core sample taken from 20 mm thick carpet?

Solution

• Carpet thickness = 20 mm → 1 m³ covers 50 m²
• Bitumen in mix = 3.3% → 0.033 m³ per m³ of mix
• Seal coat: 1 kg/m² × 50 m² = 50 kg bitumen
• Density of bitumen ≈ 1013 kg/m³ → Volume = 50 / 1013.1 ≈ 0.04935 m³
• Total bitumen volume = 0.033 + 0.04935 = 0.08235 m³
• Total volume (mix + seal coat bitumen) = 0.967 + 0.08235 = 1.04935 m³
• Effective bitumen % = (0.08235 / 1.04935) × 100 ≈ 7.85%

Bitumen Consumption in Open Graded Premix Carpet (20 mm)

Method 1: MoRTH Table 500.10 (Per 10 m²)

Material	Quantity	Bitumen (kg)
13.2 mm aggregates	0.18 m³	9.36 kg (@52 kg/m³)
11.2 mm aggregates	0.09 m³	5.04 kg (@56 kg/m³)
Total bitumen		14.4 kg per 10 m²

→ 1.44 kg/m² → 0.00144 MT/m²

→ 72 kg/m³ (since 1 m³ covers 50 m² → 14.4 × 5 = 72 kg)

Method 2: Density-Based

• Density of premix carpet: 2.2 MT/m³
• Bitumen content: 3.3%
• Mass per m³ = 2200 kg
• Bitumen mass = 0.033 × 2200 ≈ 72.6 kg/m³
• Bitumen per m² (20 mm) = 72.6 / 50 ≈ 1.452 kg/m² ≈ 0.00145 MT/m²

Both methods give nearly identical results (~1.44–1.45 kg/m²).