Bitumen Production Process & Calculator

Follow us on Twitter
Question, remark ? Contact us at contact@myengineeringtools.com

1. Introduction
2. Bitumen production process
3. Benefits of air blowing method
4. Quality Control & Interactive Calculator

1. Introduction

Bitumen is a main binder in road construction. It can be used to bond the aggregates well together and form the asphalt.

Different types of bitumen can be used in flexible pavement. The main types of bitumen grades are VG bitumen (Viscosity Graded) and Pen bitumen (Penetration Graded) which can be used directly in the hot asphalt.

These two types of bitumen are produced directly from distillation of crude oil. Generally, bitumen can be obtained by different ways including straight run, air blowing, semi blowing, solvent deasphalting and blending.

💡 Engineering Rules of Thumb: Bitumen Oxidation

Air Flow Rate: Typically ranges from 50 to 150 Nm³/h per tonne of charge.
Temperature Control: Oxidation is exothermic. Keep the reactor between 230°C and 270°C to prevent thermal cracking.
Penetration vs Softening Point: As oxidation time increases, penetration decreases (bitumen hardens) and the softening point increases.
Safety: Maintain the vapor space oxygen concentration below 5% to prevent internal fires/explosions.

2. Bitumen Production Process

Bitumen production process infographics

2.1 Crude Oil Distillation

The journey begins in the petroleum refinery. Crude oil is heated in an atmospheric distillation tower where lighter components like gasoline and diesel are separated.

2.2 Vacuum Distillation

The "long residue" from the atmospheric tower is further processed in a vacuum distillation tower under reduced pressure. The heaviest fraction obtained is the Vacuum Bottom (VB), which is the primary feedstock for bitumen.

⚠️ ENGINEERING NOTICE & EDUCATIONAL DISCLAIMER: This interactive calculator is for preliminary estimation of bitumen properties after air blowing. Real-world results depend on specific crude source (SARA analysis) and reactor efficiency.

Bitumen Air Blowing Estimator

Initial Penetration (dmm)

Initial Softening Point (°C)

Blowing Time (hours)

Blowing Temperature (°C)

Estimation Results

Penetration Index (Initial): -

Estimated Final Penetration: - dmm

Estimated Final Softening Point: - °C

Final Penetration Index: -

2.3 Air Blowing and Oxidation

In the air blowing process, the vacuum bottom is exposed to controlled airflow at high temperatures (230-270°C). This induces dehydrogenation and polymerization reactions. The Penetration Index (PI) is defined as:

\[ PI = \frac{20 - 500 \cdot A}{1 + 50 \cdot A} \] Where \( A \) is the temperature susceptibility: \[ A = \frac{\log_{10}(800) - \log_{10}(Pen)}{SP - 25} \]

These equations help engineers classify the bitumen grade based on its rheological behavior.

3. Benefits of Air Blowing Method

The air blowing method offers several distinct advantages:

Enhanced Control: By adjusting temperature and air flow, manufacturers can produce specific Pen grades (e.g., 60/70, 80/100).
Modification of Properties: Oxidation improves adhesion and resistance to UV aging and weathering.
Versatility: Allows the production of specialty grades like Polymer Modified Bitumen (PMB).

4. Quality Control and Testing Procedures

Common physical properties tests conducted on bitumen samples include:

Penetration Test: Measures hardness at 25°C.
Softening Point (Ring & Ball): Temperature at which the bitumen becomes fluid.
Ductility: Ability to stretch without breaking.
Viscosity: Measured in Poise (absolute) or Centistokes (kinematic).