Behind a continuously operating asphalt mixing plant that consistently produces high-quality batches is the perfect combination of modern engineering technology and human skill. So, how is the process of creating hot mix asphalt — a crucial material for all transportation projects — carried out? Let’s explore the entire journey with VIPEC.

1. Main Components of Hot Mix Asphalt

A standard batch of hot mix asphalt is formed from three basic components:

Aggregate

Mineral filler

Bitumen (or asphalt binder)

Among these, the aggregate comes in various sizes, depending on the mix design.

The mineral filler consists of two types: new mineral filler and reclaimed mineral filler.

The bitumen is heated to a viscous liquid state to easily coat the aggregate.

Depending on the required asphalt grade for each project, engineers will calculate different mixing ratios to ensure maximum strength, durability, and stability.

2. Feeding and Screening of Aggregate

First, the aggregate is loaded into the cold bin by a wheel loader. From there, the aggregate moves through a horizontal conveyor and is transferred to the primary vibrating screen to remove oversized stones.

Next, the qualified material is transported through a cross conveyor to the drying drum area — where the drying and heating process begins.

3. Hot Drying in the Dryer Drum – The Heart of the Mixing Plant

Inside the dryer drum, temperatures can reach 180–185°C. The combustion efficiency of this process directly depends on the burner technology and the drying – heat recycling system. Here, the aggregate is completely dried

and heated to the necessary temperature so that when mixed with bitumen, the mixture achieves optimal plasticity and adhesion.

4. Classification of Aggregate and Waiting to Mix

After being heated, the aggregate passes through a hot screen to separate by particle size. This allows the operator to create different mix designs for each type of hot mix asphalt.

The screened aggregate is stored in hot bins, waiting to be fed into the mixing drum according to predetermined ratios. Typically, each plant has about 5–6 different aggregate bins for flexible mixing.

5. Mineral Filler Component – The Reinforcing Factor

The mineral filler is the second component, helping to fill the voids between the aggregates, enhancing bonding and durability of the mixture.

There are two types of mineral filler:

New mineral filler: introduced from outside.

Reclaimed mineral filler: fine dust collected through the baghouse dust filtration system after drying the aggregate, reused to reduce waste.

Both types are stored in separate silos and pumped into the mixing chamber via a screw conveyor as needed.

6. Bitumen Component

Bitumen is the main binder of the hot mix asphalt mixture.

Before mixing, it is heated in bitumen tanks to about 150–170°C to achieve the necessary viscosity and plasticity.

Depending on the layout design, the tanks can be positioned vertically or horizontally, insulated, and equipped with automatic temperature control to ensure stability.

When it comes time to mix, the bitumen is pumped through pipes to the weighing chamber and then accurately poured into the mixing drum.

7. Weighing and Automatic Mixing

When all three components (aggregate, mineral filler, and bitumen) are ready, the automatic electronic weighing system will measure each type of material according to the design formula.

There are two discharge gates – one large and one small – to ensure the highest accuracy in weighing.

The feeding sequence is as follows:

Feed the aggregate first.

Next, the mineral filler.

Finally, the bitumen.

After all materials have entered the mixer, the mixing process begins.

A complete mixing cycle usually lasts about 45 seconds, including mixing and discharging time.

8. Finished Product – Hot Mix Asphalt

When the mixing process is complete, the hot mix asphalt is discharged into a waiting hopper or discharge conveyor, then loaded into specialized trucks.

If the plant has a hot storage silo, the mixture can be temporarily stored before being transported to the construction site.

At the construction site, the hot mix asphalt is spread using a paver, compacted with a vibratory roller, and cooled naturally, creating a smooth, durable, and highly elastic asphalt surface.

9. Summary of the Process

The entire process of producing hot mix asphalt is a closed, highly automated chain, including:

Feeding → Drying → Screening → Weighing → Mixing → Storing → Transporting.

Each step requires optimal precision, temperature, and time to produce a finished product that meets technical standards and superior durability.

That is why behind every perfect asphalt road is a system of technology – engineering – and people operating in harmony, constantly innovating and improving.

🎬 Watch the detailed process video at: