Hot In-Place Recycling

Hot In-Place Recycling

Hot in-place recycling is a low-waste technology that significantly reduces the need for raw materials during the reconstruction of surface and binder layers of roads.

This advanced method reshapes and improves the quality of the existing asphalt layer, and within the same work cycle, it allows the simultaneous application of a new wearing course (REMIX PLUS).

 

Advantages of Hot In-Place Recycling

• Low cost and time requirements for repairs
• Extended lifespan of the asphalt surface and overall road structure
• Environmental benefits (conservation of natural resources, energy savings, and waste reduction)
• REMIX and REMIX PLUS are seamless technologies – both transverse and longitudinal joints are thermally treated during application. The binder and wearing courses are hot-compacted into each other.
• Improved ride comfort and increased road safety for users

 

Technology and Areas of Application

The hot in-place recycling train consists of preheaters that gradually heat the asphalt layer to the required temperature using propane-butane infrared heaters. The core of the system is the remixer, which breaks up the heated layer using a milling drum and thoroughly mixes the reclaimed material with any added components (asphalt binder, aggregates, or asphalt mix).

The final section of the remixer includes two independently heated screeds that spread, shape, and pre-compact the homogenized mixture.

Final compaction of the recycled layer or layered structure is performed using two tandem road rollers.

This technology enables four primary variants of hot in-place asphalt recycling. The most commonly used methods are REMIX and REMIX PLUS, while RESHAPE and REPAVE are used less frequently.

 

Remix

Reshaping of the existing pavement layer through recycling, along with quality enhancement of the asphalt mixture.

The original asphalt layer is modified to achieve the desired physical and mechanical properties by adding specific components. The construction of the remixer allows for the incorporation of asphalt binder and asphalt mix according to a predefined mix design.

The REMIX process consists of the following steps:

• Spreading of additional aggregate on the road surface (only when aggregate is added separately)
• Heating of the asphalt layer designated for recycling
• Breaking up the heated asphalt layer
• Adding necessary materials (rejuvenating agents, road bitumen, pre-blended aggregate mix)
• Mixing the heated asphalt material with the added components
• Re-laying the modified asphalt mixture
• Compacting the modified asphalt mixture

 

Remix plus

Reshaping of the pavement surface through recycling, with enhancement of the existing asphalt layer and simultaneous laying of a new wearing course.

With the REMIX PLUS technology, two asphalt layers are laid in a single work cycle. The original pavement layer is modified using the REMIX method by adding necessary components to form the recycled binder layer. On top of this, a new “plus” wearing course is applied immediately in the same pass.

The REMIX PLUS process includes the following steps:

• If the original elevation needs to be preserved, a layer is milled off to the depth of the new “plus” layer
• Spreading of additional aggregate to adjust the grain size of the recycled mix
• Heating the asphalt layer designated for recycling
• Breaking up the heated asphalt material
• Adding rejuvenating agents or road bitumen to the loosened layer
• Mixing the recycled asphalt with the added materials
• Re-laying the recycled asphalt mix using the first heated screed
• Laying the new wearing course (pressed-in layer) using a hot-on-hot application with the second heated screed
• Compacting the asphalt structure (recycled layer + new wearing course)

 

 

Hot In-Place Joint Repair

Longitudinal cracks and open construction joints are a common issue on roads, typically appearing at the connections between traffic lanes. If these defects are not repaired in time, the wearing course gradually degrades, leading to potholes and reduced pavement lifespan.

For repairing longitudinal and construction joints, a remixer with a fixed working width of 300 mm, 500 mm, 600 mm, or 1000 mm is used, depending on the defect width and equipment. In hot in-place recycling, the pavement is preheated to a depth of 60–70 mm using the remixer’s infrared burners, while the recycling itself takes place at a depth of 30–40 mm.

The surface is heated with propane-butane infrared heaters. Once heated, the asphalt layer is loosened by the remixer and enriched with asphalt emulsion and new hot-mixed asphalt. Since the layer is only broken after it has been sufficiently heated, aggregate particles remain intact—unlike in conventional cold milling—so there is no need to adjust the gradation by adding fresh aggregate.

The modified mixture is then laid back and pre-compacted by the remixer’s screed. Final compaction is performed using a tandem roller.