Asphalt Recycler: Turning Millings Into Hot Patch Mix

An asphalt recycler is a trailer-mounted machine with a heated, rotating drum that turns old asphalt (millings, saw-cut slabs and broken chunks) back into hot, workable patch mix. Crews load it with a loader or skid steer, let the drum tumble and heat the material for a few minutes, and dump hot mix into a hot box, a truck or straight into the hole. It lets a public works yard keep doing hot patches in January, after the plant has closed for the season.

Below: how recyclers work, published capacity and fuel figures, what old asphalt brings to the drum, what DOT testing says about recycled patches, and a worked winter patching example.

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Where a recycler fits among patching machines

Patching equipment gets lumped together, but each machine does a different job:

Asphalt recycler. Makes hot mix from cold material. Its only job is to take something that has already cooled and hardened and bring it back up to working temperature.
Hot box. Keeps hot mix hot, usually during the drive to the job and through the day. Some can reheat a partial load overnight, but they are holding vessels first. Our asphalt hot box guide covers them in detail.
Infrared heater or heater/reclaimer. Heats the existing pavement in place so a failed spot can be raked, rejuvenated and re-rolled. Some tow-behind units pair an infrared heater with a small heated hopper of mix. Our pothole patcher overview compares these with spray injection.

Recyclers and hot boxes are usually used together. KM International's manual for its T-2 recycler tells owners to move each finished load into a hot box to hold its temperature during transport, and warns that hauling hot mix in the recycler drum itself can damage the machine and void the warranty.

How an asphalt recycler works

The process is close to a small, slow batch plant with no aggregate bins:

Load. Millings or chunks go in through a hopper or chute. KM rates the T-2 for broken pieces up to 12 inches and about 2,500 pounds per drum load.
Heat while tumbling. A diesel burner heats the drum while internal flights keep the material rolling. The U.S. spec sheet for Bagela's BA10000 says the flame never touches the asphalt directly, and Bagela describes the drum wall doing most of the heating, with chunks breaking down into fines as they warm.
Add binder near the end. KM's instructions are to add asphalt cement or another binder source, such as torn-up roofing shingles, just before the load reaches temperature, with the drum stopped while anything is added by hand. Shingle nails and the plastic strip on the back have to come off first because they will not melt.
Check temperature and dump. KM targets 335°F for the whole load, says to go by the coldest reading and says not to exceed 350°F. The drum reverses, tilts slightly, and the flights push the mix out.

Batch machines like the T-2 finish one drum at a time. Bagela's machines run continuously: material goes in the front and comes out the back, and the company says the discharge gate can be opened after about 10 minutes of heating.

Capacity, fuel and weight by model

The figures below come from current manufacturer and authorized-dealer spec sheets. Bagela publishes its own numbers in metric tonnes (a tonne is about 1.1 U.S. tons), and both makers note that real output varies with the moisture and temperature of the material.

Model	Rated output	Burner	Operating temperature	Weight
KM International T-2 (batch)	Up to 4 tons/hour; about 2,500 lb per drum load	700,000 BTU diesel, about 4.7 gal/hour	280–360°F (spec); 335°F target in manual	Max 8,600 lb; 14,000 lb GVWR, dual 7,000 lb axles
Bagela BA 7000 F (continuous)	Up to 7 tonnes/hour	280 kW, about 5 kg fuel oil per tonne	Operator-controlled	2,300 kg (about 5,070 lb)
Bagela BA 10000 F (continuous)	Up to 10 tonnes/hour	400 kW, about 5 kg fuel oil per tonne	280–350°F (U.S. spec sheet)	5,000 kg; 11,000 lb GVWR (U.S. spec)

Fuel per ton works out similarly across brands. The T-2 burns about 4.7 gallons an hour at up to 4 tons an hour, so roughly 1.2 gallons per ton at full output. Bagela says one tonne of asphalt takes about 6 liters of fuel, or about 1.4 gallons per U.S. ton. A wet stockpile pushes that up, because the burner has to drive off water before the binder softens.

The weights matter if you plan to tow one behind a pickup. The KM bid specification calls for a 3-inch pintle hitch and electric brakes on all four wheels, and the manual warns against towing with a vehicle rated below the trailer's load rating. Check your truck and hitch before you buy.

What old asphalt brings to the drum

A recycler can only reheat what you give it. FHWA's user guidelines for reclaimed asphalt pavement (FHWA-RD-97-148) describe the raw material:

Binder content. Reclaimed asphalt typically holds 3 to 7 percent asphalt cement by weight, and RAP from surface mixes usually falls between 4.5 and 6 percent.
Aged binder. That binder is harder than new asphalt cement because years of exposure to air oxidize it. This is why KM tells operators to add fresh binder: heat alone softens old asphalt, but it does not replace what aging took away.
Moisture. Stored RAP picks up water. FHWA cites 5 percent or more in stockpiles and as much as 7 to 8 percent after long rainy periods. Cover the millings pile you plan to recycle, or keep it on a pad that drains.
Gradation and contamination. Milled RAP comes out finer than crushed RAP, and stockpiles can pick up soil, base stone and debris. FHWA says quality control is needed before RAP is reused, and for patching that starts with keeping the recycling pile clean.

FHWA puts the unit weight of milled or processed RAP at 120 to 140 pounds per cubic foot. That range is useful for estimating how much feedstock a pile holds. For loose-pile weights by the yard, see our asphalt millings weight chart.

Do recycled patches last?

Public research does not test any single recycler brand, but two DOT studies bear on the question:

Ohio DOT (FHWA/OH-2014/2). Researchers installed more than 60 winter pothole patches and compared a tow-behind infrared heater/reclaimer against throw-and-roll and spray injection. The infrared patches performed significantly better and had a much longer expected life, but the method was much slower. Raveling was their main failure, while the other two methods mostly dished. The report also found that the properties and storage of the patch mix affected how the heater/reclaimer patches performed.
New Jersey DOT (FHWA-NJ-2024-001). Rutgers researchers tested hot mix with 0 to 50 percent RAP, chose a 30 percent RAP mix for field potholes and preheated the holes with infrared. Cores showed the recycled-content patches performing about as well as or better than conventional hot mix.

Neither study is a test of 100 percent recycled mix from a trailer drum, so do not read them as proof that any batch will match plant mix. What they support is narrower and still useful: hot, well-compacted patches outlast cold throw-and-roll repairs, and recycled content is not a weakness when the binder and temperature are right. In practice that means adding fresh binder, hitting temperature, cleaning and drying the hole, and compacting hard.

Worked example: one winter patching day

Say a township crew has 60 potholes to fill after a thaw. The plant is closed until spring, which is normal in cold regions (see why asphalt plants close in winter). The yard has a covered pile of millings and a KM T-2. These numbers are for illustration; measure your own holes.

Patch volume. Average cut-out hole: 3 ft × 3 ft × 3 in deep. Each is 9 × 0.25 = 2.25 cubic feet, so 60 holes need 135 cubic feet of compacted mix.
Tons of mix. At 145 pounds per cubic foot (the compacted density our calculator uses), 135 × 145 = 19,575 lb, or about 9.8 tons. Add 10 percent for handling and overfill: about 10.8 tons. You can run your own dimensions through the how many tons of asphalt calculator.
Drum loads. 10.8 tons is 21,600 lb. At about 2,500 lb per load, that is 8.6, so plan on 9 loads.
Machine time. At the rated 4 tons an hour, 10.8 tons takes about 2.7 hours of drum time. Wet millings or a cold morning will stretch that.
Fuel. 2.7 hours × 4.7 gallons per hour is about 13 gallons of diesel for the burner.
Feedstock. About 21,600 lb of millings. At FHWA's 120 to 140 lb per cubic foot, that is roughly 155 to 180 cubic feet, about 6 to 7 cubic yards from the pile, plus a little fresh binder per load.

The plan that results: start the recycler first thing, empty a drum into the hot box about every 19 minutes (2,500 lb at 4 tons an hour), and send the patch truck out with the first full box rather than waiting for all nine loads. A continuous machine at up to 7 tonnes an hour would need well under two hours.

Safety and daily care

Heat and fire. KM's manual says to keep a fire extinguisher on site at all times, to inspect fuel lines daily and to stay clear of the burner end, which remains hot after shutdown.
PPE. The same manual lists heat-resistant gloves, safety glasses and ear protection. You spend the day next to a burner and a diesel engine, so earmuffs such as the 3M Peltor Optime 105 hi-viz are worth having.
Drum rules. Never heat an empty drum, always keep it turning while the burner runs, and never let mix cool and harden inside.
Cleaning. KM's method is to tumble about a quarter cubic yard of crushed limestone through a hot drum so the leftover asphalt sticks to the stone, then dump that stone onto the RAP pile to be recycled later.
Temperature checks. KM ships its recycler with an infrared thermometer. A spare industrial unit that reads well above 350°F, such as the Fluke 62 Max, is also handy for checking mix in the hot box and the patch.

Small patches seldom justify a roller. A heavy steel hand tamper such as the Truper 8x8-inch cast steel tamper handles edges and corners, followed by a plate compactor or a few passes of a truck tire on larger holes.

Is an asphalt recycler worth it?

A recycler makes the most sense for agencies, campuses and contractors that patch through the winter, already generate millings or tear-out, and are far from a plant that runs year-round. It makes less sense if a plant down the road sells hot mix all year, if your patching is mostly summer work done straight off the plant, or if your only stockpile is dirty, mixed rubble. Before buying, compare fuel, binder and labor per recycled ton with what you now pay for hot mix in season and cold patch in winter.

Asphalt recycler FAQ

What is an asphalt recycler?

A trailer-mounted machine with a heated, rotating drum that reheats asphalt millings, saw-cut pieces and broken chunks into hot, workable mix, mainly for patching when plants are closed or far away.

How many tons per hour does an asphalt recycler make?

It depends on the model and the material. KM International rates its batch-type T-2 at up to 4 tons per hour in loads of about 2,500 lb, and Bagela rates its continuous BA 7000 F and BA 10000 F at up to 7 and 10 tonnes per hour. Wet or cold feedstock lowers output.

What temperature should recycled asphalt reach?

KM's manual targets 335°F for the whole load, judged by the coldest reading, and says not to exceed 350°F. Spec sheets list operating ranges of 280–360°F for the KM T-2 and 280–350°F for the Bagela BA10000.

Does an asphalt recycler need new binder?

Usually some. FHWA notes that the asphalt cement in old pavement has hardened from oxidation, and KM tells operators to add asphalt cement or another binder source, such as cleaned roofing shingles, just before the load reaches temperature.

The bottom line

An asphalt recycler reheats millings and chunks into hot patch mix: about 4 tons an hour for a batch trailer like the KM T-2, up to 7 or 10 tonnes an hour for Bagela's continuous units, at a little over a gallon of fuel per ton. Keep the feedstock clean and covered, add fresh binder, bring loads to about 335°F without passing 350°F, haul in a hot box and compact hard.

Sources

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