The Marathon MM350ADT is the most capable mastic trailer Marathon builds. It pairs the 350-gallon tank with the oil-jacketed Helix auger drive, which makes it the configuration for contractors and agencies running mastic as a large-scale pavement preservation program rather than a spot repair method.

Two things drive that positioning. The first is capacity. Wide-area mastic repair consumes material quickly, and at 350 gallons per load a crew spends measurably less time shuttling material and more time on the road. On highway shoulders, airport aprons, bridge decks, and municipal road programs, that difference compounds over a season.

The second is the auger. Marathon’s Helix auger system is engineered specifically for heavier, thicker, and denser mastic materials, dispensing them at a consistent rate instead of relying on gravity. That controlled rate is what makes wide repairs practical: with Marathon’s optional adjustable drag box, up to 4 feet wide, towed behind the trailer, a crew can place mastic across a full wheel rut or a wide distressed strip in one uniform pass. Trying to achieve that by gravity pouring and hand-working the material is slower and far less consistent.

The auger assembly is oil jacketed and fed from the machine’s own heat transfer oil system, with heated oil delivered through corrugated stainless braided hose. Rubber, hydraulic, and PTFE-lined lines are unacceptable at these temperatures. The auger itself carries a high-temperature coating. The result is that material stays hot through the discharge, which is where dense mastic otherwise stiffens and causes inconsistent flow or clogging. Auger forward and reverse plus heated oil flow are controlled from a rear-wall hydraulic manifold with lever handles and a dedicated pressure gauge, so the operator manages discharge from the working end of the machine.

Upstream, the MM350ADT uses Marathon’s oil-jacketed double-boiler tank design, with heat transfer oil covering the material vat front, rear, and both sides. The flame never contacts the material tank, so heat is distributed evenly through the load and the steel is protected, giving oil-jacketed units a longer service life than air-jacketed alternatives. Ceramic insulation in the firing chamber limits heat loss, and engineered hot airflow shortens heat-up time and reduces fuel consumption.

Agitation is a full-sweep horizontal design with angled paddles running forward and rearward, driven off the diesel engine through a HECO Gear model 16 gearbox at 5.2:1 producing 2,500 ft-lbs. On a load this size, the agitator’s ability to draw material through the vat rather than simply lift it from the floor is what keeps aggregate suspended and mix consistency even from the first pass of the day to the last.

Temperature is regulated by dual digital thermostat controllers holding material and heat transfer oil to independent setpoints via continuously monitored thermocouples, with calibrated analog dial thermometers at the rear and automatic burner shutdown on thermocouple fault. Overnight heaters keep the load warm between shifts so the crew is working sooner the next morning.

Power is a 23 hp three-cylinder, water-cooled, direct-injected Tier 4 Final diesel engine with electric start and full auto-shutdown protection, feeding a 340,000 BTU diesel burner. Engine, burner, fuel, and hydraulic reservoirs are laid out for straightforward daily service access. Safety features carry across the line: a top loading door interlock that stops agitation when opened, a low material loading height so operators do not step up onto the trailer to load blocks, a vented oil expansion tank, a mounted fire extinguisher, heat-resistant decals, and conspicuity tape along the frame.

Construction is fully welded heavy steel on a gusseted 6-inch channel frame, finished with epoxy primer and a urethane topcoat, and backed by Marathon’s two-year unlimited-hours machine warranty and five-year frame warranty.

For Canadian contractors bidding large mastic and rut-leveling programs, and for municipalities, airports, and bridge authorities standardizing on mastic for preservation work, the MM350ADT is the top of the range. Roadly supplies and supports the full Marathon mastic trailer lineup across Canada.