The correct operation process of a road crack sealing machine follows the core logic of "Preparation - Crack Cleaning - Heating - Sealing - Curing". Meanwhile, details should be adjusted according to the equipment type (small-sized/large-sized) and pavement crack conditions to ensure operation quality and safety. The specific steps are as follows:
Check whether the power system (engine, motor), heating system (combustion chamber, temperature controller), material tank, material conveying pipeline, and spray gun of the crack sealing machine are in normal condition, without faults such as leakage or jamming. For small hand-pushed machines, check the stability of wheels and handrails; for large towed machines, confirm that the traction connection is firm.
Commission the temperature control system: set the heating temperature according to the type of crack sealing material (e.g., asphalt-based crack sealant, polyurethane-based crack sealant). Generally, the temperature is 160-180℃ for asphalt-based materials and 120-150℃ for polyurethane-based materials. Preheat the equipment and let it run idly for 3-5 minutes in advance to ensure uniform and stable temperature.
Check safety devices: confirm that fire extinguishers, warning lights, and reflective signs are complete and effective. Operators should wear protective equipment such as protective clothing, heat-resistant gloves, and goggles.
Select crack sealing material that matches the crack width and pavement type; do not use expired or caked materials. Slowly add the crack sealing material into the material tank, and the filling amount should not exceed 80% of the tank capacity to prevent overflow during heating.
Prepare auxiliary tools: crack cleaning machines (high-pressure air guns, wire brushes, grooving machines), blowers, tape measures, warning cones, enclosures, and pavement cleaning tools.
Implement traffic control in the operation area, set up warning cones, enclosures, and construction signs, and clearly define no-entry or slow-down areas to prevent interference from vehicles and pedestrians during the operation.
Clean the operation pavement: remove gravel, dust, stagnant water, and weeds around the cracks to ensure the cracks and their surrounding areas are dry and clean. (Damp pavements need to be dried in advance; otherwise, the adhesion of the crack sealing material will be affected.)
For fine cracks with a width of ≤5mm, use a high-pressure air gun (air pressure ≥0.6MPa) or a wire brush to repeatedly clean dust and debris inside the cracks. If there is oil stain in the cracks, wipe them clean with a special cleaning agent and let them dry.
For cracks with a width of ＞5mm or loose edges, first use a grooving machine to cut a groove along the center line of the crack. The groove is usually "V"-shaped or "U"-shaped (the depth is 1.5-2 times the width). After grooving, use a high-pressure air gun to thoroughly remove the residue inside the groove.
Confirm that there is no moisture inside or on the surface of the crack. This can be checked by inserting a tissue into the crack. If the tissue is damp, extend the air-drying time or use a heat gun to dry the crack to prevent moisture from causing the crack sealing material to peel off from the pavement.
Start the heating system of the crack sealing machine. After the temperature of the crack sealing material in the material tank reaches the set value, maintain constant-temperature stirring (some equipment has a built-in stirring function; for equipment without this function, manual regular stirring is required) to ensure the crack sealing material is evenly melted without caking. The insulation time should be no less than 30 minutes (adjust according to the material instructions).
Check the temperature of the material conveying pipeline and spray gun to prevent the crack sealing material from cooling and solidifying in the pipeline. If blockage occurs, use a high-temperature cleaning agent to clear it in a timely manner.
Small-sized machines: The operator holds the spray gun, aligns the muzzle with the crack (or the grooved opening), and keeps the muzzle at a 45°-60° angle to the pavement. Push slowly from one end of the crack to the other. The filling height of the crack sealing material should be slightly 1-2mm higher than the pavement (to reserve space for shrinkage) to avoid missing filling or voids.
Large-sized machines: Move the equipment at a constant speed through the traction device, adjust the height and angle of the spray gun, and cooperate with the automatic material supply system to control the material output, ensuring continuous and uniform sealing. For curved or intersecting cracks, reduce the speed and manually adjust the position of the spray gun.
Handling of special cases: If the length of the crack exceeds 10 meters, seal it in sections, with an overlap of 5-10cm at the junction of each section. When encountering branched cracks, first fill the main crack, then handle the branch cracks.
For pavements with high requirements, after sealing, a small amount of dry fine sand or stone chips can be spread immediately on the surface of the crack sealing material to enhance skid resistance and prevent the material from being stuck by vehicle rolling.
Control the time to open traffic according to the type of crack sealing material and ambient temperature: Asphalt-based crack sealant requires 1-2 hours of curing at room temperature, and the time should be extended to 3-4 hours in low-temperature environments (＜10℃); polyurethane-based crack sealant usually requires 2-4 hours of curing. Specific requirements should follow the material instructions.
During the curing period, vehicles and pedestrians are strictly prohibited from rolling over the operation area, and special personnel can be assigned to guard the area.
Turn off the heating system. After the temperature of the material tank drops below 80℃, export and recycle the remaining crack sealing material (to avoid waste). Rinse the material tank, material conveying pipeline, and spray gun with a special cleaning agent to remove residual crack sealing material and prevent blockage due to solidification.
Check the wear of various equipment components, add lubricating oil to parts such as the engine and bearings, clean dust and residue on the equipment surface, and store the equipment properly (small-sized machines should be placed in a dry and ventilated place; large-sized machines require anti-rust treatment for the traction device).
After the crack sealing material is completely cured, remove traffic facilities such as warning cones and enclosures, clean up residue and tools at the operation site, and restore normal pavement traffic.
Keep away from flammable and explosive materials during operation. Prohibit personnel from staying in the heating area. If crack sealing material leaks, turn off the heating system immediately, cover the leaked material with sand, and clean it up.
Avoid operation in rainy, snowy weather or environments with a temperature below 5℃, as low temperatures will affect the fluidity and adhesion of the crack sealing material.
Conduct regular inspections after sealing. If problems such as cracking or falling off of the crack sealing material are found, repair them in a timely manner to ensure the sealing effect of the cracks.
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