Tunnel fire retardant coating is a cement structure fire retardant coating made of porous thermal insulation materials (such as vermiculite, perlite, etc.) as aggregate and binder. Through its own flame retardancy, low thermal conductivity and certain coating thickness, it forms a thermal insulation protective layer, thus effectively delaying the heating time of cement base in tunnel. Its characteristics are stable physical and chemical properties and long service life, which can delay the damage of high temperature to concrete or steel tunnel during fire, gain time for personnel evacuation and fire rescue, protect the integrity of tunnel main structure and reduce the cost of post-disaster repair.

area of application

Tunnel fire retardant coatings are mainly used in tunnels, such as: highway, railway tunnel petrochemical engineering and air-raid shelter.

Description of construction technology

Construction process flow

1. Clean the floating dust and oil stain on the concrete surface of the tunnel, and sprinkle water for wetting. Repair uneven places to ensure the smoothness of tunnel concrete surface. At the same time, the place where the concrete surface is particularly smooth requires plastering with mortar. Where there is water leakage, water must be stopped to make up for it.

2. Remove the floating dust and oil stain on the concrete surface of the tunnel, rinse it with clear water, and keep the base surface moist without Mingshui.

3. Repair uneven places, and chisel or mortar plaster smooth areas to ensure smooth base surface; Leaking parts need to be filled with water first.

4. Treatment of construction joints: cut along the original expansion joints (1cm in width and 1cm in depth) or reserve 3mm for thermal expansion and cold contraction joints to enhance the adaptability of the coating.

5. The paint is mixed with water according to the following ratio: paint = 7: 10 ingredients. In the blender, water is gradually added into the paint in proportion and stirred into thick paste, and the stirring time is strictly controlled for 20min (the mixing time must be ensured, and the paint should be used with it), and the prepared paint should be used up within 30-40min. Due to different construction machines and weather conditions, water can be added as appropriate.

6. Before coating, use a small amount of slurry to mark the thickness of horizontal bars with a spacing of 2.5m as a reference for spraying construction.

7. Spray the tunnel from the waist to the top (from bottom to top) with a spraying machine, with a thickness of 3-8 mm each time. After the first spraying is basically dry, continue spraying for the second time, and so on until the spraying reaches the design thickness. Because the spraying surface is not smooth enough, after the last spraying, it is necessary to fill, level and trim the coating by hand with slurry immediately to make the coating surface smooth and ensure that the coating reaches the design thickness.

8. After the base course is completed, the coating surface shall be flat, smooth and clean. When mixing, the slurry is too dry, so the water-cement ratio can be increased appropriately. Subject to suitable construction. In the process of mixing, spraying and daubing, the scattered and rebounded slurry can be recycled in time, and the contaminated slurry and the slurry that has been over 2 h cannot be reused. Once the paint packaging bag is opened, it should be used immediately, and the paint that is caked with moisture should not be used. It needs to be cured for 35 days after application.

Construction requirements

1. Before construction, the construction scaffolding shall be set up, equipped with safety net and low-voltage lighting equipment, and the construction personnel shall conduct safety education and on-site training in a unified way. After the construction operation is disclosed, they can enter the construction site. The construction personnel shall wear work clothes, masks, safety helmets, protective glasses and fasten their seat belts when working. It is forbidden to overlap and throw objects up and down, and they shall be equipped with ladders and mobile workbench. When in use, it shall be managed and monitored by special personnel.

2. The spraying machinery shall be managed by special personnel, and the gauge pressure of the air compressor shall be controlled at about 6-8kg/㎡. The power cord shall be connected with the construction power distribution cabinet with high-voltage insulated wires, and the power distribution cabinet shall be equipped with panic button, so as to cut off the power supply in case of emergency.

3. Inspection: measure the thickness of each layer after spraying, knock to check the hollowness, and remove the unqualified parts for re-spraying.

4. Materials need to be stored in a ventilated and dry warehouse with a temperature above 0℃, away from fire sources, and rain, exposure, heavy pressure and inversion are prohibited.

quality requirements

1. The coating thickness is greater than the required thickness for fire protection limit.

2. The coating is free from peeling, hollowing, pulverization and cracks.

3. The surface is smooth without unevenness, and the flatness is more than 80%.

4. The appearance and color of the coating are consistent.

5. In order to improve the physical and chemical properties and decoration of the fire retardant coating, it is suggested to make a top coat on the surface of the fire retardant coating, and the top coat should be leveled with putty before construction.

store

Storage period: 6 months.

Storage environment: the temperature in dry and ventilated shade is 5-35℃.