Construction Technology Scheme and Method of Spraying Polyurea Waterproof Coating

In recent years, polyurea waterproof coating has been applied in more and more high-quality waterproof and anti-corrosion projects; Its excellent waterproof effect has been unanimously affirmed by many owners;

Polyurea waterproof construction technology;

Technical Scheme for Spraying Polyurea Elastic Waterproof Coating

Construction steps of polyurea spraying:

1、 Calibration equipment: Wiring inspection of spraying equipment. The total current required by the spraying equipment is 60A. The on-site electrician shall wire safely.

Calibration of painting equipment. Before spraying, the host and other equipment shall be calibrated. First, check whether the power connection phase (positive and negative) is correct, and then check whether the following equipment is normal.

A. Check whether the oil-water separator of the air compressor operates normally;

B. Whether the heating system of the spraying host can operate normally;

C. Whether the connection between the output air pipe and the air pipe of the host is normal;

D. Release the water in the oil gas separator in the air compressor cylinder to prevent the water from spraying out with the building paint to reduce the performance of raw materials;

E. Check whether the temperature of raw materials is in the effective range (21 ℃ - 45 ℃). If the temperature is too low, heat the raw materials properly.

2、 Base course treatment:

First check whether the surface layer of the base course (including the root of the safety protection wall) can be leveled, cleaned, dry or free of water, no hollowing, loosening, honeycomb pitted surface, scum, floating ash, mold release agent and oil stain. If so, use solvents, detergents and other methods to remove oil stains, asphalt and other foreign matters from the substrate surface, and wash with water to dry. Secondly, shot peening is preferred to treat the concrete surface to form the required roughness (0.4-0.7mm). Meanwhile, equipment with the function of simultaneous removal of laitance and dust absorption is used to properly treat the base course of bridge deck concrete. And clean the loose and porous parts of the concrete surface. Finally, use polymer cement mortar, polyurethane or epoxy resin mortar, putty paste or mortar (the strength is not lower than the base strength) to smooth the surface defects of the base course such as dents and holes. After curing, grind them flat. Use clean, dry compressed air or vacuum cleaning method to remove the dust and debris on the base course surface. The metal base course shall be derusted.

3、 Base course primer:

The roller coating or spraying process is adopted for the construction of the base course treatment agent to improve the efficiency, ensure the quality and reduce losses. Where there are many surface defects, coating construction shall be carried out so that the base treatment agent can penetrate into the pores of the base material and easily penetrate into corners and voids.

4、 Spraying waterproof layer:

A. After the construction of the base course treatment agent, spray the polyurea elastic coating before the curing of the base course treatment agent, so that the chemical reaction between the polyurea elastic coating and the base treatment agent will occur and the chemical binding force will be generated. It is forbidden to spray polyurea waterproof coating after the foundation treatment agent has solidified..

B. The spraying method shall be determined according to the construction operability and construction time, that is, mechanical spraying or manual spraying. The general principle is: mainly mechanical spraying, supplemented by manual spraying. Mechanical spraying method should be adopted when the rain is fully waterproof and large-area spraying; The corners should be sprayed manually. If manual spraying is adopted, the spray gun shall be perpendicular to the base course to be sprayed, with moderate distance and uniform moving speed. The spraying sequence is from difficult to easy. From top to bottom, it shall be continuously operated for one or more times. The vertical and horizontal spraying shall meet the design requirements.

C. For the coating to be overlapped, if the spraying time interval is short (≤ 3h), the surface within 80mm of the coating joint edge shall be polished and cleaned, and then the polyurea waterproof coating of the same material shall be sprayed directly for the second time. If the spraying time is long (>3h), the surface within 80mm of the coating joint edge shall be polished and cleaned, and then the adhesive shall be brushed after it is completely waterproof. After the surface is dry, the polyurea elastic coating of the same material shall be sprayed to make the whole coating continuous, dense and even. During spraying operation, if any abnormal condition is found, the operation shall be stopped immediately, and the construction can be continued only after the fault is checked and eliminated.

D. After spraying, the polyurea surface shall be checked on site for flatness, no sagging, pinholes, bubbles, hollowing, cracking and foreign matters.

5、 Spraying surface (exposed part):

First, clean the surface of the polyurea waterproof layer in the corresponding area to ensure that the surface of the rain proof polyurea waterproof layer is dry and free of dust, oil and other contaminants. Secondly, the aliphatic polyurea surface layer shall be constructed by spraying or roller coating, and the corner grooves shall be supplemented by brush coating. No people or vehicles are allowed to pass before the coating is cured and within the specified time. Finally, visual inspection shall be conducted after construction. The surface layer shall be painted evenly with uniform color and shall not be missed. The coating shall be free of bubbles, cracks and peeling.

Inspection and acceptance:

After painting, acceptance shall be carried out in time. After the acceptance, the unexposed parts shall be constructed in time, and attention shall be paid to the protection of spray polyurea layer.