Sewage tank polyurea antiseptic scheme
Since August 2007, our company has undertaken the anti-corrosion projects of the sewage pools and drainage ditch of your company's 320, 510, 521, 515, 517 and other workshops. Each workshop pool adopts epoxy mortar layer plugging and anti-corrosion scheme for modified vinyl ester resin glass fiber reinforced plastic.
Epoxy resins and vinyl ester resins have been widely used in the anti-corrosion treatment of sewage facilities. With the advent of polyurea, the level of anti-corrosion of sewage pools has reached a new level.
The following factors are mainly considered in the workshops of your company when selecting the anti-corrosion of the sewage pool:
1. First, the curing speed of the coating is fast, because the sewage pool generally has only 5 days of downtime;
2. In addition, a small amount of sewage may enter the lagoon during shutdown. If this happens, the pool must be washed again with water and the surface will become damp, so the coating is required to be insensitive to water during construction;
3, the surface is smooth, the sludge is not easy to gather;
4, good corrosion resistance and can withstand changes in pH.
In the anti-corrosion of the pool, polyurea provides a new advanced waterproofing process. Due to the advanced polyurea spraying machine spraying process, the whole construction has no joints and the coating thickness is uniform. The re-dominance of the heterosexual structure is unmatched by traditional anti-corrosion materials, and the excellent physical properties, weather resistance and chemical resistance properties make SPUA spray polyurea elastomer technology the best solution for pool anti-corrosion.
First, the system design
According to the characteristics of the concrete substrate, combined with the anti-corrosion requirements of the sewage pool and the inspection and maintenance work during the production operation, we suggest that the thickness of the polyurea anti-corrosion layer should not be less than 3mm.
Second, the construction steps
1. Preparation for entering the field
Coordinate the various tools, polyurea spraying machines, materials and personnel required at the construction site to ensure smooth implementation of the construction according to the schedule.
2, construction protection
According to the specific construction site conditions, a simple protection barrier is set up to ensure the safety of construction work, wind protection, and protection of the working surface to reduce the degree of pollution. Areas or parts that do not need to be sprayed with polyurea are covered or wrapped to protect them from contamination.
3. Construction base inspection and treatment
1) Surface condition check
A. Contamination check: Check the concrete surface for contamination, including grease, dirt, dust or other splashes. It must be cleaned before the putty is leveled.
B. Base surface defect inspection:
a, edge area and corner parts: all corner parts should be ground into an arc shape, there should be no corners and sharp angles.
2) Base surface processing steps
Step 1: Firstly grind out the cement layer on the concrete surface, thoroughly clean the surface of the pollutants, such as oil, dust, etc., and use the electric wire brush to polish the loose parts of the surface, the dust in the gap and the recess with a brush Carefully clean it.
Step 2: Apply a special interpenetrating interface agent to the parts to be repaired, and then fill or repair the defect with special putty. (The putty itself is generally viscous and has poor permeability. It can only adhere to the gray layer of the concrete surface. If the putty is repaired directly on the concrete surface, the adhesion of the putty from the concrete is generally low.)
Step 3: After the putty is dried and cured, sandpaper is smoothed and smoothed.
4. Polyurea construction:
4.1, special primer for painting polyurea
Before the primer application, the integrity of the construction base should be checked again to ensure that the construction can be carried out without any problems.
1) The role of primer
a. The primer can penetrate into the concrete base, which not only can fix the floating ash of the concrete surface to the base surface, but also can close the capillary structure of the concrete and greatly strengthen the structural strength of the concrete surface.
b. Because the polyurea coating sprayed by the polyurea sprayer is an ultra-fast curing coating, the gel time is only a few seconds or tens of seconds, and it can not be fully wetted with the base surface, which will reduce the adhesion of the polyurea to the substrate. . The special primer is a polyurethane series. It has similar molecular structure and chemical properties to the polyurea coating. It can fully wet the concrete base surface and prevent blank spots on the contact surface between the polyurea layer and the substrate. It can be polyurea coated. Subsequent construction provides a surface that aids in adhesion.
2) Primer construction method
The primer is applied by the roll coating method, and after the primer coating, the solvent in the primer is completely evaporated, and then the next step is performed.
4.2, base protection
When the polyurea is sprayed by the polyurea spraying machine, the polyurea mist will fall on the surrounding construction base and gradually accumulate to form flocs or particles. When the polyurea is sprayed on the already contaminated base surface, the polyurea layer cannot completely cover the floc or particles adhering to the base surface, causing the surface of the polyurea layer to be not smooth or a large amount of sand holes, which is serious. Affect the quality of construction.
Manually cleaning or eradicating the floc or particles on the base surface to be applied in the next step before the polyurea spraying machine works can effectively reduce the defects of the polyurea coating. Before the polyurea coating is applied, the surface of the polyurea coating that has been applied and the area or part that does not need to be sprayed with polyurea are completely covered with plastic cloth, cotton cloth or other coverings, which can ensure the quality of polyurea construction. And can reduce pollution.
4.3, polyurea spraying
1) Construction environmental conditions
The weather should be avoided in wet dew. Generally, the polyurea spray construction requirements meet the following conditions:
a, construction environment temperature: 15 ° C or more;
b. Construction environment humidity: 70% or less;
c. Surface temperature of the workpiece: higher than the dew point temperature of the workpiece by more than 3 °C.
2) Polyurea spraying machine conditions
When in use, the heating temperature of the A material and the R material is set between 65 ° C and 75 ° C, and the heating temperature of the pipe is set between 65 ° C and 75 ° C. The dynamic working pressure of the polyurea sprayer must be maintained above 2000 psi unless a small mixing head is used for good atomization. Depending on the climatic conditions, the specific pressure and temperature settings can be adjusted appropriately.
3) Spraying construction method
a. Because there may be color paste precipitation in the polyol component (R material), before inserting the pump of the polyurea spraying machine into the polyurea raw material tank, the barrel containing the polyol component should be rolled, shaken or Stirring is used to mix the materials evenly to ensure uniform color of the sprayed polyurea layer.
b. The first time of spraying with polyurea spraying machine shall be based on the invisible base surface, no leakage coating point or one coating too thick.
c. The spraying construction should be completed in different areas, and the construction should be carried out in an area of 50m2—100m2.
d. When the construction area is large, first complete the area according to the specified thickness, and the rest of the day will be completed by the same method.
e. Pay attention to the observation during construction and touch it by hand to determine whether the ratio of R component to component A is correct.
f. The thickness and thickness uniformity of the polyurea layer coating are important factors affecting the quality of the project. Therefore, in addition to ensuring that the thickness of the polyurea coating reaches the design thickness, the thickness uniformity of the polyurea coating should also be ensured.
g. For the treatment of special parts, refer to Appendix III, “Special Parts Treatment Methods”.
4) Coating repair
If the coating is unqualified (thickness does not meet the specified requirements; there are leaks, leaks, sag, drums, bubbles, pinholes, etc.) on the surface of the coating, further repair is required. The main processing steps are as follows:
a. Clean the problem coating as required, or repair the flat.
b. Smooth the edges and smooth them.
c. Applying a special interface agent for repairing polyurea coating to enhance the adhesion between polyurea layers.
d. After the primer is cured, the area outside the problem area is shielded or protected to prevent the polyurea from spraying mist or contaminating other parts.
e. Re-spray the polyurea in the problem area.
5) Thickness detection of polyurea
1. The surface after spraying should be evenly cleaned, the color is even, and there is no pit.
2. The thickness is detected by the owner or the supervisor using a thickness tester, and the part where the thickness does not meet the design requirements shall be refilled.
3. Strong impact and other external force damage should be avoided on the surface of the coating within 24 hours after construction. Strong impact and other external damage to the surface of the coating should be avoided within 72 hours after construction in winter.