Common problems and solutions in the construction

Common problems and solutions in the construction of polymer waterproof coating

polymer waterproof coating is composed of non-toxic and non polluting polymer organic materials and a certain proportion of powder. Because it can bond well with the base course with cement as the cementation material and spandex industry, which takes several months for mass production, and the adaptability of polymer waterproof materials to various waterproof requirements, it has been widely used. In order to make the polymer waterproof coating better meet and serve the requirements of engineering waterproof, it is necessary to further discuss and understand its construction characteristics

I. factors affecting the quality of waterproof layer:

the film formation of polymer waterproof layer has similar characteristics with other varieties of waterproof coatings; That is, in addition to the quality of the material itself, the formation of the waterproof layer depends on the quality of the tread of the membrane, that is, the surface quality assurance of the waterproof building. The second is the process of forming the waterproof coating. The third is the protection and durability of the waterproof layer after forming. The factors affecting the quality of the waterproof layer of the polymer waterproof coating are:

the quality of the waterproof material itself: refers to the amount of raw materials, Whether the mix proportion is appropriate and correct

surface shape of waterproof base: refers to the slope, flatness, edges, corners and details of the surface to be waterproof

quality of waterproof base: refers to the internal quality of the base, whether it is firmly combined with the structure, without hollowing, cracking, delamination, peeling, surface smoothness, smoothness, etc

the process and environment of the film forming process refers to the process operation method of the multi pass film forming process, the quality of the inter pass stacking process, the control of harmful environment, etc

protection of the process and end of the waterproof layer: the construction process of the waterproof coating layer is often in the cross environment of multiple types of work, which requires the protection of the whole process. At the end, it is necessary to construct the protective layer in time to ensure the construction results

II. Cause analysis and overcoming methods of common construction quality problems

according to the cause analysis of the quality of the waterproof layer of polymer waterproof coating, there are many factors. In addition to the verification of the certificate of conformity and on-site sampling inspection of the material quality according to the regulations, this paper mainly refers to the common construction quality status in the construction site operation process after the completion of the base course, and summarizes the overcoming and treatment methods of construction practice

(I) quality problems caused by improper quality of the base course

1. Cracking of the waterproof membrane: it usually occurs at the water outlet, around the embedded parts, the installation joints of the prefabricated objects, the pipeline crossing parts, etc. due to temperature deformation, structural stress, the embedded parts are not firm, the secondary pouring is not solid, and the change of pipelines or facilities, structural cracks and cracks are generated, which drives the cracking of the waterproof membrane

overcoming methods: during the acceptance inspection of the base course, we should understand the structure of the building structure, strengthen the inspection of the parts where the results are suitable to produce cracks, and negotiate with the designer to strengthen the waterproof operation of this part, such as setting a waterproof coating reinforcing layer

2. Irregular waterproof layer damage and crack: the location of occurrence is uncertain and the crack is irregular. It is mainly due to the hollowing and cracking of the surface cement mortar of the structure, which drives the cracking of the waterproof membrane; Or the area of the surface cement mortar is too long, which cracks under the action of temperature, driving the cracking of the waterproof membrane

overcoming method: carefully check the surface quality of the base course before operation to see if there are hollows and cracks. Whether there are separation joint measures for large-area base

3. External corner trauma: because the external corner of the base is relatively sharp, it is not made into an arc corner according to the specification requirements, which makes it difficult for the external corner to hang and adhere to the coating of sufficient thickness. At the same time, the sharp corner is easy to be damaged by external forces, resulting in the defect of the waterproof layer

overcoming method: the external corners of the base must be accepted according to the specified arc corners, and those that do not meet the requirements should be repaired. During the construction process, the protection of the external corner coating should be strengthened, or a cloth tire reinforcing layer should be added, such as at the crossings with frequent human logistics

4. Exposed sand on the surface of the coating: some base courses do not have iron troweling, and sand particles are exposed; The coating layer has sand particles protruding, making the waterproof layer incomplete or vulnerable

overcoming method: if there is sand outburst during the base course inspection, it can be removed by grinding with a grindstone

5. There are protruding edges on the coating surface: the surface of the base course is rough and uneven, forming a strip-shaped protruding edge at the concave convex junction. The coating thickness at the protruding edge is insufficient and vulnerable, making the waterproof layer incomplete

overcoming methods: use a sanding wheel to make film ridges, or fill the concave grooves

6. Local isolation: the base course is polluted and bonded by a certain thickness of silty materials such as clay and ground ash before operation, so that the waterproof layer cannot penetrate and combine with the base course, so that the waterproof layer is isolated from the base course. Under the action of external forces, the waterproof layer at this part is broken, causing the integrity of the waterproof layer to be damaged

solution: clean the polluted surface carefully

7. Delamination: it refers to that the waterproof layer cannot be bonded with the surface of the structure to be waterproof. Generally, it is the construction sequence of the waterproof layer first and then the structural layer for external prevention and internal coating. For example, in the basement floor, the waterproof layer can only be made on the cushion of the structure first, and then the mortar or fine aggregate concrete protective layer of the waterproof layer is made after the waterproof layer is completed, resulting in the separation of the waterproof layer from the structural surface. If the cushion breaks during settlement, the waterproof layer will also break, causing the integrity of the waterproof layer to be damaged

overcoming method: improve the current structural practice, see another discussion of the author

8. Structural cracking: refers to the damage and cracking of the waterproof layer caused by the accidental cracking of the structure, which is caused by the deformation of the structure beyond the allowable bearing capacity of the design. This kind of cracking is often unpredictable

overcoming methods; There is no preventive method before coating operation. If it occurs, the waterproof layer can be reinforced and repaired only after the structure is repaired

9. Sand inclusion: uncompacted from the base course: during the brushing process, individual sand particles are turned up and mixed into the paint to form an uncompacted coating with sand holes

overcoming methods; Check carefully before construction, and remove or reinforce the surface that may sand in case of any inaccuracy

(II) quality problems caused by improper operation process of waterproof layer

1. Falling: generally occurs on the facade or slope with large slope. As the base course is relatively smooth, the first layer of painting is not too thick, resulting in falling; Or the coating of the lower layer is applied with the coating of the upper layer that has not solidified, and the coating of the lower layer that has not solidified will fall together. The falling waterproof layer causes insufficient thickness of local coating, and the falling coating is easy to wrinkle, which is high and vulnerable

overcoming method: strengthen the control of brushing thickness and pass time to prevent the occurrence of falling. The sags that have occurred should be carefully eliminated and repaired

2. Thick wrinkle: it occurs on the plane, the slope with small slope, the corner, etc. due to the uneven and concave base, the ductility of the coating makes the coating gather in the low-lying parts, making the coating thicker. The covering of the previous layer of coating makes the water here difficult to evaporate. In the later stage of molding, the water here finally evaporates, and the wrinkle occurs. The wrinkle with small thickness affects the appearance quality, and the wrinkle with large thickness will produce the linear thinning of the coating layer

overcoming methods: the low-lying areas on the surface shall be filled with base paint first, or locally coated with paint first, so as to reduce and prevent the accumulation and thickening of paint

3, delamination and peeling; The waterproof layer is painted and formed by several times. If the time of dividing the layers is too long, the combination between the layers of the waterproof layer is poor and there is layering phenomenon. If the time is long and there is foreign matter pollution and isolation on the layer, the separation of the upper layer may cause peeling, which affects the internal quality of the waterproof layer, and the effective thickness of the waterproof layer is insufficient

overcoming method: strictly control the time interval of each pass according to the actual environmental conditions, prevent the pollution of the surface of the pass, and remove the existing pollution. The peeled ones shall be removed and repaired. The method of thickening and reinforcement shall be adopted for the layered ones according to the situation

4. Wind pollution and rain separation: during construction in windy days, the surface of the coating is stained with silt and other pollutants due to the large amount of dust in the environment. Rain barrier refers to the continuous rainy days during the construction process, which causes a long interval between layers, affecting the combination of upper and lower coatings

overcoming method: referring to the above layering and peeling method is to overcome the treatment

5. Sand staining: when the paint is not condensed, the sand brought by the operation forms local sand staining. If the personnel step on the shoes, or the machines and tools move, the result of sand staining will slightly affect the bonding of the layers, and seriously cause sand holes in the coating

overcoming method: the brushing operation should be withdrawn to the channel, and the construction process should have anti trampling measures. It should be checked before each operation. For high-tech enterprises with local sand, which are formed by gathering the domestic top powder metallurgy composite expert team, it should be cleaned or brushed and reinforced

6. Dry polymerization: it is mainly constructed under high temperature and sunlight, and some surfaces are relatively dry. After painting, the water content of the coating is quickly evaporated or sucked dry, so that the organic powder in the coating cannot play a role, resulting in brittle defects of the coating

overcoming method: the painting operation should avoid the period of high temperature and high evaporation, and the dry and hot base should be sprayed with an appropriate amount of water 24 hours in advance

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7. Trauma: refers to various forms of trauma caused by the collision of personnel or machines and tools due to improper protection during each operation. It usually occurs in areas with large personnel logistics, such as both sides of the channel, exit thresholds, corners, etc., and is caused by the next or cross process of the coating

overcoming methods: reliable precautions should be taken against parts that are easy to be damaged. The operation area should be closed, the flow route of people should be delimited, warnings should be set, and frequently vulnerable openings should be covered with protective covers. The next or surrounding cross operation processes should be protected, and the measures should be reliable, effective and complete

8. Reinforced cloth layer separation: refers to the parts designed with tire cloth reinforcement. Because the tire cloth cannot invade the coating layer, the reinforcement is separated up and down, or partially suspended. It is mainly caused by the reinforcement cloth not being pressed in time or partially bouncing and hanging in the air after the next painting, or the lower coating is too thin to fully soak and stick the reinforcement cloth. Some details have complex shapes, which make the reinforcing cloth wrinkled and cannot be completely soaked with paint. The overlapping part of the cloth is prone to dry sticking

overcoming method: it is better to choose textile reinforced cloth, so that the upper and lower layers of paint at the reinforced cloth can be filled with paint through many textile cloth holes, so as to achieve the integration of adhesion and dissolution between the upper and lower layers. The next coat of cloth to be laid shall be thickened appropriately, and the cloth shall be soaked and compacted in time. For details, measures should be taken to prevent rebound, and the wrinkled parts should be painted many times to ensure that the coating is saturated. The overlapping part shall be coated with overlapping adhesive paint

9. Improper handling of details: it refers to insufficient or omitted details that fail to meet the design requirements of the specification, and the process sequence is wrong

10. Improper structure of protective layer: there are many forms of protective layer of coating waterproof layer. How to structure depends on the market of China's plastic machinery enterprises. According to the design, improper structure refers to that it is not firmly adhered to the waterproof layer, and the separation of the separation is not complete. Secondly, the waterproof layer is damaged due to the untimely construction or the construction of the protective layer. Thirdly, the quality of the protective layer cannot meet the requirements, resulting in the damage of the waterproof layer

overcoming method: work carefully according to the different forms and structures of the protective layer, strengthen the effective protection of the waterproof layer during the construction of the protective layer, and work on the protective layer in time

(III) quality problems caused by cooperative division and management of waterproof layer operation

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