Polymer cement waterproof coating, JS waterproof coating for short, with its good physical properties, simple construction methods and can be constructed on the wet grass, etc., has been rapidly developed and widely used since the end of the last century to the beginning of this century. However, in recent years, this type of product has caused a great number of quality problems, leaving a bad impression on many construction units and management departments. It is regrettable that new products have faced the embarrassment of being inferior to inferior ones in less than a decade after the advent of new products. The reason is that in addition to the low price competition manufacturers' intention to sacrifice quality and poor supervision of the construction process, it is also related to the improper application of this product. . Why is it misapplied? This is related to the misconceptions that many people in the industry have about this product. Waterproof experts summarize it for you:

1. Misunderstanding of latex selection and ingredient ratio

The basic principle of JS waterproof coating is the inorganic cementitious material whose main component is cement and quartz sand modified by synthetic polymer polymer latex. The formed coating film basically maintains the high strength and strong water resistance of the cement cement material. Based on the characteristics, its flexibility (ie, elongation) is maximized. At the same time, polymer latex also brings a negative effect, namely the decrease of hardness and the weakening of long-term water resistance and aging resistance. The negative effect size is closely related to the type and amount of latex used (ie, the modification ability of latex). There are two main types of latex used in JS coatings on the market - polyacrylate latex and polyethylene-vinyl acetate latex. The former has better modification ability than the latter, and the former with the same performance is also significantly less than the latter, and the negative effect is also significantly less than the latter. However, most people mistakenly believe that JS paint should be used as much as possible, and the better the amount of latex used, the more the same price should be used when selecting products from different manufacturers. Therefore, some manufacturers or businesses in order to show that the amount of latex used in their products, the purchase of latex raw materials mixed with water before the preparation of JS coatings, its product quality and real JS coating far, even worse, some construction teams in After low-cost contracted waterproof projects, the use of commercially available polyvinyl acetate latex (commonly known as white latex) or polyvinyl alcohol glue (commonly known as 107 glue) after the construction of mixed, the consequences of disastrous, seriously damaged the reputation of JS coatings. Of the JS paints currently used extensively in construction projects, less than 10% of polyacrylic acid latexes are actually used, which is the main reason why JS paints slide into “low-quality” products.

2, lack of understanding of the use of classification

JS waterproof coating elongation and the amount of latex directly related to the size, but the size of the latex directly affects the long-term water resistance of the coating, in order to resolve this conflict, the technical specifications of the engineering specification and product standards will be JS coating Divided into two types, Type I is a large amount of latex, elongation requirements of more than 200%, for intermittent water immersion in the engineering parts (such as roof, exterior wall, etc.) to meet the larger deformation requirements. Type II uses slightly less latex and has an elongation as high as 80% to meet the engineering site (basement, toilet room, etc.) with small deformation but long-term water resistance requirements. However, in many projects, there is no distinction between use, from the basement to There is one type of roofing, Type I or Type II, not only failing to achieve the desired results, but also many quality risks, disappointing.

3, coating thickness and the number of construction times

Even the best waterproof coating must have a certain coating thickness as a guarantee of quality. In the Technical Specifications for Roof Engineering and Technical Specifications for Underground Engineering, the basic thickness of JS coatings is 1.5 to 2.0 mm. In the actual project design and construction monitoring, only the number of construction times is ignored but the final thickness of the coating is ignored. It is often seen that some design drawings only indicate “the use of JS waterproof coating several coats of cloth” without indicating the thickness requirements. Site management also only cares about painting several times. For some lack of integrity of the construction team drill hole, add water to dilute the paint, than the design requirements painted one or two times also get the praise of on-site management personnel, in the low-cost contract to the project can also make a lot of profit , The product with excellent performance can't stand such damage.

4, ignoring the importance of on-site mixing state of the film performance

JS coating is a two-component product. It is actually the last process of product production—mixing and phase separation, left to the on-site construction team to complete. It is not known that the "mixed" and "phased" states of two-component products are critical to the formation of film properties, and that JS coatings are "powder-liquid" two-component rather than other "liquid-liquid" components. Mixing and phase separation of products is easy. Although the manufacturer's product manuals all show the correct method of on-site mixing, many of the construction team's mixing processes are perfunctory, and some do not even have dedicated stirrers. The on-site finding sticks are manually mixed and stirred. A very small number of people know the judgment and mastery of the “phase end point”, and the performance of the final molded film is greatly compromised because of incomplete mixing and phase separation.

5, misunderstanding of the tensile strength

In the JS coating product standard, the tensile strength requirements for the coating film are I type ≥ 1.2MPa, type II ≥ 1.8MPa, many people mistakenly believe that the higher the tensile strength, the better, in fact, otherwise, in the JS coating stretching Among the performance test methods, there is a standard curing process of heating and curing at 50°C for 24 hours after 7 days. Many coating products have a rapid increase in tensile strength due to the migration of plasticizers during the heat curing process at 50°C, indicating that these products are exposed. The use of heat aging in the performance changes quickly and does not last long. Therefore, products with abnormally high tensile strength should be vigilant. If necessary, heat aging retention test can be done. Rather than unilaterally thinking that the higher the tensile strength, the better.

6, randomly set the base position

In some engineering details of the joints, in order to avoid stress concentration, additional carcass layers are used to extend the dispersion stress and reduce cracking of the coating. Therefore, the position of the tire base directly affects the use effect. It should be that the closer the tread base is to the base layer, the more it can achieve the effect of decentralized stress. Actually, many projects randomly set the position of the tire base uninterested to set it in the middle of the coating. In some projects, the foundation of the tire is laid on the surface of the coating. I once found this phenomenon at a construction site and asked why the construction personnel exposed the foundation to the surface. The co-workers answered: “The money that the contractor will use to settle the child’s foundation” is ridiculous.

7, one-sided understanding "can be in the wet base construction."

JS waterproof coating is more than other waterproof coating features can be used in the wet base construction, there is a degree of moisture, not that any humid climate conditions or very high primary moisture content can be applied under construction, because JS coating latex Is cured by volatilization, too high base layer moisture content and too humid climatic conditions on the latex curing film is unfavorable, will reduce the coating elongation. At the same time, the cement in JS coating is cured by hydration. The base layer and weather conditions that are too dry are not good for cement curing. Therefore, during the hot dry season, some water should be sprayed on the base layer before construction. In fact, JS coatings still have some requirements on the construction temperature and humidity range. Generally, the temperature is between 5°C and 35°C, and the humidity is between 50% and 70%. It is suitable for construction despite the temperature and humidity conditions, although it can also form a film. However, the performance of coating film is far away.

8, misunderstanding of the deployment of water can be added

Most of the manufacturers stated in their product specification that when the first pass is applied, water can be added to dilute the paint to improve the penetration of the base layer and increase the adhesion to the base layer. Therefore, many people misunderstood as JS coating is free to add water, which is very harmful, JS coating two component ratio - poly ash ratio (polymer and cement ratio) and water-cement ratio (water and cement ratio ) is determined by the manufacturer through multiple tests. Any change in one of the components is more significant than the effect on the film performance. The phenomenon of increasing the amount of powder and then adding water to adjust the consistency in the actual project is abound. Many projects are using the name of JS coatings to steal materials, so that the application of JS coatings will continue.