8 myths in the application of polymer cement waterproof coating

Eight myths of the application of cement waterproof coatings
polymer cement waterproof coatings
(JS waterproof coatings), because of its good physical performance, simple construction methods and can be moved on the wet grass, etc. , since the end of the last century, has been rapidly developed and widely used. However, in the process of use, there are also a number of quality problems. On the one hand, it is due to the defects in the quality of the product itself, on the other hand, it has a lot to do with the improper application of the product and the misunderstanding of its understanding by many
industry
.
there is a misunderstanding about the choice of latex and the ratio of ingredients
JS waterproof coating is based on the synthesis of polymer latex modified cement and quartz sand as the main components of the
ormeric gel gel material
, the formation of the coating film with cement gel material with high strength, strong water resistance and other characteristics, but also has flexibility (i.e. elongation). However, polymer latex will also bring some negative effects to cement-based materials, i.e. the decrease in hardness and long-term water resistance and aging resistance, the negative effect size is closely related to the type and doping of latex used (i.e., the modified capacity of latex).
There are two main types of latex used in JS coatings on the market at present -
polypropyl acrylic latex
and
polyethylene-vinyl acetate latex
, the former has better adaptability than the latter, in the case of the same waterproof performance, the former in the paint is significantly less than the latter, its negative effect is significantly less than the latter. However, a considerable number of consumers mistakenly believe that JS coatings, the greater the amount of latex, the better, when buying products, at the same price, usually will choose a large amount of latex coating products.
refore, some manufacturers or merchants in order to increase the amount of latex of their products, in the purchase of latex raw materials, mixed with water and then the preparation of JS paint, the quality and performance of this product is not guaranteed at all. What's more, some construction team in the low-cost contract waterproofing project, with the market-purchased polyvinyl acetate latex (commonly known as white latex) or polyethylene alcohol glue (commonly known as 107 glue) for doping construction, after completion of the waterproof effect should not be, seriously damaged the reputation of JS paint. Some experts believe that the current construction of a large number of JS coatings, the real use of polyacrylate latex may be less than 10%.
not know enough about the use of
The elongation size of JS waterproof coating is directly related to the amount of latex, but the size of latex doping directly affects the long-term water resistance of the coating. In order to solve this contradiction, the technical treatment of engineering specifications and product standards is to subtype JS coatings: I. type for latex dosing is large, the elongation rate requires more than 200%, for
intermittent immersion
of the engineering site (Such as roofing, exterior walls, etc.) to meet its deformation requirements, II. Type is a slightly small amount of latex, elongation rate as long as 80%, to meet the deformation is small but has long-term water resistance requirements of the engineering site (basement, toilet, etc.). However, in many projects there is no distinction between use, from the basement to the roof using a type (I. type or II. type), not only does not achieve the desired effect, but also leads to a number of quality hazards.
the relationship between the thickness of the coating and the number of
the waterproof coating must also have a certain coating thickness as a quality guarantee. In the "Roof Engineering Technical Specification" and "Underground Engineering Waterproofing Technical Specification", the basic thickness requirements of JS coatings are 1.5mm to 2.0mm. However, in the actual engineering design and construction monitoring, often only notice the number of construction times but ignore the final thickness of the coating. Some design drawings only indicate that
using JS waterproof paint a few cloths
" does not indicate the thickness requirements, and site management only cares about painting a few times, do not care how thick brush. This makes some lack of integrity of the construction team can be drilled, the paint and water, than the design requirements to apply one or two times, not only by the site management staff praise, at a low price contracted to the project can also earn a lot of profits.
the importance of on-site mixing state on the performance of the coating film
JS coating is a two-component product, in fact, the product production of the last process - mixing phase, left to the site construction staff to complete. Unbeknowed, the two-part product mixing phase state is very important to the formation of coating performance. JS paint for powder-liquid double-parts, not as easy as other liquid-liquid two-group products mixing and mixing, although the manufacturers of product manuals have explained the correct method of on-site mixing, but many construction team mixing process is perfunctory, some do not even have a special mixer, the scene to find a stick hand-mixed a few times, almost no one knows how to judge the final form of the coating film performance because of mixing.
the misunderstanding of stretch strength
In the product standard of JS coating, the requirements for coating film extrusion strength are I.≥1.2MPa and II.≥1.8MPa, respectively. Many people mistakenly believe that the higher the stretch strength, the better, in fact, it is not. In the extrusion performance test method of JS coating, there is a 24-hour test of 50 degrees C heating maintenance after 7 days of maintenance, and many coating products in the process due to the volatile migration of plasticizers lead to rapid growth in stretch strength, indicating that these products in the exposure to the use of thermal aging performance changes quickly, life is not long. Therefore, for products with unusually high stretch strength, alertness should be raised and, if necessary, thermal aging hold-up tests can be performed, rather than one-sidedly considering that the higher the stretch strength, the better.
set the tire base position at will
in the node details of some projects, in order to avoid stress concentration, the addition of tire base to spread the stress, reduce the phenomenon of coating cracking. Therefore,
the setting of the fetal base position directly affects the use effect
, which should be the closer the fetal base to the grass roots, the more it can achieve the role of dispersed stress. In fact, many projects set the tire base position at will, but no one asked, and set in the middle of the coating for many, and some projects should lay the tire base on the coating surface, which will also lead to the completion of the project, waterproof effect is not good.
one-sided understanding of the "can be called construction in the wet
" JS waterproof coating is different from other waterproof coatings, can be built in the wet grass, but also pay attention to the degree of humidity, not that any humid climate conditions or what kind of grass water content can be constructed. The latex in JS coating is cured by volatile,
excessive grass water content and too humid climatic conditions are detrimental to the curing film of latex
, which will reduce the elongation rate of the coating film. At the same time, the cement in JS coating is cured by hydration, too dry grass and climatic conditions are not conducive to cement curing, so in the hot and dry season construction should be slightly sprayed at the grass roots before construction. In addition, JS coating on the construction of the temperature and humidity range there are some requirements, generally should ensure that the temperature in 5 degrees C to 35 degrees C, humidity in 50% to 70%, regardless of temperature and humidity conditions at will to construct JS coatings, although can also be filmed, but the coating performance is far away.
Misconceptions about water-added deployment
most manufacturers will explain in their product descriptions that the coating can be diluted with water during the first brushing construction to improve penetration of the grass roots and improve the bonding power of the grass roots. Therefore, many people mistakenly think that
JS paint can be free to add water, in fact,
is wrong
. The ratio of two components in JS coatings - the poly ash ratio (the ratio of polymer to cement) and the water ash ratio (the ratio of water to cement) is determined by the manufacturer through a number of test studies, and any change in one of the components has a great effect on the performance of the coating film. In the actual project any increase in the amount of powder and then casually add water to adjust the consistency of the phenomenon abounds, which also makes the waterproof effect of JS paint greatly reduced.