The liquid rubber – what is it ?
The name of «liquid rubber» is well-knownalready to many professionals, builders and other consumers of construction services and products: advertising, research results, many articles on the Internet and print publications describe in detail the various products that are grouped according to this term and we are not going to discuss this topic in the framework of the proposed article.
What we propose here is to objectively consider only the one interesting detail which is not often found in our lives so directly, namely the fact of strange substitution of terms and concepts, not criticizing specific products and different points of view, but only to show their composition, properties and characteristics together exactly and impartially, giving Dear Readers to make the right conclusion and choice.
To begin with, the term «liquid rubber» often explained as "bitumen-polymer emulsion, water-based ...": Let’s just think about it, we are faced with a variety of terms in our life, that describe different aspects of our life quite accurately and, in this case, all it is - "bitumen-polymer emulsion" consists of bitumen, polymer and water, but where's the tires !?
If we bear in mind the "polymer", we must understand that its content in the bitumen-polymer emulsion is from 10% to 15% (i.e. - an aqueous emulsion of chloroprene latex), respectively, it should be called the "liquid bitumen" or "water-bitumen emulsion ", but not rubber! The so-called "modified bitumen" (bitumen with polymer additives) is increasingly used in various fields such as road construction, which is explained by only the physical properties of bitumen as a cheap, but short-lived and extremely unstable to aggressive environments material in its pure form. In this case, only its application in waterproofing coatings in construction somehow mistakenly referred to as "liquid rubber", which is obviously a misnomer, leading to a lack of understanding of the product and its scope.
Next, let's briefly review the principle of formation of a protective coating of bitumen-polymer emulsion and how it works:
The dispersed particles of bitumen in water (about 45% - 65% of total product), coated with a thin film of surfactant (emulsifier), carry a positive electric charge, which allows them to repel each other and do not "adhere" in the water forming an emulsion. Obviously, when removing the electric charge in any way, the particles of bitumen should be, almost instantaneously (in view of their small size and high density), connect with each other - to coagulate and to form a solid, whole bitumen coating. How to achieve this? It’s simply: to enter in any electrolyte solution, removing an electrostatic charge from the bitumen particles. The most simple and inexpensive electrolyte used in all the proposed bitumen-polymer emulsions : an aqueous solution of calcium chloride salt (CaCl). Those from dear readers who have seen this process on their own, would agree that it looks very impressive: two liquids are converted into bitumen coating, right at the time of application, almost instantly!
Whathappens to the major component of the emulsion mass - water or in this case with salt solution already when the two-component emulsion is applied on the insulated substrate? Obviously, if the salt solution can not pass through the solid insulated surface (concrete, metal, etc.) - it goes "up" through a bituminous mat, forming a puddle and drops on the surface. We already know that salt instantaneously (at the speed of light!) removes an electric charge to the particles of bitumen that instantly coagulates it- the same happens when the saline goes up – i.e. bulk salt solution forms a lot of channels passing through the formed carpet which, strictly speaking, is no longer fully insulating coating.
But here there is one problem: some of the salt solution, nevertheless, remains under the coating. The simplest proof of this fact is that the water based material has absolutely no adhesion (does not stick) to the surface, even slightly moistened with water! This happens because of the salt, remaining under the coverage, and it has a much stronger adhesion to the substrate. We are constantly confronted with salt solutions of calcium chloride and sodium living in cities - these salts are used, in particular, for anti-icing treatment of our roads and pedestrian areas. We all know how aggressive these salts, we know how they are destroying our shoes, and even the asphalt, but we are not always aware of how quickly they corrode metal, concrete and destroy the top layer of the base in a few years.
There are a number of strange unexplained "properties" of bituminous coatings also, sometimes declared as if "in addition": an independent "healing" gaps and cracks of the coatings for example - that we will consider as part of this objective discussion, it is obvious absurd and frankly ridiculous - simply because the melting of any substance does occur in nature sometimes, but in the case of bitumen (melting point about 90C), it is not independent.
Thus, summing up this short review, we just want to emphasize the following:
- The term «liquid rubber» is suitable for the liquid polymeric materials, in fact consisting of a rubber-like polymers. For bitumen-polymer materials - the most correct name is "bitumen, polymer modified" or something like that;
- Bitumen-polymer emulsion is a convenient, low-cost material for certain types of waterproofing works, providing fast and secure seamless membrane formation of polymer-modified bitumen with low labor costs;
- The service life of bitumen-polymer materialsis limited by durability of the main component - the bitumen (because of the small volume part of a polymer) and is, for waterproofing purposes, no more than 3-4 years;
- The usage of the bi-component bituminous materials for waterproofing is limited by the presence of calcium chloride salt, used as the second component of the bitumen-polymer emulsion, which is strongly aggressive to concrete and metal bases and destroys them, thereby narrowing the range of use of this materials.
We hope that this review will help you get a more objective picture in a variety of modern market offers and make the most correct and profitable for you to choose from!