It should be mentioned that the term “rubber emulsion” is an informal term. Obviously, this term has arisen when observing the characteristics of some construction material that resembles rubber. In practice, the term “liquid rubber” is used more often. According to the classic definition, liquid rubber is a two component bitumen-polymer emulsion. Hence, it appears that the material may be called a liquid rubber when it is liquid and based on bitumen (bitumen-polymer emulsion).
Mankind has been using natural bitumen for a long period of time to solve construction and waterproofing problems. Since the natural resources of bitumen are limited, people have started to derive it from oil and oil products. But, the difficulty is that such material is not a liquid substance and the construction industry requires bitumen to be in a liquid form.
Further, let us consider how the raw material for liquid rubber waterproofing is produced. There are three ways to dilute bitumen.
The first one is called the “hot method” when bitumen is warmed up to between 100 to 200?С.
The second approach involves the dilution of bitumen by special solvents. It is very energy consuming since it requires heating, though to lower temperatures hten used in the hot method. Additionally, the cost of liquid bitumen increases as the cost of the solvent is added to the mixture.
In general, this method is characterized by an increased fire hazard, the risk of explosion and the environment preservation when performing jobs. In some cases, some bubbles and pores are formed on the surface of the waterproofing membrane.
In today’s industry, liquid rubber is obtained from the emulsification of bitumen in water. From a technical point of view, this process may be realized with the help of such equipment as a colloid mill. Usually, it is a part of the more complicated equipment, meant for production of binders. Such units are located at special plants, so it will be difficult to obtain liquid rubber at a remote construction site.
Dispersion is a fine grinding of a substance that allows for obtaining emulsions, powders, and suspensions. When dispersing, solid bodies are broken down. The resulting substance looks like small bitumen droplets evenly distributed in water. These droplets are called bitumen emulsion.
Theoretically, all bitumen particles should be of the same size. But in practice, it is very difficult to achieve such uniformity. Therefore, a certain small size variation is acceptable. The smaller the size of the bitumen particles, the more homogeneous the final product will be.
Theoretically, there should be between 63 to 67% of bitumen particles by volume in a measured unit of emulsion. There are however, some materials where this value is only 30% and results that in a low quality product and is not good for the liquid rubber. On he flip side, too much bitumen will do no good as well. The upper limit is 70%.
If for some reason this limit is exceeded, bitumen droplets will change their shape since the volume of emulsion will not properly contain them. If the content of bitumen is between 63 to 67%, which is recommended when producing liquid rubber, the substance will be liquid enough to ensure the technological effectiveness of laying and fast water withdrawal. If the job is done correctly, there should appear a homogeneous film that is provided by the small size of bitumen particles after spraying emulsion on the surface.
Modification by Latex
To produce a waterproofing layer, bitumen emulsion is sprayed with the help of special units that allow for getting a seamless bitumen film that, in fact, features a waterproofing membrane.
The main disadvantage of such a coating is that it possesses the same characteristics as a coating obtained when heating and spreading the usual bitumen. These characteristics include fragility at freezing temperatures, fluidity at high temperatures, poor adhesion, and destruction under ultraviolet radiation. These difficulties may be avoided if the process modifies the liquid bitumen by the aqueous polymer solution. In other words, it is mixed with latex. So, what is the difference? It’s quite simple. You take a piece of oil bitumen, warm it up and spread it on the surface with an anti-adhesive lubricant. After it cools down, it forms a bitumen film with a thickness of 3 mm. Then you remove the film, take it and give it a pull. What do you think will happen? It will break.
The application of latex as a polymer provides pavement that is resistant to mechanical damages. It is easily stretched and then returns to its original state, firmly fitting to the base. In fact, it is not a bitumen membrane but a bitumen-polymer coating. It preserves all characteristics of bitumen and adopts the physicomechanical charac