- The essence and properties of the material
- Delivery forms
- Base for coating
- Application technique
- Coating maintenance and repair
The question of choosing a covering for the courtyard of a country house is rarely put at the forefront, at the same time, certain types of materials provide different operational properties. Today we will talk about one of the most unusual coatings – rubber crumb, its varieties and work technology.
The essence and properties of the material
Crumb rubber is a product of secondary processing of industrial rubber products, as a rule, automobile tires. During the manufacturing process, rubber is cleaned of contaminants, crushed and sorted into fractions, sometimes colored. The highest quality material is obtained as a result of complex thermochemical treatment, at the output a porous crumb is formed, colored in the mass and equipped with a certain set of physical and mechanical properties.
As a rule, rubber chips are used as a filler for road or floor coverings. In the mass of the finished coating, the grain is bound with glue – usually polyurethane, less often based on silicone. Due to the chemical homogeneity of the components, high-quality adhesion is observed, while the application method can be either manual or automatic using a gunning machine. As a result, a coating layer up to 30 mm thick lays on a solid and rigid base, thus providing protection against erosion, ultraviolet radiation and mechanical damage. Rubber coatings do not necessarily have to be used only in the walk-through area; this material has proven itself as a roofing material, as well as for finishing open terraces and building facades.
The crumb rubber coating is lightweight and durable, but at the same time provides a highly hydrophobic surface. Many are attracted by physical and mechanical qualities: elasticity, resistance to harsh mechanical stress and anti-slip properties. Due to its elasticity, the coating can stretch freely and survive thermal expansion in the absence of expansion joints, that is, it can be laid in a continuous contour over an unlimited area. Due to the application of crumb rubber, hard surfaces become much less traumatic, which explains the high popularity of the material in the decoration of gyms and children’s playgrounds. The crumb can also be used for interior decoration: neither EPDM rubber nor glue contain volatile compounds, the only unpleasant quality of such a coating is a specific smell at the first time after application.
In the construction market, crumb rubber is not at all uncommon. It first appeared about 20 years ago, during which time the material has gone along the path of evolution from free-flowing granules to ready-made roll coatings, tiles and multicomponent mixtures ready for application..
In the standard form of delivery, bulk crumbs are distinguished by color, shape and size of the fraction. This is the most affordable type of material, at the moment the price per kilogram of crumbs does not exceed 20 rubles, with bulk purchase volumes – no more than 15 rubles. The cheapest crumb is black, the coatings from it are colored after application, you can also buy granules with a colored coating on a polyurethane base.
The shape of the granules can also vary. The most popular are cube-shaped chips; there are also shapeless granules and crushed needle-shaped rubber. The advantage of the latter type is a strong binding of the filler in the coating massif, which ensures extremely high resistance to damage. In terms of size, the crumb is subdivided into small (up to 2 mm), medium (2–4 mm) and large (from 5 mm) fractions. The larger the filler, the lower the specific gravity of the coating, however, it is when small chips are used that the highest strength values are achieved.
Also crumb rubber can be supplied in the form of tiles or rolls, which are glued to the base. As a rule, this format of products is preferable for the device of removable coatings, however, there are cases of surface finishing with a large area using seamless technology. The thickness of the finished products can be absolutely any, but the practical limit is 20 mm.
Base for coating
The appearance, performance and durability of crumb rubber coatings are largely dependent on the substrate. On the one hand, due to its elasticity, the material is undemanding to the rigidity and solidity of the base, however, under intense loads, vibrations of the substrate can lead to cracks and tears. It should be noted that when performing work on applying crumb rubber by third-party specialists, the preparation of the coating is almost always performed by the customer..
The classic method for preparing the base is the pouring of a concrete screed. This method is usually used in the manufacture of coatings that are under the open sky at all times. A strong and monolithic base guarantees the safety of rubber spraying for a long time at an operating load of more than 1 t / m2. Also, the screed surface can be suitably treated to ensure good adhesion. As a rule, for this purpose, the screed, after holding for 28 days, is subjected to grinding to remove the upper low-strength layer. Immediately before applying crumb rubber, the surface is coated with a primer for self-leveling polymer floors, which can be replaced with polyurethane glue diluted to 1/3 of the initial concentration with a solvent of the corresponding type.
Another base option is tongue-and-groove flooring. The fastening on the locks excludes the deflection of individual boards, due to which high resistance to concentrated loads is provided. The same properties of the base can be achieved by sheathing the flooring from a conventional edged board with sheet materials. The quality of adhesion to the coating is ensured by removing lint from the surface of the wood, thoroughly drying it and removing greasy stains. Additionally, we note that the wooden base does not have to be rigid: the elastic coating perfectly perceives the vibrations of the base and eliminates the feeling of sagging when walking.
The crumb rubber is mixed with polyurethane adhesive immediately before application. Mixing should be carried out continuously using a hand mixer as thoroughly as possible in portions up to 40-50 kg. The most important condition for preparing the mixture is to ensure that the glue envelops the filler over the entire surface. In general, the ratio of crumb and binder by weight is 4: 1, however, depending on the viscosity of the glue, it can be diluted by adding about 1/4 of the solvent. Also, when kneading the crumb, coloring pigments and reinforcing fibers can be used, they are added before adding glue.
On average, the consumption of cooked crumb is from 7 to 10 kg per 1 m2. The prepared mixture is evenly scattered over a limited area, based on the average consumption rate, then distributed as a rule until a visually flat surface is formed. Depending on the brand of glue, the life of the composition can be from 1 to 4 hours, therefore, it is necessary to properly schedule the sequence of work. When the composition is spread over the surface, it is crushed using a wide trowel or roller. The degree of shrinkage during crumb compaction should be about 20-25%.
To prevent the glue with crumbs from sticking to the tools, they are wiped with a cloth abundantly moistened with turpentine before use. In general, the coating technology is very similar to the process of paving asphalt concrete, with the only difference that the compaction force must be significantly less. It is very important that in the course of the work it is excluded the ingress of water on the base or into the mixture, this greatly reduces the life of the mixture.
Coating maintenance and repair
The upper layer of crumb rubber has a porous structure, which is why it is susceptible to the accumulation of dust and dirt. It is convenient to clean using household detergents with active foaming. Strong contamination can be removed by active chemistry; all coating components are insensitive to alkalis and acids. The main danger for crumb rubber is presented by automotive technical fluids, as well as organic solvents. If they get on the surface, it is necessary to absorb the remnants of the caustic liquid with paper or chalk powder as soon as possible, and then thoroughly wash the damaged area with a detergent.
Rubber crumb practically does not wear out and retains its integrity for at least 10 years. Damage is only possible when exposed to cutting tools or from falling heavy solid objects. All kinds of defects are very easily eliminated, it is enough just to preserve part of the crumb with the desired color tone in advance as a repair kit. The edges of the damaged area must be cleaned of crumbling fragments of the coating, greased with glue and filled with a repair compound according to the same principle as when laying the coating.