Ceresit CT 85 adhesive mixture is a composition for fixing polystyrene foam boards and further forming a reinforced protective layer on them. In the latter case, we are talking about work in which there is a need to install a system of external thermal insulation of external walls using the "wet method" technology.
Main characteristics
Ceresit CT 85 has a lot of advantages, among which are high adhesion with polystyrene foam and mineral bases, elasticity, vapor permeability, weather resistance, as well as environmental safety. The composition contains reinforcing fibers, the mixture is shockproof, frost-resistant and technologically advanced. In order for the composition to show all its positive characteristics, sometimes there is a need to additionally prepare the surface, which should be degreased and cleaned of foreign objects that interfere with strengthening the insulation boards as evenly as possible to obtain an ideal surface suitable for decorating the wall.
Area of use
Ceresit CT 85 has a fairly wide scope, for this reason, consumers acquire this composition, refusing alternative solutions. This glue can be used to fasten boards that are made of expanded polystyrene. Their fixation is very effective. The mixture is suitable for the manufacture of reinforcing layer on such plates, when the facade is formed by "wet" technology. This mixture can be used for insulation of new buildings or thermal protection of old buildings. When insulating building facades with a "wet" method using mineral wool boards , this glue is also used.
Specifications
Ceresit CT 85 is a mixture of mineral aggregates and cement, reinforcing microfibers and polymer modifiers. The density of the dry mixture varies within 1.3 kilograms per cubic decimeter. Approximately 6.75 liters of water will be needed per 25 kilograms of dry mix in the manufacture of the solution. After cooking, the composition should be used up within 120 minutes, while the temperature should be kept from +5 to +30 degrees. Operating temperature varies from -50 to +70 degrees.
Quite often, builders are interested in such a characteristic as adhesion to polystyrene foam. So, it is equal to 0.1 MPa. As for adhesion to concrete, it is 0.6 MPa or more. Glue "Ceresite" is able to undergo about 75 cycles of freezing and thawing. If you plan to form a layer whose thickness will not exceed 8 millimeters, then after 28 days all cracks will be absent. It is very important to consider the consumption of Ceresit glue. If necessary, fix the slabs or form a protective layer, the flow rate will be 6 and 5 kilograms per square meter, respectively.
Preparation of the base before installing polystyrene foam boards
If you decide to use the composition of Ceresit CT 85, the characteristics of which were described in detail above, then you should familiarize yourself with the technology of preparing the base when installing the plates. The surface should be as durable as possible, free of contaminants and foreign substances that would be able to reduce the adhesion of the adhesive to the base. These include lubricants, coatings, oil, fats and bitumen mastic. If on the surface there are loosely held areas, then they must be disposed of.
If there are recesses that exceed 20 millimeters in size, the voids should be filled with Ceresit CT 29 material, and this must be done three days before the start of the insulation work. Ceresit CT 85, the flow rate of which was mentioned above, must be applied to a surface that is completely free of contaminants. You can get rid of them with a jet of water supplied under high pressure. To cope with such work, you can also use a solvent or mechanically.
If the polystyrene foam boards are fixed on plaster, oil or synthetic coatings, then when preparing the dry mixture, the adhesive additive Ceresit CC 81, which is diluted with water in a ratio of 1: 3, should be used. Thus, one part of the additive will need 3 parts of the liquid. If paint coatings are present on the surface, they must be sanded and dusted.
Additional preparation guidelines
Ceresit CT 85 polystyrene adhesive is applied to the wall, which is completely devoid of areas exposed to fungi, algae or moss. Such surfaces are cleaned with brushes and treated with the fungicidal preparation CT 99.
Those walls that have not been plastered and have been used for some time should be dusted off by rinsing with water under pressure. The walls are left to dry completely. Sometimes you have to work with highly absorbent substrates. This should include surfaces made of aerated concrete or silicate blocks. They are treated with a primer and dried for 4 hours.
Recommendations for the construction of a protective layer
Sometimes it happens that after fixing the floor slabs remain in the open air for 2 weeks or more. You should not rush to cover such bases with an adhesive protective layer, for a start they are examined. If the surface has changed color, dust has appeared on it, then the insulation is treated with rough sandpaper and dust free.
Application of the composition
Glue "Ceresit" must be prepared exactly in accordance with the instructions. To do this, use cold water (its temperature should be in the range from +15 to +20 degrees). The mixture is added to the liquid and mixed, while achieving a homogeneous mass. Mixing is effectively carried out with a mixer or drill with a nozzle. The speed of rotation of the working tool should not be more than 800 revolutions per minute. Then the master leaves the mixture for 5 minutes to "ripen", after it is mixed again.
Installation of expanded polystyrene boards
As mentioned above, Ceresit glue is used for attaching polystyrene boards. If the walls have irregularities from 3 to 15 millimeters, then the composition is applied with a trowel along the contour of the plate. In this case, the strip of glue should be equal to 4 centimeters in width. In the central part of the insulation beacons are applied. The number of such spots on one canvas should be 8. Their diameter is 10 centimeters. A strip of glue along the contour should be applied with gaps, which will eliminate the formation of air bubbles. The height of such strips should be equal to 20 millimeters.
When irregularities are up to 3 millimeters in size, the glue is applied in a continuous layer, and the indent should be three centimeters from the edge. In this case, use a notched trowel. Choose a tool whose tooth dimensions are 12 millimeters. As soon as the stucco-adhesive mixture was applied, the plate is applied to the surface and pressed with blows of a grater. The area of adhesive contact after pressing the sheet should be 40 centimeters from the area of the bonded surfaces.
The plates are fixed in one plane so that the dressing of the seams has a T-shape. It is important to ensure that the gap between the plates is not more than 2 millimeters. Larger seams can be filled with polyurethane foam or polystyrene scraps. Glue "Ceresit" will dry completely in three days, only then you can proceed to additional fixation, if necessary. For this, masters are advised to use facade dowels. After this period, the master can form a reinforced layer.
Formation of a protective layer
These manipulations should be started only after additional fastening of the insulation with dowels. Their number per square meter of the surface of the facade should be determined by calculations. The stucco-adhesive mixture is distributed by a steel grater on the surface, while the layer thickness can vary from 2 to 3 millimeters. An alkali-resistant fiberglass mesh is laid on the adhesive layer. It is important to ensure an overlap of the canvases from 5 to 10 centimeters wide. Immediately you can start applying the second layer of glue, the thickness of which should be 3 millimeters. You can smooth the surface evenly so that the grid is not visible. After three days, a decorative coating of thin-layer plaster or alkali-resistant paint can be applied to the protective layer. Fresh glue residue can be disposed of with water, while dried elements are removed mechanically.
For reference
Ceresit brand adhesive can be carried at an air humidity that does not exceed 80%. All indicators set forth in the technical description are correct at an ambient temperature of +20 degrees. In this case, the relative humidity should not be more than 60%. If the conditions are changed, then the drying of the material and the time of consumption will be different. If there is a need to carry out work on thermal insulation of the facade in the cool season, when the thermometer column varies from 0 to +20 degrees, then an additional modification of the Ceresit ST 85 Winter glue should be used.
Cost
Ceresit CT 85, whose price is 620 rubles. per 25 kg bag, delivered in pallets. You can store the mixture for no more than 12 months from the date of manufacture.