What glue is used to join foam blocks?
Over the past decades, foam blocks have occupied a leading position among building materials. They are used in the construction of residential buildings and utility rooms, the construction of interior partitions, for insulation and improvement of sound insulation. To connect bricks made of foam concrete to each other, glue for foam blocks is used, which not only provides strong and durable adhesion, but also allows you to fully preserve all the positive qualities of cellular concrete.
How is glue better than cement mortar?
Foam blocks are made from foam concrete, which is a mixture of cement, sand and water with the addition of a foaming agent. As a result of this connection, a lightweight cellular material is obtained, which is used for the construction of all kinds of buildings and structures. Foam block differs from brick in structure, size, and weight. The technology for laying this material is also different from the construction of a brick wall, therefore, certain requirements are imposed on the composition used to connect individual elements.
The fact is that the thermal insulation qualities of foam concrete are much higher than those for cement mortar. Layers of cement 1–1.5 cm thick make the structure easily blown. As a result, additional thermal insulation has to be installed. A special adhesive composition with additives that increase elasticity and water resistance forms a thin (3 mm) hermetic layer and successfully solves this problem.
Adhesive for foam blocks has a number of other advantages that distinguish it from cement mortar.
- High connection strength.
- The rapid hardening of the adhesive composition allows you to reduce construction time.
- Impossibility of mold and mildew.
- With a sharp temperature change, the adhesive layer does not crack or collapse.
- Convenience and ease of use of the adhesive composition.
- Cost-effective - glue is more expensive than cement, but it will be needed several times less, resulting in lower cost of masonry.
Important!
The cement composition contains a large amount of water, which, when the block is installed, begins to be absorbed into the porous structure. To avoid this, each row has to be treated with a special water-repellent primer, which wastes extra time and money.
Composition and technical characteristics of the glue
Any adhesive used to hold foam blocks together contains cement, sand and various additives that improve the characteristics of the product and enhance one or another property of the adhesive.
The dry mixture contains the following components:
- finely crushed quartz sand - allows you to make a seam no more than two millimeters wide;
- Portland cement – provides the highest joint strength and rapid hardening of the adhesive;
- polymer additives - make the composition more elastic and pliable, capable of penetrating into the most inaccessible cracks and cavities that are always present on the surface of the foam block; a plastic seam prevents the formation of cracks during sudden temperature changes;
- additives that improve the water-repellent properties of the adhesive composition and prevent the formation of mold.
On the building materials market you can find summer and winter glue.The first type of adhesive contains white cement and is used at an air temperature of at least +5°C. Due to anti-frost additives, winter glue can work even at temperatures of -30°C.
Adhesive for foam blocks is sold in the form of a dry mixture, packaged in 25 kg bags.
Glue consumption per 1 m3
Many manufacturers indicate on the packaging how much adhesive is needed for 1 m2 masonry Before you buy glue, you need to study the label and calculate how many bags will be needed for the construction of a particular object.
Moreover, we should not forget that the consumption rates indicated by the manufacturer are averaged, and the actual figures are added up depending on many circumstances, such as:
- builder's qualification level;
- air temperature during masonry work;
- evenness of the surface of the foam block;
- number and thickness of connecting seams.
Typically, the standard glue consumption for a layer thickness of 1 mm is 1.3–1.5 kg per 1 m2 masonry area. To make the connection strong and reliable, the adhesive layer should have a thickness of 3-5 mm. This means, if we take it to the maximum, then by 1 m2 It will take 6.5-7.5 kg of mixture.
Based on the fact that the height of a standard foam block is about 20 cm, you can calculate the number of layers per cubic meter. There will be five of them. The maximum amount of glue required for laying 1 m3 walls, will be 32.5-37.5 kg, that is, one and a half bags of dry mixture.
Advice
After completing the masonry, it is recommended to re-treat the external seams with glue. This must be taken into account and glue should be purchased in reserve.
Manufacturers and prices
All adhesives used to join blocks have approximately the same composition.The only difference is the proportion between the filler and polymer additives. Therefore, when choosing adhesive for foam blocks, special attention should be paid to the temperature at which the composition is used and whether it is suitable for construction in specific conditions.
Experts advise following the following rules when purchasing glue:
- do not buy a suspiciously cheap product;
- give preference to trusted manufacturers;
- take into account the season of work;
- take the mixture with reserve.
Here are some of the most popular adhesive compositions manufactured by well-known manufacturers and which have earned positive reviews from experts. Prices indicated are for one package (25 kg).
- Praktik Bergauf (winter) - 274 rubles;
- Aeroc — 179 rubles;
- Ceresit CT 21 -265 rubles;
- "Osnovit Selform T 112" — 167 rubles;
- Praktik Bergauf — 165 rubles;
- "Volma" - 190 rubles.
Osnovit Selform glue is recognized by many experts as the best adhesive composition for working in the summer. Among frost-resistant ones, the winter adhesive called Aeroc has the best characteristics. The connection formed with this product withstands temperature changes. Working with the composition is simple and convenient, since the glue does not set immediately and there is time to adjust the location of the block.
How to lay foam block on glue?
Before starting construction of a wall made of foam blocks, it is necessary to properly prepare the adhesive composition. The glue package contains detailed instructions, which should be followed when combining the adhesive powder with water.
To prepare a high-quality solution without lumps and clots, it is better to use a construction mixer with a special butterfly attachment. You can use a regular bucket as a mixing container.
After two hours from the moment of preparation, the glue will begin to gradually thicken and harden, so it is advisable to prepare as much of the mixture at one time as is needed for two hours of work. Of course, you can dilute thickened glue with a small amount of water, but the quality of the product will noticeably decrease, since the proportions between the components will be disrupted.
Important!
Preparing glue from a dry mixture requires strict adherence to the ratio of the amount of water and powder specified in the instructions.
Before starting laying, it is necessary to carry out the necessary markings. To do this, foam blocks are placed at the corners of the future building and a fishing line is pulled between them. The upper part of the block must be located strictly level.
The first row of blocks is laid on the foundation using a cement-sand mortar and only starting from the second row an adhesive mixture is used. If possible, it is better to choose blocks with a flat surface, without deep depressions and bulges. This will allow you to make a thinner seam. A surface that is too uneven can be sanded. Before installation, you need to blow off dust from the block and remove small debris.
It is better to apply the glue with a notched trowel. Using uniform smooth movements, coat the top and side of the foam block with glue, removing the residue into a bucket. The layer thickness should be 2-3 mm. To ensure that the block fits exactly into place, it can be carefully adjusted with a rubber hammer.
Important!
It is necessary to check the verticality of the wall and the evenness of the masonry after gluing every 3-4 foam blocks.
The glue begins to harden 15 minutes after application. If something goes wrong, you can still fix the problem within a quarter of an hour.
If you decide to build a house from foam blocks, you need to pay special attention to the choice of glue.After all, the quality and durability of the building will depend on the tightness, strength and water resistance of the connecting seam.