Masonry

The correct choice of materials is one of the critical factors that determine the strength and durability of the structure:

• Ensure that the masonry materials meet the physical and mechanical characteristics required by the project.
• The sand for the mortar should be clean and free of clay, with the grain size not exceeding 2.5 mm.
• Use cement with the strength class 400 – CEMARK UNIVERSALNYI and CEMARK MITSNYI are the best choices for this type of work.
• The strength class of cement-sand mortar should be lower than the strength class of the wall material. For example, M100 bricks require M75 masonry mortar.
• Ensure proper storage conditions for materials to avoid adverse environmental impact.

Prepare the mortar 

• The proportions of bulk materials depend on the mortar strength class:

• First, mix the dry ingredients thoroughly, then add water.

Further addition of water will decrease strength, so to increase the workability of the mortar, it is advisable to use plasticisers. 

During masonry work:

• Use tools that will control the geometric parameters, thickness and horizontality of the seams:
  - the average thickness of horizontal seams within a storey must be 12 mm – not less than 10 mm, but not more than 15 mm;
  - the average thickness of vertical seams must be 10 mm – not less than 8 mm, but not more than 15 mm. 
• Rebars should be placed in the brick masonry at the points where they contact reinforced concrete structures. The rebars should be welded to the steel imbeds of the reinforced concrete structure.

• Pay special attention to the correct location of the first row of masonry relative to the wall line and height. While you do this, lay 4-5 rows at all the corners. The walls in-between are then laid from the corners and aligned against the mason cord and the level tool. 
• Apply the mortar a little in excess to make laying the wall material easier before the mortar loses workability. After laying brick or block, clean the wall material from the remnants of the mortar.

Avoid premature, rapid drying of the mortar, especially in sunny weather.

The laying of critical structures must be performed under the technical supervision of a resident civil engineer.

• To reduce the risk of cracking of the masonry around the door and window openings:
  - Follow the recommended mortar composition and material proportions.
  - Protect all masonry during construction from mechanical impacts.
  - Insert reinforcement into the seams directly above and below the openings in the wall – use a mesh when working with aerated-, foam and polystyrene concrete blocks.
  - Place precast lintels on the mortar – they must work as one with the wall. It is necessary to provide them with a sufficient area of support on the brickwork – if the opening is up to 1.5 m wide, the total width of the area of support of the lintel on both sides should be at least 25 sm for a larger width of the opening it should be 35 sm. The area of support is decreased when the wall material has greater strength, for example, in the case of a concrete wall, and increased when the wall material has lower strength, for instance, in the case of aerated-, foam concrete.