Aerated concrete blockwork in Batumi, plus clay block and brick

Aerated concrete blockwork in Batumi: where a straight wall starts

The first course sets the straightness of the whole wall. We lay it in cement mortar on a horizontal damp-proof course, setting every block with a level. A mistake in the first course cannot be fixed later with adhesive or render: it carries into every course above. So the first course takes a disproportionate amount of time, and we do not rush it.

After that aerated concrete is laid in thin-bed adhesive, with a joint of about two to three millimetres. The adhesive is spread across the full width of the block with a notched applicator, and vertical joints are filled too if the block has no tongue and groove. Irregularities in a course are taken off with an aerated concrete plane, not with a thick layer of adhesive. For the material itself, densities and thicknesses, see the page about aerated concrete houses, and for how it differs from similar foam concrete, the aerated concrete vs foam concrete comparison.

Bond, reinforcement and anchors

The vertical joints of neighbouring courses are offset so the wall works as one piece, not as a stack of separate columns. The offset is usually at least a third of a block length. Joints are reinforced to the design: in the first course, under windows, above lintels and every set number of courses. In aerated concrete we cut chases for the bars and fill them with adhesive; in brickwork mesh goes into the mortar joint.

If the wall fills a frame, it is anchored to the columns at the courses the engineer specifies. Under a beam we leave a gap and fill it with a flexible material, not mortar. How the wall works with the frame and the types of wall are described on the page about load-bearing walls and partitions, and ring beams and cores in load-bearing masonry on the page about reinforcement.

Clay block and brick

Large-format clay block is laid in mortar or a special adhesive, with vertical joints usually dry in tongue and groove. The block is brittle, so we cut it with a saw rather than break it, and only special fixings go into it later, otherwise a plug turns in the voids. We do not use foam adhesive for load-bearing clay block walls.

Brick is laid in cement mortar with a joint of about 10–12 mm, bonded and reinforced with mesh to the design. Facing brick is tied to the main wall with flexible ties, stainless steel by the sea. Mortar is mixed in batches for an hour or an hour and a half of work, not for the whole day.

Checks on every storey

• level of every course and plumb of corners and openings with a plumb line or laser;
• flatness of the wall with a two-metre straightedge;
• opening sizes to the window design, so frames fit without trimming;
• anchors to columns and joint reinforcement photographed before they are covered;
• filled joints without voids for the wind to blow through later.

Weather and protecting the masonry

We do not lay in the rain, and the top of the wall is sheeted over at night: water running into the joints from above washes out the mortar and soaks the blocks. In summer dry blocks are dampened before the adhesive, otherwise they draw water out of the joint. Pallets of blocks are kept under cover. We try to close a finished wall with the roof and facade quickly, so it does not stand through the winter in wind-driven rain.

How much masonry costs

Block wall masonry, labour only, costs from 40 ₾ per m². With materials: 30 cm aerated concrete from 145 ₾ per m², expanded clay block from 150 ₾, large-format clay block from 210 ₾, brick from 240 ₾ per m². Aerated concrete partitions are from 76 ₾ per m², a cast-in-place lintel from 100 ₾ per linear metre. The final cost is set from the wall schedule in the design and the chosen material, after agreement on the estimate.