Facing brick
Facing bricks are masonry bricks that are used for the outside of the single-shell and the facing shell of the double-shell masonry . The facing brickwork (the facing shell) is usually designed as exposed brickwork . The facing brick must be frost-resistant. It is classified as a frost-resistant stone in accordance with DIN EN 772-18 (test with 25 or 50 frost / thaw changes).
As a generic term for frost-resistant stones (facing bricks, clinker bricks, brick slips and facing bricks), only the name facing brick is generally used. It should be noted that facing bricks are subject to increased requirements (frost resistance, dimensional accuracy, raw materials). If the requirements placed on the visual design are particularly high, facing bricks should be selected due to their greater dimensional accuracy.
In many cases, particularly in the case of facades from the period 1870–1914, particularly precisely manufactured clinker bricks were used as facing bricks , in contrast to brickwork bricks. The joints are particularly narrow and precise. As a rule, this precision was no longer achieved with modern facades.
Brick slips (flat facing brick)
Bricks are flat, frost-resistant ceramic plates for cladding facades. Traditionally, they are around 10-20 mm thick. However, straps 5 - 25 mm thick are also available. They are either shaped and fired specifically for this application or cut in the brickworks from the solid clinker bricks or facing bricks from ongoing production and should be manufactured in accordance with the masonry brick standards DIN 105 and DIN EN 771-1. Alternatively, they can also be manufactured in accordance with DIN 14411 for ceramic split tiles .
In addition to the flat panels, matching angled brick slips are usually offered, which can be arranged on the corners of the building in such a way that a facade clad with brick slips is practically indistinguishable from a solid brick wall.
Economy facing brick
Economical facing bricks are clinker bricks or facing bricks which, with a depth of around 50 mm, are only about half as wide as conventional bricks. Similar to the brick slips, they can be made by splitting regular (vertical perforated) bricks in the formats NF and DF (more rarely also 2 DF) along the longitudinal axis.
processing
DIN 1833 VOB Part C "Masonry" prescribes the subsequent grouting of "external facing and exposed masonry". The still fresh masonry mortar must be scraped out to a depth of at least 15 mm in order to ensure sufficient anchoring of the joint mortar applied later.
Occasionally, after the mortar has set, the masonry is cleaned by acidifying mortar residues before the final grouting . When using hydrochloric acid , the volume fraction should not exceed 2%. Before cleaning, the masonry must be pre-moistened until it is saturated. After cleaning, you should rinse with plenty of water from the bottom to the top so that the rinsing water does not run down over the lower areas, which in the meantime have dried off again and can therefore be absorbed by the acidic water.
The Fachverband Ziegelindustrie Oldenburg, on the other hand, recommends avoiding all of these work steps and instead smoothing the joints straight after the bricklaying in order to avoid the formation of efflorescence on the brick surface. Absorbent bricks should be prewetted before processing so that the complete setting of the mortar is not endangered by dehydration. Otherwise, the finished masonry should be protected from further moisture penetration in order not to mobilize the soluble salts contained in the mortar and, to a lesser extent, in the bricks. The use of hydrochloric acid can lead to the conversion of the carbonate binders contained in the mortar into calcium chloride and other salts, and also to discoloration of the stone surface itself. If efflorescence occurs, this can be partially removed by brushing. A strong moisture penetration of the wall during the construction phase could lead to efflorescence three years after completion.
literature
- Sand-lime brick: planning, construction, execution . 5th edition. Verlag Bau + Technik GmbH, Düsseldorf 2009, ISBN 978-3-7640-0511-5 .
- Hans Rich: sand-lime brick. The mason's primer . 7th edition. Verlag Bau + Technik GmbH, Düsseldorf 2004, ISBN 3-7640-0453-3 .
Individual evidence
- ^ Günter Neroth, Dieter Vollenschaar, Wendehorst building materials science: Basics - building materials - surface protection ; accessed in September 2016
- ^ Nasser Altaha: Water and Acid? Attention! , Fachverband Ziegelindustrie Oldenburg; B + B 6/98; In: Ziegelindustrie.de