"Red brick is a humane material, it is part of the essential nature of culture. It has an influence that touches one, it is warm and familiar. The charm of brick is the charm of old cultures."
Hanni Sippo, architect SAFA, Alvar Aalto Foundation
A brick is a walling unit not exceeding 337,5 mm in length, 225 mm in width and 112,5 mm in height. The form may be defined generally as a rectangular prism. Brick is made of clay. Clays are fine-grained deposits, laid down by deposition from still water. With the breakdown and disentegration of rocks, it contains certain constituents. The main constituents are %60 silica and %20 alumina. It may also include iron oxide and salts of calcium, magnesium, sodium and potassium.
Properties and Classification (according to sizes of voids):
- Solid Bricks:
They do not have holes, cavities or depressions.
- Perforated Bricks:
They have holes not exceeding 25% of the gross volume of the brick.
- Frogged Bricks:
They have depressions known as 'frogs' in one or more of the bed faces, but their total volume does not exceed 20% of the gross volume of the brick.
- Cellular Bricks:
They may have cavities not exceeding 20% of the gross volume of the brick, a cavity being a hole closed at one end.
- Clay bricks may generally be said to perform well in the following respects:
* Aesthetic appearance
* Resistance to rain penetration
* Compressive strength
* Fire resistance
* Sound insulation
* Low thermal and moisture movement
* Versatility in application
* Low maintenance requirements
Qualities of a Good Brick:
- Well burnt
- Ring (when struck with another brick, or with a trowel, good bricks emit a clear ringing sound. A poor brick gives a dull sound)
- Water absorption
- Compressive strength
- Strength and density
- Materials (clays for bricks should be composed of well-blended materials which will produce a good-quality product.)
- Soluble salts - Blemish free - Colour Classification of Bricks: - Commons: * These have no special claim to aesthetic distinction and are defined as 'suitable for general building work'. * Thus the term 'commons' is applied to many varieties of clay bricks which fall outside the 'engineering' or 'facing' classifications. * They are widely used for foundations and as a backing for rendering, plaster of colour wash. - Facings: * Specially made or selected to give an attractive appearance when used without rendering or plaster or other surface treatment of the wall. * They combine attractive appearance with structural strength and good resistance to exposure. * Today, facing bricks are available in a wide range of colours, textures and strengths for use above ground level. - Engineerings: * These are generally classified as either Class A or Class B. * They are further sub-divided into facings and commons according to their appearance. * They are dense, strong, semi-vitreous bricks possessing both the required strength and absorption properties.
Most Important Brick Types:
- Coal Measures (Carboniferous) - Oxford Clay (Jurassic) - Glacial Clays of the Pleistocene - London Clay (Eocene) (was once a very important building material, but today it is little in use.)
Characteristics of the Main Clay Types:
- Etruria Marl: * It is a highly prized clay for producing bricks of very high strength and low water absorption. * It is used to great effect on bridges and sewers (the reason why they are also called 'engineering bricks') * Due to an extremely high iron content, the bricks will burn red or blue according to different firing methods, and have a wide vitrification range, allowing the bricks to 'glaze' without excessive shrinking (this is almost impossible with other clays as extremely high temperatures would be needed).
- Mercian Mudstones (formerly k.a.: Kemper Marl): * It is the most widespread brickmaking clay after Oxford Clay. * Because its being particularly soft, it is desirable for both machine- and hand-made bricks. * When fired, it produces bricks of low strength and high water absorption. * It has two types of different iron contents: - fires buff - red
- Lower Oxford Clay: * It is a unique clay with a high carbonaceous fuel content allowing it to be fired inexpensively. * It is a hard, shale-like clay which in spite of its high water content (16-20%), can be ground and pressed into brick shapes. * It is used to make Fletton bricks in a manufacturing method known as the semi-dry process.
- Weald Clay: * It is traditionally used for hand-made stock bricks although it is also used for engineering bricks. * When fired, the predominant colour is red, but there is a long tradition of adding coke breeze or coal slurry to give a black finish to the face.
Assessing Clay For Brickmaking: Few clays are found ready for use; most require certain preparatory processes before they are suitable for the manufacture of bricks. The Manufacture Process Of Brick:
- Clay Winning and Preparation: * Some small yards still excavate by hand or with small machines, often seasonally, whereas larger companies working on volume production excavate all year round using a variety of heavy plant.
* The preparation process involves crushing, grinding and mixing the clay in different ways.
* Water content is carefully monitored to give a clay ready for shaping. The moistureness of the clay can vary from very wet (over %30 moisture) to relatively dry (under %12 moisture).
- Shaping the Bricks: * The method adapted varies according to the nature of the clay used, its water content and the type of brick required. * There are five systems, which are described briefly as follows: Hand-made:The traditional method of brickmaking, whereby the warp or lump of clay is rolled in moulding and thrown by hand into a frame mould on a wooden stock, producing individual, attractive bricks of various colours and textures. Hand-made bricks usually have a single frog, but may be solid.
Soft-mud: This is an adaptation of the hand-making method.
Again, a clay with a high moisture content is used, dropped between two rotating rollers and mechanically thrown into metal moulds.
Soft-mud bricks generally have a sinlge frog.
Semi-dry: The Fletton-type brick is produced using this process.
A ground clay is fed into machines and pressed into moulds by heavy hydraulic pressure. The facing bricks are sand-faced or machine-textured.
The Fletton bricks have one frog.
Stiff Plastic: A similar process to semi-dry although the clay tends to have an inherently low moisture content. After grinding, extra water is added to the clay dust before delivery to an extrusion pug.
Sometimes, a second pressing is deemed necessary for facing bricks.
With the wirecut process, this method has now been largely supplanted.
Apart from clays with naturally high levels of water, most clays are suitable for this process.
Prepared clay is extruded through metal dies and then textured by scoring or brushing and/or coloured by spraying.
Finally it is cut to the specified gauge by a series of wires. Wire-cut bricks do not have frogs, although most contain a variety of perforations, or holes formed during extrusion.
* An important stage for hand-made, soft-mud and some wire-cuts, where the moisture level is relatively high.
* Drying is vital for shrinking by releasing excess moisture. * Drying can take place naturally outdoors in what are known as drying hacks, or in drying chambers where bricks are open-stacked on pallets so that a flow of heated air can pass over them.
* When the clay brick is fired at a sufficiently high temperature for a controlled length of time, chemical changes occure and these result in a harder and more lasting product.
* The properties can be summarized as follows:
- The softness necesarry for moulding is lost
- The clay shrinks
- Mechanical strength is greatly increased
- Material becomes durable and resistant to weathering
- Changes in colour occur
The colour of the burnt brick can be a complex area to study. However,a general rule is that it is the iron content which produces a range of colours, depending on the amount of oxygen within the kiln.
In a reduced atmosphere, used for the production of blue bricks, the colours will range from brown to blue, and black can even be produced.
In a fully oxidized chamber the colour range will be from cream to yellow, red and brown.
Multi-coloured facing bricks are produced in some regions such as Surrey and Sussex, by the addition of fuel to the clay bend. This produces a colour range which is only varied by the amount of fuel added - from silver-grey and pastel ranges to deep purple-blue and black.
2- Intermittent Kilns
3- Continuous Kilns
4- Tunnel Kilns
Coal or coke are still employed, altough oil (and more recently gas) are now widely used in the kilns, contributing to their greater control.
The finished brick may be classified by the shaping style as well as the manufacturing method used:
1- Hand-moulded (clamp or kiln burnt)
2- Machine-made, simulated hand-made (kiln burnt)
3- Machine-made extruded, wire-cuts (kiln burnt)
4- Machine-made pressed bricks (kiln burnt)
Other Types of Bricks:
Besides traditional clay bricks, other types have been developed for a variety of different, often specialized uses.
1- Calcium Silicate Bricks
2- Concrete Bricks Bonding of Brickwork: - Reasons for Bonding: * Strength * Appearance * Economy - Types of Bond: Stretcher Bond:
Tools and Accessories: - Cutting Tools: Brick Axe:
The 13th Istanbul Biennial: "Mom, Am I A Barbarian?"Antrepo No. 3
"A Drawing Series of Christoph Schaefer" Christoph Schaefer
Born in 1964 in Essen, Germany; meanwhile living in Hamburg - is a conseptual artist, draughtsman, uninvited city planner who explores collective desires for reshaping urban life by combining theory, activism and artistic production. He works from within social movements. He is a member of 'Park Fiction'.
But... What is 'Park Fiction'?
Park Fiction is an independently organized initiative, which began in 1994. It emerged as a planning project for a public park in response to the redevelopment of the harbour area in St. Pauli, Hamburg.
Schaefer developed playfool tools to create platforms of exchange and coproduction in the community, which helped residents imagine a park as if it existed. In the end, they succeeded - the city recognized the space as a park which was opened in 2005: 'Park Fiction St. Pauli'.
After the Gezi Protests in Turkey, the park was renamed into 'Gezi Park St. Pauli'. This renaming was the starting point of Schaefer's drawing series that he is showing us in the 13th Istanbul Biennial.
Christoph Schaefer's Drawing Series
The starting point of Schaefer's drawing series was a photo taken by filmmaker Margit Czenki, showing a group of people celebrating the renaming of the 'Gezi Park Fiction St. Pauli'.
Schaefer draws this photo as the beginning of his series.
Schaefer shows different situations in Turkey during these protests, but the most interesting part is that he never saw these situations live: he made all of his drawings according to researches, interviews etc.
As well as Turkey's situations, Schaefer also drew some similar situations between Turkey and Germany in that days, such as: a walk from the stadium to the park, the piano play, demonstrations in the stadium, making 'Gezi Park' T-Shirts etc.
In his drawings, Schaefer emphasizes the colours green, blue and brown - so the natural once. By doing this, he probably aimed to emphasize the importance of natural elements.
One more thing that Schaefer did in his drawings was representing people in forms like trees. He probably did this as well to emphasize the importance of nature, by trying to say: "Nature is equal to humans.".