Clay Bricks (0)

Introduction (slide 2)

In this presentation I’d like to give a brief overview of clay bricks . I’ll speak about 15min to allow time for questions at the end.
Firstly clay bricks are known for centuries as one of the most solid and reliable structural elements is set to play a role in reducing global warming .
Apart form the many benefits obtained from using clay bricks in construction , such as their durability, insulation properties and aesthetic qualities, recent findings show that they also produce less carbon emissions than any other masonry material .

History (slide 3)

In more detail the earliest bricks were dried bricks, meaning they were formed from clay-bearing earth or mud and dried usually in the sun until they were strong enough for use. The oldest discovered bricks, originally made from shaped mud and dating before 10000 BC, were found in Mesopotamia related to the first known cities.
Ceramic or fired bricks were first introduced by the Romans . These were mainly flat , broad thin sections, not unlike a tile, which is probably why they ‘burnt’ so well, causing them to last for centuries.
In Estonia the fired clay bricks came in to use in 13 century . The greatest buildings from that time are the St John's Church and the Tartu Cathedral. (Jaani kirik ja Toomkirik )

Moving on, What is clay? (slide 4)

Clay is fine-grained, firm earthy material that is plastic when wet and hardens when heated. Clay minerals are size of (point zero one mm)0,01mm. It is consisting primarily of hydrated silicates of aluminum and widely used in making bricks, tiles, and pottery.
Clay minerals are typically formed over long periods of time by the gradual chemical weathering of rocks, by low concentrations of carbonic acid and other solvents. These solvents, usually acidic, migrate through the weathering rock after leaching through upper weathered layers. In addition to the weathering process , some clay minerals are formed by hydrothermal activity . Clay deposits may be formed in place as remainder deposits in soil , but thick deposits usually are formed as the result of a secondary sedimentary deposing process. Clay deposits are typically associated with very low energy depositional environments such as large lakes and marine basins.
(slide 5)
Clays exhibit plasticity when mixed with water in certain proportions. When dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur . These reactions, among other changes, cause the clay to be converted into a ceramic material. Because of these properties, clay is used for making pottery items , both practical and decorative, and construction products such as bricks, wall and floor tiles.  Depending on the content of the soil, clay can appear in various colors , from a dull gray to a deep orange-red.

Clay in Estonia (slide 6)

There are 3 basic types of clay in Estonia. Firstly from Cambrian era the blue clay, which has blue-greenish color and deposit fields round 100m thick found in North -Estonia. Secondly from Devon era the Red- Brown colored clay mostly find in South-Estonia and finally the layered clay found on islands mainly. The quality of the layerd clay is poor beacause it is limestone -rich. There are aroud 30 filed mineral deposits in Estonia.

What is a brick ? (slide 7)

A brick is a block or a single unit of a ceramic material used in masonry construction. Typically bricks are stacked together or laid as brickwork using various kinds of mortar to hold the bricks together and make a permanent structure. Bricks are typically produced in common or standard sizes in bulk quantities. They have been regarded as one of the longest lasting and strongest building materials used throughout history.
In the general sense , a "brick" is a standard- sized weight -bearing building unit. Bricks are laid in horizontal courses, sometimes dry and sometimes with mortar. When the term is used in this sense, the brick might be made from clay, lime-and- sand , concrete, or shaped stone. In a less clinical and more informal sense, bricks are made from dried earth, usually from clay-bearing subsoil. In some cases , such as adobe , the brick is merely dried. More commonly it is fired in a kiln of some sort to form a true ceramic.
(slide 8)
On this slide you can see 3 different types of bricks compared with each other in thechnical numbers . As you can see Clay brick has somewhat better characteristics , but is also a little bit more expencive.

The making of bricks (slide 9)

Modern clay bricks are formed in one of three processes – soft mud, dry press, or extruded.
Mud bricks
The soft mud method is the most common, as it is the most economical. It starts with the raw clay, preferably in a mix with 30% sand to reduce shrinkage. The clay is first ground and mixed with water to the desired consistency. The clay is then pressed into steel moulds with a hydraulic press. The shaped clay is then burned at 1000 °C to achieve strength .
In modern brickworks, this is usually done in a continuously fired tunnel kiln, in which the bricks are fired as they move slowly through the kiln on conveyors, rails, or kiln cars, which achieves a more consistent brick product. The bricks often have lime, ash, and organic matter added, which accelerates the burning process.
Dry pressed bricks (slide 10)
The dry press method is similar to the soft mud brick method, but starts with a much thicker clay mix, so it forms more accurate, sharper-edged bricks. The greater force in pressing and the longer burn make this method more expensive .
Extruded bricks (slide 11)
For extruded bricks the clay is mixed with 20% water. This mixture is forced through a die to create a long cable of material of the desired width and depth. This mass is then cut into bricks of the desired length by a wall of wires. Most structural bricks are made by this method as it produces hard , dense bricks, and suitable dies can produce holes or other perforations as well. The introduction of such holes reduces the volume of clay needed, and hence the cost . Hollow bricks are lighter and easier to handle, and have different thermal properties than solid bricks. The cut bricks are hardened by drying for 20 to 40 hours at 50 to 150 °C before being fired. The heat for drying is often waste heat from the kiln.

Characteristics of Brick (slide 12)

Clay bricks are good insulators. As wall materials, clay bricks make walls heavy and dense and conduct heat slowly. This slow heat conduction reduces peak cooling loads in summer and peak heating loads in winter making your home energy-efficient all year round.

• The characteristic thickness and density of a clay brick wall reduces noise transmission and deflects noise from the outdoors for a peaceful and quiet home.
  
• Clay bricks do not warp, rust , split , peel or fade over time. They do not harbor termites and appear more beautiful as they grow older.
  

While clay bricks may be expensive to acquire, their low maintenance and durability make these materials a cost effective option for the exterior of your home. Clay brick structures last for hundreds of years

• Clay brick homes generally have a high resale value as homebuyers prefer the upscale appearance and easy care of a brick home.
  
• Clay bricks do not burn and reduce the possibility of fire where they are used.
  
• May be used for exterior and interior works
  
• Clay controls indoor climate by adjusting the huminity and temperature fluctuation
  

Areas of use (slide 13)

Aside from using clay bricks on walls, these may also be used for paving, constructing a firebox or for roofing
Clay bricks are available as common bricks, facing bricks, load bearing bricks and damp proof course bricks. Common bricks are used for general brick work where aesthetics is not a concern as these require plastering while facing bricks are used for the exterior of homes and walls and have a smoother finish. Load bearing bricks, damp proof and engineering bricks are stronger and have less water absorption properties making these ideal for civil engineering works.

Clay brick- an environmental product (slide 14)

To sum up the clay brick includes the four natural elements: earth, wind, fire and water. Therefore, they contain no pollutants or allergens and are resistant to noxious insects . They are also known to have a gentle effect on the environment.
Most clay brick manufacturers harvest the natural ingredients as close as possible to the natural source, so as to minimise energy consumption and the environmental effect on the land . In most cases, all mined land is also converted lakes and natural preserves.
Waste is reduced by converting rubble into usable materials. Burnt brick waste is also recycled into a sub- base , which is used in civil development and infrastructure, such as roads.
Apart from protecting the environment with some of the lowest levels of carbon emissions, the natural insulation properties of clay brick also contribute significantly to the life cycle of a building. Clay brick has the ability to absorb heat during the day and release it at night , thus reducing the need for artificial heating in winter and cooling in summer. So much so, that clay brick has become the preferred choice for many residential and commercial projects.
Slide 15
Thank you for listening !
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