Ceramics and Clay Product

Ceramics and Clay ProductChapter 2BricksStandard Brick size is 2 1 I 4 x 3 3/4 x 8 in.The basic ingredient of brick is clay.Specific properties of Clayplasticity -- so that it can be molded or shapedtensile strength -- to keep its shape after formingclay particles must fuse together when subjected to sufficiently high temperatures. A small rectangular block typically made of fired or sun-dried clay.

Three Principal FormsOf ClaySurface Clay found near the surface of the earth.

Shales Clays which have been subjected to high pressure until they have come relatively hard.

Fire ClaysFound at deeper levels and usually have more uniform physical and chemical qualities.

Two Classes of Clay1. Calcareous clays- contains about 15 percent calcium carbonate and burn to a yellowish color.

2. Noncalcareous clays -composed of silicate of alumina, with feldspar and iron oxide.- burn buff, red or salmon depending on the iron oxide content which vary from 2 to 10 percent.

TextureTexture are applied by attachments which cut, scratch, brush, roll, or roughen the surface or by applying or spraying glazes on the brick before or after burning.BarksStippleRugsMatt

Typical Brick TextureCeramic glaze consisting of spraying a coating of a mixture of mineral ingredients on one or more surfaces of the brick. The glaze melts and fuses to the brick at a given temperature, producing a glasslike coating which is available in almost any color

Salt glaze -consisting of solution of sodium iron silicate. Salt glaze is transparent so the color of the brick is presented under a lustrous gloss.

Classification of BricksLoadbearing BricksLoadbearing bricks, which can be either common or facing bricks, conform to specified average compressive strength limits.

Common BricksCommon burnt clay bricks, which are accepted for use in general brick work with no special claim for attractive appearances. Walls built with common bricks require rendering or plastering.

Facing BricksQuality burnt clay bricks, which give attractive appearance in their color and texture. It is used without rendering, plastering, or other surface treatments

Damp Proof Course-Clay bricks of specified low water absorption used at the base of a wall (minimum two courses) to resist the upward movement of ground water. - Their use is recommended for free standing wall where otherwise a sheet of DPC material would create a plane of weakness causing the wall to be vulnerable to lateral forces.

Engineering Bricks-bricks burnt at exceedingly high temperatures-possess a dense and strong semi-vitreous body and conform to the defined limits for strength and water absorption. - primarily used in civil engineering works that require high load bearing capacity, good damp-proof, and chemical resisting characteristics.

Properties and Functional Performances Strength -well known for their compressive strength that depends on;- the raw materials used- the manufacturing process- the shape and the sizeAesthetic Appealpossesses the natural and pleasant colours of burnt clay. Its colour formation is achieved through a complicate physical chemical reaction during the firing process. In contrast to colour of stained body, brick colour is permanent and will not be faded during weathering process. Different clay compositions, firing temperatures or kiln atmosphere can lead to different colours of the burnt products.

Porositythe porosity of brick is attributed to its fine capillaries. By virtue of the capillary effect, the rate of moisture transport in the brick is ten times faster than in other building materials. Moisture is released during day-time and re-absorbed during night-time. The ability to release and re-absorb moisture (a "breathing" process) by capillary effect is one of the most useful properties of brick that helps to regulate the temperature and humidity of atmosphere in a house.Fire ResistanceBrick is inherent with excellent fire resistance. A 100 mm brickwork with 12.5 mm normal plastering will provide a fire-resistance of 2 hours and a 200 mm non-plastered brickwork will give a maximum rating of 6 hours for non-load bearing purposes. Brick can support considerable load even when heated to 1000oC in contrast to concrete wall at only up to 450oC due to loss of water of hydration.

Sound Insulationbrick wall shows good insulation property due to its dense structure. The sound insulation of brickwork is generally 45 decibels for a 4-1/2 in. thickness and 50 decibels for a 9-in. thickness for the frequency range of 200 to 2,000 Hz.

Thermal InsulationBrick generally exhibits better thermal insulation property than other building materials like concrete. Bricks absorb and release heat slowly and thus keep the house cool during daytime and warm during nighttimes.

Wear Resistancedepends on its particulate bonds. Bricks shows high wear resistance because of its extremely strong ceramic bonds formed by the effect of heat at high temperature. Flexibility in ApplicationsBrick is used for an extremely wide range of applications in an equally extensive range of building and engineering structures. In particular, it can be used for load bearing structures which greatly simply the construction process so as to save materials, time and labour. Besides, brick can be make into convenient shape and size to facilitate the construction work. It is very flexible and handy in application almost everywhere. DurabilityBrick is extremely durable and perhaps is the most durable man-made structural building materials so far.

Brick BoundsPattern Bond The method of laying bricks in a wall in order to form some distinctive pattern or design

Structural BondThe method by which the individual units in a brick structure are tied together either by overlapping or by metal ties.

Flushed JointFlushed joint is used when a smooth finish is desired

Raked Joint- The mortar is raked off by about 8mm back from the brick face.- This type of joint is used when a rustic look is desired, emphasizing the individual brick

Rolled JointA commonly used joint formed by a round bar mortar to give a smooth finish and create a half-circle indent Weather Struck JointA joint formed by cutting mortar at a single angle to brick face with a trowel. Struck joint is generally used against weathering

Mortar Bond The adhesion of mortar to bricks or to steel reinforcements used in conjunction with them