2010年8月6日星期五

Brick and brickwork

  • A brick is defined in BS 3921 as a walling unit with standard size of 215mm length, 102.5mm width and 65mm height
  • With a 10mm mortar joint, the working size became 225x 112.5 x 75
  • The majoriti of the bricks used today are made from clay , although bricks can also made from sand and lime or concrete
  • Brickwork is used primarily in the construction of walls by the bedding and jointing of bricks into established bonding arragement
  • A brick wall has very good fire resistance , is a moderately good insulator against transfer of heat , does not , if well built , deteriorate structurally and requires very little maintenance over a long period of time
Material for bricks
Clay brick
  • Clay is ground mills , mixed with water to make it plastic and then moulded , either by hand or machine , to the shape and size of brick.
  • Bricks that are shaped and pressed by hand in a sanded wood mould and then dried and fired have a sandy texture , are irregular in shape and colour
  • Machine made bricks are either hydraulically pressed in steel moulds or extruded as a continuous band of clay
  • THe continuous band of clay is cut into bricks by a wire frame . Bricks made this way are called wire cut
  • THe moulded brick is baked to dry out the water and burned at a high temperature so that part of the clay fuses the whole mass of the brick into a hard durable unit
Calcium silicate Brick
  • Generally known as sand-lime bricks
  • THe bricks are made from a carefully controlled mixture of clean sand and hydrated lime , which is mixed together with water , heavily moulded to brick shape , and then the moulded brick is hardened in a steam oven
  • THe resulting bricks are very uniform in shape and colour and are normally a dull white
  • THe material from which they are made can be carefully selected and accurately proportioned to ensure a uniform harness , shape and durability that is quite impossible with the clay used for most bricks

没有评论:

发表评论