material for blocks

1. Clay blocks

• Standard size of 290mm long x 215mm high x 75 , 100 or 150mm width.
• &5mm cavity block is intended primarily partitions
• 150mm cavity block has been used for the inner skin of cavity walls , but also used in the warmer climates countries such as Malaysia as a single-leaf external walling with rendered and emulsioned finish
  
• THey are made from selected brick clays that are press moulded and burnt
• THese hard , dense block are hollow to reduce shrinkage during firing and also to reduce their weight
  
• THey are grooved to provide a key for plaster
• Clay blocks are comparatively lightweight , do not suffer moisture movement , have goof resistence to damage by fire and poor thermal insulating properties

2.Concrete blocks

• Density of a concrete block gives an indication of its compressive strength
• THe greater the density , the stronger the block
• Classification is by compressive strength categoties : 2.8 , 3.5 , 5 , 7 , 10 , 15, 20 and 35 N/mm square
• Density will also give an indication as to the termal conductivity and acounstic properties of a block
• THe lower the density , the lower is the thermal conductivity factors , whereas the higher the density , the greater is the reduction of airborne sound through the block
• For use as a facing material , a wide range of concrete blocks is manufactured from accurate fair face blocks to rough exposed aggregates finishes
  
• Standard concrete blocks are manufacture as solid , hollow or cellular blocks from cement and either dense or lightweight aggregates
• A cellular block has one or more holes or cavities that do not pass wholly through the block
• A hollow block is one in which the holes pass through the block
• The thicker blocks are made with cavities or holes to reduce weight and drying shringkage
• The most commonly used size of both dense and lightweight aggregate concrete blocks is 440mm long x 215mm high
• The height of the block is chosen to coincide with three courses of brick for the convenience of buildings in wall ties and also bonding to brickwork
• For the leaces of cavity walls and internal loadbearing walls , 100mm thick concrete blocks are used .
• For non-loadbearing partition walls , 60 or 75mm thick concrete blocks are used .
• Concrete block or blockwork