bulk resources

• Bulk resources are low value, high volume materials extracted from quarries. 
• Sand and gravel is used as aggregate, mainly extracted from recent quaternary river, glacial and shallow marine deposits. 
• Aggregate is a material with a cementing material used to form concrete mortar or plaster. 
• Glacio-fluvial deposits are made of sediments from meltwater streams flowing from a glacier, sorted by water. 
• Black hill quarry on Woodbury common is made of Triassic age gravel thought to represent prolonged transportation and deposition by a large river. 
• Mining companies require thick beds, with no lateral/vertical variation in deposit (uniform deposit) and no impurities. 
• Sand is used for concrete, mortar and plaster. 
• Pure quartz sand is used for glass making. 
• Gravel is used to make concrete if pebbles are rounded. 
• Cement is made by mixing crushed limestone with powdered clay and heating it in a kiln. 
• Concrete is a mixture of aggregate, sand, cement powder and water. 
• Bricks are made from clay, moulded into shape and fired in a kiln. A clay is chosen as a brick clay and is composed of clay minerals with:

  • Sodium, calcium and magnesium to fuse the constituents. 
  • Carbon compounds to make clay self-firing to save energy 
  • Iron compounds which oxidise to make the brick red
• Building stone is a rock suitable for the use in construction in its natural state,

  • Colour and appearance
  • Resistance to weathering 
  • Porosity 
  • Load bearing proximity 
  • Proximity to quarries
  • Thickness of beds 
  • Joint patterns in the outcrop 
• Roadstone should be strong, compact, resistant to polishing and able to bind with tar. 
• Rocks which are too well-jointed for building stone may be used as roadstone. 
• Roadstone examples - dolerite, quartzite and gabbro. Composed of different rates, giving a rougher wearing surface for traction. 
• Limestone is a poor roadstone, most sedimentary are unsuitable because they crumble and break along lines of weakness.