Construction and processing materials used in civil structures over time


  • The earliest remaining bridges were made from stone/masonry materials.
    • These date back to the Romans.
  • They were successful due to the excellent structural design and massive weight.
  • However they were often labour intensive and were expensive.


  • Obviously one of the first materials used in bridges
  • It holds excellent compression, tension and bending stress
  • But it has very poor weather resistance and rots.
    • Many of the older bridges don't exist today.
    • Innovations such as the lamination of large cross sections of timber can increase its durability.


  • Developments in the shaping of iron allowed it to be used in bridges
  • Cast iron was used in the late 18th century.
    • Yet cast iron was extremely brittle and poor in tension, making it a relatively bad material for bridges
  • Developments in Wrought Iron made it the dominant material in the mid-19th century.
    • Wrought iron was relatively difficult to make, and had some undesirable properties.
  • Ultimately, Steel replaced Wrought Iron in 1890
    • Steel was a much better material:
      • It was malleable and ductile
      • Production was simple
      • Stronger in both tension and compression

Recent developments

  • Modern bridges utilise Steel reinforced Concrete within bridges.
    • This allows for a material that is extremely easy to shape and yet strong in both tension and compression.
    • Pre-tensioning and Post tensioning may be used to further reinforce the material
  • Different cross sectional shapes such as I-Beams and Box Girders are being used to reduce the amount of material used while keeping the same strength.
    • I-Beams have the best efficiency as it has the most material away from the neutral axis.
    • Box girders can withstand unusual torsional loads