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Civil Engineering & Construction vocabulary · Roads and Bridges

Subgrade

Meaning in civil engineering & construction, with examples

/ˈsʌbɡreɪd/nounAdvanced term

In civil engineering & construction, subgrade means: The natural or prepared soil at the bottom of a road, on which all the pavement layers are built. Its strength largely decides how thick the pavement must be.

In Turkish: taban zemini, yol tabanı, doğal zemin

How it is used

Engineers test subgrade strength, often as a CBR value, and may improve weak subgrade by compaction, stabilisation or replacement. The prepared top surface is called the formation level.

Example sentences

  1. The subgrade has a CBR of only 2%, so we'll need a capping layer.

  2. Rain softened the subgrade before the sub-base could be placed.

Common collocations

  • subgrade strength
  • subgrade preparation
  • weak subgrade
  • CBR value
  • formation level
  • pavementThe layered structure of a road, runway or parking area that carries the traffic, usually asphalt or concrete laid over granular base layers.
  • compactionPressing soil or fill together, usually with rollers or plate compactors, to remove air, make it denser and stronger, and reduce later settlement.
  • earthworksAll the work of moving soil on a site: excavating, transporting, filling, compacting and shaping the ground to the required levels.
  • asphaltA black road-surfacing material made of stone aggregate bound with bitumen. It is laid hot and compacted with rollers.
  • drainageThe system of pipes, channels, gullies and ditches that collects rainwater or wastewater and carries it away from a road, building or site.

More terms: Roads and Bridges

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