What is the CBR value for sub grade in road construction?
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CBR value for subgrade in road construction in India :
California bearing ratio(CBR) value is used to decide the thickness of road pavement
CBR value for subgrade in road construction in India
IRC: 37-2012 = 3 – 15%
CBR value for
3% to 15%
In India IRC: 37–2012 is used for design of flexible pavements. It gives design charts for pavement on the basis of CBR value for subgrade material ranging from 3% to 15%. However for subbase layer, MR (modulus of resilience) value is now considered.
CBR value for subgrage indicate subgrade material quality
CBR value is taken at 2.5mm & 5 mm penitration.
For road construction we use irc37 code
in subgrade material CBR value should be nearly 15-19% .
A clayey soil generally has a low CBR value (less than 8). Sands are more granular and drain better and will generally have CBR values between 15 and 35. Gravel will have the best CBR values, generally 25 and up. That is why it is suggested to save the best material to cap the subgrade.