## Soil Consolidation: Cc or Cr index?

Hi everybody,

I'm just an undergraduate student so this will probably seem like a dumb question but I can't find anything about it on the internet or my books and my professor tends to disappear at this time of year conveniently -_-

I was wondering: when calculating the void ratio change (Δe) associated with the initial and final effective stresses, how do you know whether to use the equation containing the Cc index or the Cr index? (which are Δe = -Cclog(σ'f/σ'i) and -Crlog(σ'f/σ'i)

I understand that the Cr index is associated with the unloading/reloading curve, and the Cc index with the normal consolidation curve - do you basically just find the over consolidation ratio and if it's above 1 for t∞, then it's overconsolidated and you use Cr? Likewise if the OCR is below 1 or equal to 1 at t∞, the soil is underconsolidated/normally consolidated and you use the Cc equation?

It is deeply puzzling me!

Cheers

DJ

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